To Stroke or Not to Stroke

[holmes14]

Well i started to read some of that and it looks like a great read, but can someone please sum up the advantages and disadvantages for stroking or not stroking? Which motor is better for what?

[BoostLover99]

Originally Posted by holmes14

Well i started to read some of that and it looks like a great read, but can someone please sum up the advantages and disadvantages for stroking or not stroking? Which motor is better for what?

I don't mean to be a jerk but are you serious? That's the whole point of reading the paper. If you don't want to read the whole thing, just scroll down to the "conclusions" part.

It's a technical paper - it's designed to make you think (preferably for yourself). All engineering is a series of compromises; what's right for you isn't necessarily right for me.

Hence posting the paper rather than a summary or synopsis of the paper.

[icantdrive75]

Originally Posted by BoostLover99

I don't mean to be a jerk but are you serious? That's the whole point of reading the paper. If you don't want to read the whole thing, just scroll down to the "conclusions" part.

It's a technical paper - it's designed to make you think (preferably for yourself). All engineering is a series of compromises; what's right for you isn't necessarily right for me.

Hence posting the paper rather than a summary or synopsis of the paper.

I think what you're trying to say is "2.0"

[Lilredbox]

Yes, the "Conclusions" section is a great reference for those who do not want to read in- depth, detailed points. I read for about an 45 mins. and finally scrolled to the conclusions and wished I would have started there. Anyway, I'm more torn than when I started to research the stroker option. I need to make a decision to go 2.3 or go "built 2.0." I think I will stay 2.0. As stated in the write-up, a 2.0 can make just as much power as a stroker, but it will simply need to be pushed harder. Besides, I do not plan to make off the wall numbers. If I'm dissatisfied with spool time, its nothing a little 25-50 shot of nitrous can't handle.

Anyway, this research paper is a great write up.

[prodigalsunn]

Originally Posted by housedj

whoa

now that's enuff info to corner the market & build motors that are turnkey 200k mile reliable as well as V8 fast.

it does kind of back the argument the v8 guys use: more displacement means fewer revs to make the same power which equals a longer lasting engine. i'm sure if a Veyron had a V8 making the same power as that 16cyl it theoretically would last 1/2 as long.

i'm surprised no one has taken 2 4G63's & made a V8 to silence some of the domestic haters.

torque wins drag races & high rpm wins top speed mph shootouts so how do we get BOTH?

kinda like a w8 or w12 from volkswagen. it would be cool to see 2 4g63's merged at the crank and 2 fp reds boostin it.

also remember the veyron has something like 16 radiators to keep it cool

[casper980]

Originally Posted by dudical26

wow that was a lot of good information but I'm still stuck as far as what to do now.

It seems like 2.1 stroker is the way to go....but there are barely any evo's with them.

Thats because the 4G63b is better designed then the 4G64. Also do you really want to replace your Evo engine with one from a Galant? Does the 4G63 not produce enough power for you? Also if you look at the conclusion it shows the 2.0l making its power earlier then the 2.1

[hlm]

deff stroke it. thats whatt i did and i love it with a bigger turbo. deff gets you alot more low end torque.. and spools awesome now.

[Sykotic]

The only decision is whether to stroke or destroke. the stock 2.0 doesnt have anything on either of them. The stroker is better on the streets than the 2.0 and the 2.1 is better on the drag strip than the 2.0. So why would you want a 2.0?

[EvoAggie2011]

very informative article!
He has weighed all the technical sides of stroking and the pros and cons
I myself was offered the stroker kit and I didn't want to go with it

[Sharkbite2000]

That's alot a data , If I had to do it again I would of stayed 2.0 there making just as much power as the 2.3L with the right parts.

[miragevo]

I read the white paper including the links that opened in the end. I am really wanting to build a stroker motor for the street, but at the same time I want it to have the better rod ratio of the stock motor. The stroker motor will enable me to get more displacement and more streetable low end torque to spool up a larger turbo. I think the best way would be to use the 4G64. Use the 100mm crank and off the shelf Manley Turbo Tuff 156mm Rods and off the shelf JE stroker pistons, or anyone's Rods and Pistons with these specs. This would give you a better rod ratio of 1.56 vs. the 1.50 of the 4g63 100mm stroker kit. It would kinda be the best of both worlds..... You can take this one step further and have JE make you custom stroker pistons (Weight - Piston : 275g , Pin : 106g) with a compression height of 1.012 (move the pin up 9mm) vs. their standard stroker piston compression height of 1.130 (which moves the pin up 6mm). I called them and they said this was not a problem and definitely doable. Have custom R&R Aluminum Rods made at 159mm, (Weight 507g) , or Groden to name a few. This would give you a 4G64, 100mm stroke, 87mm bore, 2378cc and a Rod Ratio of 1.59, not to mention a lighter rotating assembly. Ffwdconnection.com can do their special knife edge and balancing job to within (.1 ounce) on a stock crank which turns it into one of their Butcher 100mm crankshafts that will reduce the weight to 26.5lbs and handle anything you can throw at it according to them. They also have their own tried and true recipe for building complete motors from the ground up, with many years in the DSM community as experience. See their website for Bee Mad valve springs, ICS Headgaskets by SCE, etc etc as well as a whole slew of nice ****. Overall, I think this is the best of both worlds....increased displacement with extra low end torque and the ability to rev it to 8000 - 8500 all day long. I am also thinking of keeping the balance shafts in the motor being that it will not be revved to the moon and should help smooth out the extra vibration that the longer crank brings with it. What do you guys think?

[JohnBradley]

Makes me wonder what the mach index of the Evo head is versus the DSM version (accepting the fact that the 2G is similar)? Seems to me I read this a long time ago, and was given the same conclusions by a former employer. R/S is a tool to maximise head flow vs RPM because of the choke that will be reached a certain piston acceleration.

[tumtum411]

this is some good information

[miragevo]

Originally Posted by JohnBradley

Makes me wonder what the mach index of the Evo head is versus the DSM version (accepting the fact that the 2G is similar)? Seems to me I read this a long time ago, and was given the same conclusions by a former employer. R/S is a tool to maximise head flow vs RPM because of the choke that will be reached a certain piston acceleration.

Can you elaborate more on this in laymans terms?

[scorke]

Originally Posted by miragevo

Can you elaborate more on this in laymans terms?

LAYMANS
Basically, due to the shapes and sizes of the head and ports and combustion chamber, and the speed with which air moves in, there is a point at which trying to shove more air in the cylinder is not effective as the engine CANNOT possibly consume any more air(READ: volumetric efficiencies worsen).


Ted B's
Engineering types may (or may not!) be interested in Mach index (Z), which is the ratio of port gas velocity relative to speed of sound:
graphic
Many cars have multiple inlet vale ports & for mean values, Piston_speed = 2 * RPM * stroke, giving:
graphic
Where:

* c = speed of sound in air (m/s). c = 340m/s (1100ft/s) at Standard temperature & pressure. (c is dependent on temperature & Fuel/Air ratio)
* dp = port diameter
* n = number of ports
* db = Bore diameter
* s = stroke

For the MGC with +060 pistons (Bore = 84.9mm, Stroke = 88.9mm) @ 6500 rpm:
Z = 0.0849 * 0.0849 * 2 * 6500 * 0.0889 / 340 =~ 0.02
As Z is proportional to RPM, @ 2000 rpm, Z = 0.02 * 2000/6500 =~ 0.006.

Scorke