ok right now i have an all stock 350 TBI w/ 87k on the ticker in my 94 silverado. this summer im looking to build a 383 following a design a friend of my dad's came up with.

this setup he has running in his 88 4x4 suburban (the big heavy, SFA solid chuck of steel model) dyno'd at approx 360 fwhp and 460 ft lbs. it also averaged 14-15mpg on the freeway before he had the torque converter replaced, which at the time was way off. this was all on the stock 350 TBI, just bored out to 2".

anyway, this engine will go in my truck, so i need the torque down low. obviously id like to squeak every bit of power and fuel economy out of this engine as possible and i think i have 3 options as far as an injection setup:

1) TBI
2) TPI
3) LT1

ive been told TPI will be illegal for emissions as i am in CA and they do a visual and TPI was never put on cars after 92. However if it came down to TPI being the best bet then i know a few places i could get by.

me and my dad plan to build this engine ourselves, just ship out the block for machine work and the heads for porting to a guy he knows who does a lot of the heads for drag guys. id also like to try my hand at burning my own chips.

all this said, what would you guys recommend for injection? stick to my TBI stuff, or upgrade? Will i see beneficial gains across the board with either TPI or the LT1 setup? Is the cost worth the rewards? Could i upgrade to option 2 or 3 at a later time without much fuss?

thanks

 

Well I think you should rule out the Lt1. That conversion is not very easy because the manifold doesnt have a hole for the distributor and its made for a reverse cooling flow engine. You could keep tbi and make decent power if you get really good at burning chips. If I were you I would go with a high flow tpi setup like the holley stealth ram, you can make killer torque with out sacrificing upper RPM horsepower and the chips arent very hard to tune and there are many people who can do it. dont try to just slap on a stock tpi setup because the stock manifold and runners wont handle more than 300 hp. Good Luck.

 

Being in an "enhanced" area in CA as you seem to be, I guess that pretty much rules out TPI (age), Stealth Ram (no EGR), converted LT1 (no egr), etc. etc. etc. You could put an actual LT1 induction in it with all of the necessary goodies, but that seems like a massive headache and expense, on top of the 383 short block.

I'm afraid you're pretty much stuck with what you've got. Probably the best thing you could do would be to get a single-plane intake with a CARB #, which the only one I know of is a certain model of Holley Stealth; and use a TBI to 4-barrel adapter. Rather than fooling around with boring stuff out, seems like it woudl be easier to jsut slap a TB from 454 on it.

I would not recommend just building whatever you feel like and hoping the inspection problem will take care of itself. Considering the penalties out there for falsely certifying cars, I wouldn't ask anyone to do that for me. You're asking somebody to put their ability to do business on the line.

 

so a complete LT1 swapshould be ruled out as well? I know a guy over on Fullsizechevy.com that has swapped a complete LT1 induction setup onto his 383 (originally TBI) and he was it was some machine work but not too bad.

I've heard that the LT1 system is better for a higher revving motor though, is this true? If TBI is actually better suited for my lower revving, high torque goal then ill stick with it. However if i could pull similar hp/torque #'s and maybe increase a MPG or two, that would be sweet.

also, are there absolutely zero loopholes as far as swapping TPI on there? seems kind of ridiculous considering you could probably pull better sniffer tests with a well Tuned TPI, effectively making your engine more environment friendly.

 

From my admittedly limited experience when I lived in CA in an "enhanced" area, I would say that you have as much chance of getting a system approved that was discontinued in 92 installed into a 94 vehicle, as keeping a snowball solid in Hell. The actual numbers don't really matter, although you're probably right that a port system could be made quite a bit cleaner than a TBI.

I wouldn't "rule out" doing the LT1; all I'm saying is, economically, it's probably not very attractive. And, it does somewhat move the torque band upwards in RPMs; but it's hard to say whether that's good or bad.

 

well, i suppose in my case shifting the powerband up the rpm range is bad. its a truck, right now on 33"s but that will soon be 36"s, then 38"s after that. we tow with it sometimes, so that's a factor too. if i could still keep very respectable torque down low then it would be worth it i think, but if its just going to shift everything without much of a benefit then i think i will pass.