I have an 87 gta with the L98 350. I have purchased the TPI head and intake kit from SDPC. it is vortec heads with the new vortec intake. they said you will get 300 hp with this kit using the stock computer and no other mods other than headers. well i put headers, the heads, intake, air foil, 1.6 rocker arms, push rods, modified maf sensor and the car doesnt fell any better than it did before i did all the work. the only thing i dont have is a cold air intake. i still have the stock air intake. has anyone bought and use this kit before and if so, did you get the gains as advertised. i am puzzled. i dont know what to do next or how or what to check. please give me insight.

 

The 300 Hp was with a free flowing exhaust and a decent bottom end. Compression will play a role. How many miles are on the bottom end? All though other things may be a factor IMHO I would have done a compression test before slaping some heads and an intake on. Timing chain, with much abuse, could be streched as well.

I saw you didnt list a change from the cat back either. That will be a restriction.
Additionally, I would have done a cam change as well. Taking in to consideration that the bottom end was in good shape.

I have the same intake with a freshened bottom end, cam, runners, some port work and exhaust and am quite pleased with the results.

Just my

 

I did a compression check and read 150-155 on all cylinders. i also did a fuel pressure check and it was at 38-40 psi. I am getting a new air intake because i have the stock air box and plan on getting a new cat back system. any suggestion on the cat back. what is the best or what is the best bang for the buck.

 

Your fuel pressure is to low. Factory is 43-45. For performance try 48. Make sure you unhook the vacuum line to the regulator before you set it. You do have an adjustable fuel pressure regulator don't you?

 

I got mine started today and so far I like it. I'm running 1.6/1.5 int/ext Trickflow full rollers and it seems good so far.

 

Do you have a link to thier claim? I don't see how (based on an L98) heads, base intake and headers will pump you up another 70 hp .

You sure they didn't test with a different cam...then added thier stuff and "wallah"?

 

SDPC Vortec TPI

That what you were looking for?

 

That's impressive, I didn't think the L98 cam had eough in it to make that much HP.

 

i have a ticking sound on the top end. i am sure it is coming from the injectors. i checked the timing and my timing keeps on jumping from 4 degrees below tdc to 8 degrees below tdc. i tried to reset it and unpluged the est wire and adjusted the timing but couldnt get it to stop jumping. i dont understand why it is doing that. this is all at idle speed. the idle does jump sometimes. any answers?