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Discussion Starter · #1 · (Edited)
Ok, I've been searching and haven't found a clear answer to my question.

Now...I have a 95 TBI 4.3

I'm wondering what kind of boost I can expect the bottom end to hold up to in stock form. With lot's of tuning involved of course.

Now along with that, I plan on using the 96+ heads and was wondering if they would increase my compression? That and a bit more aggresive cam are coming here soon...and I know both of those could effect how much boost I could safely pull off.

Now...for the compressor...despite my purchase of "Turbosonoma.com"...I've decided to go with a centerfugal s/c...like the ProCharger P-1SC, but maybe not exactly, since I haven't got around to chosing the ideal s/c for my budget/setup.

After lots of tuning, 96+ heads, cam, better intake, headers, water to air i/c, etc, I want to pull off 15psi, without rebuilding the bottom end.

Should I keep dreaming? Cause I've noticed a few people running over 10psi

I really wish I had more details, but the route I take all depends on the $ I make. Right now, I can't afford the downtime that comes w/ rebuilding the bottom end, so I want to do what I can for now.

God that post makes me feel like a n00b
 

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15 psi on the stock bottem end is risky to say the least, The sytys were pulling off around 20 on stock bottom ends and thats with better connecting rods and nodular end caps, lower compression pistons, not to metion better map sensor, and ecm. Our engines have lower compression then the vortech engines with a dish piston which is a good thing.. the vortec heads will raise the compression but not a ton, the shop i delt with did some quick math on the chambers sizes etc and it still sounded like it was going to be a good deal lower then a 96+ motor.

Now that being said the next thing is the miles on the engine, If its had a hard life and has any slop in the engine if it seems detnonation it will take it out. I personaly feel that by 10psi you need a intercooler or meth injection and i personaly felt 10-12psi was going to be it for actually usable stable power. I Personly think the engine will hold 15psi IF you can get the tune right before it takes itself out but even then i think its days will be numbered not only because the first time it detonates it will take out the motor, but your talking about displacing almost 550 cubic inches under full boost though a motor with stock internals...It maybe a tough motor but i dunno i just think it would take all the reliability out of just being able to beat the daylights out of it..

Now next step, fueling it, currently i am running a built 4.3, tbi, vortec heads with work done on them, a pretty aggressive cam, headers, whole 9 years, i am running roughly 5 lbs of boost and i am running 75% duty on 2 350ci 5.7L injectors already. I plan on getting to 8-9lbs on these injectors by raising the fpr's base pressure from 14 to up to 20 if needed, these injectors can handle about 35 psi but can't take much past 90% duty, Then i'm onto cop car injector and then 454 injectors which probably won't idle worth a damn, leaving you with extra injector on a stand alone computer.. The fueling can be done though just takes more thinking, planning and time.

Basicaly because we have a 1 bar map sensor its up to other units and devices to retard timing, and adjust the fuel curve so its not lean up top or rich down low in boost....

Anyways let me know what your thinking and what you plan on doing and i'll see if i can't help out. Check out my pictures page on my sig it has the steps i went through putting together the built TBI motor with stock bottom end. Also on a side note i've been having mine shift at 5600-5800 rpms right now and soon going to 6000.. but in order to get those kinda rpms you need a good intake manifold, good heads with a little work done, good headers and y pipe and exhaust etc etc not to mention some awsome vavle springs that don't float into the high 5's...
 

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Hey i just noticed you had a 5 spd, Is you ecm under the hood on the coolant tank or under the dash. If your ecm is under he hood i only know of one place that can possibly tune that and they want 300-400 to do it, if its under the dash game on www.tbichips.com is the only place to be.
 

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Discussion Starter · #4 ·
thanks for the input

I think I rushed into things without thinking when I posted, because this truck needs to be reliable still...so I'll start off small and work up from there. I'll just keep looking around until then, to see what kinda of boost people are running on these things safely. Who knows, by then, I might just have time to rebuild the bottom end.

Of course I have a long way to go still, but I guess I'm planning for the future.

As for the last question, the ECM is under the dash. I have a buddy that can burn me a new memcal, and he might even help me tune it. But for the most part, I'll be doing the tuning, kinda trial & error till I get things right.
 

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Well on the tuning note, brian at TBI chips, on our 6-7th chip by this point and have everything pretty good but im installing meth and a bigger pully soon, so then it will be off again.. but i'll say this Its going to take ALOT of trial and error, brian has tuned supercharged TBI's before and were still having taking some time to get it all smoothed out. I have all the hardware and software to burn flashchip at my house so all we do is email the files back and forth pretty awsome deal.

On a side note my all stock 94 with 40k original miles pulled roughly 126RWHP with only 4lbs of boost on a www.wynjammer.com supercharger i was able to steadily pull mid 170's RWHP with stock everything including original clogged cat and muffler..

no idea what its pulling with my new setup but its strong i'll tell ya that ;)
 
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