Low compression on V6 essex

[geshan]

Hi. I have a sierra xr6 with the high compression pistons.10.5:1. I need the compression down to about 8.0:1 or 8.5:1. I thought of the taimar v6 turbo setup and would like to know if anyone knows how this engine was decompressed or have any ideas how I can achieve this.

Regards,

[Slow M]

The CR reduction has to come out of the heads or pistons.
In all likelihood, new, dished pistons.

B

[heightswitch]

geshan said:

Hi. I have a sierra xr6 with the high compression pistons.10.5:1. I need the compression down to about 8.0:1 or 8.5:1. I thought of the taimar v6 turbo setup and would like to know if anyone knows how this engine was decompressed or have any ideas how I can achieve this.

Regards,

Are you turbo or supercharging?

Alternative Pistons are available but I have also heard of thicker Gaskets. Adrian will no doubt be along shortly who will tell you about Turbo's and what was done with their engine spec.

N

[heightswitch]

geshan said:

Hi. I have a sierra xr6 with the high compression pistons.10.5:1. I need the compression down to about 8.0:1 or 8.5:1. I thought of the taimar v6 turbo setup and would like to know if anyone knows how this engine was decompressed or have any ideas how I can achieve this.

Regards,

[Barkychoc]

I just googled copper head gasket and came up with this as an example

http://www.ferriday.co.uk/cnc/decompression_plates...

though 10.5 down to 8.5 sounds like you need a lot of head gasket!

[geshan]

I'm in south africa. And ppl don't make that type of gaskt here. I don't want to have to import gaskets everytime it blows. Would much prefer to get a piston that came of a taimar or something that is sustainable when the car breaks. And also, it is a turbo setup.
Thanks for your help.

[TVR_owner]

When Broadspeed turbocharged the Essex engine, it ran 8.5:1 IIRC. With some blueprinting and other bits and bats, the engines ran a realistic 225-230bhp (against a claimed 265bhp). Pistons were forged pistons modified to suit and early engines did have problems in this area.

Turbo technology and availability has come a long way since those days and 290-300 bhp is available with 14-15lb boost. Head gaskets? I would be looking at ringing either block or heads if you intend to run much over 5 or 6lb boost.

Remember wild cams will end up depositing unburnt fuel into exhaust systems that will slow turbo rotation when you least want it.

[Turbster]

Heads from Transits are low compression due to a bigger combustion chamber. A friend of mine has a supercharged essex and that has custom forged cosworth pistons with bigger dishes

Edited by Turbster on Thursday 18th February 18:58

[Slow M]

heightswitch said:

Are you turbo or supercharging?

Alternative Pistons are available but I have also heard of thicker Gaskets. Adrian will no doubt be along shortly who will tell you about Turbo's and what was done with their engine spec.

N

Thicker head gaskets to accomplish a dramatic difference in compression ratio does not work. It increases the distance between the top of the piston and the quench area of the head too severely.

This distance is idealised for each application but look for about .040". Remember to factor in the distance from top of piston to deck.

B.

[heightswitch]

Slow M said:

heightswitch said:

Are you turbo or supercharging?

Alternative Pistons are available but I have also heard of thicker Gaskets. Adrian will no doubt be along shortly who will tell you about Turbo's and what was done with their engine spec.

N

Thicker head gaskets to accomplish a dramatic difference in compression ratio does not work. It increases the distance between the top of the piston and the quench area of the head too severely.

This distance is idealised for each application but look for about .040". Remember to factor in the distance from top of piston to deck.

B.

Bernard. You read too many books. get into your garage
N

[Slow M]

heightswitch said:

Bernard. You read too many books. get into your garage
N

Neil, still too cold although it was a lovely day, warming all the way up to ZERO. Spent about 15 minutes in the garage taking chassis measurements before my hands were claws. Compared to this, England looks like the South of France.
B.

[geshan]

So would it be fine to just slap on a 3mm copper gasket???

[heightswitch]

geshan said:

So would it be fine to just slap on a 3mm copper gasket???

Yes. but I would also advocate renewing all the head bolts with very good quality. certainly the cheapest way to get the compression down to the figures you need

You might also want to look for commercial essex engines as posted above in low comp form as per above.

N.

[Adrian@]

As said you can work both ways ....I have the heads in low comp and pistons too (I stripped a Robin Rew Rooster booster engine down last week that had both)..I have in the past been unsuccessful with trying to use copper gaskets with my own car when it was producing 400 BHP on the rollers but at that same time it broke the skirts off the pistons!
Adrian@