garage19
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| posted on 15/12/04 at 01:00 PM |
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Is 12.7:1 CR way to high for a pinto!
Is 12.7:1 CR to high for a road going pinto engine? I fear so!
The problem is i am building theis engine for a friends locost and he has sourced all the bits and just gave them to me to get on with it.
The Holbay head he bought from ebay already has a lot skimmed from it (43.5 cc chambers) and to make it worst the 93 mm pistons and 1.5mm stroked
crank have increased the swept volume by quite a bit!
In the past i have built road going pintos to 11:1 at the most.
If he uses optimax and CVL turbo mix he can run an 102ron fuel but i still don't know if he will be ok with this engine without dialling out all
the advance and loosing shed loads of power!
Any thoughts?
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stephen_gusterson
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| posted on 15/12/04 at 01:04 PM |
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go the whole hog and run it on diesel 
Im not an engine expert, (or anything for that matter) but the highest I think ive seen an engine at is 11:1.
atb
steve
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garage19
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| posted on 15/12/04 at 01:14 PM |
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WSB zxrs used to run 16:1
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Deckman001
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| posted on 15/12/04 at 01:31 PM |
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Yeah, maybe, but how often does your friend want to rebuild his engine, every 100 miles or so ?? 
Jason
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MikeRJ
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| posted on 15/12/04 at 03:11 PM |
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12.7:1 might be ok if he's going for a ridiculously wild cam, but I'd say that's really going to be too high otherwise.
Is there enough meat in the pistons crowns to have them machined down in the middle?
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timf
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| posted on 15/12/04 at 04:14 PM |
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open the cc in the head to lower the cr
else look for a spacer shim for a janspeed turbo pinto conversion
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dblissett
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| posted on 15/12/04 at 08:05 PM |
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what about using a different thickness head gasket in the burton catolouge they list different types and iirc the felpro one is alot thicker than
standard for a road engine you should be at about 10.5 if posable
cheers dave
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Stu16v
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| posted on 15/12/04 at 10:07 PM |
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11 - 11.5/1 is the absolute limit on pump fuel.
Check out Ferriday Engineering, they will make metal head gaskets to the thcikness IIRC.
HTH Stu.
Dont just build it.....make it!
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MikeRJ
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| posted on 15/12/04 at 11:11 PM |
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Big problem with compression plates and thick head gaskets is you lose squish, which itself helps prevent detonation.
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Stu16v
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| posted on 16/12/04 at 06:04 PM |
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quote:
Originally posted by MikeRJ
Big problem with compression plates and thick head gaskets is you lose squish, which itself helps prevent detonation.
Indeed, but with 12.7/1 CR, the holes in the pistons will be preventing detonation if it goes anywhere near pump fuel...
Dont just build it.....make it!
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MikeRJ
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| posted on 16/12/04 at 08:40 PM |
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quote:
Originally posted by Stu16v
Indeed, but with 12.7/1 CR, the holes in the pistons will be preventing detonation if it goes anywhere near pump fuel...
Hehe, very true!
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