Ok here is the deal, a buddy of mine can pull my 56,000 mile 350TPI in my IROC and stoke it to a 383 for around $500. My question is, can I still run my stock L98 heads and all the intake equipment if i get them ported and polished, which will only add about $100 to the total? If so do they need to be gasket matched? Also with the 383 will I have to upgrade the prom and if so which company makes the best chip for me to use? Another thing....the 383 will probably run about 10:1 and I'm wondering what the CR is on my stock 350? I know right know that I can run 87 octane fuel with no problem and get pretty good performance, but will the 383 run on 87? And lastly will it pass smog? I live in California and obvioulsy it must pass...I plan to leave the cat on it but should it pass? Thanks in advance.

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1989 IROCZ28, 5.7 liter TPI, 700R-4, 2.77 Rear, Gutted Air Boxes, Flowmaster 80 series muffler with dual 3 1/2" tips, Clarion 8575 Head, Infintiy Kappa 4x6 plates, Stock 6x9's, Alumapro 10" Aluminum Sub in sealed box, Orion 400 watt amp

 

Anyone else? I know there has to be someone out there who has done this...


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1989 IROCZ28, 5.7 liter TPI, 700R-4, 2.77 Rear, Gutted Air Boxes, Flowmaster 80 series muffler with dual 3 1/2" tips, Clarion 8575 Head, Infintiy Kappa 4x6 plates, Stock 6x9's, Alumapro 10" Aluminum Sub in sealed box, Orion 400 watt amp

 

Remember that your newly stroked engine will now be a torquer with the TPI. Your stock TPI will doubtless choke quite a bit of the performance out of that engine. Consider getting an aftermarket base, aftermarket runners, and a ported plenum. Get that stuff before you get any bigger injectors or throttle body.

Personally, I've been playing around with SLP siamesed runners. There's a lot of misinformation on these pieces; most people are simply installing them without considering the changes required to make them work. Check out: http://www.isthq.com/~dan/efi.html on some ideas for making the most of your TPI to help the 383 breathe. You'll want a fairly mild cam; something like 214/224 degrees duration at .050" lift, max. Keep the LSA at 112 degrees.


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Daniel Burk
http://www.isthq.com/~dan/fcar.html
'84 Trans Am WS6/L69
KB SFC, Moser axles, Torsen Diff. PST suspension, Braided stainless brake lines, Koni struts, 11-inch rear disks,Spohn Adj. torque arm,
Ported 305 heads w/1.94"intake valves, Comp Cams XE262H, Griffen alum. radiator,
Turbine Technologies 2500 stall converter, underdrive pulleys, Crane Hi-6 & more.
1.05g skidpad verified.
New best E/T! 14.039 at 100.82 MPH in 41 degree air at Stanton, Michigan.

 

You should have no problems swapping over your current intake system,including heads. Any extra flow you con get out of it will help your new combo(porting and gasket matching). As far as other parts you will need balancer from 400sb,and flex plate also from 400sb. A chip matched to your combo would also help, I dont know if this is mandatory but I know it would help performance wise.
I think with your knock sensor you could probably get away with 87 but performance would suck,it would kind of make that 10 to 1 comp. ratio a waste. As far as emmissions go as long as you dont go to wild on your cam choice I dont think it would be a problem. We dont have any emissions around here so I dont know for sure. One other thing to watch for is you may also need a new starter.

 

I'm running stock chip with mine (it would run better with a custom one, but I'm trying to see how far I can go as is). Is your friend using a 400 crank or is it a SCAT or equivalent stroker crank. With the latter you don't need to use a 400 balancer or flexplate. On mine, I've the stock flexplate and balancer and I had it internally balanced ($50 cost). It looks just like any other 350 sitting out there without giving away that it has been stroked.

So far, it has ran a best of 13.2 at 105.48 with the computer pulling out 12 -15 deg of timing right in the middle of my powerband (2400 -4000 rpms). I finally got that fixed, only to have the tranny frag as I was on my way to the track (still ran a 13.6 at 99mph coasting from the '1000 ft mark).

Your stock TPI stuff will choke some of the performance, but you will still have a stout car.

Sparks a flyin'