I am rebuilding the engine in my '85 Vette. The block has been bored .040 over. I will be using aluminum 8113 heads from an '89 Vette. With those heads, my CR will be right around 10.4,10.5:1. I plan on using the Comp Cams XE268H-14 cam. Specs on that are 224/230 @.050 .479"/.480" lift, 114 LSA. Induction may remain mostly stock TPI for now, except for a K&N filter, descreened MAF, and taking down the EGR walls behind the TB in the plenum and maybe some porting on the runners. Exhaust will consist of ported (AIR pipes removed and taken out of tubes, flanges ground to match D-port better) stock header/manifolds, and MidAmerica true duals out to Flowmasters. I am using the Hypertech cap/coil/rotor setup and the Hypertech chip and 160* stat. Injectors are 24#. How do you guys feel it's going to run until I can get a custom tune? I know it will run with the current chip, but just how good/bad? Any hints/tips are very appreciated. TIA!

 

I know some if not most of you will say the TPI is going to be my "bottleneck". I simply can not afford to go any other route right now. So it's "run what ya got" for me for now. I just want to hear how some of you think this setup is going to perform. You guys with knowledge regarding ECMs chime in please. '85 Vettes were MAF only systems, and only measures air consumption and calculates fuel delivery based on that, so essentially it looks up a/f ratios in the fuel map based on coolant and air intake temps. Correct me if I am wrong. So even with a healthier cam reducing the manifold vacuum, all the computer will see is the engines air consumption and bases load on that. Maybe since it will be breathing a little better, I could see maybe increasing the fuel pressure a bit to give the engine more fuel throughout the load range. You guys with MAP systems..well..that is a totally different ball game..once you drop in a bigger cam and lower the vacuum, the computer instantly sees this as an increased load and then increases fuel delivery..hence, rich running car. This is all based on theory, correct me if I am wrong again, I just want to set things straight. Thanks again!

 

with a LSA of 114, you will still run decent on the current chip.

 

Thats what I am hoping for. Thanks for the reply "we tah did". Anybody else?

 

Im not sure wich will be more of a restriction, Stock exhuast or Stock Induction...

Yeah, It will probrably Run. ( walk? )

But with that Cam, Your going to give up a bit of your low End Pull, and Not pick It back up Ontop with your curent exhuast and Induction.

Why Not take the Stock TPI and hog it out, and then save your pennies for some SLP's... Then You will be moving

 

The ONLY thing stock on the exhaust is the stock "headers", and those are going to be modified. Like I said before, I'm running true duals, !CAT, out to Flows. I plan to do some work to the plenum (taking down the EGR "walls"). When you say "hog out" the intake, do you have a link to a page to show/describe what you mean? I have read good and bad about siameseing, and don't know that I trust myself to take it to that degree...haha. What I am most curious about is whether or not the "stock" Hypertech chip will be able to manage the engine well enough. Or will a reprogram be a necessity to even make it drivable? Thats why I posted the stuff about the MAF. Thanks again...

 

Personally, i think you should go with a cam that has a similiar lift and lsa #'s, but you need less duration. the stock tpi is going to disapprove of that big time...

Steve

 

You will gain about 20-25hp from porting those #113 heads. And you could open up the chambers a little too. With that much CR you will need to reduce the quench area some to avoid octane sensitivity.

Take a look at the ZZ-9 cam or the Super L98 to compare durations. You may get by with ported heads but it should be a little "loppy".

Don't worry about a chip change since you're MAF, just add an AFPR to tune fuel flow to air.

You may have some fitment problems with the '85 base & '89 heads as the bolt angles changed in late '89. But you can machine the hols to work.

The stock manifolds are shorty headers so should flow pretty well with that setup but TPIS headers will give you another 20hp.

I have a used stock base comming in tomorrow. I plan to siamese the base runners as some here and on Corvette Forum have done. I'm combining this with AS&M LT runners on my '88 Vette to push the torque curve without losing that great low end torque.