now just imagine 8000rpm with a 3.15 1st gear.

 

Its all good,,thats what its about sharing and learning..
But there are a few that try to out talk or try to act like they are in the know,probably to be one up on others because they can write/talk good so know one questions them but others don't get the real info...

 

Have fun with the question. I love to hear what others have to say.

Below is a pic of stock 100 mm liner on the left and a far stronger 102 mm steel liner on the right.





Here is a set of 105.7 mm liners prior to interior being bonded. Trick because 105.7 mm will not fit a Porsche case ...... unless the thickness of the liner walls are varied. Certain steels are also part of the equation to provide designed strength.

 

I am a firm believer in Nikasil..
It always has showed benefits in my builds. Porsche knows the hot ticket.
Had bad luck with chrome plating and wouldn't use it again.

 

Porsche Nikasil plated liners are great providing you don't exceed their designed power range for the liners base material. The stock Porsche liners become a very weak link at a certain power point. Agree with chrome plating .... very bad idea. I'm sure people understand nikasil is a plating. If your plating needs repair the old nikasil must be completely remove and the liner re plated.

If you look closely at the above pics you can tell which liner is nikasil plated and where nikasel was used.

 

I would think with our opposed crank lay up that wouldnt make a difference because you don't have side thrust loading like on conventional stroker cranks exhibit..

 

Fair question ...... to make that determination I would first want to look at the piston rod ratio (piston speed). Std Porsche is about 1.63-1. Extra work is prudent when you start going below 1.60-1. A further concern is the limited deck height for lengthening the length of the rod so as to acquire a somewhat safe PR ratio. All important to design strength and side loads of the liners. Bottom line ... different loads are encountered depending on the angle at BDC. This can be controlled by the length of the rod. Stock rods with a 78.4 mm stroke and 100 mm liner dictate an approx (don't remember exactly) 126 mm rod length to attain a 1.63-1 PR which is ideal for side thrust. You raise the stroke and the bore and try using the same rod length and the PR starts to go down and this results in increasing side thrust. The lower the PR below 1.60-1 (without major strengthening) and you run far more risks as you increase the rpm's.

Another question, have you ever seen a Porsche turbo application nikasil liner larger than 100 mm? You can get Porsche NA (normally aspirated) nikasil liners to 102 mm which isn't really designed for turbo applications/loads. Throughout our build we never assume anything. Total calculations as to as to required strengths, plastic part mock ups and then final manufacturing is what is required to properly avoid weak links. Then ..... unfortunately we still seem to miss something.

 

Sorry I don't know Porsche aftermarket parts like that,, not that knowledgeable in that extreme area of Porsche stuff.
A short rod will always put more side load on sleeves and a stroker crank will have a higher piston speed causing faster sleeve wear also..
Cast iron cylinders always wore out faster and contaminated the oil as they wore But that . 003 thick coating extended my life and made more power longer..

 

John, nikasil coating is extremely tough. On aluminum, steel and I'm not sure about ductle iron. Just try honing it.

Now I an not trying to argue .... just making a point. A stroker does not mean it has to have short rods. KA had a 82.4 x 105.7 motor. Ideally a 134.0 mm rod length should have been use. Short of a very expensive deck extension along with a longer (redesigned) timing chain) this was not possible. We should have limited the stroke to no more than 80.2 mm where we could have gotten by with a 131 mm rod.

We were able to stretch our rod length to just under 130.0 mm but that required eliminating the piston bottom ring to shorten the piston, designing a smaller diameter wrist pin using higher strength steels and applying to them a near indestructible coating called black like diamonds, offset small rod center lines to obtain a perfectly true center line and designing a thicker head gasket that would hold up to 2.6 bar. A lot of bucks for an additional 3 plus mm. We would have been in heaven with a 80.4 mm stroker. As it is our PR is around 1.58-1. Not bad but it should have been better. This mistake required that we lower our redline by about 600 rpm's. This after we designed and built single lobe turbo intake and exhaust cams with GT3 Street markers having a lift of just under .450 . I wasn't happy with the screw up as the original design provided for a 9400 redline.

 

I use and believe in fitting the longest rod possible,, Smokey Yunick tech stuff.... LOL
But sometimes it's not possible, sometimes you only can do it if you move wrist pin higher and make shorter skirts which doesn't help reliability of pistons.. BUT YOUR porsche builds and parts are so different from my non-porsche stuff..
We are just gear heads talking shop talk 101..

 

Generally when you use shorter skirts you hurt reliability. Notice he added support. The bottom rings, the shorter wrist pins. The rods were rifle drilled as to allow oil to flow to the wrist pins from the lower rod bearings. Rods are internally cooled a la 965 technology allowing heat to be extracted via oil.

 

Nice,, coatings and thin ring pack,, good thickness from top ring to deck for Turbo boost.
You probably run solid pins over taper due to boost/load.

 

So if steel rods are used along with the lighter GT3 crank, does anything need to be done to the valve train to safely increase redline to 7500 or maybe 8000? Stiffer valve springs perhaps? Would you need new cams or are the stock ones sufficient?

 

These things are like gold. Extreme strength and with the BDC coating can be run without oil .... will not gaul or seize.

 

Steel rods are great. GT3 crank is nice but not necessary for 7500 redline. Would not recommend any higher redline without valve train modifications. Don't forget a proper tune. Turbo cranks are pretty stout. I do not know where their limit is.

Have some pics of some real trick valve trains, but I've probably gone a little too off topic already. Sorry.