Crossfire conversion
Thread Starter
Heel & Toe
Joined: Jun 2001
Posts: 19
Likes: 0
From: Middletown, Ohio
Crossfire conversion
Has anyone converted from the misfire FI to a 4bbl, kept the computer, and lived to tell about it? It looks pretty straight forward w/ the exception of the TPS input...also not sure about a fuel pressure regulator or using the FI fuel return line.
Drifting
Joined: Nov 2001
Posts: 1,498
Likes: 0
From: Bucks county Pa
Re: Crossfire conversion (82 2-tone)
I did in an 82 but I was using a Turbo 350 trans. I left the harness intact underhood and computer in. I used stock feul pump with in-line reg and stock return line. In an 84 I would leave it F.I. unless it was broke or missing. Just throwing a 4 bbl on a L83 wont be a substantial improvement and wont have the drivability of feul injection. Plus you need to consider the dash the trans converter lockup etc. JMHO :)
Drifting
Joined: Aug 2000
Posts: 1,251
Likes: 0
Re: Crossfire conversion (82 2-tone)
Ive an 84 thats all stock.Ive often thought about changing intakes.
Weve got to think about hood clearance & where it gets air.
Does yours get air thru the hoos like the 84?
You can get a TPS for some carburators.
You deffenatly will need a fuel regulator.
There should also be a return line fitting.Ask were your buying the carb.
What are you gonna go to?
Why not a newer F.I. unit?
Weve got to think about hood clearance & where it gets air.
Does yours get air thru the hoos like the 84?
You can get a TPS for some carburators.
You deffenatly will need a fuel regulator.
There should also be a return line fitting.Ask were your buying the carb.
What are you gonna go to?
Why not a newer F.I. unit?
Le Mans Master
Joined: Jul 2001
Posts: 5,297
Likes: 0
From: Stamford VT
Re: Crossfire conversion (bogus)
Does the ceasefire system use the same/similar ECM as the later throttlebody cars? If so... you might be able to swap in a TPI setup and piggyback an aftermarket TPI controller designed to use the tbi computer. Of course, if you're going to do all that... you might as well just swap in the proper TPI ecm. Nevermind. :lol:
Le Mans Master
Joined: Jul 2001
Posts: 5,297
Likes: 0
From: Stamford VT
Re: Crossfire conversion (Jim85IROC)
1 more thing... there are converter lockup modules designed to work with non computer-controlled carbs. Anybody with an older car that's running a big holley and a 700R4 has one. They're about $60 and work on vacuum.
Melting Slicks
Joined: Nov 2000
Posts: 3,388
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From: X
Team Owner
Joined: Sep 2001
Posts: 62,128
Likes: 1,727
From: Athens AL
C7 of the Year - Unmodified Finalist 2021
C4 of Year Finalist (performance mods) 2019
Re: Crossfire conversion (JonM)
you should look at the Xram, and talk to the guys at the Crossfire Vault
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Burning Brakes
Joined: Apr 2001
Posts: 904
Likes: 0
From: Langley, BC, Canada
Re: Crossfire conversion (vader86)
changing to a carb will gain you little power and you'll loose torque, unless you are planning on doing some serious mods to the engine. Get an xram, have the tbis bored out and it'll perform better than a carb. Dan on the crossfire forum can bore them to flow 750cfm for a few hundred.
Guest
Posts: n/a
Re: Crossfire conversion (82 2-tone)
I had a 86 Camaro that had an ECM/Electronic Rochester Carb. It was on a 305 and netted 186 HP or something like that. I wouldn't think a carb change would do that much unless you modified the engine too. There have been a few guys gone to carb and modify the engine that have posted some pretty good numbers. Try the crossfire forum guys for low cost alternatives, moving to later FI is quite a job and pricey. If you go later FI, I can help, let me know.
Mark
Mark
Thread Starter
Heel & Toe
Joined: Jun 2001
Posts: 19
Likes: 0
From: Middletown, Ohio
Re: Crossfire conversion (nobodyunknown)
I think a "dropped" air filter (from Summit and others) may do the trick..a TPI is probably the way to go (but probably a royal PITA to adapt...and I've got a 'puter already) and I'll consider that on another short block w/ more compression and a little better cam; however, I think a 600 CFM on the right short block and a "loose" torque converter may be capable of 300 hp or so. The cam required for this is probably a little too lopey for an automatic, but if you have the right torque converter, then..with the rear end ratio we have...sounds like a lotta tickets.. Who has the TPS for a carb?? that may save the fabrication time..I haven't contacted Holley yet to see if there is a return fitting that will work. I'm hoping that the lo-pressure FI pump we have won't be too much for the needle valve in the carb and if it is, regulators are pretty cheap...
Burning Brakes
Joined: Apr 2001
Posts: 904
Likes: 0
From: Langley, BC, Canada
Re: Crossfire conversion (82 2-tone)
I dont understand why you want to use the tps on a carb. Just get a vacuum advance distrib and a lockup kit for the tranny and toss the ecm in the garbage. If 300hp is your goal thats simple enough with a cam and head swap on the stock engine. Dont butcher it if you dont have to.
Also the stock pump puts out to much pressure 14psi a carb wont like that.
Also the stock pump puts out to much pressure 14psi a carb wont like that.
Thread Starter
Heel & Toe
Joined: Jun 2001
Posts: 19
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From: Middletown, Ohio
Re: Crossfire conversion (nsimmons)
I agree...but it's not power I'm after right now...Chevy (and Ronnie) blessed us with an engine with the compression ratio of a worn-out Yugo, and a rear end ratio that makes 25 mpg seem reasonable. This effort is to start w/ what hurts the worst first, increase the fun-factor, and then have an intake that will transfer to a 350 the way it should have been done (and was done in earlier years)
Thread Starter
Heel & Toe
Joined: Jun 2001
Posts: 19
Likes: 0
From: Middletown, Ohio
Re: Crossfire conversion (nsimmons)
Knock sensing.....good...especially with the swill that passes for fuel in Ohio. Yep, I agree that an HEI w/ advance and a lockup would work...but I think the pieces are there to make a go of it with the only thing the computer is probably good for...pulling the timing back and (w/ the hypertech chip in it) leaving the lockup RPM where it won't be constantly locking and unlocking.
Burning Brakes
Joined: Apr 2001
Posts: 904
Likes: 0
From: Langley, BC, Canada
Re: Crossfire conversion (82 2-tone)
check the gmefi section on http://www.diy-efi.org
i think there some articles about retaining the computer for lockup and ignition. I would suggest using a 7747 ecm from a pickup. It will splice in and you'll be able to modify the spark curve via the eprom yourself. One problem the ecm might go into shock from half of it being disconnected, and run in backup mode which will kill your timing. You'll need to retain all the sensors, and just disconnect the fuel injectors.
i think there some articles about retaining the computer for lockup and ignition. I would suggest using a 7747 ecm from a pickup. It will splice in and you'll be able to modify the spark curve via the eprom yourself. One problem the ecm might go into shock from half of it being disconnected, and run in backup mode which will kill your timing. You'll need to retain all the sensors, and just disconnect the fuel injectors.
Thread Starter
Heel & Toe
Joined: Jun 2001
Posts: 19
Likes: 0
From: Middletown, Ohio
Re: Crossfire conversion (nsimmons)
I cant help but think the stock ECM with all if the inputs (including TPS) would do the trick. The outputs to the TBI's are (to the best of my knowledge) "dumb" in that the ECM receives nothing back from them...like the EGR, vapor purge, and "fresh air" solenoid. If hypertech went to all the trouble to burn a performance PROM, why not use it?
Thread Starter
Heel & Toe
Joined: Jun 2001
Posts: 19
Likes: 0
From: Middletown, Ohio
Re: Crossfire conversion (nsimmons)
boy, that's strange to hear that a chip that increases the lockup RPM and provides a more aggressive timing profile (using RPM and MAP as inputs) would make a car slow down. My experience, especially at wide-open throttle(s) is just the opposite. One thing I have noticed though is that the engine is much more sensitive to fuel octane. Even with our somewhat pathetic 8.0:1 compression ratio, with old or under-octane fuel, you can still get pre-ignition with the timing map that Hypertech uses. I'm not sure how much advance is pulled out by the knock sensor, but it is noticable. Their "cold engine" chip (160F thermostat) seems way more forgiving...I guess if all else fails, just dump more fuel in the mix. Have you ever seen a compsrison of the 2 chips?
Burning Brakes
Joined: Apr 2001
Posts: 904
Likes: 0
From: Langley, BC, Canada
Re: Crossfire conversion (82 2-tone)
on the crossfire forum we have members who documented a loss at the strip with the hypertech, and then a gain with the stock and even more gain with the ads, you'll have to ask i dont remember who is was
