Can we supercharge a tbi engine ?

[carzboyz]

I would like to know if we can supercharge a 2.5 tbi engine without changing elctronics and some other parts ? Thanks you

[ZoskalonMPI]

Well, you can do anything to any engine, in theory, its all a question of difficulty. All it is, is that you're shoving more air into the cylinders and your oxygen sensor should be able to detect the addition air and tell the ecu to send more fuel, I still don't understand how the map sensor really helps.

Now, with only one injector, you can only go to a certain point. Someone once brought up the question of using a tbi injector off a bigger tbi car, like a mini or whatever, not sure how much, if at all, that would help. Someone can tell you exactly how much more fuel you could squeeze out of that injector. You can always do the MPI conversion, its not really that much work at all, and you keep your stock electronics. This would solve your fuel problems.

Now, the other problem, I've heard the TBI engines can withstand only about 150HP on stock internals. Although I am still trying to figure this all out exactly. I don't know if by running an upwards of 150HP would require you to lower the compression, which is an ass to do. Also, the exhaust valves cannot withstand the increased temps, but I don't know up to what boost you can go with the stock valves.

And in terms of the actual supercharger, I'm not to sure of. The only real way, is by fabbing up a bracket or whatever and attaching it to where the A/C would go, and then routing pipes to the throttle body. Someone else on here can inform you more on the supercharger issue, unless you want an electric supercharger hahahaha!

[TurboTurismo]

I have a BIG ass electric motor out of an old vending food machine that may bolt up somewhere LMAO Just kidding.......Glad to see there are a few tbi people around still

Robb
1984 Plymouth Turismo with 90 TBI SBEC

http://www.cardomain.com/ride/2291434

[tkelly27]

Quote:

Originally Posted by ZoskalonMPI Well, you can do anything to any engine, in theory, its all a question of difficulty. All it is, is that you're shoving more air into the cylinders and your oxygen sensor should be able to detect the addition air and tell the ecu to send more fuel, I still don't understand how the map sensor really helps. Now, with only one injector, you can only go to a certain point. Someone once brought up the question of using a tbi injector off a bigger tbi car, like a mini or whatever, not sure how much, if at all, that would help. Someone can tell you exactly how much more fuel you could squeeze out of that injector. You can always do the MPI conversion, its not really that much work at all, and you keep your stock electronics. This would solve your fuel problems. Now, the other problem, I've heard the TBI engines can withstand only about 150HP on stock internals. Although I am still trying to figure this all out exactly. I don't know if by running an upwards of 150HP would require you to lower the compression, which is an ass to do. Also, the exhaust valves cannot withstand the increased temps, but I don't know up to what boost you can go with the stock valves. And in terms of the actual supercharger, I'm not to sure of. The only real way, is by fabbing up a bracket or whatever and attaching it to where the A/C would go, and then routing pipes to the throttle body. Someone else on here can inform you more on the supercharger issue, unless you want an electric supercharger hahahaha!

That's the long way of saying no.

[DaytonaTurbo87]

It could be done, but not with stock electronics. The stock map sensor won't even read boost, so once you start building 1psi, the computer doesnt' know to inject more fuel. I'm not sure on how much fuel the tbi injector flows, but I wouldn't bank on it being enough for any decent HP. Plus spark advance curve will be too aggressive with a tbi computer. You'd either have to change to carb or to turbo electronincs.

Internals will take it, compression is high though.

[JeremyL]

It *could* be done. The easiest way would be to get one of the aftermarket blower kits designed for 2.2, and instead of mounting the carb to the top of the blower fab up an adapter plate to mount the TBI unit there. No changing electronics, no different map. Of course, I dunno how much fuel a factory TBI setup can put out.

[ZoskalonMPI]

Quote:

Originally Posted by JeremyL It *could* be done. The easiest way would be to get one of the aftermarket blower kits designed for 2.2, and instead of mounting the carb to the top of the blower fab up an adapter plate to mount the TBI unit there. No changing electronics, no different map. Of course, I dunno how much fuel a factory TBI setup can put out.

The point of the map is to detect the boost pressure fuel can be accommodated. You'd need a map sensor that could detect boost pressure and you'd need a computer that could read that map sensor and know what's going on.

And again, the spark curves are not ideal for this setup.

[JeremyL]

Quote:

Originally Posted by ZoskalonMPI The point of the map is to detect the boost pressure fuel can be accommodated. You'd need a map sensor that could detect boost pressure and you'd need a computer that could read that map sensor and know what's going on. And again, the spark curves are not ideal for this setup.

I'm well aware of how a MAP sensor works. Yes, it wouldn't be ideal, but it COULD be done. The map would never see boost if it got it's vacuum signal above the blower. You're thinking in terms of blowing through the TBI itself. If you were going to do that, then yes you'd need a different map & calibration for sure.

The aftermarket blower kits for the older style GM trucks mounted the TBI right on the back side of the whipple charger, with it pulling air and fuel through the blower. That'd be the easiest way to do it on a TBI Dodge as well.

[t1turbo]

for more fuel just use pressure switches and ad injectors. use an O2 gauge to make sure your not running lean. I think that is the easeiat way

[19omni87]

i agree cold start injectors would be nice. or megasquirt it. or make a batch fire setup. only problem is the 2.2 superchager setup is for carb use. so definetly have to fab a tbi mount for the supercharger. might want to try an old style like 84 tbi that uses an actualy injector and drop a turbo 2 injector i there or gaffle one from a 318 tbi maybe. just my random babbling thoughts

[The Pope]

a commander 950 will run a TBI and you can change the map. Run a 85 lb injector @ 21 PSI, then up the fuel pressure for over 100 lbs of fuel. Still not a huge power maker but enough for a old B&M. You can mod a TBI cal thats used with the big TBIs and 6-71 blowers. Just tweak it to match the 4 banger.

[supercharged024]

Well, to increase fuel output to the injector, you need to set up the pressure regulator with a boost reference signal. As boost increases so does the fuel from the injector. I haven't worked with the Chrysler TBI units but the concept is the same as the GM stuff. Install an inline pressure regulator on the return line and run a vacuum line to it from the boost signal.

[19omni87]

actually the tbi pressure regulator bolts on top of the tbi u can pull the small plastic tab out and put a barb on it maybe

[supercharged024]

The problem with the stock pressure regulator is that is set at one constant pressure and doesn't change with vacuum signal. You'll simply have to install one downstream from the stock one on the return line. That one will simply override the original one without any problems. Connect a vacuum line to the regulator that gets a boost signal and play with adjusting the fuel pressure until you get it dialed in.

[InfinityShelbyZ]

The real question is....Why?