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Individual Throttle Body Selection


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Well I made an impulse buy on Ebay and bought throttle bodies from a BMW motorcycle. The Bike is a 2002 K1200lt that makes 119 HP. My thinking was that my Spitfire would never make 119 HP so they would be big enough. The bore at the butterfly is 1.3” (33 mm)and they open up to 1.55 at both manifold and airbox ends which confuses me. Why would you want a venturi at the butterfly? They don’t have injector bungs so that gives me the flexibility to mount them far from the head while keeping the injector close. My Webers have 4 28mm chokes and it doesn’t seem to be gasping for air at 6K. it came with a TPS and a stepper motor to control Idle speed. 

To me the hardest mechanical part is going to be mounting them to the head. I already have a crank sensor for my Megajolt ignition. I welded a bung in the collector for a Bosch 4.2 LSU O2 sensor and I have an AEM gauge to read it.

You have to spend about $600.00 On a Megasquirt2 to get sequential not batch injection. I don’t see the point of spraying fuel at a closed valve. https://rusefi.com/ Is much cheaper and may suit my needs 

The pics show the throttle bodies sitting with a spare head. The sticks show the angles that the runners would have to be at. It doesn’t seem to bad to me.  I think they should go into the head as straight as possible but the ports are really close together.

So… what do you think of these throttle bodies?  Should the butterflys be closer to the head? Should I look for something bigger?

Any advice is appreciated. I don't want to start this long journey in the wrong direction.

 

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Hey I did see that a while back. You were sending me subliminal messages when I decided to hit the "buy it now" button. The ECU will be one of the last things that I buy so if I can pull this off at a reasonable price I may spring for MS2. 

Full steam ahead Cap'n

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  • 1 month later...

OK

After being inspired by Nick Jones (possibly the most prolific Triumph enthusiast on this blue/green ball we call earth). This is where I'm at. I made all of the runners the same. the only downside was that the linkage that connects the second and third throttle bodies will have to be extended. My questions are as follows.

All of the high pressure fuel pumps brag about how much pressure they can push but none advertise how well they draw, suck, or pull. This is my low pressure pump feeding my twin DCOE's. I have searched the internet including this site and can't determine if a high pressure  pump would work. The idea of a low pressure pump feeding a high pressure pump through a swirl pot seems over complicated to me. Can this pump suck fuel up and out of a Spitfire tank? Genuine Bosch 044 Inline External FuelPump 300lph 180day warranty 0580254044 E85 | eBay  Would I burn a hole in a piston from running too lean after sucking air from the tank on a long left hand turn?

Which OE fuel pressure regulator do you recommend? Here in the US we used to be able to walk through a junk yard until somebody did something stupid and sued the owner. Now you can't get past the counter and you have to know the exact part you are looking for.

Any reason not to use copper tubing for a fuel rail? I've soldered thousands of fittings in my business and I'm 100% confident that my joints won't leak. especially if I use the silver bearing solder that I use on AC systems. I can't imagine the tubing or fittings failing. All of my lines would be 3/8" steel or braided hose. Fire scares me.

I'm told that the manifold is the hard part. But it doesn't feel down hill from here.

Thanks 

Mike

 

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It has been done before, there was an MG Midget 1500 with DIY fuel injection using copper pipe as a fuel rail:

th?id=OIP.qH14FynBnuHI45tHDHtYHwEsDh%26p

Owner's name Bob Tooke, was a while ago but you might find something still on online searches.

Throttle bodies look great. Yes needing a swirl pot or baffles etc is a pain, but you don't have the luxury of carb float bowls in an EFI set up - you are making a big design change there and need to compensate somehow. There are so many variables you are having to design in this kind of system, that any kind of known constants you can achieve are really important because you will end up forever chasing your tail otherwise.

 

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or there is this
https://www.webcon.co.uk/products/15149-efi-fuel-pump-swirl-pot-assembly/
 

slightly less expensive solution but just works. I spent so much on all the other bits that I just went for the easiest solution! 

I am using it on my EFI Herald (1500) and use a small electric pump and filter to feed it.   Sits in the boot of the Herald next to the tank. used the original pipe as the return and ran a new copper pipe to feed the fuel rail. I drilled and tapped the original drain bolt at the bottom of the tank and fitted a banjo connector for the feed. I fitted an extended pipe in the bajo bolt so its sucking from about 50 mm above the bottom of the tank. Has worked very well for the last 2~3 years, no problems with loss of pressure or surge.
Like the idea of using copper pipe, it is surprisingly strong, I once tried to burst a  length by pumping it up with a hydraulic pump... ;) 

Mike

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Thanks for the link to the RUSEFI, looks like  a very intering alternative to microsquirt.

Congrats the manifold looks great!
Don't think the angle will matter, did you take a look at the weber manifolds?

"Any reason not to use copper tubing for a fuel rail? "
It could crack due to vibrations if it's not well supported.:ninja:

Don't know if you intend to but a Bosch 044 fuel pump, but that's way overkill for an engine only making 119 BHP.
Although the one in the link is very cheap for a genuine Bosch 044 pump. I would look to a smaller fuel pump.
This one will draw a lot of amps and heat up your fuel.

External or internal swirl pot are a necessity with fuel injection unfortunately.
EFI pumps don't suck fuel well at all and always have to be mounted below the fuel tank/swirl pot.
Swirl pots are necessary because EFI systems don't have a "reserve" like carburetors have with the float bowls.
So if the fuel supply is interrupted, due the pick up sucking up air, the mixture will instantly go lean.
This can happen when you're you braking, accelerating or cornering, especially when the fuel tank level is low.

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Great advice. At first glance they seem expensive but your getting a surge tank and a pump which takes some of the sting out of it. But the tightwad in me thinks that I can make something similar with a very common (cheap) pump. The Fitechefi one is also huge. I'm looking for mass produced value and OE quality so I'm leaning towards Bosch. Long ago I had a generic fuel pump fail that led to a long walk to a parts store. I don't want to repeat that.

Would tall and skinny be better than short and fat to cope with fuel sloshing away from the pick up? What is the minimum volume that I should shoot for?

Thanks

Mike

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I have used a Golf IV intank pump. Used a SH one which cost a tenner, and seems to work well despite being on the RH side of my spitfire tank to avoid the original fuel sender (though I could have adapted my gauge to work with the golf sender if I had though about it). 

At one of the shows there was a custom tank specialist, had an ali spit tank on display with a peugeot in-tank pump. Looked extremely similar to what I had done. I say me, a friend brazed a metal ring with brazed-in studs to the tank, which was all a bit of a challenge so he says.

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  • 3 weeks later...
On 11/24/2020 at 7:17 AM, zetecspit said:

I have used a Golf IV intank pump. Used a SH one which cost a tenner, and seems to work well despite being on the RH side of my spitfire tank to avoid the original fuel sender (though I could have adapted my gauge to work with the golf sender if I had though about it). 

At one of the shows there was a custom tank specialist, had an ali spit tank on display with a peugeot in-tank pump. Looked extremely similar to what I had done. I say me, a friend brazed a metal ring with brazed-in studs to the tank, which was all a bit of a challenge so he says.

Like this?

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Well here is where I'm at. This fuel pump is from a Chevy van. As common as belly buttons here in the states so cheap and available everywhere. I scavenged 16' of this aluminum tubing a long time ago. It is 100mm ID with 1.5mm wall. At 300mm tall it should hold about 2L when you account for the amount of volume the pump displaces. I need to cut it to length and weld a ring around it to clamp it down. It will be mounted in the boot on the left side near the tank. 

I plan to keep this full with the existing 5psi pump. my return line from the pressure regulator will be my existing 3/8" line. I think I can get a bulkhead fitting in the top of the tank through the sending unit hole. 

Any recommendations on an OE pressure regulator? A cheap Bosch unit from a BMW, AUDI, Merc Etc. 

I should have named this thread "PI on a shoestring" I have about $225.00 US dollars in this so far.

Does anybody have experience with Speeduino? It seems like an affordable way to control everything and I have a nerdy friend who can't wait to get his hands on one.

Thanks

Mike

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6 hours ago, SpitfireBGT said:

Well here is where I'm at. This fuel pump is from a Chevy van. As common as belly buttons here in the states so cheap and available everywhere. I scavenged 16' of this aluminum tubing a long time ago. It is 100mm ID with 1.5mm wall. At 300mm tall it should hold about 2L when you account for the amount of volume the pump displaces. I need to cut it to length and weld a ring around it to clamp it down. It will be mounted in the boot on the left side near the tank. 

I plan to keep this full with the existing 5psi pump. my return line from the pressure regulator will be my existing 3/8" line. I think I can get a bulkhead fitting in the top of the tank through the sending unit hole. 

Any recommendations on an OE pressure regulator? A cheap Bosch unit from a BMW, AUDI, Merc Etc. 

I should have named this thread "PI on a shoestring" I have about $225.00 US dollars in this so far.

Does anybody have experience with Speeduino? It seems like an affordable way to control everything and I have a nerdy friend who can't wait to get his hands on one.

Thanks

Mike

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Is there any reason you don't want the fuel return straight back to the pump? I guess with a 2L swirlpot you may be worried about heat, but I would worry that the HP pump would empty the swirlpot PDQ without the fuel return. 

But you will still need a small  vent pipe from the top of the swirlpot back to the tank. 1/4" should be plenty, plobably smaller so the original pump isn't clattering away, and just keeping the pot topped up with fuel used.

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My son has a Speeduino ECU on his Spitfire.

You get a lot of features for your buck. However..... unlike MS which became quite a stable and unified platform early on and was always very well documented....... the world of Speeduino seems somewhat anarchic.

We had problems with documentation (lack of), hardware defects (we may have caused one of them to be fair), we had problems with firmware versions and we had problems with noise. Big problems. May not have been the fault of the ECU, but I’ve not had such problems with 3 MS installs except where the ECU was definitely defective. To be fair, the vendor was extremely responsive and helpful, even though he’s in a very different time zone and was often answering our questions when he very reasonably might have been sleeping!

If you are an electronics person, or have a really tame one to hand, May be worth a go. Otherwise......

If you do go this route, do yourself a huge favour and get one with a proper connector system. The basic molex (?) is unfit for purpose and randomly self-unplugging pins can really mess you up!

Very much liking the pump solution. Should I ‘squirt the GT6 I’ll likely follow this route, with the emphasis on finding the most compact pump cradle I can as a start point. 

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15 hours ago, zetecspit said:

Is there any reason you don't want the fuel return straight back to the pump? I guess with a 2L swirlpot you may be worried about heat, but I would worry that the HP pump would empty the swirlpot PDQ without the fuel return. 

But you will still need a small  vent pipe from the top of the swirlpot back to the tank. 1/4" should be plenty, plobably smaller so the original pump isn't clattering away, and just keeping the pot topped up with fuel used.

There is a third opening in the top of the pump that a pressure sensor goes into. That opening will have a 5/16" supply line from the low pressure pump. The return line will have a reducing T in it. The T will have 2-3/8" openings and 1-5/16" opening. My thinking is that the fuel will take the path of least resistance (3/8" to the swirl pot). When the pot is full then the 5/16" line to the tank will be the path of least resistance and fuel will go into the tank.

Is there a check valve that could be put in the supply line from the low pressure pump? I'm thinking that the return pressure may be higher than the supply pressure from the low pressure pump. The supply pump probably won't like having fuel pushed into it's out line. 

 

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The LP pump is there to keep the swirl pot topped up, nothing more. So only needs to supply the fuel needed by the engine. 

The HP pump has most of the fuel it supplies returned. I do wonder if one of the swirlpot jobs is to buffer the fuel level, so when demand is at its highest, the level in the pot may drop momentarily? (as the LP pump may not keep up) 

The T idea bothers me. Can't put my finger on why. Except IF the fuel level fell, how well would it refill? You are trying to feel fuel back into the swirlpot via the same bit of pipe you want the air to escape from. 

I would be more inclined to combine the fuel return with feed from the LP pump (with  3/8 pipework, there should be very little pressure in the pipe as it is open in the pump inbuilt swirlpot), then have a separate air bleed. But my concerns may be unfounded. 

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Zetec

Your idea will definitely keep the swirl pot full which is the top priority. it might increase the back pressure on the feed pump though. I'll do some research into a check valve but it shouldn't be needed since any pressure in the pot will be sent to the tank. Either way this is the low pressure side and it will be easy to change the rubber lines to try different combinations. The high pressure side will be Aeroquip braided stainless and hardline.

The advice is appreciated

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On 12/12/2020 at 7:14 PM, spitfire6 said:

Like this?

Fueling (18).JPG

Very neat there @spitfire6 that's what I am planning on doing when I convert my tank for efi to avoid the need for a separate LP pump and swirl pot. Although will be using a Range Rover PRC8318 (Classic 1986-1990) pump as they are plenty big enough, cheap to get hold of and quite compact.

@SpitfireBGT  I like your idea of using a bit of tube as a reservoir in the tank too.

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Hello All

                That is the fuel pump I used in Spitty 3 years running with no problems except i did not baffle the tank as well as I thought and when the tank is 1/4 to 1/3 full she cuts out on left handers!

But I just keep the tank full and slow down if getting low!

Roger

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