In the process of building a 383 stroker for my 1991 crewcab 4x4 which will be used for towing a 26ft trailer. The engine will have stock 76cc heads c/w original tbi intake and throttle body. The cam is an extreme 4x4 comp. Cam. 12-235-2 grind ( .447/.462 lift, duration 210 218 lift @50, 111 lobe separation) . unit has hypr. Flattop floating pistons, eagle cast crank, 5.7eagle rods. 9.2:1 comp. The engine is for max. torque between 1800-3500rpm. My question is will the stock tbi be enough to feed the displacement, and will I require a new prom for this application? Also, has anybody else done this tbi stroker setup before that can give me tips for the tbi upgrades or things i have to expect. it would be nice if the oem tbi and all components would work the way it is setup for the tbi 350


thanks
pete

 

I too am in the process of doing a 383 TBI'er. So is speedlvr ..i think he's further into it than i am. I've been browsing the web to try and look up some info on this and so far, the majority if not all posts I have found have experienced less than ideal performance. It runs ok, but not like its supposed to. Many have ditched the TBI in favor of a carb and lived happily ever after but I doubt you want to go that way. I'm praying that someone will shoot this reply down with a sucessful story so I will have a little more confidence.

 

what heads are you using and i may take the plung and learn about eprom programming so the setup will work.

 

Im using stock GM 76cc heads as well. I think the castings are 882 (whatever they are its not the "good ones"). I think I'm gonna have Ed Wright from Fastchip.com burn my chip. You and I have similar setups, except the cam (I'm using Cranes 2030 204/214 @.050) and the compression(mine is 9.5:1). Check out:
speedlvr post -
https://www.thirdgen.org/messgboard/...ML/000893.html

and my post -
https://www.thirdgen.org/messgboard/...ML/000800.html

for more info. these are the most recent postings for 383 TBI's

 

The things I have done that have caused a noticable increase in power are:

Fabricated an open element air intake from the stock one with a dremel moto tool,
am using a K & N filter,
got a new o2 sensor,
put 350 injectors in the 305 throttle body,
broke out the plug in the fuel meter and opened it fully.

Right after the motor was put in performance SUCKED. Now it runs pretty good but not where I want it yet. The way I look at it is this: Through all the sh*t, trouble shooting over and over, being pissed off and even wanting to sell the car (just because I was pissed off at the time, I have learned more about what makes cars run than I ever would have otherwise. Nothing truly worthwhile is ever free or easy. All of the guys on this board who really know what they are talking about have been where you and I are today. Some day I will be able to help more people out. Great wisdom in any area only comes from experiencing EVERYTHING having to do with that area. Challenges make you grow and that is a damn good thing! When all is said and done if you don't give up you will have won.

Future mods are:
454 throttle body
new fuel pump
prom
Hooker ceramic coated headers
3.42 posi (has 2.73 now, sux)

 

Well said!!!
BTW . Noticed that you're still using the 305TBI??? holy smokes man!!! You're gonna suffocate the poor mouse. Get that 454TBI soon and tell us how it goes. I got mine at a salvage yard (they pull the part for you type) for $100, hope i didnt get suckered for that price. Everybody says they are hard to find so i guess i got lucky.

 

Trigen, I hope that works out good for you. I'm supposed to get a new unit today. I'll post what it did.

 

I decided I'd better get some headers first. I have ANOTHER exhaust leak right next to the heads, the 3rd on in 2 months. Adding more power now would be a waste without first having an exhaust system that allows for more flow.

 

speedlvr, just out of curiousity, how did you get the spring to compress so, much when you were putting your fuel pressure regulator back together, without having it bind up?

You have what engine again? maxed fuel pressure with 350 injectors? Its not a 305 is it? I dont think it is, is it? I seem to remember you droppin in a big engine am i right. If so what is it, and what does your o2 read?
Im just curious as to what size engine fits perfectly with both wide open pressure and 350 injectors. How much hp are you making. With this info i can maybe derive other info to help calculate what combo of injectors and pressure for people to use over a wider scale.

 

The smaller 1-11/16" TBI will be PLENTY enough to feed a 383 low-rpm torquer motor... Will need injector pressure increase perhaps, and probable PROM burn but you DO NOT need the big TBI!!!

 

do i need larger injectors say 68# if i use the stock tb unit. also i decided to change the stock heads and use the trick flow 23deg c/w performer intake and adapter plate (holley)

why do you say i don't need the larger tbi? i was hoping i didn't need a 454tb.

 

It all depends on your max rpm, IMO. You can use the 55lb injectors if you move pressure up to say about 15-20 lbs, depending on what your combo needs. You will need a scantool to check the BLM's of the computer to do it right. Airflow wise, too, if you are not going to go above 5000 rpm on a regular basis (like run WOT at the track all day long) the smaller TBI will be fine.

FYI, I am at 15psi with 55lb/hr injectors and small TBI and dynoed at 245hp. I still have flow left, I think, and can still crank the FP on the injectors higher, or swap to 65lb injectors for cheap, but don't need them, yet.

It sounds to me like this is a daily drive/workhorse vehicle for you, that's why I say these things. Yeah, you might be able to eek a little more high-rpm power at WOT out, but not worth the time/effort/$ to do it for the kind of vehicle you mentioned.

[This message has been edited by FastBroker (edited February 26, 2001).]

 

Well, when I had the fuel pressure reg off I kept gouging around the metal plug until the factory set screw was able to be turned. I turned the screw with a pair of needle nose pliers until the meter was opened as far as it would go. Then I just put it back together as usual. That helped a little along with all the rest of the little things I've done. BTW, it's a 383. It still is running like crap when it's cold, but when it warms up it does okay, though not where it should be. The chip is just not programmed to allow for the correct operation of a 383. At times though, I nearly get whiplash when the throttle hits a sweet spot. So I know that if there was a different prom in it, the fuel intake would be sufficient. Of course it COULD improve with a bigger TB after I get an adequate chip for it.

 

Speedlve, you run a scantool and check for BLM's??? I think you might be surprised in that you are running too high a fuel presure... Beg/borrow/steal a scantool and read your data stream for BLM's and post them here.

 

Would that be too high pressure for the chip? Doesn't the chip monitor and control how much fuel is taken in anyway?

 

Here are all the readings as car is now:

idle park:
kpa volt & map: 28kpa, .94
o2 voltage: 4 mv, low and high
block learn: 143
integrator: 128

idle drive: (readings in same order as above)
45kpa, 1.86
98 mv low, 794 mv high
143
129

driving @ 2000 rpm: (same order)
41kpa, 1.62
173 mv low, 786 mv high
153
130

 

That is right where your BLM's would be if your EGR was disconnected, not installed or not functioning. Do you have EGR installed and is it functioning? RIght now, this is a stock motor, right?

 

I WAS getting an egr code but not anymore. I am suspecting that the electric solenoid is bad. I have taken the valve itself off and checked it out and it is fine. I just havent had time to deal with the egr lately. It's a 383 stroker running on 305TBI electronics.