On a 1984 C4 with the cross ram FI, what is a better FI system complete. :o

 

Ok where is Frizle? he'll know

 

Present and accounted for Sarge.

Before I answer, I need to know two things of the OP:

1. What your budget is. Speed = $$$. How fast do you want to go?
2. What you performance goals are for the car, and what you will use it for primarily. Daily driver? Weekend track duty from time to time? Autocross? All out quarter mile warrior?

Also....I guess a third question....Do you have emissions testing in your area, and do you want to keep it emissions compliant?

Answers will range from a ported CFI manifold, X-Ram, cam & heads, headers and exhaust, aftermarket EFI, carburetor, etc. No single answer is right for everyone.

 

My son's C4, he will use it for a DD. I was thinking about a tuned port system. The car may get heads,cam,headers later in the build.

 

OK....daily driver, just want more power, right? Here we go.....Maximizing your Crossfire 101 by Frizlefrak.

For now, at least, skip the Tuned Port. You will gain little, if anything, on a stock long block. It will be a lot of work for little benefit. Start with the following;

Port the crossfire intake. Time consuming, but essentially free. Pick up a spare intake on eBay so there is little downtime. There are dozens of articles here and on the Crossfire Injection Forum (which you should join, if you haven't already) on how to port the intake. Essentially, glue a gasket to the head mating surface so you don't gouge anything, get a die grinder, and open the ports to match the gasket (you'll see what I mean....the crossfire intake is VERY restrictive.

This mod alone, done correctly on a properly tuned engine will get you into early TPI territory power wise.....probably better, since half the early TPI's probably aren't tuned correctly any more.

While you have it apart, do a full tune up....plugs, wires, cap and rotor, and all filters. When you reassemble the intake, balance the throttle bodies. The instructions are in the factory service manual as well as the Haynes. You will need to buy or build a manometer to do so....very simple and cheap to just make one. And if the engine has over 100K on it, CHANGE THE TIMING CHAIN and gears. I can't emphasize this enough. A sloppy timing set will cost you timing advance, and power. A new timing chain will result in better timing, smoother idle, better vacuum signal, and an overall happier engine. When that's done, set the BASE ignition timing to 10 degrees. If no detonation, leave it there. If it pings, back it down to 8...or 6 if necessary. Don't forget to reset the TPS when you're done.

The Crossfire isn't a bad system, it's just restrictive. So is the TPI by the way. Hog out the intake, balance the throttle bodies, change the timing set, tune the engine, and be amazed at the difference. Now you have a system that operates properly, and breathes better. Headers and exhaust can be next....and we all know what happens then....the mods keep going. And going. And going. CFI-EFI has a Crossfire that runs 13.9 on the stock 160K mile long block. All he's done is intake porting, exhaust, and torque converter.

Happy wrenching

 

Friz, one of these days I'll beat you to delivering the CFI info....probably not

 

You will.....And you'll probably do a better job explaining it than me too.

 

Thanks for the info, sounds like I need to work with what is there rather than replace parts

 

Yep. Dial in the tune first, then mod. Also, check your fuel pressure (not easy on a crossfire....check my profile on how to mod the setup to make checking FP easy). The crossfire "likes" around 12-14 psi to run correctly. They will run on less, but it will cost you power. Upgrade to an 85 fuel pump if yours is getting weak.

And really, you'll be surprised how much power is still on the table. I'm a big advocate of maximizing everything you have before deciding to spend a lot on mods. I've seen people put a ton of money into mods to make their car go fast, when the timing set has 140K on it and they're losing 6 degrees of timing advance.....and they're down 10 psi on fuel pressure.

I've driven some stock early L98's that my 150K mile Crossfire would mop up just because my car is tuned correctly and theirs isn't. I'm not even running a ported intake....my only "mod" is 10 degrees of base timing, 85 fuel pump, and correctly balanced throttle bodies. These cars were probably down 20% on power just from being out of tune.

If you want to make it fun, dyno the car before you do anything....then do the stuff I outlined above and dyno it again. Bet you'll like what you see.

 

Yeah, you've got a solid foundation. Do some research and have some fun waking that crossfire up. I got my '84 in July and have tuned it and made sure everything was running properly (which it wasn't), now I've spent the winter in the garage doing some mods and having fun learning about my car. Just take care of the basics first...we're here for you too!

 

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