Check out the specs on the ACL website, they have a 7.5cc dome and state a comp ratio of 10:1 @ 57.5cc.
They're probably going to be used in my next project for more comp.
14:1 Compression Pistons for 202 to 210
Started by
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, Dec 21 2012 07:52 PM
147 replies to this topic
#51
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Posted 25 May 2014 - 07:09 PM
#52
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Posted 25 May 2014 - 07:13 PM
Excellent Jonesy,
we need pictures too
#53
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Posted 25 May 2014 - 11:31 PM
Afaik acl stopped making the 253 lumpy tops 15+ years ago and they are a heavy piston.
They would still have to be milled to suit the combustion chamber and come with the other problems of a cast piston.
Definitely a step backwards from the lightweight Ross forgings your using now.
Doesn't Ross make a dome piston for a Holden??
They would still have to be milled to suit the combustion chamber and come with the other problems of a cast piston.
Definitely a step backwards from the lightweight Ross forgings your using now.
Doesn't Ross make a dome piston for a Holden??
#54
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Posted 25 May 2014 - 11:39 PM
Yep, pretty FAT piston in IMHO. The skirt looks as long and full as a grey motor and it has a FAT head by the looks?
Ol' skool.
Ol' skool.
Edited by rodomo, 25 May 2014 - 11:40 PM.
#55
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Posted 25 May 2014 - 11:48 PM
If you want a good motor why not just take OJ's advice from his excellent thread instead of trying to reinvent the wheel ?
#56
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Posted 26 May 2014 - 08:40 AM
Thank-you Kevin, Rob and Mark,
I did see how long the skirt was, but never thought about how heavy they were or even the milling of the Head,
so that would make those Pistons cost $3000 in the End.
Now to look into the ROSS DOME Pistons.
Oldjohhno and I didn't Invent the Holden Red Six Motor, and it is how they Spin the Wheels. Dave I
The Quest of a 14:1 Dynamic Compression Motor is getting Closer
#57
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Posted 28 May 2014 - 11:33 PM
Kev's right about ACL lumpy tops, long gone. Unless you can miraculously dig some up from somewhere...
FYI they weighed in at 513g and still nowhere near as ugly as those weslite pistons.
Ross do have a set of dome custom pistons listed for a descent price, mine were $900ish, and would have to come in a bit lighter than the ACL's.
Looks like my plans just changed too Dave.
FYI they weighed in at 513g and still nowhere near as ugly as those weslite pistons.
Ross do have a set of dome custom pistons listed for a descent price, mine were $900ish, and would have to come in a bit lighter than the ACL's.
Looks like my plans just changed too Dave.
#58
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Posted 29 May 2014 - 11:55 AM
Thank's for the Piston Information Jonesy,
Tonight I will put some more info up Here that Rob supplied,
and the Seller got back to me about the Weslite Pistons,
and they are 800 grams each with Pin. Dave I
Tonight I will put some more info up Here that Rob supplied,
and the Seller got back to me about the Weslite Pistons,
and they are 800 grams each with Pin. Dave I
#59
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Posted 29 May 2014 - 12:19 PM
Thank's for the Piston Information Jonesy,
Tonight I will put some more info up Here that Rob supplied,
and the Seller got back to me about the Weslite Pistons,
and they are 800 grams each with Pin. Dave I
800 grams.That's roughly 300 grams too heavy. Might be Ok in a slow reving truck engine.
#60
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Posted 29 May 2014 - 12:29 PM
Yeah Warren,
Bit of a shame really,
as they looked great having heaps of dome material and had the deceiving brand name.
Well we are getting close with the 550 to 600 gram with pin ones.
Bit of a shame really,
as they looked great having heaps of dome material and had the deceiving brand name.
Well we are getting close with the 550 to 600 gram with pin ones.
#61
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Posted 29 May 2014 - 03:32 PM
how much gain @14:1 over 13:1 will there be Dave? is it really worth pursuing? Is it really do-able?
just wondered out loud,mervx
#62
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Posted 29 May 2014 - 05:10 PM
how much gain @14:1 over 13:1 will there be Dave? is it really worth pursuing? Is it really do-able?
just wondered out loud,mervx
Exactly.
Gains from increasing the CR get progressively smaller. In other words you gain a lot more by going from 10:1 to 11:1 than you do from 13:1 to 14:1. And in my opinion breathing and a good burn trump CR every time. So while I'd have no qualms running 14:1, it'd have to be on the condition that it had no negative impact at all on these other more important factors.
If it meant it increased the burn time even a little bit I'd gladly sacrifice some CR. Likewise if it meant I lost a few CFM I'd happily trade off some compression, or if I had to compromise the tune in order to avoid deto then again I wouldn't be able dump the compression quickly enough.
That car back in the 70's that smoked the tyres from a 180mph roll-on (or whatever it did) didn't run well because it had 14:1; it did it because it had a good package and compression is only a part of that package. So by all means go for 14:1 but realize that if you have to run ugly pistons or compromise more important factors to do so then you're probably not getting as much power as you could. Also note that if an engine responds well to unusually high cranking pressures then it's often just a indicator of poor breathing.
#63
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Posted 29 May 2014 - 05:41 PM
Thank-you very much Oldjohnno and Mervx,
I have read that Mazda can only achieve 3 to 5 % increase in Torque and Fuel Economy from 13:1 to 14:1, and are using 91 Fuel with special pistons, headers, etc.
And the reason behind this here is that it was done so I was Just wanting to try and do it.
Oh and welcome back Oldjohnno
I have read that Mazda can only achieve 3 to 5 % increase in Torque and Fuel Economy from 13:1 to 14:1, and are using 91 Fuel with special pistons, headers, etc.
And the reason behind this here is that it was done so I was Just wanting to try and do it.
Oh and welcome back Oldjohnno
#64
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Posted 29 May 2014 - 06:55 PM
Why would you need 14:1 if you had one of the fastest toranas in Newcastle in the early 80's?
Just asking....
Just asking....
#65
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Posted 29 May 2014 - 07:52 PM
Evening Hip6,
As usual,
I am curious to see what the difference is to what I had, and to what 14:1 can do,
mainly to see what the compression per pot is, but as the Title say's,
I though it was a matter of getting 14:1 pistons, and that was that,
but as we now know, you cannot just go and buy them. Dave I
Why would you need 14:1 if you had one of the fastest toranas in Newcastle in the early 80's?
Just asking....
still have the same Red 6 Head
#66
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Posted 29 May 2014 - 08:07 PM
Fair enough...good luck with that.
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Posted 29 May 2014 - 08:48 PM
Why would you need 14:1 if you had one of the fastest toranas in Newcastle in the early 80's?
Just asking....
Are we talking fastest 1/4 mile times here Dave or is that warp speed??
What was the combo for that?
#68
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Posted 29 May 2014 - 08:50 PM
this is the link Rob gave me,
and the weight of a 10:1 piston and pin is 578 grams:-
http://www.aclperfor...u/6MKRY9118.htm
and here is the side shot of the 800 gram piston and pin:-
$_0.JPG 18.02K
2 downloads
#69
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Posted 29 May 2014 - 08:58 PM
I would certainly choose a drop of 222 grams reciprocating weight over a point of compession any day of the week....
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Posted 29 May 2014 - 10:07 PM
X2 DJ
The JE pistons weigh in at around 460 grams afaik.
That is still heavy for a piston of that bore size, a modern design piston with a short compression height and inboard pin bosses will weigh even less
The JE pistons weigh in at around 460 grams afaik.
That is still heavy for a piston of that bore size, a modern design piston with a short compression height and inboard pin bosses will weigh even less
#71
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Posted 29 May 2014 - 11:27 PM
#72
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Posted 29 May 2014 - 11:33 PM
That one looks good Jonesy,
Look's modern too
maybe 600 grams with pin
#73
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Posted 29 May 2014 - 11:36 PM
It's 513g std bore piston + 95g for the pin.
#74
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Posted 31 May 2014 - 02:19 PM
I still think you're taking the wrong approach.
The obvious solution is to fit a Starfire head. I seem to remember Planckman Racing pioneering this conversion in the early eighties.
Place your short motor in the deep freeze for a couple of weeks. Pack around it with packets of frozen vegetables to enhance the chill factor.
When you are ready to assemble simply preheat your oven (fan forced is best) to around 500C then bake the Starfire head until it begins to soften around the edges, remove, then place on the still frozen block and quickly bolt into place.
Voila. You should have somewhere around 14:1 without the need for expensive and difficult to obtain custom pistons.
#75
_oldjohnno_
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Posted 31 May 2014 - 07:41 PM
I still think you're taking the wrong approach.
The obvious solution is to fit a Starfire head. I seem to remember Planckman Racing pioneering this conversion in the early eighties.
Place your short motor in the deep freeze for a couple of weeks. Pack around it with packets of frozen vegetables to enhance the chill factor.
When you are ready to assemble simply preheat your oven (fan forced is best) to around 500C then bake the Starfire head until it begins to soften around the edges, remove, then place on the still frozen block and quickly bolt into place.
Voila. You should have somewhere around 14:1 without the need for expensive and difficult to obtain custom pistons.
And don't forget to brush the mating surfaces with egg white to ensure a good seal.
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