Turbo engine rebuild

[Paul V8]

Hello,

My i'm helping a friend give his engine a freshen up,
Its a 3.5 turbo, the engine code is 25G, cant find out where its from.
It was running 1.5 bar boost up until the head gaskets gave up.
The block is stamped as 8.13:1 compression with tin head gaskets and 36cc chambers.
As im new to turbos, does anyone have any comments, im planning to use comp gaskets because i believe they are better, would this affect the compression.

[ChrisJC]

Comp gaskets are about 0.5-0.7mm thicker, and will both reduce compression and cock up lifter preload.

Conveniently skimming the heads by the extra thickness addresses both problems!

Chris.

[topcatcustom]

8.13:1 is low already if you use composites they will put it well into the 7:1's! This is too low unless you are running stupid boost but even then people use higher compression. Skimming the heads is a better idea and fitting composite gaskets as Chris said. That is basically what Rover did when they stopped using tins, skim the same off the heads as the extra thickness of composites over tins, about 28thou.

[ian.stewart]

Devonman is the fella to talk to, he has been running home brewed turbo engines for about 25 years, and has had plenty of combinations to give you advise, Im sure he will be along soon

[stevieturbo]

Hello,

My i'm helping a friend give his engine a freshen up,
Its a 3.5 turbo, the engine code is 25G, cant find out where its from.
It was running 1.5 bar boost up until the head gaskets gave up.
The block is stamped as 8.13:1 compression with tin head gaskets and 36cc chambers.
As im new to turbos, does anyone have any comments, im planning to use comp gaskets because i believe they are better, would this affect the compression.

need more info.

And 1.5 bar sounds like a lot ? Are you sure ?

What fuel/ignition system does it use, type of turbos, intercoolers ? etc etc

TBH, I really cant see a std tin gasketed RV8 taking that much boost, even if it did have ARP studs.

Is this an engine you have bought, or one you actually ran ?

[Paul V8]

Sorry for delay.

I havent had much to do with this engine until i was given a box of bits.

As far as i can see the engine was a standard low compression on SU's with a home made turbo kit, dont know what turbo, with an external waste gate running 1.5 bar. No intercooler.
Was in the car running for 5 years, now taken out due to a head gasket and warped head.
Ignition is also standard, something else that needs looking at.