Craig's GT6 MK3 in Aus.

[GT6Steve]

Here's what I did based on what I could glean from Gareth's hints  

 

[CHRIS211083]

HHHOOOOOOOO AAAAAARRRRRRRRRRR Automotive Bling!!!!! Nice.

 

Chris.

[pomwah]

.... and judicious application of a grinder won't solve the problem? 

[GT6MK3]

Yep,

 

I'm hoping Gareth with chime in here regarding secondary lengths for the two enginr types.  Happy to measure primary lengths if instructed how.

 

Been looking hard at some intake options - have ordered some parts and some stock to mill after studying as many efi manifolds as my eyes can take in. Think I have a workable single TB solution for the short term, although there's also a wicked 6 x 32mm individual butterfly solution roiling the creative division of my brain.  

 

Nick J, would you mind banging a photo of your vitesse IM into this thread for comparison?

 

Cheers

 

C.

[GT6MK3]

.... and judicious application of a grinder won't solve the problem? 

 

Nope - it's pipe on pipe.  No matter - from adversity comes opportunity!

 

C.

[toofast2race]

Craig,

Not sure if you are sticking with the TR5 cam ( I would go nuttier to get the benefit of your bottom end) but my next iteration will have six butterflies - it is very hard with a 288 duration cam to get perfect behaviour from 1000 to 1800rpm with a single butterfly - mine pulls like a train from 1800 to 7000 but light throttle in traffic at low revs is a bit of a pain occasionally - it's fine on the open road but my car is used for the commute too

Not sure how much influence batch fire has on this problem, James C - did you use sequential in the end?

[GT]

Yep,

 

I'm hoping Gareth with chime in here regarding secondary lengths for the two engine types. 

 

C.

 

err.

You now have the jig now that the illustrated sections were made from.

It will be good enough.

 

You also need to know some history.

 

The only major complication as you can see is making 1D bends.

You will need to find someone with a mandrel bender typically for making light aircraft exhausts.

I didn't want to do that any more, because when I offered to make a batch people said it cost too much.

 

Secondly:- (there were many changes).

 

The ACTUAL outlet 3-1 size on the Jig was too small, I was quite disappointed with that oversight from "experienced guys".

(iteration 1) It had to be enlarged.

 

As can be seen it was modified at that 3-1 point, (iteration 2) then taken back from 3 into 2  in hand-made mild steel section... (iteration 3).

It then had a fork to take it back into a STANDARD transverse rear silencer.

 

The original system in the photo shown went into a STANDARD GT6 silencer, which after some tests proved to hit a BRICK WALL at 150bhp.

Getting rid of that STD restriction brought approx another 25-28bhp (!) with no extra noise.

 

....which in fact in the end result (final iteration) ended up into a 2 piece-dual silencer and the final fork/2-1 bridge was binned, as was originally planned.

 

For interest:-

There were substantial gains on the Jaguar 24V DOHC 6 cylinder when I made changes to the secondary lengths.

That engine has a longer stroke of 92mm, (and 2 inlet valves a similar size to the GT6) so once the various mods had been done it made/makes phenomenal torque at 1500-2000rpm.

 

Prior to that, the exhaust manifold on that 24V engine was quite disappointing in the torque curves, and didn't work so well at high rpm with mild cams. That engine returns 30mpg quite easily, - not bad for a 1.75T car with 3.5L.

 

As you increase the efficiency of one bit you find problems in other bits, so I had to enlarge the 2 over axle pipes (again hand made) by 25%.

 

Back to the little Triumph.

All the Mike Randall exhausts (as of 1982) from which copies were universally held up and acclaimed as being "beaming sunlight from far away galaxies" .....suffered this "twitchy" torque curve depending on the state of tune of the engine (I could count on most people to detune their engines no matter what manifold they used....).

 

Phoenix of course then set about making piles of cash with my idea, but making simply horrible manifolds clearly based on the Mike Randall design.

They must have thought how smart they were..... (!)

 

I know this because they copied all the above defects and stuck the leaky slip joints in exactly the same place, where it gets twitched from side to side by the motion of the engine loading torque on its mounts....!

(go figure eh, but people all over the world buy them?).

 

The manifold you are showing here of course, being a modular design doesn't suffer from leaks because the secondaries are inserted vertically not horizontally....

It is also quite nice in having a "cross over" design which removes the difficulties inherent in the distance/length conundrum of the centre pipe lengths versus the outers.

No doubt, having seen it, there will be more attempts to copy it, and people claiming it was their "smart new design idea"....

 

Making more peak torque earlier & flatter, using a higher gear ratio means quite large improvements in fuel economy with lower frictional + pumping losses and less wear.

That's a win-win.

 

The TR5-6 manifolds I make, have been using the much longer secondaries for a year or more, but I simply no longer have time or patience for spending months back to back testing stuff then have loads of people slag it all off gratuitously.

 

+

 

oh & btw I can't edit my posts, which is a major inconvenience here.

[GT]

 

Terry, the guy who built my engine.....says that Triumph's inlet ports are already too low, that he's raised them in race engines to improve breathing, and that angling PI manifolds down will only make matters worse.

 

I have no idea where he gets this idea from.

The 6 cylinder inlet ports are TOO HIGH UP, they are also rather big.

 

I really don't know why you are messing with the original Pi manifolds, they are perfect, suffer zero turbulence and flow fantastic.

They are just TOO SHORT, and the injectors are too close to the valve for a sports engine.

If they come close to the bonnet DROP THE ENGINE.

I never saw an issue with the PI cars and the bonnet, and I did have a 2L pi cabrio.

 

further:-

The port to bore offset is really quite large on the GT6, and is only saved in extremis on the 2L engine by having a really shallow chamber on the end of it.

 

It's considerably less on the Spitfire, because there's only ONE pair of true siamesed ports to worry about, and all the aggravation present in not having ports inline with the bores was poured into the centre exhaust ports.

(they are really messed up on that engine, and not fun to correct)

 

Again, all the longer stroke Spitfire engines struggle by having a 1/2" chamber stuck on the end,- much like the 2.5L TR6, hence my work to run a 2L GT6 shallow head on the 2.5-2.7L.

 

The moment you get a 1300 high compression engine behind a Spitfire engine,  you can slice off 1/5 to 1/4" off the head to make it work properly, run it into a 0.320-340" chamber and the ports ACTUALLY start doing something useful.

 

The end result is an engine that goes from 80bhp/L to 110-115bhp/L.

[triumphlux]

Looks like everybody is working on GT's 6 cylinder manifolds

 

More details about my work in the Vitesse project thread.

[GT6MK3]

Left hand drive?  Added bonus here is avoiding the steering column/rod...

 

C.

[Nick Jones]

 

If they come close to the bonnet DROP THE ENGINE.

 

Steering rack?

 

As requested some red monkey fabricated inlet manifold pics.  Not a work of art but fairly effective.  It's made from thin wall steel (exhaust tube) which is nice and easy to work, cheap and actually pretty light.  If you wanted tapered runners there are people out there selling tapered tube or you could even make yourself.  Tapered runners would make them hard to bend but I only bent mine to miss the clutch master and actually bent them too far and it all got a bit tight at the front.  But, the point is, you can make what you want without much expense.  I'd always thought I might make others to improve on it but I've been too happy with it to bother.  This may change with a wilder cam though.  Suspect I'll either have to go sequential or multiple TB (or just go back to a less aggressive cam) as Andy is saying - he's the man with the direct experience of that issue.

 

This manifold was made using hand tools and portable drill only.  The flanges were not alot of fun.  The rest not so bad.

 

Nick

[zelrik]

Nope - it's pipe on pipe.  No matter - from adversity comes opportunity!

 

C.

Craig

I have a friend who makes complex 'pipe bends' for light aircraft exhausts (he's near Essendon Airport but most customers are in Moorabbin). He also does small bent tubes for invasive medical work.

Has done stuff for porsche 911 exhausts.

Contact me if you want an intro.

Peter

[GT6MK3]

How to build an inlet manifold, Step 1.  Measure well...

 

 

[Nick Jones]

Jeez man...... didn't anyone ever tell you that the "C" in CAD stands for cardboard? 

 

Looking forward to the continuing story!

 

Nick

[GT6 Nick]

I'm guessing these measurements are for the manifold's base plate? Watching with interest...

[CHRIS211083]

This is going to be very cool.

 

Chris.

[GT6MK3]

"There was movement at the station, for the word had passed around
That the colt from old Regret had got away,
And had joined the wild bush horses - he was worth a thousand pound,
So all the cracks had gathered to the fray.
All the tried and noted riders from the stations near and far
Had mustered at the homestead overnight,
For the bushmen love hard riding where the wild bush horses are,
And the stockhorse snuffs the battle with delight..."

 

 

So almost 2 years after I sent the diff off to have the Quaife LSD Vegas Steve so generously helped me out with installed, I've finally decided to get over whatever hurdles get put in front of me and get the car driveable so I can tackle the intake/header/exhaust issues and figure out some solutions.

 

Step 1 is to put the diff back together. It came back from it's ludicrously expensive re-assembly unpainted and in 4 bits - front/back/2 stubs.   Spinning the stubs it was clear they've sandblasted everything, and there's grit in the output stub bearings.  No biggie - I called the local bearing suppliers and ordered 2 with matching numbers on the Toyospares account (30% of retail as it turns out - good to have friends.).

 

Next it became clear I'd need new oil seals too.  These looked specialty, so I searched the local triumph breakers and supplies without success other than one place I've dealt with quite successfully before, who said they may be able fo find some...

 

When I headed into the local bearing place to pick up the bearings, I took a seal sample with me, just on spec.  They ran a vernier over it and handed me 2 new ones a minute later.  Six bucks each.  They're slightly slimmer than the original, by maybe a mm across the x axis, , but the id and od are fine.  As I left, the local triumph guy rang to say he'd sourced some for me.  I didn't wan't to burn the relationship, and he's only another 15 minutes away. so I headed up the road to get some for him as a comparison.  On arrival, his were exactly the same as what I already had, but $15 each.  I ran a quick calculation in my head - he'd rung me at least twice, rung a bearing place at least twice, had them delivered, and had them waiting for me.  I could disappoint him, or pay him for his time effort and energy..  Paying $30 for 2 spares was a no - brainer.  Bit of a chat later I'm his goto guy to call for first option if anything GT6 turns up, and he's got a bonza untouched Mk2 2000 head for me to play with for a nominal sum.  I like triumph guys!

 

Today I had my last day of school for my Training and Assessment Cert IV (Apparently you can teach an old dog new tricks), and we finished early.  

 

I came home to a quiet house, and thought "What should I do?"  On the train on the way home, I'd been reading some Banjo Patterson, and the first stanza of The Man From Snowy River jumped into my head.  Time for some movement.

 

Rhe GT6 is dusty and unloved, but it's been there before.  It needs some work and dedication.  Tonight I cleaned, pasivated, and POR15'd the housing and diff.  They're drying, and should be ready for rebuild and re-install this weekend.

 

There's movement at the station...

 

 

 

C.

[CHRIS211083]

GO TO IT MAN!!!!  Nothing can stop you now!!!!!! Except the wife maybe. Doh.

[GT6MK3]

Ahhh POR15.  It has an uncanny ability to flow to exactly where you don't need it, then dries into a glass hard mess.

 

So after a fun day spent scraping, wiping, scraping, wiping, cleaning, gooing, pressing, and bolting,

 

1 newly refurbed Gt6 quaife LSD diff, complete with magnetic drain plug, and new seals and bearings on the outer shafts.

 

 

Tomorrow it goes back in (unless I get the urge for a skydive).

 

C.

[GT6 Nick]

Don't do it, Craig. Don't jump!

[GT6MK3]

Was waaaay to windy and gusty for any sky-jumpin tomfoolery!/

 

So back to the garage.  First I spent a couple of hours finding sorting and replacing the tools I've been strewing across the countryside into some semblance of order in my toolboxes.

 

Then I started to clean out the various bits I had been storing under the car in preparation for rolling the diff under.

 

What do you store under GT6's that need headers?  More headers of course!

 

 

And the odd exhaust, gas tank, engine stand etc...

 

 

Then I hefted the diff into the trans-jack to put the rear poly's in.

 

 

Which is where I came to a screeching halt.  The long rear bolt that I thought was up under the car, isn't.      

 

So at this point I'm stuck.  I either order a 136869 from England, or find one here in Oz.  I know it's a 7/16th bolt, anyone able to measure one's length for me?

 

Drat, buggerit etc...        

 

 

[pomwah]

You're welcome to use mine. Only took the rear suspension apart 18 months ago, it's in a box somewhere!

Edited September 28, 2014 by pomwah

[GT6MK3]

That'd be great James - any idea when you can go hunting?

[GT6Steve]

 

IMG_35681.JPG

 

 

My garsh that diff spacer looks familiar...Did I give you that??

Edited September 28, 2014 by GT6Steve

[GT6Steve]

I just buy socket head cap screws at the local bearing/bolt house.  Always readily available off the shelf.  8" under head...