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1.7 litre 90 mm Pistons
Posted: Fri Oct 05, 2018 4:15 pm
by HotelRomeo
I need to find some 90 mm forged pistons with a compression ratio of about 10.5:1 for a 914 historic racer. JE dont have any off the shelf and waiting to hear back from Wiseco. Any clues?
Re: 1.7 litre 90 mm Pistons
Posted: Tue Oct 09, 2018 10:26 pm
by raygreenwood
Which 914 was this? Historic....I assume restoration?
None of them...type 4 based had forged pistons. That being said.....if you can find some of the original 1.7L , domed 90mm pistons.....trim the cylinders or the case deck....because the deck height to the pisyon edge from the factory was betqeen .069" and .079".....bring it down yo about .040". then flycut just a bit...bit do not remove the excellent quench dimple in the 1.7L heads.
Without the factory head gasket...and base shim....the stock 8.2:1 increases to about 8.5:1. Get rid of the excessive piston edge deck ...say....by trimming the cylinders or case deck....and you are at about 9.0:1. Flycut a little from the chamber...and you can probably get 9.5:1 without much work. Ray
Re: 1.7 litre 90 mm Pistons
Posted: Thu Sep 12, 2019 8:54 am
by Ephry73
Even the domed 1.7 pistons won’t get you there. Perhaps a custom set is in order.
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