How hard is it to put a LT1 into a 1991 L98 C4?

 

Why would you want to do that, basically a 350 is a 350, what you need to do is begin upgrading intake and exhaust on what you got and maybe a good cam designed for what your going to do with the car. There's alot of potential in what you've got.

 

There is, but the LT1 is a great starting point for that, and brings with it more modern engine management software - faster more reliable and smoother!

If you install a 1994-1995, you still get ODBI complaince, but, you also get sequential injection and the ability to program it with a handheld device.

If you are concerned about these things, the LT1 comes with a MUCH more effiecent exhaust system. I mean... dual cats, resonator and such, versus the L98 system that is much more restrictive and, depending on state, UNCHANGEABLE. The EPA mandates that if you change the engine in car, it must meet the requirements of either the year built (original) or that of a newer engine.

How this works: You have a 1988 (example), and want to install a 1994 engine. To start with, you need the ECM, harness and perhaps the CCM (I am still working this one out). You also get the use the entire exhaust design as a basis for the new exhaust. The upside to all of this is the newer electronics and such.

If you are running a 700R4, this is a good time to upgrade to 4L60E. They are completely electronically controlled.

The end result? SEFI based LT1s can get 30mpg highway. You would NEVER get those numbers on the average L98.

The LT1 starts at 300hp... from there, it's whatever you want. Add 1.6:1 rockers, a mild cam and some hand porting, and you have well over 350~360hp. Without effecting drivability (or mileage if you are so inclined).

Keep in mind that the new Z06 (all 7 litres of it!) gets 26mpg hwy!!!

The L98 would ultimately cost more to upgrade... the intake is $1000, head work and such will make you poor. A good used, low mileage LT1 WITH the 4L60E, harness and computers should be well under $3000. They made SO MANY of them!

 

It would be a very easy swap. Get a LTx engine from a 92 and later C4. Get the PCM from a 94 and up F body. Then just drop it into the car. You could get a aftermarket LT1 street rod custom harness, or you can get the GM harness from a C4. However a C4 PCM would have to be programmed as a F body using the C4 maps which are not much different.

The C4 PCM will want to communicate with its original CCM. If the CCMs are the same for 91 and 94/95 which I really can't say for sure but I doubt it because of the hardware differences. But lets say that they are not. You would have to install the later CCM. Then that is another can of worms. The CCM harness pinout maybe different. If you research it and find that the pinout is the same. Then you could get a 94/95 CCM with about the same mileage as your car, or get a new one. Then drop it in and wire in the new harness.

The easier route would be to use your original CCM and just piggy back the new PCM on top of the old ECM. Then the CCM has someone to talk to which means all of your dash funtionality remains. Even your VATS will remain functional. The only basic issue would be to find a new home for the PCM.

 

Can I thank you for this information 7 years late? I stumbled on this while looking into this swap on google and you covered almost all the questions I was trying to find answers to. Thank you!

 

The easy answer is to sell the L-98 car and buy an LT-1 car - then you don't have to do ANY swap work.

The mods will be locking this down for being revived from the grave...........

 

well first of all IBTL
and second its not worth it if your going to do a swat go LSX.

Look at this:
http://forums.corvetteforum.com/c4-t...my-swap-2.html

 

lol, glad to see your still thinking about it Chaos...

 

I'm not thinking about it it's done. I ran in a bit and my trans went out its going back in soon.