Throttle body for aftermarket ECU

[RallyBob]

One of the problems with trying to get an aftermarket ECU to work with an Opel fuel injection manifold is the lack of a proper TPS (throttle position sensor) on the throttle body.

I found one possible solution quite easy to implement, by adapting a late model throttle body to the Opel intake manifold. The throttle body I've used is from a 1991-1994 Nissan SR20DE engine (found in the Sentra SE-R and the Infiniti G20). The bolt pattern of the throttle body is exactly the same as an Opel's, but the securing hardware is different. Opel uses 6mm studs to hold the TB in place, while the Nissan TB is held down by 8mm socket cap screws. I simply removed the Opel studs with vise-grips, then drilled the holes out a bit and tapped them to 8mm x 1.25 thread. Now the Nissan TB bolts right up with the stock Nissan bolts. Even though the Nissan TB is 60mm vs. 55mm for the standard Opel part, the intake plenum opening is already large enough and no port matching is required.

The only thing left to consider is the throttle linkage attachment, which has a few possibilities.

[spdkilz02]

ill have to remember this one for when i put the FI on mine, ill definately get this for it.

[markandson]

Bob,
Would a TPS from an '85 2.2 Rekord Motor be OK? What is it about the TPS that makes it no good for late model EFI computers? I am in the process, as I am sure you know from all of my previous posts, of putting together a 2.2 with some sort of EFI on it. I have a line on an AFM which I was missing, but am I wasting money if I buy it? Maybe I should be going to a more modern system in the first place. I have a good starting point since I have the 2.2 EFI motor and intake, although I am looking for a 3.0E intake to do what you did to make a better flowing system.

[RallyBob]

Bob,
Would a TPS from an '85 2.2 Rekord Motor be OK? What is it about the TPS that makes it no good for late model EFI computers?

As long as you have an actual TPS then you can make it work with an aftermarket ECU. The problem is that the 1975 Opels that have L-Jetronic have no TPS at all. Those early air-flap systems didn't rely on a TPS, they relied on the movement of the air flap to 'meter' fuel correctly. There is a high-speed enrichment switch on the old L-Jetronic throttle bodies, but it exactly that...a switch. It's on or off, while a TPS is essentially a 0-5 volt potentiometer.

Bob

[bendele]

Bob,

What are the vaccum port looking things on top of the TB?
Seems like there's a lot of extra stuff on the TB itself.

Chris

[Paul]

Bob,

I presume there is no good way to remove the enrichment switch and scab on a TPS to the 75 Throttle Body?

[RallyBob]

Bob,

What are the vaccum port looking things on top of the TB?
Seems like there's a lot of extra stuff on the TB itself.

Chris

That's water passages to heat the TB. Not needed. I've already removed them, but they could also just be left 'as is'.

[RallyBob]

Bob,

I presume there is no good way to remove the enrichment switch and scab on a TPS to the 75 Throttle Body?

It could be done, sure. I was looking for an alternate method though.

[neuropel]

Which manifold are you working with here Bob?

[RallyBob]

Which manifold are you working with here Bob?

Stock 1975 Opel. Just washed and glassbeaded it. It's going to go on a bone-stock late model 1.9, and will get a stand-alone ECU. I hope to use it as a guinea-pig for my upcoming turbo manifold. I basically wanted to create a replicable engine package based on the turbo manifold I'll be building.....I hope it will fit the Manta and GT chassis without mods. Once it's all assembled, I want to see just how much HP a stone-stock low compression 1.9 can handle before blowing it up....and I'm not afraid to pop the motor in the process! Then I can offer just the turbo manifold, and make 'how to' video and parts list so it could be built in your own garage. The real weak links will be the clutch/tranny/axle, but this project it all about the engine.

[nobody]

Just an odd idea I had while reading on the Mega squirt. There is a TPS with the right ohm values used on Weber sidedrafts. I got one of them when I got the OMs. It's the same size as a Weber shaft and attaches with two screws to the body and a set screw to the shaft. Told you it was an odd idea, but it might make things more universal.

[neuropel]

What are you planning to use for injectors? Seems that if you could use aftermarket injectors there would be a lot of good possibilities with this manifold mod, even with no turbo. Am I correct? In fact, with a nice flowing head on a 2.2 block, wouldn't something along these lines compare favorably with the 2.2 injection setup...again, minus the turbo?

Does the stock 75 manifold flow good enough that one could make good power without modifications, assuming you can graft on different injectors and this throttle body? That throttle body you have on there looks like it was made for it! Very cool...I LOVE to see stuff like this, where common everyday, easy-to-get items (cheap) can be used to bring our Opel engines up to modern standards. Would/could such a rig perform comparably to say, a dual carb setup on the 1.9? The cost has to be cheaper...and for those of us less afraid of software and modern electronics I suspect we may really be onto something.

Am I off the mark?

Todd K.

[RallyBob]

What are you planning to use for injectors?

Bosch hose-barb style injectors, #0 280 150 036. Rated at 45 lbs. min @ 45 psi. I may have to run up to 50 or so psi to get the ultimate fuel flow I need for a turbo engine. These are a direct fit to the stock intake, and are more than enough for any normally aspirated Opel engine. I will make a larger fuel rail (diameter) to dampen pulsations in the fuel system.

Seems that if you could use aftermarket injectors there would be a lot of good possibilities with this manifold mod, even with no turbo.

I have another 1.9 intake I'm preparing which will have aluminum injector bungs welded directly to the intake. With an aftermarket custom fuel rail, I can use any modern o-ring style injector.

In fact, with a nice flowing head on a 2.2 block, wouldn't something along these lines compare favorably with the 2.2 injection setup...again, minus the turbo?

Absolutely, a prepped 1.9 head with 1.9 intake can surpass a 2.2 head with a 2.2 intake.

Does the stock 75 manifold flow good enough that one could make good power without modifications, assuming you can graft on different injectors and this throttle body? That throttle body you have on there looks like it was made for it! Very cool...I LOVE to see stuff like this, where common everyday, easy-to-get items (cheap) can be used to bring our Opel engines up to modern standards.

The '75 intake manifold flows well enough for pretty much any streetable 1.9/2.0/2.2 litre engine.

Talk about cheap...I was able to get the TB for free from my friend's machine shop, he had a core engine sitting outside and all the accessories (intake/exhaust/alternator/bracketry) normally end up in the scrap metal recycling bin.

Would/could such a rig perform comparably to say, a dual carb setup on the 1.9? The cost has to be cheaper...and for those of us less afraid of software and modern electronics I suspect we may really be onto something.

Well, Irmscher used to sell 2.0 litre rally engines in their catalog...one version with twin 45 DCOE's made 177 ps, the fuel injected version (with special air flow meter and ECU) made 172 ps. I suspect that if you eliminated the restrictive air flow meter (which a programmable ECU does BTW), and added the larger throttle body (60mm), the EFI system could surpass the 45 DCOE system quiet nicely, with better torque (due to plenum and longer runners), plus improved driveability and idle quality.

Am I off the mark?

Do you really want me to answer this one?

Bob

[neuropel]

So, on this system you're designing, how much will the turbo and the turbo manifold add costwise? I'd assume some extra cost would also have to go into beefing up the rest of the ENGINE (not even thinking of the rest of the drivetrain)?

[RallyBob]

So, on this system you're designing, how much will the turbo and the turbo manifold add costwise? I'd assume some extra cost would also have to go into beefing up the rest of the ENGINE (not even thinking of the rest of the drivetrain)?

Part of this 'exercise' is determining how much power the stock engine can handle (a reasonably fresh engine, not 200k old!). If it blows up at 240 hp then I'd probably say keep it down to 200 hp or so to make it last a while.

Of course, if you invest in forged pistons, stronger rods, a better head gasket, etc., you can expect to get more hp safely.

I don't have an actual cost yet on the turbo manifold, it's not built yet. The trick is making it fit multiple Opel chassis'. The turbo is nothing I'd be looking to sell, I would just build the manifold to fit a particular turbo, and could give suggestions as to possible vendors for that turbo. So far it looks like the turbo will run about $700 based on quotes I've had. http://opelgt.com/forums/showpost.ph...&postcount=223
This thread describes the estimated costs for the components.

Bob

[Paul]

Bob,

This thread has gotten me interested in a kit of parts, throttle body, TPS, throttle linkage, fuel rail, etc that would be needed/allow the installation of a programmable (Megasquirt) ECU.

[RallyBob]

Bob,

This thread has gotten me interested in a kit of parts, throttle body, TPS, throttle linkage, fuel rail, etc that would be needed/allow the installation of a programmable (Megasquirt) ECU.

I'm not sure if this is directed at me or not(?), but I'm not really interested in supplying a kit. I was more or less looking at working out the kinks, and making a list of parts available to fit. The only thing I was going to 'produce to sell' was the exhaust manifold. As an added 'option' I could make a video showing how to modify and install all the accumulated parts, give suggestions for intercooler pipe and exhaust diameters, and top it off with some tuning tips perhaps (or even video tape a dyno session).

Bob

[neuropel]

For the turbo setup Bob, what details would you recommend for exhaust? Or...Does that require further testing? Very cool thread.

[spdkilz02]

no kidding, this comes just in time, cuz this winter im putting up my motor and putting on the FI and turbo in my manta

[RallyBob]

For the turbo setup Bob, what details would you recommend for exhaust? Or...Does that require further testing? Very cool thread.

For the hp intended and the turbo size, 2.5" would work great. Unlike a normally aspirated engine, you will actually gain (throttle) response time with a larger exhaust diameter. In the case of the 'Carlisle' turbo Manta, I am using a 3" exhuast off the turbo (bigger turbo, more HP potential), but will reduce it down to 2.5" about 5 feet back from the turbo. Once the heat energy has dropped, the exhaust diameter is not as critical. In fact, on my friend's old turbo Alfa GTV, we ran 3" off the turbo, and gradually stepped it down to 2.25" by the time it got to the rear of the car. We ran a gutted out resonator, with no muffler...still was quiet thanks to a turbo's natural tendency to mute sound waves.