3uzfe 98mm bore gasket issue

[thalj]

I Have a custom 98 mm bore (ductile iron sleeve) 3uzfe 11:1 compression. i used the stock toyota gasket and it cracked and failed . then i used a the cometic 98mm bore with .040 thikness and it also failed.

the question is if i make a custom gasket how big should be the bore so that it wont fail again ?

 

[cribbj]

Where exactly are the gaskets failing? Between adjacent cylinders?

 

[thalj]

Yes there is burning marks around gasket bore and the heat will extend to other places and make it crack

 

[stevechumo]

Make sure the gasket shouldn't protrude into the cylinder bores at all. If it does, then it'll crack.

 

[JBrady]

Have these sleeves been proven in another 3UZ or xUZ engine?
I doubt it.

Sleeves must fit precisely and securely to provide stability for the area between bores.
All engines "move" or "flex" during operation so gasket sealing is an engineering exercise. The less metal between the bores the harder this is to achieve. Also the heat of combustion must be dissipated and less metal increases this problem.

The stock 3UZFE has 91mm bores. The dividing metal thickness between the bores on a stock engine is only 14.6mm. This is down from the original 1UZFE which had 18mm. The original engine was engineered for 87.5mm bores and was only targeting 250hp of output.

The 2UZFE using an iron block which is more stable than iron liners in an aluminum block stretched the engineering to 94mm bores which would reduce the area between the cylinder bores to a mere 11.6mm.

By increasing your bore to 98mm you reduce the separation of cylinders to 7.6mm. IMO you just do not have sufficient metal between the cylinders to provide the stability and thermal management needed.

I am sure you have a great deal of money and time in this project but I do not believe you are going to be successful with this combination especially with the intent of increasing power.

I don't know if you are running atmospheric pressure or you want to turbo/supercharge the engine. If high power is your goal it is better to have stability and thermal management in the engine. I would rather use the 87.5mm bores to give the strongest block.

What is the combination and goal for your current build?

Whatever you choose... best of luck and keep us posted.

 

[thalj]

Its a n/a engine with 11:1 compression and stroked up to 5.4 liter so what your advice then

 

[cribbj]

As JBrady points out, your increased bores without changing the bore spacing have resulted in insufficient sealing surface for a normal head gasket.

Your only hope may be to o-ring the block or heads, but once that's done, you'll probably not be able to pull the heads off again without welding & repairing the grooves made in the heads by the o-ring.

I would consult with some high end engine builders about this and get their advice.

 

[thalj]

what about a custom gasket 99mm bore ?

 

[JBrady]

I don't think you are getting what the problem is.

Here is a picture of the 3UZFE block from this site.

http://www.lextreme.com/3uzblock.html

This is with the stock 91mm bores.
The distance between cylinders is only 14.6mm.
When you try to run your 98mm bores you lose 7mm of distance between the pistons.
This leaves too little metal to support the forces that the gasket is trying to seal.
7.6mm is just not enough material.

 

[thalj]

For your notice the block was made by bensons one of the best sleevers in the usa. Ill try to make a custom gasket 99mm

 

[cribbj]

For your notice the block was made by bensons one of the best sleevers in the usa. Ill try to make a custom gasket 99mm

What are Bensons' recommendations then? If they already know the block, and they know what they're doing, then they should have some ideas how to best seal it.

 

[thalj]

gasket fail

it keeps failing near the water jacket and this is a cometic gasket

 

[ash]

Head is lifting, and compression to the water port.
You may have to try a o ring method and localize extra pressure to seal the gasket.