NefMoto

Looking at stroking the engine out.

I'm liking the idea of the 2.1, with the 95.5mm tdi crank and 83mm bore.

I was just wondering, is there any tuning involved from just stroking the engine? I've searched the forum and found a topic about KUMSRL, which is the calculation for cylinder filling? Is it that simple? And how would I scale it from 1780.88cc to 2066.86cc? Divide and scale by the difference or something else? What's the equation?

2066.86/1780.88 = 1.16058353174. Or am I way off?

95.5mm will limit your max rpm decently as your piston speeds gonna be hitting some high levels. also 83mm makes for a significantly weaker wall on the 1.8, deffo dont go above 83 if that.

Second stroker changes have been covered multiple times on the forum, use the search function or google.

http://letmegooglethat.com/?q=stroker+%20site%3Anefariousmotorsports.com

Yeah, I wont be going over 83mm pistons. I know some people have gone to 83.5 with the euro spec 100mm crank and it was mentioned that it's dangerously close to the water jackets. I did search before posting and came across one of those topics, and from what I read it was just KUMSRL that needed modifying. I just wanted to make sure that I could just calculate the difference in displacement and scale by the difference, like with maf scaling. Better to be safe than sorry.

Quoted: Well I worked it out, but I figured I'd post it for everyone to view. At least here's how I understand it, correct me if I'm wrong Grin

KISRM= zkorr/(Vs/VH)*z          where
 
zkorr= .90 (correction factor based upon # cyl out of funktionsrahmen)
Vs= 3136cm^3 (volume of intake manifold from throttle blade to inlet valve)
VH= 1781cm^3 (engine displacement)
z= 4 (# of cylinders)

My stock bin (2001 Audi A4 1.8t AWM) has KISRM at .1278 so

.1278=.90/(3136/1781)*4

I didn't have time today to figure some of this out, so actually I had help from member "TTQS" for tanslating and bouncing ideas off of (and some math!!). Thanks Doug!!! Wink

So assuming that it's all correct for the same block/intake manifold with a stroker kit I came up with:
.14407=.90/(3136/2008)*4

I assume I would have to recalculate this with an AEB intake manifold?

Quoted:This thread is irrelevant. KISRM is simply a time filter on load, so that there are no jumps.
This mumbo-jumbo math is not important at all, you look how your load looks like and set it accordingly.

KUMSRL is the one you have to adjust for changes in displacement. It is the base constant.

PS: There is a difference in piston speed of 2.3 feet per second between the FSI Crank and the TDI Crank @8000rpm. I read a few interesting posts from INA, although this places more force on the piston, a decent set of JE Pistons are easily capable of dealing with the extra force imposed. And most people seem to agree that the valve train is still the limiting factor. Heard of quite a few built 2.1 strokers running at 8k rpm without issue. I doubt I'd be going above 7k for now anyway, as I'm going more for a Torquey engine with nice mid ranged power, as apposed to massive a/r housing and 8k rpm dyno princess. It will be a D.D after all.