low compression 6 head

[quango]

Hello,i'm trying to source a low compression 6 cylinder head,if anyone has or knows of one for sale in uk,sorry it's in this section but was unable to post in classifieds.

Any help appreciated,

Thanks

[Tim D.]

These are quite hard to get hold of. Spent 6 months looking for one for my supercharger project without much success. Eventually had to increase the size of the combustion chambers to get the desired CR. 

[ianc]

I've never owned a 6-pot, but wonder whether one could lower the CR by fitting a solid copper gasket in addition to the usual gasket. 

I see that Moss have a solid copper gasket 32 thou thick - one would need to do the sums to see how much effect this would have.

On my TR4, I have two solid copper gaskets because I had to have the head skimmed after the engine had overheated when the water pump disintegrated whilst the engine was flat out on a rolling road in the early 1990s.

Ian Cornish

[quango]

Thanks both,

I had a quote of around 600dollars carriage from the US,i may have to machine up a spacer plate with 2 gaskets and use a standard comp head by the looks of it.

Could supercharge a standard c/r but it kind of defeats the object.

[BlueTR3A-5EKT]

3 hours ago, quango said:

Thanks both,

I had a quote of around 600dollars carriage from the US,i may have to machine up a spacer plate with 2 gaskets and use a standard comp head by the looks of it.

Could supercharge a standard c/r but it kind of defeats the object.

I am surprised there is not a North American spec air injection head floating around looking for a new owner. 

Have you asked Chris Witor? https://www.chriswitor.com/index.php

Hi head id chart  https://www.chriswitor.com/datasheets/head_applications_chart.pdf

Or you could go the whole hog  -  Fit a flat plate and dry deck the engine..

I've never seen it done on a Triumph but the A series racers favour it.

 

Edited March 23, 2021 by BlueTR3A-5EKT

[Peter Cobbold]

tried TR Bitz ? most USA 6's were low compression, IIRC 7.75:1 in final year.

[Tim D.]

South Africa also had low compression for their saloons. Precovid I used to travel to SA regularly. So did some investigations but no luck. 

[Mike59]

I may be able to help you. I will have a look tomorrow but I think I have a low compression head from a stripped North American Engine. Mike

[Peter Cobbold]

On 3/22/2021 at 9:58 AM, ianc said:

I've never owned a 6-pot, but wonder whether one could lower the CR by fitting a solid copper gasket in addition to the usual gasket. 

I see that Moss have a solid copper gasket 32 thou thick - one would need to do the sums to see how much effect this would have.

On my TR4, I have two solid copper gaskets because I had to have the head skimmed after the engine had overheated when the water pump disintegrated whilst the engine was flat out on a rolling road in the early 1990s.

Ian Cornish

Ian,  I reckon roughly 3mm copper would be needed, judging from the low compression head (8.5) having 3mm as full bore compared with flush-with-squish platform of the 9.5.  Peter

[ianc]

Peter - that equates to about four of the 32 thou solid copper gaskets.

Possible, I guess, but not cheap.

Ian Cornish

[stuart]

1 hour ago, ianc said:

Peter - that equates to about four of the 32 thou solid copper gaskets.

Possible, I guess, but not cheap.

Ian Cornish

Better done with a steel plate shim surely as used in Tank applications for Jaguar engines to run on any available fuel by lowering compression ratio down to 6.5-1

Stuart.

[Motorsport Mickey]

2 hours ago, stuart said:

Better done with a steel plate shim surely as used in Tank applications for Jaguar engines to run on any available fuel by lowering compression ratio down to 6.5-1

Stuart.

+ 1  Also the same set up with the TR 4 cylinder engine and it's low compression kit for overseas with a shim and steel headgaskets 20 thou thick.

Mick Richards 

[Peter Cobbold]

Quango, The problem with low compression is the engine becomes rather 'soft' off-boost and mpg is hit. Have you considered a stock 9.5 head and using   water injection to abolish detonation?

https://supertrarged.files.wordpress.com/2016/01/tr6se-35-water-injection-revisited.pdf

https://supertrarged.files.wordpress.com/2016/02/tr6se36-water-injection-effects-on-combustion-pdf.pdf

Peter

 

[dingle]

Too bad shipping is prohibitive. I would gladly exchange a late NA head (7.5 CR) for a PI (9.5 CR) one. 

Berry

[quango]

On 3/23/2021 at 8:46 PM, Mike59 said:

I may be able to help you. I will have a look tomorrow but I think I have a low compression head from a stripped North American Engine. Mike

Thanks,that would be good.

[quango]

Thanks all for input,

I'll try a ring round suppliers,i'm not in any real hurry as i have other stuff (garden) to do anyway but i'm trying to collect parts together for when i'm able to get on with it.

[Lebro]

Why not grind out the chambers to drop the CR & improve gas flow at the same time ?

Bob.

[Tim D.]

22 hours ago, Peter Cobbold said:

Quango, The problem with low compression is the engine becomes rather 'soft' off-boost and mpg is hit. Have you considered a stock 9.5 head and using   water injection to abolish detonation?

https://supertrarged.files.wordpress.com/2016/01/tr6se-35-water-injection-revisited.pdf

https://supertrarged.files.wordpress.com/2016/02/tr6se36-water-injection-effects-on-combustion-pdf.pdf

Peter

 

Peter,

That's interesting. As you know, I am running the Moss Supercharger setup with CR around 8.5:1 and a Holley 2 barrel. Seems pretty good on Fuel efficiency running better than 30 mpg on long runs. Some of this comes, I think, from the SC being taken out of the system at high manifold vacuum.

Have been playing around with increasing the ignition advance when the supercharger is out of the circuit which may help somewhat.

Cheers

Tim