Thread: 3.4 Upgrade??
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Edelweiss Edelweiss is offline
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Join Date: Feb 2013
Location: Essen, Germany
Posts: 172
Stroke

Dear cdill,

When you stroke up an engine you have to take several points into your consideration.

First of all clearances - which in this specific case it not critical at all - the difference from the 3,2 / 3,3 crank to the GT 3 crank is from 74,4 mm to 76,4 mm just two millimeter.

So under the line it goes one millimeter more up and one millimeter more down.

Depending on the conrod configuration you just have to get the cylinders adjusted in length with cylinder to block spacers, this is also uncritical in a certain range.

What you have to focus is the change of static compression ratios if you modify bore and stroke the same time.

The length of the conrod will also influence the adiabatical compression and different to a normally aspirated engine the longer conrod is not automatically the better conrod.

Anyhow - the common lengthes in Porsche engines are between short and too short so not the biggest point in this coherence.

So when your static compression ratio is rising you can react with an appropriate camshaft on the dynamical side.

Just give it a little more lift in TDC and you are fine; making the best out of it.

When stroking up an engine you should use the opportunity to work out a most possible perfect working squish band - this is one of the most important points and very often underestimated if not unconsidered at all.

Detonation and pinging is to be found and resolved there.

If you are in need of any crank just let me know - for example I have the requested 74,4 mm std. available ex stock as well as 76,4 mm / 80,4 mm / 82 mm / 84 mm.

All this together with the Porsche Titanium conrods or our own steel versions.

By the way we also produce and offer pistons for those application made from Mahle 124. Due to this Material combined with a special heat treatment this pistons are very very reliable and good for the hardest possible application.

Remaining with best regards,

Dirk
Old 04-21-2014, 08:13 AM
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