Corvette0096

I have a 85 vette that needs a new motor and want to add some ponies to it. I have been doing some reading on the zz4. How and the heck are you guys getting these things to pass emissions? And what is needed for the swap? What kind of mileage are you getting now?

Corvette0096

TTT.

Aggravated4life

The ZZ4 is a L98 engine style with a bigger cam, and carb. set up.It uses the stock L98 corvette allum. heads.
So you see its not hard to pass emissions with them.
These engines run pretty clean with the TPI set up.

But the best and cheapest route to go is have YOUR motor rebuilt and improved. Or if you dont mind spending the 3,300 bucks for the new ZZ4 go for it.

18carfan

Keep in mind that the ZZ4 uses the aluminum L98 heads as apposed to the iron heads like the ones used on you '85. The aluminum heads do not have EGR ports hence the reason for the EGR pipe that goes from the RH exhaust manifold to the intake on the alum head engines. You're current EGR system will not function properly with the ZZ4. You will either have to change it over to the later style or delete the EGR. Of course, deleting the EGR will create a problem with passing emissions as you mentioned. Also, as mentioned in many previous posts, the distributor, water pump, and balancer on the ZZ4 will have to be swapped out along with the intake setup. -Jeff

cohocarl

I'm not sure what heads come on the ZZ4, but is the bolt pattern the old style like the 85's TPI? May want to change over to a carb anyways.... :cool:

RICH86'ZZ4

The ZZ4 has 10:1 compression and it has PM steel connecting rods, undercut rolled and forged steel crank, the heads have the LT4 springs and the pistons are High silicon hypereutectic aluminum with offset pins. Does this sound like an L98 ? I don't think so. I also used the stock TPI before I got the SR, and I didn't have any problem with the egr pipe or system.
Also this is a NEW motor not rebuilt. I was going to rebuild my L98 and got prices from $1800.00 to $2800.00, for $3200.00 new, that was the way to go for me.

corvette1990

The cost of the crate zz4 is just the begining. You could just do an even swap with your old parts such as water pump, distributor, balancer, fuel injectors, intake and exhaust. My EGR tube was compatible till I put those TPIS Headers on, then Had to have the 1989 EGR tube. My ZZ4 is makin 420 torque at 20mph, and getting 23 mpg with 3.07 rear gears. The idle at 825rpm is slightly rough to let you know you have a ton of torque waiting. Wish someone would rebuild my L98 engine in the garage for $750 . I guess I live in an expensive area of DC east coast. The two center intake bolts are at a diff angle than stock. So You either wallow out those holes on intake with drill or buy LPE/ACCEL superram intake like I did. Oh, I forgot....and all that power - will eat a stock 700r4 transmission in 2 weeks (with 20K miles on it). how much you got to spend? :confused:

18carfan

The '85 has no EGR pipe. Only the alum headed L98's used it. If your '85 is still original, you WILL HAVE to adapt to a later style EGR setup. Also, the L98 in the Corvette NEVER changed to the late style intake bolt pattern with the center bolt holes angled differently. If an intake off a L98 Corvette is used, it will bolt right on. The intake bolt pattern only changed on the TPI F-bodys with the iron heads ('87-'92). -Jeff