89 l98 build
Thread Starter
Racer
Joined: May 2009
Posts: 364
Likes: 3
From: merced ca
89 l98 build
I'm rebuilding the engine for my 89 vette. Looking for some suggestions. I already ordered the engine kit and I'm getting flat top pistons. I'm racking my brain on what cam to get. I want something better than stock but I want to pass smog test also. I'm also on a budget and I don't want to have to do any tuning. I'll listen to any and all sugestions.
Le Mans Master
Joined: Sep 2006
Posts: 6,050
Likes: 147
From: Phoenix AZ
2021 C4 of the Year - Modified Finalist
If you use flat top pistons, you shouldn't use the 58cc heads it came with. I did that in my 86, and I have to use the expensive gas all the time. when it's hot and you are in a hurry, the knock sensor retards the timing a lot
Le Mans Master
Joined: Jul 2007
Posts: 5,043
Likes: 8
From: Tampa Florida
Yep you'll want to use the (expensive) higher octane stuff once you crank the compression up with the flat tops.I'm in the process of doing my own "Operation: Budget L98 Rebuild & Refinements" and I've selected a flat top piston (with 4 valve reliefs) as well....see pics below. The block has been freshened up to .040 over stock and I'm going in with a ZZ4 cam which doesn't technically require a "re-tune" from a stock chip. I've been running a "mail order tune" but am having a re-burn done anyway to ensure close to maximum effeciency/effectiveness for the build. A "tune" can also desensitise the knock sensor.
"Operation: Budget L98 Rebuild & Refinements" write up (with tons of pics) will commence once the project is complete.....here is a glimpse.
Pro
Joined: Jan 2008
Posts: 584
Likes: 1
From: Near Lockport NY Black 1986 Coupe
Ouch, those older pistons look horrible.
Before you go swapping in a camshaft, what modifications are you going to do to the motor other than pistons? If nothing, the ZZ4 cam will work, along with the XR258HR-12, X4260HR-11, or even the XR252HR-10 for improved low-end torque over the stock L98 cam. When building around the stock intake, it's important to remember that more RPMs = less power, so you build to make peak power @ or around 4500 RPMs. Anything higher than that, unless the runners are aftermarket/siamesed, will have no effect on power.
Aftermarket intake/runners and you're looking at longer durations, most notably the LT4 hotcam - but that requires a tune.
Before you go swapping in a camshaft, what modifications are you going to do to the motor other than pistons? If nothing, the ZZ4 cam will work, along with the XR258HR-12, X4260HR-11, or even the XR252HR-10 for improved low-end torque over the stock L98 cam. When building around the stock intake, it's important to remember that more RPMs = less power, so you build to make peak power @ or around 4500 RPMs. Anything higher than that, unless the runners are aftermarket/siamesed, will have no effect on power.
Aftermarket intake/runners and you're looking at longer durations, most notably the LT4 hotcam - but that requires a tune.
Last edited by Master__Shake_; May 31, 2009 at 12:16 PM.
