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Head Specs for higher compression ratio

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Stampy Avatar
Stampy Silver Member Scott Stamp
Victoria, BC, Canada   CAN
Getting the engine out this weekend and then it's off to get the head ground and valves done.

Is there a spec sheet out there to reference for the process?

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Tonyfixit Avatar
Tonyfixit Tony M
Duncan, British Columbia, Canada   CAN
Do you mean combution chamber cc v compression ratio?

tapkaJohnD Avatar
tapkaJohnD John Davies
Lancaster, Lancashire, UK   GBR
Plus 1 for Tony's words, if I interpret them correctly.
People often say - skim off Xthou to get a Compression ratio of Y - but that ignores so many other factors, in particular, has the head been skimmed before?

MEASURE the combustion chmamber volumes. Needs a chemist's burette and a bit of setting up, but this will tell you exactly how big they are, and if they are equal across the head.

THEN, some arithmetic. CR = (Stroke volume + combustion chamber volume) / Combustion chamber volume (I simplify) and you can go for up to 10.5 on the best pump fuel (99 RON octane, equivalent to 90-92 MON, or 95 by AntiKnock Index, commonly cited in US)

May I humbly refer you to my article on the Sideways Technologies site, "Raising the Compression Ratio. How to do so safely and effectively, by measurement and calculation"?
: http://sideways-technologies.co.uk/forums/index.php?/topic/7551-how-to-raise-the-compression-ratio-safely-and-effectively/&tab=comments#comment-99739

John

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dsixnero Avatar
dsixnero Dan Colanero
Westville, New Jersey, USA   USA
Scott, read the competition prep. manual by R.W.Kastner for tr-250/tr6

titanic Berry P
Albany, Oregon, USA   USA
Here is a link to a chart for TR6 head thickness/CR. Note that the CR increases as the bore increases. Most people go for about 9.5 for street use. https://www.goodparts.com/shop/index.php?ukey=auxpage_tr6-compression-ratio
Berry

Stampy Avatar
Stampy Silver Member Scott Stamp
Victoria, BC, Canada   CAN
Alright

Thanks all for the advice.

Got the engine out this weekend and she's sitting proud on the stand awaiting a trip to the shop.

Going to pull the cam and get it profiled at the same time rather than buying a new one.

Scott


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tmpass Avatar
tmpass Tim P
Medway, MA, USA   USA
1970 Triumph GT6+ (MkII) "Capo"
1970 Triumph GT6+ (MkII) "Blue Oxide"
In reply to # 1496274 by Stampy Alright

Thanks all for the advice.

Got the engine out this weekend and she's sitting proud on the stand awaiting a trip to the shop.

Going to pull the cam and get it profiled at the same time rather than buying a new one.

Scott

The machine shop should be able to let you know how much milling needs to be done for target compression ratio.. I would also have them machine the block for "zero deck" which means the top of piston will be flush with top of block. (or closer to it.) You should also have them balance the rotating assembly while they are at it, as well as a three angle valve grind on the head. (its not my money) grinning smiley

aaaaand as stated, you should read Kas Kastners competition manual about some very minor combustion chamber grinding/clean up for performance smileys with beer

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Stampy Avatar
Stampy Silver Member Scott Stamp
Victoria, BC, Canada   CAN
Okay....That Kas Kastner manual is chock full of info.

Thanks for the tip Tim and Dan.

In reading the manual there is mention of a Triumph team participating in a cross Canada Rally back in the 60's
But there were just scant photo's of this team. Does anyone else have pictures of this incredible endeavor?

I'd love to see the paint scheme they used for it if anyone knows?

Cheers from the Wet Coast

dsixnero Avatar
dsixnero Dan Colanero
Westville, New Jersey, USA   USA
The nice thing about that little manual is that it's old school and you can do a lot of the work yourself with some port grinding tools. Make sure the valve train geometry works well with the new profile. Dan

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YankeeTR5 Dan M
Seattle, washington, USA   USA
The Shell Rally cars (4 of them I think??) were some of the few factory entered racing efforts and were TR4's fitted with Surrey tops. The paint schemes were Robins Egg blue (Wedgewood Blue?....whatever light blue was called in those years from Triumph) with gold American Racing magnesium wheels. The frames, I believe, were painted white for better crack detection. There were a couple of other mods - like the scuttle vent being more of a scoop and a driving light mounted on the front of the surrey top. A few have survived. The last one I saw for sale in the UK was circa 2002'ish and was offered for around $40K then a couple years later at same dealer for $90K. Wonder what'd it go for today?

In the late 90's a resourceful researcher read about one of the cars that was wrecked along the rally. He actually went along the route and asked along the way if anyone knew about it. Turns out after being wrecked, the Triumph team just left it where it was and the farmer whose land it was on put it in his barn and there it sat for decades until said researcher came along and found it and was able to acquire it. It had taken a serious bashing with a bent frame and body panels, but it was complete and restorable.



Edited 1 time(s). Last edit at 2017-11-20 04:25 PM by YankeeTR5.

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