Hey guys I need some opionions or advice. I'm gathering parts for an engine build for my 84 crossfire vette and so far I've accumulated a set of Patriot Performance Alum. Cyl heads (190 cc runner, 64 cc combustion chamber). Offy crossram intake base with custom top plate for throttle bodies. 2.13" bored throttle bodies. 7747 Ecm with h.a.m., prominator, and embedded lockers software from dynamic efi. I haven't purchased yet but I also plan on running 454 tbi injectors and a 85 corvette fuel pump. The short block I plan on using is an 010 block .060 over with trw forged pistons (10.63:1 with 64cc head). First of all anyone see any issues with any of my components? I'm worried that the cylinder heads are too large and might kill low speed power? What ya think? Also what camshaft should I run. I like the XFI flat tapped cams from Comp cams, just not sure which grind to go with. This car isn't a daily driver and might see a little track time. The car is an automatic with 3.07 gears and 2500 rpm stall.

Mark

 

I guess the first question is how much power do you want to make? You want to pick the smallest cam that will meet your goal. Set your HP goal and call a couple of cam hotlines and see what they recommend. Come back and let us know what they say and I'm sure others can chime in on their experiences with certain grinds.

As for the size of the intake port on your heads, it seems fine to me for a reasonably mild build or better. I would be more worried about the low mixture velocity in the Offy crossram intake base.

The compression ratio seems a little high, any way to get it closer to 10:1 or just below? You may need a bigger cam with a narrow LSA in order to bleed off excess cylinder pressure at low RPMs to aviod detonation. EFI doesn't like a narrow LSA because it causes vacuum fluctuations at low RPM - makes the engine harder to tune.

also consider whether you need forged pistons. If not running nitrous or a blower, quality cast pistons could save you a few bucks - use the savings somewhere else in your build.

 

XE 262 H. 218/224 @ .05. 114 LSA

Quote: Offy crossram intake base with custom top plate for throttle bodies.

I would rethink that. I believe the cross section and runnner volume is huge. Better fit for 383+++ cid. Often used to replace the CF manifold that was poor on flow #'s. It was available and worked for the TB configeration with new top plate. That will give you a max challenge in tuning car. It will require a large AE aka pump shot. Same with 2.13 TB. 2.00 TB is a better idea. Will be easier if the heads/manifold has coolant crossover. 190 cc are not terribly large. 180cc would be better ans and easier to tune. Velocity is as important.

Add IAT control. That will help when manifold is cool. Or air temps cooler.

I am sure you are aware of the Renegade manifold. That with 2.00 TB's would be my choice. Actually I would go port fuel but that is just me.

 

Yeah, That renegade manifold looks like a nice piece. I bought my setup off another crossfire injection forum member a few years ago before that intake was being developed. You're right the runner volume is HUGE on the offy and I really could use some more cubic inches with this setup, but thats not in the cards right now. I think I might sell offy setup and get me a renegade and some 2" throttle bodies.

If anyone is interested in the offy setup let me know. It comes with the offy base, custom lid, 2.13" throttle bodies with custom made throttle shaft seals for turbo or supercharged blow through system, Custom Throttle body cover for blow through setup, and a modified windshield wiper motor (required to clear the intake in vette's). Here is a link to the builder's website: http://jobyteknik.homeip.net/corvett..._installation/

 

XE262 sounds good. I certainly wouldn't go much past that - a 268 maybe.

I'll be upgrading from an X-Ram to the Renegade fairly soon too.

 

Do you guys think my intake and throttle bodies would be better suited for a 400 sbc? I found a deal on craigslist.

I've heard the 400's don't have a provision for a knock sensor. Is this true?

 

I have a knock sensor on my 400 (70's wagon/truck block) but given that I'm throwing code 43 all day, I'm unsure if it's the correctone. It's for a 5.7l (350ci)
... haven't found one yet listed for a 400, but still looking.