Kevin,

How do these pistons compare to Forged pistons such as Hepolite and Mahle?

And why the dished pistons for 1275's when every race engine I've seen has flat top's?

HRS

I will leave the question on he comparisons to kevin and throw something in about flat tops in racing.

Its without question that flat tops take compression ratios to levels that highly developed racing engines need for all out performance. The trouble is that road cars and the current fuels do not allow those sorts of compressions to be used.

So if we accept the reduced compression ratios then to enhance road performance we look towards head and camshaft development as the means. Interestingly the modern mini racing motors reflect this development direction and produce more power than those ultra quick minis of the late sixties and seventies. They also are much more reliable engines.

Paul Gulson (for example) had a rocket ship engine but it only lasted one race meeting.

[quote="1360 LS"]Nice looking pistons and for my engine size yummy. Bet they're worth a fortune too, good thing I'm not in the market for any at the moment coz I would have to buy them and go broke in the process.[/quote]

at least then you could say you were piston broke

_________________
"Show me the Mini!"

GR HAS done the dish this way for a reason.
He pointed it out to me last weekend... something about the larger flat suface around the pison top... but he iis the only one that can answer the questions.

For the $$ they are awesome and they can be custom modified if you talk to him.

Cheers,
Peter.

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Click here for the Turbo Conversion Thread!

[quote="HistoricRacingS"]Kevin,

How do these pistons compare to Forged pistons such as Hepolite and Mahle?

And why the dished pistons for 1275's when every race engine I've seen has flat top's?

HRS[/quote]

not to mention Omegas.....

What I am interested in is wrist pins ( )......if someone is asking....does GR recommend the standard gudgeon pins (or summfing else) and will his pistons take the ceramic buttons Cheers, Mick

_________________
"Show me the Mini!"

i was under the impression that all race winning mini engines are one meeting wonders

The early motors destroyed themselves - burnt pistons (Paul's did anyway) . Different thing to a rebuild for racing purposes.

I think you guys are confusing the stove-hot, power at all cost Sports Racing Closed engines with the mostly reliable other lot .....1966, nine near standard Minis first across the line at Bathurst etc

The likes of Foley, Manton, Stewart etc etc etc all had very good runs in there improved Minis

_________________
"Show me the Mini!"

Yes - that was the nature of the race in that period of time, hence the controversy about the Cortina GT 500 limited production run.

George Sheppard did an awful lot of work to make those cars "near standard" My brother owned a ex-67 works Bathurst mini and it was quite a potent little car. It lapped Oran Park just slighty slower than my improved production mini of the that time.

I'm not really buying into this gabfest, but...
1275 pistons:
1. Racers usually deck 3mm at least off a 940 head to reduce valve shrouding and inprove gas flow into the cylinders. This means for a sane C/R, the dish in the piston needs to be a bit bigger.
2. GR has found this shape gives MORE power on the dyno in big bores, that's why it's the shape it is.
Previously, for this same reason, he used to reshape the dish in the Hypatec ones on many motors that he built.
3. In case you were wondering there is more than enough thickness still to allow the piston height to be reduced for strokers.

998 pistons:
1. 998 Cooper actually had D-top pistons, they stuck up 1mm or so to get 9:1 C/R with the big 295 chambers.
2. Sprite 1098 with 295 head had flat tops.
3. Metro 998 A+ motors had flat tops.

??? Nothing wrong with flat tops in a small bore, if you want decent C/R.

_________________
DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

bring on the 1098 ones

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Starlet Conversion:
http://www.ausmini.com/forums/viewtopic.php?t=15484

They're on their way

Peter

_________________

Click here for the Turbo Conversion Thread!

Kev,
Are they planning on filling the oversize gaps (ie +020, 040). Seems a shame to bore a 1275 or 1293 out to 1360 just for GR's pistons!

I suppose you'll tell me that's what hypertecs are for!

i think GR can make you whatever you want mate

Kev,
I think he's gone for +.040s and up because most motors are 30+ years old now (unless been hidden in a barn somewhere).
Going bigger on pistons puts more old blocks into use. Badly needed with smallbore ones.

As you say for 1275s Hypatecs are available, so are Hepolites still.

I did ask about getting 74mm ones too, but he says the bores are getting a bit thin by then.

_________________
DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.