Changing Wheel Size To Overcome Power Problem On Hills

[oldtuckunder]

Ah!  you mean something like this Nick.

 

Turn on MAP sensor, should come up at about 4.9v atmospheric, partially fill a clear U shaped plastic tube with water, plug one end onto MAP sensor and Syringe in the other, mark inch increments up the plastic above static atmospheric level, and then slowly apply vacuum with syringe noting voltages for each inch of vacuum?

 

Neat, simple, clever if that's what you meant.

 

Alan

[oldtuckunder]

Sorry should have added picture

 

[Nick Jones]

Yes, pretty much that, though I think the sensor and vacuum source need to be on the same side.  Seems like it should work in my little monkey brain......

 

And I just found this

 

http://validyne.com/blog/simple-manometer-calibrates-pressure-sensors/

 

which seems to agree.

 

Nick

 

And Dwyer instruments sell almost the same thing with their series 1211 (sorry, no linky, work laptop is being an arse!)

[oldtuckunder]

Ok discovered that not only can I be baffled by bullshit I can be blinded by science.

 

Or lets say that what started out as I thought to be a simple exercise to calibrate my MAP sensor output to real inlet manifold vacuum readings so that I could measure its efficiency and also hopefully analyse what appeared to be the carbs becoming a restriction at high rpm's, has turned into a learning exercise about barometric pressure, altitude, and the discovery that what I was taking as real "scientific?" data was actually about as accurate as comparing apples to pears.

 

But its a tale worth telling.

 

Firstly my 1 bar MAP sensor appears to be exactly that, and its voltage out from 5v at atmospheric down to 0v -1bar appears to be perfectly linear, and I have been able to produce a calibration table that (given perfect conditions) allows me to reference between logged output and either inHg (mercury) or inAg (water).  I did this in two ways by one creating a U tube water manometer that gave me a measurement range between 0-24 in Ag (I actually thought I'd made one that gave me a range of 0-12 inAg, but only later discovered that you have to take the difference between the two column heights not how far one drops or rises, so my careful applications of vacuum to move a column 1" actually turned out to be a movement of 2" vacuum). The second cross reference I used was to use a Speedograph vacuum gauge and take MAP output readings for each indicated inHg of vacuum. This turned out to be fairly inaccurate as an inHg is actually quite a large step, and a small vacuum gauge dial make it very hard to differentiate between say 1.9/2.0/2.1 inHg, however it was a useful cross reference to check the sensibility of the inAg results, and good enough to extrapolate a real reference table in inHg after doing the inAg one.

 

Below is the table.

 

 

I was very very lucky that when I calibrated the MAP sensor to free air before applying vacuum to it and the simple manometer I got a reading of 4.99v i.e. almost perfect atmospheric. How lucky I was I didn't find out until later. I then applied a vacuum with a manual pump (that would hold a constant setting) inch by inch (or 2 x 2 as it turned out) whilst taking the indicated voltage reading from the data logger. These are the Voltages shown in column A as (Volts Real) from 0 - 24 inAg. The calculations shows that over 24 inHg the voltage dropped 0.3 volts, thus giving an average 0.0125v drop per inAg. I then created an extended range column C to calculate the voltages at that average drop right through to 402 inAg or - 1Bar, and given that it agreed exactly at a real measured -24 inAg and ran out to 0v at just about the exact point, I'm fairly confident that there is a good linear output from the MAP sensor that I can use especially in the 0-30 inAg rage I'm really interested in.

 

Columns G-J are really a repeat using the vacuum gauge, but I found that doing the calculation in column I that by -1 bar it would have been requiring negative voltage outputs (which couldn't be correct) so recalculated column J which gives a good linear progression that again comes out at 0v at -1bar, and as real measurements cross referenced into both tables I was fairly happy that the calibration of the MAP sensor was good, and that I could now use my data logged testing run results to find out what was happening in the inlet manifold.

 

Need to take a break from this, but in the meantime I'll leave you to guess/workout why my data logged results aren't much use, and a little teaser that opening a big air hole in your inlet manifold or fitting an Emission Control Valve can have positive benefits.

 

More later.

 

Alan 

[oldtuckunder]

So back to the story.

 

As some of you may have twigged from the extra columns on the above chart showing height in feet and meters against different inAg readings, as soon as I came to start looking at my data logged results It became apparent that there was something wrong. In fact for me it started the very next day before I had even finished the above chart. I wanted to do a couple of test runs to log the inlet vacuum's as it was, then with a manually operated extra air feed into the inlet manifold, and a third with the original ECV valve fitted. So out to the garage where I done the calibration the day before and low and behold my base free to air MAP voltage had dropped from 4.99v to 4.84v! Now that's a whole 13 inAg or 1 inHg difference or just about half the entire efficiency range of an inlet manifold that I'm working on i.e. 5-30 inAg and the car hasn't moved!

 

Bol..ks. Now I knew that atmospheric pressure changes, but in my innocence I had thought I might see a couple of inAg difference which I could either ignore or factor in, but this kind of difference means that unless I accurately record a base figure before any tests and recalculate all results. I can't do a test one day log the results and then make a change and repeat the test the following day and compare the numbers without adjusting every result back to a common base point.  

 

Ok if changes in atmospheric pressure can have such an impact on the numbers, how much difference does altitude make?  I had naively  assumed that as I'm fairly low down not far from the river severn, and as most of my testing is either done on the flat around here or on the local hills that I think of only being a few hundred meters high that altitude pressure loss/gain would be negligible.  Turns out I was wrong, there is a pressure loss of around 13 inAg or 1 inHg for every 1000ft or 304m. 

 

So it occurs to me that looking at the results from a log taken at one venue and trying to cross reference back to either my calibration table or a log taken somewhere else is completely useless unless I know what height the results were logged at!  A bit of googling turns up a great map resource that allows you to find out altitude for virtually anywhere on the planet. https://www.freemaptools.com/elevation-finder.htm

 

Turns out I'm at about 100ft ASL, my test hill starts at around 500ft ASL and rises to 680ft ASL, and if I navigate to Shelsley I find the course starts at 182ft ASL and climbs to 535ft ASL or in data log terms it means I have to factor in 5 inAg pressure differential in the inlet manifold from top to bottom of the hill, before I can even start calculating what I think the increase in vacuum is caused by the carbs maxing out as the revs climb.

 

OK so all in all I have to give up comparing results from different test runs in different locations at different times because there are too many variables. The best the MAP sensor can tell me is what's happening relative to the start of a run, and that really all the testing ought to be on the flat to exclude any altitude variations unless I do actually record the altitudes of the tests and factor the results in.  However it has all revealed what I do need which is a differential pressure meter so that I can measure the difference between Atmospheric and inlet manifold, as that will automatically factor in/out changes of altitude and atmospheric pressure. Looks like they are available via ebay for around £30 and even have a recoding mode. Won't be able to tie it into the data logger but at least it will give me some meaningful data. The only other thing I could do is buy another identical MAP sensor hook it up to the data logger but leave its input free to air so that I'm logging current atmospheric to compare with inlet manifold vacuum (sort of like creating a simple differential pressure sensor) Will think on this!

 

Anyway back to the start of the whole issue from a number of posts back #21 where I was postulating that the increase in inlet manifold vacuum I was seeing on a data logged run from Shelsley was an indication that at higher revs the carbs/inlet were causing a restriction and the AFR's can be seen going richer and richer. I was seeing a logged increase from 25 inAg at WOT at the start to 39 inAG at WOT 6.3K rpm at the top of the the hill. From the above we now know that I can discount 5 inAg of that down purely to altitude, so I'm probably looking at 9 inAg that might be carb restriction.

 

Sorry need a break from this again, next instalment Hose Pipes & ECV's

 

Alan

[Nick Jones]

Good to see you today.  Some very interesting research going on with some unexpected findings!

 

You are using an "absolute" sensor at pressure which is sealed on one side of the sensing element and referenced to full vacuum.  You could instead use either a "differential" sensor with one port left open to atmosphere or you could use a "gauge" sensor which is the same thing in this context in that it is also referenced to atmosphere but lacks the connection point on that side.

 

Couple of Farnell links you might find interesting.  Don't see why you couldn't find one that could be connected to your data logger?

 

http://uk.farnell.com/pressure-sensors

 

http://uk.farnell.com/panasonic-electronic-components/adp5101/pressure-sensor-100kpa-1-port/dp/2448061?aa=true&vw=&selectedCategoryId=&categoryId=700000004367&eq=N%3D203338%2B2031%26amp%3BNs%3DP_STORE_MARKETING_RANK_FARNELL_UK%257c0%257c%257cP_MAN_PART_NUM%257c0%26amp%3BNtpc%3D1%26amp%3BNtpr%3D1&searchView=table&iscrfnonsku=false

 

Cheers

 

Nick

[oldtuckunder]

So the theory which seems to be backed up by other odd old references (including some on this forum) is that on a 2ltr Vitesse/GT6 engine twin 1.5" CD carbs run out of ability to flow sufficient air to get a controlled AFR around 6K rpm, and at that point at protracted WOT they have a tendency to go over rich. This seems to equate to around 115cfm per carb or 230 cfm for a pair which just about equates to 110bhp. Now those are real "todays" bhp not the old factory quoted bhp figures, IMHO the quoted factory bhp of 105 for a MK2 Vitesse/GT6 is probably 20% over what would be accurately measured today. This is ignoring two factors, 1) A good (or bad depending on how you view it) rolling road operator can probably easily give you a +/- result 25% off from actual, so I'm fairly certain you could get a RR output showing a std Vitesse/GT6 around 100bhp, which may make you feel good, until you find when you try and set times that that bhp/tonne should provide that its impossible. 2) This also excludes outright race applications, Vizard has quoted a 1.5" SU as being capable of flowing 140cfm, and theoretically a 1.5" Stromberg shouldn't be much different. And people like Kas have claimed that they were getting up to 180bhp from the 2ltr 6 on twin 150 Strombergs at around 8.0k rpm, and whilst there may be some question about what size horses those actually were? It is highly likely that on an engine built for continuous high rpm operation, (which is probably totally intractable below 4-5k rpm) that the carbs could be set up to operate and deliver higher bhp figures in that narrow band, you just probably couldn't drive the car on the road, and it certainly wouldn't have the right power bands for sprints/hill climbs.

 

Another factor that tends to indicate that twin 150 CD's were undersized, is that its almost impossible to find any other performance 2ltr from the same period that used twin 1.50" carbs they all used twin 1.75". Even Triumph used 175's on the similar engine sized TR4. 

 

So the problem with the 150's is not that they can't deliver enough fuel, they can and the fact that the AFR's go richer proves it, they just cant flow enough air to mix with the fuel to give good AFR's. So you start looking at the carbs and wondering how (apart from fitting bigger carbs) you could make them flow more air. One could try some of the SU mods to piston, body etc described by Vizard in BMC A series Tuning, but the only reports I can find have not been favorable, or again there appears to be a compromise between what might be of benefit at high rpm's and the degradation anywhere below that. Doesn't mean I might not play with a spare set of carbs at some point but I'm not hopeful.

 

So we have fuel but not enough air to mix with it. So back to my idle thoughts in post #21 about allowing more air into the inlet manifold directly after the carbs either free air or via the ECV.

 

Have now had a chance to do some testing on this idea, and I'm pleased by the initial results.

 

OK now you get some pictures :-)

 

Below are three logged hill pulls in 2nd/3rd/4th

 

The first is with the inlet manifold with the original ECV port plugged as it has been for decades.

The second is with a passenger with a long length of 1/2" hose running from the inlet manifold back into the cockpit, and removing a thumb at a measured point to allow more air direct into the inlet manifold.

And the third is with the original ECV reinstated and pulling air from the rocker cover.

 

What I can tell you is that for the first two runs atmospheric was 4.80v and for the third run about an hour later it was 4.84v  which as you can tell from the chart above means a 4 inAg difference in the base measurement that has to be factored when doing the comparison. Also as my test hill climbs 200ft we have to factor another 2.6 inAg pressure drop within the run.

 

I'm primarily interested in what happens in 3rd gear as that is the longest logged section, you can regard 2nd & 4th as winding up to and down from the test.

 

Yellow is TPS, Blue is MAP (the one we are really interested in) Red is rpm, and the other two are front rear carb AFR's.

 

 

OK this is the base run, we first go WOT at 2:15 (ish) at around 2.2K so this is the point where manifold vacuum should be its lowest and using the above table we have a 4.57v reading or around 32 inAG, comparing this to our 4.80v base atmospheric of 16 inAG, which gives us a pressure drop of 16 inAG. Which if we use the rule that anything under 10 is actually quite good, anything over 20 is poor and anything over 30 bad, we have an average OKish carb & manifold set up. At 2:24 we have changed to 3rd are at 4.5K and our voltage has dropped to 4.44v or 44 inAG (lets deduct 1 inAg for 100ft) 43 inAg. So our inlet system is now seeing an extra 11 inAg increase in vacuum which can only be due to restriction. If we move on to 2:35 and call it 6k we are down to 4.38v or 49 inAg (deduct 2 inAg for 200ft) 47 inAg. So now our inlet system is seeing an extra 15 inAg in vacuum.  So with atmospheric at 16 inAg and manifold at 47 inAg we have a total restriction of 31 inAG at 6K, now firmly in the BAD category.

 

 

Ok this is the Hose Pipe run. We have a hose pipe running to the inlet manifold old ECV port which has an ID of about 9mm, and at 2:20 we remove the thumb and as you can see we get a sudden drop in vacuum. I won't repeat all the calculations but at 2:25 at 6.1K we now a steady 4.54v (34 inAg) (minus base 16 inAg) or 18 inAg restriction or actually back in OKish restriction territory, and the AFR's are also holding up. The keen eyed will spot the thumb going back at about 2:32.5 :-)

 

Well that's actually quite a results, but a bit inconvenient having to have a length of hose and a passenger with an audible triggered thumb mechanism.

 

 

OK so lets see what happens if we reinstate the original ECV valve!   The ECV is designed to open its maximum at low manifold vacuum's (i.e. WOT) and almost close at high vacuum idle,lift,cruise but it never fully shuts. NB the fully open port size in the ECV is about 5mm dia, or about a 1/3rd of the Hose Pipe, Just fitting the ECV lifted my rich AFR tickover (i.e. ECV almost closed) by about 150 rpm. 

 

 

This is the ECV run, with the ECV feed taken from the rocker cover, I left the crank case breather running to the catch tank.

 

Base atmospheric this time is 12 inAg, and going WOT at 2:18 we have 4.66v or 27 inAG pressure drop of 15 inAg. Note that after change to 3rd at 2:28 we have 4.60v and this holds fairly steady dropping slightly to 4.55v at 2:37 at 6.1k. If we do the calculation at 2:37 including altitude adjustment we have about 33 inAg or 21 inAg over base. Not as good as the 18 inAG with the hose pipe, but way better than our base run of 31 inAg! Note the AFR's are starting to get richer as we head up towards 6k.

 

So reinstating an emission device seems to have a positive benefit!

 

I actually re-jigged the set up and ran the rocker breather and crank case breather to the catch tank, and then took the outlet from the catch tank to the ECV and ran with this at Loton Park at the weekend. Looking at the logs at 6k I was actually getting a vacuum increase of only 16 inAG which is actually better than even the Open Pipe, the vacuum was fairly constant right through the rev range, and was at it worst at one peak of 6.6K rpm at 26 inAg. Note the increase of 10 inAg for that last 0.6K indicating that around 6K we reach a diminishing returns point. 

 

I'm very happy with these results, and its interesting to find that the old Triumph ECV was actually a well tuned device that actually had positive benefits.

 

My theory is now that as AFR's aren't going too lean with the introduction of air directly into the inlet manifold, that more might be even better! but that's some further experimentation to come!

 

Alan (Go Emission Control!)

[Nick Jones]

Your PHD thesis is coming on nicely sir!

 

Must do some runs with mine - seeing as all I have to do is plug the laptop in........

 

Nick

[oldtuckunder]

Must do some runs with mine - seeing as all I have to do is plug the laptop in........

 

 

Nick If you get anything as poor as my readings with your set up, either I need to scrap my theory, or you need to take a hard look at your inlet 

 

Alan

[Nick Jones]

Yeah..... though as I observed before I think the cross sectional area of my throttle body is more or less the same as 2 x 1.5"........ though not very hard to change.  My inlet took whole minutes of considered design I'll have you know 

 

The other minor issue is that with a 3.63 diff, 6k in 3rd needs a private test track.......      I've been meaning a book a RR session for months but life keeps interfering.  I seem to get less spare time with a 3 day (paid) working week than I ever did when I worked 5 days. I forgot Rule 1 (Never volunteer) Parish Council....?  Just run.  Fast and far!

 

Nick

[oldtuckunder]

Ok further progress :-)

 

Almost tempted to just post the picture and let you ponder, "but we don't want to give you that"

 

So this is the next stage, after seeing the improvement in reducing manifold vacuum and improving AFR a bit by reimplementing the ECV valve, next stage was to see if I could combine this with the idea of injecting more air directly into the manifold (post carbs) as the revs were rising and I was seeing the inlet manifold vacuum increasing and AFR's richening.

 

Knew I needed to do it with some form of valve that could be triggered at a given rpm/point and above, as at lower RPM's smaller throttle openings allowing neat air in any quantity will just stall the engine out.

 

Also had a couple of major problems. I want this working when in real terms manifold vacuum is actually quite low i.e. under 30 inAg or about 2 inHg, and most purpose built solenoid valves require a pressure differential bigger than that to open. The other problem is that if you look at the spec of most solenoid valves (even those specifically for air) whilst they may have 1/2" or 3/4" pipe fitting internally they actually have a tiny port maybe something like 5mm and actually their ltrs/per min flow rates are not that high. This works fine on the high pressure air/liquid they are designed to work with, where the pressure can increase dramatically at a pinch point without dramatically reducing flow, whereas my requirement was to flow as many cfm as I could through a 1/2" pipe where the pressure differential between atmospheric (my supply) and the inlet manifold may only be 20 inAg (1.5 inHg). So no 5mm orifice was going to hack it!

 

I also spent ages looking at different electronic ECV and PRV valves from moderns, but they all had problems they were either normally open, and closed when voltage applied or they were designed to be controlled by an ecu that provided small and fluctuating voltages to operate. And I needed something where the fail position was closed, otherwise a mechanical or electrical failure would leave me with a dead engine. 

 

In the end I had to design and make one, from a 12vDC solenoid and make my own valve body that would open to full bore when triggered. That was a fun learning curve as I discovered why most valves need a pressure differential to work, and how much force you need to actually overcome a relatively small vacuum. No pickies yet as the current prototype has pipes all over the place, but later in the week I hope to have it neatly installed inside the air filter box as it works!

 

In simple terms at the inlet manifold where the ECV normally sits, I have a T, one goes off to the ECV valve that is now located at the oil catch can, which in turn is fed from the crank and rocker breathers, the second goes off to my PAV (Performance Air Valve) which is open to clean air when actuated.

 

Ok here is a log from a simple 3rd gear pull (on the flat as trying to reduce complexities of altitude recalculations)

 

 

Normal colours, Yellow TPS, Blue MAP, Red RPM, Black & Purple front/rear AFR's

 

OK from previous posts you will be aware that to measure anything we need a base point and the atmospheric pressure at the time/altitude of the test was Base 4.83v or 14 inAg. 

 

When I go WOT in third at 22.20 you can see the Map falls to 4.60v (31 inAg) at 4750 rpm. This means we have a 17 inAg differential to atmospheric, this is with the standard ECV operating and is much better than the non ECV figures that you can see in previous logs. 

 

Then at 23.76 at 4820 rpm you can see an instant jump to 4.71v (22 inAg) or only a 8 inAg differential to atmospheric, this was when my PAV cut in automatically! Now as you will have gathered from previous posts we are now in holy grail territory where anything under 9 inAG can be considered excellent! And then as the revs climb up to 5600 the voltage actually increases a bit to 4.73v (21 inAg) or only 7 inAg differential to atmospheric.

 

So wow you say you have managed to let air into the manifold, big deal, whats the benefit?

 

Now look at the AFR traces, they were starting to dive as we went WOT at 22.20, and then the instant the PAV cuts in they level out at a bit above 12 and hold there as the revs rise, so the additional air is mixing with the fuel/air mix in the manifold and holding the AFR's even rather than them getting richer and richer as you can see they normally do from all the logs in post #32.

 

So at first testing adding more air seems to have the effect I hoped for. And whilst I would love to get the AFR's up a smidgen more to around 12.5 by adding more air, at the moment I have done this without any mods to the inlet manifold, which of course avoids any technical questions about modifications to the inlet manifold or carb chokes sizes. Don't think I have ever seen anyone query the removal or modifications to an ECV?

 

Oh for the sharp eyed of you guess what happened at 31.0 and 37.0 And the next little tweak I have to work on?

 

Alan

[Nick Jones]

Interesting alternative to bigger carbs........ 

 

Presumably you now need to convince your new valve to close a bit more promptly when you lift off?

 

Nick

[oldtuckunder]

Interesting alternative to bigger carbs........ 

 

Presumably you now need to convince your new valve to close a bit more promptly when you lift off?

 

 

 

Yes and Yes 

 

Any increase in power at the moment is subjective seat of the pants, but it felt better, but as I wanted it to be better I could be kidding myself. When I get it installed properly I will log some of my flat and hill test runs, and compare the results back to back with previous logs.

 

At the moment I can activate/arm the PAV when I choose, and it then automatically opens when the MAP drops to the trigger point, but I have to switch it off. Looks like RS components and a simple cheap washing machine part may solve the auto close problem, and I think will also do a snap close/re-arm at each gear change 

 

This is a fun project!

 

Alan

[oldtuckunder]

OK the saga continues, but there are some pics!

 

May have to split this into two, installation then back to back test results, will see how it goes.

 

When I left this I had the problem that whilst I could activate my Air Valve by flicking a switch, it didn't actually open until the manifold vacuum dropped to about 40 inAg (this is because the light solenoid I choice doesn't have enough pull to free the valve from it seat against strong inlet manifold vacuum) this is fine because its only at WOT and very low manifold vacuums that I wanted it opening anyway. But having opened it, it required me to switch it off to close it, this was a pain and also meant as you can see from the above pic I got a real lean spike during gear changes ) probably not a problem but I didn't like it. Anyway a cheap vacuum switch (also fed from the manifold) set to go from closed to open at 70 inAg or above (its actually adjustable so I may tweak when) inserted in the circuit between switch and solenoid valve means that I can switch it on, leave it and the vacuum switch automatically shuts it (breaks the circuit) whenever the vacuum goes above the set point i.e. on gear changes or lift, and it automatically reopens when the vacuum drops again.

 

OK here is the installation  (Nick will like it lots of plumbing)

 

 

Ok this is it. Yes all the pipework is yellow! working on the theory that when I go senile in a few years if I can't remember what all the pipes do I might at least remember that Black is Water, Blue is Oil, and Yellow is Air 

 

I have the feeds from the Rocker and Crank going to the sealed catch can, the standard ECV valve plugged on to it, with a feed that T's into the air feed from my PAV filter box, and then goes to the inlet manifold.

 

Made hopefully a neat use of the original ECV valve location in that instead of being mounted horizontally as they were normally I have it standing on its side with the inlet pointing down into the catch tank. Looking at how they are constructed I don't think it makes any difference to its operation, and I'm hoping that with the inlet facing down any oil being carried in the air will drop back down into the catch tank rather than sit in the ECV valve clogging it, which I think they had a tendency to do.

 

However made a bit of a mistake trying to "simplify?"   the pipework locating the the new Air Valve and its filter box near the catch tank and T'ing it into the the single pipe to the inlet manifold. I was originally going to put the Air Valve in the main Filter box and run a pipe to T with the catch tank pipe at the inlet manifold. Should have stuck with that rather that trying to be elegant, having the Catch tank only a short length of common pipe away from the Air Valve means that oily fumes in the pipe condense at the air valve making it dirty and oily. Maybe if I had made it higher than the catch tank it might not have been a problem, but anyway am going to separate them and run a pipe from each to a T at the inlet manifold. 

 

 

This is the new Filter Box (well actually its a reworked biscuit tin plus some ITG filter foam) containing the Air Valve, and side on shot of Catch Tank and ECV valve.

 

 

And this is the Solenoid and my home made Air Valve, you can't actually see the valve but its a conical rubber bung on the end of the solenoid. There is actually some extra gubbins in there i.e. the funny arm on the outside of the solenoid and below it a small micro switch. Yes I found another problem when it came to testing!  As the vacuum switch actually cuts the solenoid in and out and it theoretically does it as the vacuum drops and rises so I could no longer see a spike in the trace, and also with the engine running other than at WOT (which I can't do stationary) there is always too much inlet vacuum to allow me to see if its working. But anyway hooked the micro switch into the high intensity oil warning light on the dash and then could test drive and see if the light illuminated at WOT. And it did so this was perhaps a waste of time, but it can all stay in the tin in case I need visual confirmation of operation in the future.

 

PS. Found another use again for that blasted bracket on the suspension/engine mounting tower, so its been saved from the lump hammer treatment yet again!

 

OK test results later

 

Alan

[oldtuckunder]

Test Results, some conclusions and observations.

 

First conclusion I need some heavier boots when doing test runs! These were supposed to be 4 identical test runs one after the other at the same location pulling WOT in 1st thru 4th, but as you can see my foot was coming off the throttle slightly in the earlier runs. I wasn't aware of it, and its not as bad as the graphs show as the TPS signal does move a lot for very little movement, but I can see it was having an effect on MAP. In my defence the way this thing takes off always catches me by surprise and I'm changing up twice in the first 7 secs whilst watching the road, watching the rev counter to try and pull the changes at the same point on each run, so I'll put it down to G forces but it does improve over the runs.

 

Second conclusion I did these tests on the flat as I was trying to avoid having to factor in inAg altitude changes. The downside is that its all over too quickly I'm at 80 mph and starting to have to brake before I run out of runway, if I'd done it on the hill the gear pulls would have been longer and it would be easier to see what was happening.

 

The ECV and/or the new PAV obviously have a measurable effect on MAP, which means that more invisible stuff is being sucked into the engine at low MAP vacuum's, its not having as dramatic effect on AFR's as I hoped on these tests, I can't quantify the exact benefit yet, the best I can say is that during WOT in 3rd the time between 5K and 6K is 3/10 th sec quicker with the PAV open. 

 

The following chart shows 4 pulls.

 

1) Inlet Manifold plugged, and Rocker and Crank Breather just going to catch tank.

2) Catch Tank plumbed via ECV valve to inlet manifold

3) Catch Tank vented to air, and New PAV valve plumbed to inlet manifold

4) Catch Tank via ECV and New PAV both plumbed to inlet manifold.

 

 

OK atmospheric at time of tests was 4.89v  or 8 inAg

 

These are the MAP pressure differentials to atmos at 3 points in the runs

  

                    5K 2nd          5K 3rd          5.9K 3rd

 

1)                 30 inAg         30 inAg        35 inAg

2)                 24 inAg         21 inAg        22 inAg

3)                   NA                   NA           11 inAg    (sorry valve only cut in going into 3rd)

4)                 21 inAg         13 inAg        13 inAg 

 

1) Inlet Manifold plugged, and Rocker and Crank Breather just going to catch tank.

2) Catch Tank plumbed via ECV valve to inlet manifold

3) Catch Tank vented to air, and New PAV valve plumbed to inlet manifold

4) Catch Tank via ECV and New PAV both plumbed to inlet manifold.

 

 

So both the ECV and the PAV show a definite improvement in reduced MAP, but the times are too close for me to reliably read anything into it.  May try some tests on the hill, but with Gurston coming up this Sunday and the fact that my gearbox is getting very stiff going into first/second and I'd like to see if I can complete the last three events of the season before fast changes down from 3rd to second become impossible, I may just play safe and see what the results from Gurston look like.  Unfortunately whilst I have logged runs from Gurston earlier in the year, I didn't have the MAP sensor installed. however I do have the trap speeds from Gurston, so I'll see if my terminal speeds at the top of the hill are improved this time around.

 

Alan 

 

[Nick Jones]

I'm liking the biscuit tin mod.... and all the colour coded pipes. In fact I'm enjoying all the lateral thinking and painstaking testing.  Pity you don't have a rolling road stashed in the barn.... though if you did you'd never get any paying work done!

 

Hope to make it to Gurston and will be interesting to see if you can beat your previous times.  Could the gearbox be something simple like a bushes in the extension?

 

Cheers

 

Nick

[oldtuckunder]

Could the gearbox be something simple like a bushes in the extension?

 

 

Afraid not, my local gearbox guru who rebuilt it last year says its the selector hub, but has offered to rebuild FOC when I pull the engine to see what the bottom end is like and fix that minor oil leak (its slightly annoying having to fit her up with a new incontinence pad before each event). Anyway three more events this season including a final Shelsley so I'm keeping my fingers crossed that one of the many changes has solved the #5 BE problem, and that the gearbox will stand a few more fast selections.

 

Alan

[Nick Jones]

Car and driver seemed in good form earlier.  Trust you made it home ok? I have a video of you leaving the start for you second run which I will attempt upload.  Sounds good......

 

Of the TR bunch yours was one of the few to pull cleanly - all the PIs were popping and farting and the 2L TR7 was running black-smoke rich.  V8s ok though.

 

Cheers

 

Nick

[oldtuckunder]

Home safely, had a minor twitch! at Karousel on that last run after pushing it through hollow :-) but recovered, so a nadgers whisker slower than first timed run but managed to take 1.07 secs off PB. Second practice in the morning had been 0.06 quicker again and the only run where I managed to squeeze an extra massive 0.04 mph at the finish line!

 

So good day, but the hoped (wished) for extra breathing delivering a few more mph at the top of the hill didn't happen. 

 

So its back to the drawing board, I'm not convinced that the extra air idea is dead yet, as I think that even more might be the answer but working out how to do that without pulling the manifold, which I don't want to do with only two events left, is taxing my ingenuity at the moment. But after Prescott and before I strip it down I will try something and also try out the new 1.75 manifold and carbs. Then comes the decision over the winter whether to stick with the 1.5's and go down a class where my times are competitive, or go for the 1.75's and more power (and maybe loose a few pounds at the front end!)

 

Looking at all the Gurston Class split times the Vitesse is as quick or quicker than many with higher bhp/ton in most of the sections apart from that long hill at the end where my terminal speed is between 8-15 mph slower and my time over that section is 1-2.5 secs slower. 

 

I still need to revisit the gearing issue, wish I'd taken the 13" wheels as well and tried them in the afternoon.

 

I also need to start thinking about the maybe irreplaceable front end, and if a fibreglass front end that I'm not worried about may be the way to go. If so that sorts the Class decision and then its just a quest for power  

 

Alan 

[Nick Jones]

Arriving at Ashes on first timed run

 

And leaving the line on the second run

 

Nick

 

 

[oldtuckunder]

But after Prescott and before I strip it down I will try something and also try out the new 1.75 manifold and carbs. 

 

Just a quick update, created a new manifold back in November almost identical to the one I have been using, but with modified mounting flanges so that I can swap between 1.5" and 1.75" carbs in about 30 mins. Managed some test runs (I have two a flat and a long hill that I have data logged about 50 times so far, so I have a good reference base to refer to) First of all I remounted the 1.5" carbs to ensure that the new manifold wasn't contributing anything, and those test runs came out within a couple of 10ths of a sec of the original manifold, so at least I knew I was comparing apples with apples when I swapped the carbs.

 

Got the 1.75's fitted, took an initial gambol with Needles and Springs, these were a pair of NOS Federal TR7 carbs, so about right engine capacity and about same max RPM, so there was a chance that they might not be far off. Setting up idle and low RPM mixtures was easy as I have twin Wide Band sensors in the manifold (one for each carb) and a few data logged road tests seemed to show whilst they were a little leaner at cruise (which wasn't a bad thing as I had always had to run the 1.5 a bit rich) and booting it showed AFR's in high 12's low 13's so at least for an initial set up test ok. So went for first proper test on my flat test run, this is a standing start from 3K, pulling to 6k in 1st. 2nd and 3rd, first impression was that it really took off from the start, however a comparison of the logs showed that time wise it made no difference split times between 1.5 and 1.75 were all within a few 10ths so no gain on the flat. The only encouraging thing was if you have been following this thread is that MAP wasn't increasing at high revs as it had been with the 1.5's. All in all a bit disappointing had been hoping the 1.75's would do something!

 

Was about to do Hill test, when a combination of very bad Man Flu, and then appalling weather, and a failing battery delayed everything (and pulling the engine for inspection) Until yesterday when with good battery, half a brain, and good weather I set out to do the Hill test.  Again a long steepish straight hill, 3K standing start then pulling to 6k in 1st, 2nd and 3rd. You can tell how steep the hill is as it takes about 10 secs longer to get from launch to 6K in 3rd.  

 

Wow real difference almost 2.5 secs quicker! and still pulling like a train when I lifted.

 

So makes no difference under lighter load on the flat, but when some real hard work is required the better flow of the 175's does seem to make a difference, and again the MAP log tells me that inlet manifold pressure was staying even and low right through the pull.

 

Well now really must pull the engine and see what the bottom end looks like, but some encouragement that 175 will be part of the pre season testing!

 

Alan

[Nick Jones]

Interesting.  Don't understand why you didn't see gains on the flat, but did see quite decent gains on the hill..... just spending more time in the zone above the 1.5s flow capability on the hill I guess.

 

Look forward to the "autopsy" report - though as it all seems to be alive and well this doesn't seem quite the right word!

 

Nick

[oldtuckunder]

Interesting.  Don't understand why you didn't see gains on the flat, but did see quite decent gains on the hill..... just spending more time in the zone above the 1.5s flow capability on the hill I guess.

 

 

I think that's it, as I said on the hill climb it was about 10 secs longer from launch to 6K in 3d, and I know from the logs that heading towards 6k on the 1.5's that the AFR's start getting richer and I think there is some sort of vicious spiral where the mixture getting  richer reduces power so the acceleration slows. On the flat we get to the 6k much quicker in each gear, there is not such a demand on power to defeat gravity and am thus changing up each gear quicker.  As I always commented on the flat I didn't have a problem, it was only climbing hills where we seemed to hit a brick wall where acceleration just petered out.

[oldtuckunder]

Why, Why, Why did SOD have to invent a law!   One final task I wanted to do before pulling the engine for inspection was run a complete compression test wet and dry, just to make sure that there wern't any hidden issues I had to address whilst the engine was stripped.

 

So today was the day, ran it up to good working temperature running sweet as a nut (almost had me thinking do I just risk the engine for next season). Pulled distributor cap and leads as it makes it easier removing #4,5 plugs, pulled all the plugs and ran the dry tests all came out +/- 1-2 of 130 (of course what they actually are is a guess as who knows how good any particular gauge is) and then a shot of about 5ml oil into a bore and restest and all came out +/- 1-2 of 150 so I was happy.

 

Put the plugs back in, put the cap and leads back and fired it up, running like dog!

 

Bol...ks must have put the leads on wrong although 153624 is tattooed on my forehead. Nope leads are correct. Maybe a fouled plug from the oil? a check of the AFR's on the data logger showed rear carb running very lean a sure sign of a cylinder not firing but which one of 4/5/6?  OK change all three plugs for new ones, no difference! OK must be faulty lead connection, remake all three no difference. Take a known good spare lead and try swapping all rear three, no difference!

 

What the F is going on, all I have done is remove distributor cap and leads, and put them back!

 

OK maybe I dropped something on the rotor arm and damaged it, so try spare, no difference.

 

Maybe there was a fault is the dissy cap and removing and removing and refitting has exposed it, change it for new spare, of course no difference.

 

Coil? hang on rear three are running lean so can't be that.

 

Test for spark at rear three, good and healthy.

 

I know its one or two of the rear three from the AFR reading, but what the F is it?

 

Ah may be its fuel? had the pump turned off whilst doing the compression tests, may be a bit of fuel was pulled out, and the float jet has stuck shut?  around to other side of engine, put finger through throat and it feels a bit damp around the bridge, enough for me to think that there is fuel rising around the needle.

 

Bol..lks am going to have to strip the new 175 on there and see. Just stood there looking and think what that black lump lying on the heat shield? pull it out and its a rubber pipe cap, where's that from?  Ah its one of the caps I fitted to block the crappy late 175 emission ports (just like the late SU's). Problem solved rear carb has been sucking air through the emission port and mixing with air and fuel from the main body, leaning it out at low revs to the point where all three rear cylinders were running but only just and very lean.

 

Refit, problem solved, apart from having to remove replacement plugs, leads, cap, and rotor and refit originals.

 

How it came off at exactly that time when I hadn't been around that side of the engine I will never know, but what are the odds of it happening between running perfectly before compression test and dropping off before restarting?

 

If it hadn't been for the extensive heat shield I have, and spotting it lying on there, I would have been stripping a carb to find nothing!

 

So for once the rule of what you have just done is probably the cause of the problem wasn't true.

 

Anyway next    that bonnet should be opening the other way shouldn't it?

 

Alan

[Nick Jones]

Just SOD reminding you who's running the show........  Think of it as a success tax?

 

Could it be that the the rubber pipe cap blew off due to a minor spit-back caused by insufficient choke?  

 

Had something similar years (25+!) ago on my Herald running 2 x 1.5 SUs on a fairly fierce 1300.  Was a bit mean with the choke when trying to leave work on a cooling summers evening, so it spat back fairly vigorously on the first starting attempt and thereafter did very little, even with full choke, apart from kick intermittently on a couple of cylinders.  After much cranking I finally got it to kind of run with the choke fully out and above 1/3 throttle only - completely undriveable.  It took me really quite while to realise that one of the little bosses on the bottom of the manifold runners, where the inlet normally bolts to the exhaust had blown clean out of the bottom of the manifold leaving a thumb sized hole........  It was lying on the chassis rail and was unceremoniously jammed back in the hole and wrapped in gaffer tape.  It escaped again just as I got home as the gaffer tape didn't appreciate the red hot 4-2-1 just under it.  Oddly enough the actual manifold is sitting on my bench right now and I still have the stray boss.

 

Nick