Navy_Vetteran

I have an 82, which has the original xfire system. I would like to have the car to produce the power of a modern vette, but I have heard that it’s not possible with the xfire system. Should I swap it for a modern fuel injection system/aftermarket racing carb? And how would I go about doing it? I also swapped the trans for manual TKO tremec 5-speed

71VetteLover

Buy a Renegade intake, install a 1985 pump, boost your fuel pressure to 14 psi, install a set of 3.73 gears, and have fun running with the later Vettes.

Navy_Vetteran

How much power does that add? And what other mods would I be able to to make? I’ve just heard it won’t run right if you try modding the engine with the xfire still installed

Dynra Rockets

A contemporary Corvette makes 450 hp. You will not approach that with bolt-ons to the 1982 L83 8.2:1 CR, head flow and camshaft.

Plan on a CR increase, better flowing heads and a cam change also to get near those power levels, and don't expect it to be very civil at that power level either. The easiest path to hang with a modern 'vette is to install a modern 'vette engine.

mrvette

the above is the route I followed some 20 years ago, but in them daze it was a roller 4 bolt truck block, L98 aluminum heads, and L98 induction, speed density computer...simplified the induction plumbing....got 24 mph with the muncie and 336 rear.....at 80/4000 rpm on the freeways....

since then I have a highly modified LT1 induction, with HEI up top where God intended....electrickery and water don't mix....nature is funny that way....

See pix below....

cv67

x2 youll need a bigger engine to even think of keeping up

buccaneer may be able to help you on that one he designed it and knows what it takes

OldCarBum

Find a local performance machine/speed shop. Talk to them and see what they recommend, then come back to the forum and ask "hey what do you guys think? There are several Chevy performance forums as well filled will all kinds of posts. Keep in mind the old equation that speed=tq/hp=$$$. I purchase something for my car every payday, set it up on the shelf, and keep collecting until I'll have everything needed to start my rebuild. I plan to run with the big boys as well, and when I am, I'm not going to be in the middle of the pack. I'll be one of the guys up front.

7T1vette

The CrossFire engine management system will do just fine at making power....if you install a decent cam, heads, intake system and exhaust system. You will need larger throttle bodies and open up the intake (or buy Renegade like suggested above). But there is nothing wrong with the ECM for managing it.

It's yours, so you can do whatever you want to it.

Navy_Vetteran

I appreciate all the input! Its not a common injection system, so I wasn’t sure what kind of things I would/wouldn’t be able to do with it. One other question I was concerned about, is that the computer always thinks I’m in neutral since I swapped my auto for a 5 speed manual. Are there any problems I might run into like that with the computer since it’s designed to work with the stats/specs that the engine has right now? The engine is completely original, so I have no idea if the car will run correctly with the current computer.

7T1vette

That computer also manages the transmission. With it disconnected (trans was removed), it won't know when you are in driving mode. Not sure what the best course of action should be in your case.

Perhaps get a salvaged TPI or MPI intake system and its ECM stuff from a later manual trans car and graft it to your engine.?

lionelhutz

Do not expect to change the engine significantly and have the stock programming still properly operate it. You can hope it will work, but in reality the best you could do is cobble together "fixes" that are just a compromise to make it run.

IF you decide to keep the CF intake system then you can use a later model GM TBI computer to control it. There are 2 options for under $500. You can add the ability to flash program it or you can add the ability to real time program it with an emulator.

You could also use a newer aftermarket computer to control it.

But, the stock CrossFire is restrictive and will ultimately require a lot of $$$ in upgrades to add a lot of engine power.

Here is a thread with some info on what it takes to make around 450hp with a Crossfire.

https://www.corvetteforum.com/forums...post1595404652

7T1vette

The computer regulates fuel flow according to the readings received from the O2 sensor. Simple as that. As long as the throttle control functions according to the needs of the original CrossFire system, it should work just fine. And, from what other posters have indicated over the years, it does just that.

lionelhutz

No, what the computer does is not that simple. It can compensate for small changes that add a few HP but can't compensate for significant changes. For example, don't expect to build an engine that should make 100+hp and have the EFI system still work as is.

7T1vette

If that's true, the stock system would not be able to respond properly when an idling engine is pushed to WOT instantly. But, it does that perfectly well....just like all electronically controlled engines.

The simplest swap is to larger throttle bodies/manifold; and I don't see why the stock CrossFire control system would have any problem doing that job.

lionelhutz

That's exactly why it's true. There are algorithms in the computer that see the sudden throttle change and responds to it by giving the engine the correct fuel and timing. The oxygen sensors are not even used when you stab the Accelerator pedal hard.

All the O2 sensors do is fine tune the fueling tables. Nothing more. There are limits to how much they can adjust. This is why you can make small engine changes and have it still run OK. They certainly are not the main input and have little to do with the fuel and timing adjustments that happen as you change the throttle position.

The stock computer can't be tuned. And if you build a new engine for more power then the computer must be tuned to match. Hence, you must switch computers to get one that can be tuned if you want to add any significant power to the engine.

It's become very obvious you have never spend any time learning how GM fuel injection systems work or done any type of serious engine modifications on a GM fuel injection engine. You don't seem to want to learn or accept how it works either. So, I'm now just responding so that others won't expect to make major engine changes and have their stock computer still work based on your bad advice.

silver74vette

Good comments here, the real issue with the stock injection systems (even on current corvettes) is that they use a narrow band O2 sensor that is just used for fuel trims during idle and cruise.

If you want to make power close to a modern Vette you will need to run something with specs like the ZZ6 engine (making 405 hp). If you want more you will lose drivability. The solution that will give you the most flexibility would to be one of the new TBI systems from FITech or Holley. These use a wide range O2 sensor and are self learning across the board. If you installed one of these on your stock engine they would run great, if you changed cam and heads, they would go through a learning period and then run great.

For example the Holley Sniper throttle body is rated at 800 CFM and is capable of supporting up to 650 horses.

I agree with Lionel, the Xfire system will need significant work once you really make performance mods.

Good Luck, Chris

lionelhutz

Narrowband O2 sensors are not an issue per say, having them just means the system doesn't self learn. A properly tuned newer GM computer is way more capable than a Sniper, similar to how a Sniper is way more capable than a carb.

silver74vette

I agree with you, the benefit of the Self Learning systems is that they respond well to incremental changes and do not have to be retuned for each specific engine iteration.

Since the OP has already done a trans swap I figured he did not want to go the LSx route which in my opinion is the best way to get current car power levels. GMs new modular computer systems are very nice.