keithnh

My 3rd generation is an 84 Cutlass with a carb 3.8. I have a rolling chassis to put the body on in the blast shop from a monte. I have a parts 89 z71 with the original 350. Am just wondering if my idea for an engine will work. I see that L99 cranks are still available and standard 350 pistons coupled to 6.0 long rods will give me a 3" stroke 302ci short block. Aluminum chevrolet corvette heads are not extremely expensive especially going with the slightly smaller valve configurations and 10.5/1 is achievable easily. I can also get a full camaro 350 TPI setup including computer from a friend and have shopped CC for a roller cam that has impressive torque numbers low and HP high for 302 cubes,uses a stock converter and is labeled "good fuel economy". Was wondering what I would need to integrate a turbo into a TPI setup and whether this setup would be street friendly for great fuel economy and a swift kick in the pants when hammered.

five7kid

iTrader: (14)

You're right, this isn't an Engine Swap topic.

techrunner

or a third gen one either

keithnh

Sorry I didnt notice the "F-body" in the logo of your forum. My interest was gaining insight into p's and q's of diddling with TPI conversion which I believe did originate or was at least present factory in 3rd generation F-body powertrains if they are 82- 90 something like I think they are. I am doing over my 1st tbi chevrolet small-block to replace a carb 3.8 buick in an oldsmobile trying to successfully convert to tpi and possibly add a turbo, that is a motor swap in my book. I have had input from 57kid I believe in another forum which I appreciated concerning this subject. Im not on the computer alot, I keep hoping to find someone who's done this already with similar goals. Sorry if you feel I bent your rules. I still would appreciate input on the subject your members may have and might like to share.

Drac0nic

If you're thinking turbo try theturboforums.com. Look for a guy named turbo355. With that being said, you're probably looking at custom pistons if you use the 6" rods. Just be prepared for it is all. Overall a pretty cool project idea, with how common roller cams are these days I'd expect to have a bit of bank in the valvetrain to get it to rev the way you'll want but it should be a screamer. Besides that, I'd consider doing something other than the L98 heads unless you get a deal on them. Paying $600+ for a set of them is probably poor economy with the heads that are out there.

Turbo wise, I'd be looking at something like a T70 or T76. An S400 if you want big power and are willing to pay the price in spool is another option but for streetability either of the former would be a great choice probably depending on your heads/cam/RPMs.

five7kid

iTrader: (14)

There may be sufficient 3rd gen related details to warrant discussion in the Power Adder forum. I'll let the mods of that forum decide.

keithnh

Thanks for moving my post to a possibly more appropriate spot. I am interested in TPI conversion from a 1989 TBI pickup motor (350) possibly adding a turbo either initially or once the straight TPI is debugged on my platform. Was there ever a factory offering of SBC+TPI+Turbo in 3GF powertrains?? The computer and parts would be a good place to start for me possibly. Might be in vettes of 3GF vintage also ?? Or particularly good aftermarket setups for TPI?
Numbers I used for rotating assy parts was factory deck height 9.025 = 5.7(Rod c-c)+3.48/2(Stroke)+1.56(CH 350 piston) with piston .025 down bore at TDC. If I make a 302 with L99 crank and long Scat I-s I have 6.0+3.00/2+1.56=9.060 ... with piston top at deck + .035. I will most likely use TRW forged pistons which can be milled that range easily for a custom fit 0-deck. I hope these numbers are accurate ... there is a little more slop available in the piston tops if they are. I would want a flush deck to maximize compression for the smaller displacement.
I like the weight savings of aluminum heads and factory would at least be tried and true, Im not sure about the intake side of SBC heads for TPI, are they TPI specific?
My 89 Chev truck motor may be factory roller cam ... I can get the HP SBC roller cam NOS from a friend who will help me plumb the turbo, he knows superchargers, but am not sure it would be as street friendly as the cc cam I am looking at. I figure most of the bank will be heads and cam.

ZZ3Astro

You can't go wrong with a TPI + turbo. Considering how well TPI 305's have done in the past with boost, I think the 302 combo would do great.

There were never any turbo V8 powertrains in 3rd gen F bodies but there was the Callaway corvette (RPO B2K) but that was a conversion done in between the factory build and dealer delivery. As I understand it, that setup ran a mostly stock TPI MAF system, but with a modifed BIN for timing. Boost fueling was supplemented by an added box controlling additional injector(s) located ahead of the throttle body.

As far as your options for electronics, you only need search the power adder forum for 'turbo tpi' to start reading! I personally used a Megasquirt and some others use a modified BIN in the factory ECM.

keithnh

Wow, thanks for that , great to find someone running a setup similar to what Im planning. I have the luxury of a friend who does accessory and conventional superchargers, he does mainly ford and before he blew it to smithers had a pretty green supercharged Ford 302 doing consistent 10's at New England Dragway. My car will not be a drag car, I just want something a little wild for the street that gets good mileage and shocks people a bit when hammered. I was hoping the turbo would give me grunt where the 302 will fall short between 1000-3500 RPM. I dont know what MAF and BIN mean I guess I have more reading to do. I know from driving a truck that my N14 turbo diesel adds grunt and boosts up to 40PSI, thats what the gauge says anyway I also know my TBI 350 in my 90 Z71 runs crappy when the exhaust leaks ( Ive been through 3) and is probably because the sensors dont get the right info to adjust the fuel mixture properly. When exhaust is tight its a different truck with ***** even at 180K. I guess in the absence of additional boost injectors the turbo addition would be dependent on the computer to report improper fuel mixture for extra fuel to be delivered in boost mode, Im already asking it to adjust fuel delivery down from 350 to 302, it might not be that smart. I got a textbook on turbo to read I better finish that. Thanks alot for your input Keith

keithnh

Was wondering about RPM limitations with TPI setup and googled a question " will TPI rev to 7000 rpm" or something like that and hit a post "Non-ecm TPI this will trip you out" . The guy said he was shifting at 6500RPM with his 305 TPI rock-stock wonder killing every car that tried him. I read through the posts trying to aswer my own question and came to the conclusion that most factory TPI engines are making power to about 5000RPM only for some reason although they will rev more. I had been researching heads and was considering factory Vortec which appear to need scary modifications to accomodate the TPI induction. I found a manifold specially designed to mate the 2, (Vortec and TPI) which builds gobs of torque low but HP peak is 4800 (Daggett-Scoggin) which seems to support TPI poops a little early for my preference. I would at least like to be able to make power to 6500 and was wondering whether the pooping is for real and is it because of flow restriction in the base and runners or the injectors just cant squirt well that fast or the computer needs a perf chip upgrade or ??. I know the CC roller cam Im looking at in Cam Quest (262fxi)makes peak torque with 302 Chev @2500 and peak HP at 7000 with 600cfm/factory TPI/large tube headers/and Garret 40mm turbo/factory HP heads spec'd torque about 480 and hp about 520. That may be all wet I dont know. Scratch that ... made boo-boo in valve sizes (exhaust valve will be 1.6 not 1.9) and flipped hp and torque numbers ... Cam Quest does stay lower in RPM even with turbo ... RPM numbers do go higher with fully ported heads ... I see sets on Ebay from "Pro-Comp" for 600$ ready to bolt on ... I would assume they are unported in this $ range. Edelbrocks are double the money ... maybe they are fully ported ??

Non turbo 260 xfi roller torque 432 @ 2500 hp peak 346 @ 5000
Above + Garrett 40mm 563 @ 2500 466 @ 5500

keithnh

Noticed on Comp Cams cam quest that for my 302 plan that stock tbi and vortec hp and torque curves were higher than stock tpi all other things equal with various inputs. My truck motor is already tbi. If I think about it tbi has 2 injectors and tpi and vortec both 8. One of my main goals was to try to get mileage as well as performance. If 2 injectors gives me middle power and better mileage maybe it would be a good idea to try to embellish the factory tbi with a performer rpm or weiand x-celerator manifold and transdapt adaptor, one is single plane and one dual. I wonder has anyone here tried that to what effect??