I have a heavily-modded L-98 that I am going to install in a ‘91 Corvette. I’ve added a D1 to it due to the engine’s higher rev ability and sturdiness. The engine has a static C/R of 8:1, which various articles suggested was optimal for a street car. So, my question is, how much boost can I reasonably expect given belt slippage, flex in the system, and the parasitic draw to turn the D1? ProCharger’s own literature says 10psi in one place and 23psi in another! I don’t terribly worried about it, but I would like to have a ballpark idea what to expect. #ad

 

The pulley is a 6-rib, 3-incher. We’re 475ft above sea level. The intake is a TPIS Mini-Ram. Injectors are Ford 42# “Green Tops” with a 58mm B&K throttle body. Ignition is all MSD CD. As it stands right now, the C/R is somewhere between 8.69:1 and 9.19:1, depending in the thickness of the compressed head gasket, which I don’t know for sure. I made a math error when I stated it was only 8:1.

 

From Day One, the engine was build to accommodate the D1. Even the bottom end had splayed 4-bolt main caps added. The heads, which are studed, are reworked aluminum L98 that were on the engine originally. Roller rockers (1.5:1) are Comp Cams Pro Magnum. The cam is a Bullet Ultradyne with the following specs:
Effective lift on both valves— .530”
Duration @ 0.050” — In. is 230* and Ex. is 238*
Lobe Separation — 112*
Intake Center Line — 108* installed @ 108*•

I pretty well spec-ed this build myself based on a lot of research and some “common sense!”

 

It’s going in a ‘91 Corvette, the same car it came out of. Fuel is provided by a Walboro (sp?) super in-tank pump. Ignition is all MSD CD controlled by the factory ECM with an Edd Wright chip programmed around the same parameters I’ve given you. Besides the intercoolers, I designed a water/meth injection system with dual squirters that that are operated by a programmable controller. In the few square inches of space left, I’m running a dual canister oil/air separator system. The extra under-hood space was found by converting to a Hydroboost brake system, which saved space and will match woh with go. Needless to say, changing sparkplugs will be a weekend job!

 

Good thing to not worry about the boost number. What really counts is the % of max blower speed. My 455 runs about 90% of max blower rpm. On the stock D-1 it ran between 10 and 11 psi. Since I had it rebuilt and modified it gets closer to twelve. I might be a little worried about only 42 pound injectors. I can only relate my experience but the 455 runs 80 # injectors and I am worried about maxing them out with the new heads.

 

80# injectors? Wow, I thought 42s were the largest made! Thanks for your input. Out of curiosity,” what was your C/R when pulling 10-11#? I’ve read a few posts that say belt slippage prevents more than about 6-8#, which would greatly disappoint me.

 

With the iron head it is about 9,25:1 Belt slip is not a problem with a 12 rib setup. I use a Fitech FI that comes with 8 80# injectors. It is rated for 1200 hp NA. There is not a rating for blow through. Do not think that my current motor needs more injector but the new one may. On our GN we have put in 60# injectors. Probably overkill for that one but never have to worry about fuel.

 

Here is a calculator for injector size: https://www.deatschwerks.com/fuel-calculators/fuel-injector-calculator I did a calculation for 900 hp and 85% duty cycle and came up with 73# injectors. So the 80's that I have are almost marginal.