Im in the process of rebuilding my EVO1 motor, there a few issues that i would like some opinions on. The motor has been rebuilt by the previous owner but i have torn it down to fix it.

1. the head is o ringed and runs a copper gasket, problem is the moron whoever cc'd the chambers has got a bit carried away with the grinder and removed too much metal in one spot. The o ring is very close to the edge of the chamber, i have to take measurements with the correct bore size to see if the gasket will seal properly. IF the head hadnt had alot of money spent on it porting it i would turf it.

2. the bore is at 85.8, will i need to use a 85.5 piston or go to a 86? what will my PTW clearance be in thou if i use 85.5 pistons? How safe is it to bore a 7bolt)2G block to 86mm?

3. if i go to a 86mm piston, what will my bore size be in mm including clearance?

4. If i do need to go to a 86mm piston, i have concerns the head gasket wont have enough sealing area for the o ring. because of the bigger bore size.

pic of the head

 

Going to depend on the pistons that you decide to run. Some company's want a really big PTW clearance. I would stay away from those ...Ross...Cough.... Anyway JE are really good and Wiseco is good for the price. Talk to the company's that you are going to get pistons from. They will ask how much boost you plan to run and what the HP goals are. They will then tell you what a recommended PTW clearance is. On the last engine i built 4G64 with 87mm pistons with Wiseco's i believe it called for a 5 thousands clearance to give you a idea.

Chris

 

so is 5 thou written as .0050 inches?

 

Yes.

And 5 thou is in mm....

.005" * 25.4 = .127mm

 

ok thanks. So for a 86mm piston running .003 clearance the bore size would be about 86.08mm?

 

what were the power goals and use of this engine?

 

10K+rpms and 45psi around 850whp.

But like i said it depends on the pistons that you decide on. Not all pistons are made with the same material. Some piston manufactuars pistons calls for allot more clearance some call for less. Just depends on how much the material is going to expand when heated.

Chris

 

im probably going to go with wiesco's as they make an off the shelf 86 in 9:1. My engine builder sugests to use around 0.003. The goals for the engine are whatever power the 35r can make full tilt, around 9krpm max. This is a weekend only street car.

 

Okay with Wiseco's call this guy. He is the main man as Wiseco for the import pistons. Tell him what you want to do and he will tell you everything you need to know. If you get all the right parts and everything is working good together you can make 600-750whp with the 35R

Brian Nutter
800-321-1364
or
800-445-7334

Good Luck with your project!
Chris

 

The head could be welded and remachined in the spot you circled.

 

is that safe?

 

dangg!

 

Yes, and it is commonly done to repair aluminium head damage.

 

even in the combustion chamber and on a performance engine? Imagine the damage if the weld failed...

 

Yep. Google it if you want more detailed info.