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turbodave
dave cox

(22 posts)

Registered:
04/30/2018 03:00PM

Main British Car:


Failure of stock cast 3.9/4.0 pistons at higher RPM?
Posted by: turbodave
Date: December 30, 2019 09:17AM

AE Hepolite
HRC1828
22059

The "books" suggest that 6K rpm is all these are good for, with maybe an occasion blast up to 6500 rpm.
Has anyone taken these higher and suffered (or not) a failure?
I'm trying to decide if I should stick with them and pick a cam that maxes out at 6200rpm.
I've got solid adjustable rockers (and would therefor use a solid, not hydraulic cam) so the only limitation will be the factory pistons.


BlownMGB-V8
Jim Blackwood
9406 Gunpowder Rd., Florence, KY 41042
(5868 posts)

Registered:
10/23/2007 12:59PM

Main British Car:
1971 MGB Blown,Injected,Intercooled Buick 340/AA80E/JagIRS

authors avatar
Re: Failure of stock cast 3.9/4.0 pistons at higher RPM?
Posted by: BlownMGB-V8
Date: December 30, 2019 10:25AM

Not sure about the Hepolites, I regularly wound a 215 with the stock OEM high compression pistons to 7K and after 30-40K miles cracked the skirt of one of them.

Jim


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