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Throttle Body Fuel Injection


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I got this quote from another thread:

 

SPFI cars, like yours (it's a Loyale) have only one injector in the throttle body.

MPFI cars (1985 GL-10, XT's, and all turbo cars) have one injector per cylinder. They also have a special intake manifold and heads that differ from carb/SPFI cars.

 

Is it possible to put the throttle body of a single fuel injected car on a fuel injected turbo model and then use the extra injector as extra fuel? I understand the intake manifold and heads being different but maybe the throttle body can possibly be fitted. Just a thought!

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I've been to lazy to look at my parts...

I was thinking of doing this (since Rick actually brought it up) to my soon to be turbo XT6.... I would think you could add the injector to the existing TB and then wire up the SPFI computer to share all the output of the stock computers sensors then it would also be self correcting.... I just wired up the SPFI for my wagon... I could do it again.. just gotta go dig in the backyard for my parts and glue them togather:drunk:

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the only big problem i see is that the spfi injector is a huge bottle neck. it chokes down to about 1/3 the size of the wide open throttle body.

 

i dont think runing the complete spfi computer for the single injector would work, you dont need any extra fuel untill you hit boost, and the spfi wouldnt know this.

 

you could put the spfi computer on a boost activated switch, to turnon only when the car is under boost... but then it seems just as easy to wire up a fifth injector in the manifold.

 

i think its too much complication, when all you realy need is a boost switch, a home made controll module, and a bosh cold start injector.

 

 

http://www.thedodgegarage.com/turbo_extrainj.html that seems way cooler

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i dont think runing the complete spfi computer for the single injector would work, you dont need any extra fuel untill you hit boost, and the spfi wouldnt know this.

 

i think its too much complication, when all you realy need is a boost switch, a home made controll module, and a bosh cold start injector.

I disagree with this. Firstly the SPFI can cut fuel completely and would do so, but I think you might get the "dueling banjos" effect where the two fuel systems would try and overtake each other for which was running the show. It does seem complicated, but would result in a more managabe fuel correction instead of just dumping "A" amount of fuel into the engine at "This" time.

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Just go with the 5th injector, I've been running mine for a long time and it works great and is way simple. maybe use two maller ones and stage them closely. I'm about to instal a 6th injector to come on at 19-23 psi. My single injector has kept my engine together at 19psi and I'm running 14.20 seconds in the 1/4 pretty consistantly. Same with my gl-10 last year, it had 200k on the engine.

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Just go with the 5th injector, I've been running mine for a long time and it works great and is way simple. maybe use two maller ones and stage them closely. I'm about to instal a 6th injector to come on at 19-23 psi. My single injector has kept my engine together at 19psi and I'm running 14.20 seconds in the 1/4 pretty consistantly. Same with my gl-10 last year, it had 200k on the engine.

 

yar! a time tested method.

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Just go with the 5th injector, I've been running mine for a long time and it works great and is way simple. maybe use two maller ones and stage them closely. I'm about to instal a 6th injector to come on at 19-23 psi. My single injector has kept my engine together at 19psi and I'm running 14.20 seconds in the 1/4 pretty consistantly. Same with my gl-10 last year, it had 200k on the engine.

 

You need to start selling this for us dumb people (like me).

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umm bob.. the spfi/carbonated hehe cars are higher cr than the turbo cars

 

so dropping turbo on a stock spfi block would result in a high comp turbo motor and with out being able to re adjust the stock ecu to fuel it correctly you can look forward to melted pistons and such ..

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umm bob.. the spfi/carbonated hehe cars are higher cr than the turbo cars

 

so dropping turbo on a stock spfi block would result in a high comp turbo motor and with out being able to re adjust the stock ecu to fuel it correctly you can look forward to melted pistons and such ..

 

not true, several people have used the spfi block (9.5:1)compression with turbos with no problem. you can safely turbo 11:1 compression as long as its tuned properly.

the increased compression does not warrant any ecu or fuel adjustments. only boost.

the spfi computer wont give you enough fuel because it wasnt designed to be turboed.... but since its a hotwire it will take "some boost" without problems though

 

i think 4 lbs is about the tops with the stock spfi stuff, and no other mods.

 

its been done a couple times;)

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not true, several people have used the spfi block (9.5:1)compression with turbos with no problem. you can safely turbo 11:1 compression as long as its tuned properly.

the increased compression does not warrant any ecu or fuel adjustments. only boost.

the spfi computer wont give you enough fuel because it wasnt designed to be turboed.... but since its a hotwire it will take "some boost" without problems though

 

i think 4 lbs is about the tops with the stock spfi stuff, and no other mods.

 

its been done a couple times;)

Yeah.. Roni/Cutie-ru/my girl friend has Steves old 9.5:1 Turbo XT... running the stock EFI system... no issues at all... Maybe at sea level without intercooled, but I dount that I'll have problems with a carb block as I'm pretty sure the carb has lower compression the the EFI blocks... but still higher then the turbo compression... I plan to only run "some boost" mostly for the fuel milage:rolleyes:

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