ShawnSmith

Well folks, after months of seeing that "6.5L stroker stealth project" claim in my sig, I can finally put some seriousness behind it.

The parts have finally all arrived. Crank, Rods, Pistons, etc.

The 88 S4 goes in on Friday for a motor-ectomy followed by many weeks of dismantling, boring, nikasil coating, internals-replacing, re-assembly and shark-tunage.

And then maybe I'll be able to finally show you just what kind of torque curve you can get on a seemingly stock S4 motor with extra big parts hiding inside.

aggravation

Congratulations! I was just thinking a minute ago how cool it would be to buy a second engine so I could build something like that. No way I'd have the patience to park my '88 as long as that project would take me, hell mine has been up on stands for two months getting a much lesser refresh!

taffelman

I'll follow this project with great interest, but I'm curious about the cost of a stroker project compared to a SC. Can you give a rough estimate of the parts cost?

IcemanG17

Shawn
I HIGHLY recommend a "fun drive" with Rob (928SS) since he also has a street legal stroker from Greg Brown......to say its quick is a horrible understatement!!

ShawnSmith

Parts and labor for the stroker are in the "senseless waste of money" ballpark compared to an SC.

I don't have exact figures, but we're talking ballparks like $3k forged custom cranks, $2k custom 968 piston sets, $1k custom rod sets, more thousands in having the block bored/prepped and plated with nikasil so you can use the darn pistons, then headwork, tons of smaller parts, and epic amounts of labor.

If a really nice SC setup is gonna run you maybe $5k in parts and $2k in labor, you can figure a proper stroker will be 2x to 3x that amount.

It makes no financial sense. But you do end up with glorious loads of normally aspirated torque, a highly reliable motor, and one which can pass California smog checks without anything seeming amiss.

Please don't hold me to the above numbers - I'm making them up to give you a sense of the scale - my overall 2x to 3x is in the right region.

mark kibort

where did you source the parts and what are they.

I think, after all the time it took to build mine, that the best way is to get a devek type crank, find some 968 pistons and use stock rods. ( I think that was the combination of andersons longest running engine)

then, the costs would be pretty darn cheap. just bore the block and do the alusil process. buy a crank and some good used 968 pistons and rings and you are all done after you put it all together.

otherwise, you have all the variables that are best left to the top engine builders like Greg B and a couple of others. ring selection, piston selection, custom rods, etc etc

I wish i knew more about the right formula, but it sure sounds like going the stock boring route is the best way.

mk

ShawnSmith

I've been on Greg Brown's waiting list for many months - he specs and sources the parts. I believe he uses some of the usual suspects (Moldex, Carillo, stuff like that) but everything cut to his exact requirements which is part of why they're so darn expensive.

ShawnSmith

PS - I saved Anderson's box full of rods from falling off a shelf when I was chatting up greg about my rebuild in his stockroom

IcemanG17

Greg does have several Moldex stroker cranks at his shop....I counted 6 when I was there in Dec.....

A Doc Brown built stroker is NOT cheap.....but once its done its done..... My guess is closer to 3-4x the price of an SC

ShawnSmith

Greg puts customer names on the cranks as they come in (he has a very fair give-him-cash-and-the-next-crank-is-yours system). The Dec ones were spoken for - mine arrived this week.

aggravation

What kind of horsepower and torque would that method produce starting with a decent 32 valve engine?

ShawnSmith

Depending on how well you tune it, and what kind of intake/exhaust work is done, pretty much all 6.5L motors should land in the 350 to 400 rwhp ballpark (add 17-20% for crank hp).

Debates about factory 968 pistons, stock rods, vs custom forged piece will tend to impact longevity and peak rpm more than changing the torque curve.

Without sharktuning, you'd probably land on the low end of my guesstimate.

All this just my opinion.

mark kibort

a bone stock S4 with the 6 liter (just the stroker crank and aftermarket pistons with a coating) makes about 320 to 330rwhp but thats bone stock. (vs the stock 270rwhp)

I have to imagine a 6.5 liter has got to be in the 370 to 390rwhp without too many mods. (ie GT or 85 cams) and headers , race exhaust and other minor mods.

Thats what im hoping for, (about 390rwhp) . I think the main differences are going to be in the longevity, and rpm limits (safe rpm limits).

But, if you are going to shift it at near 6k and not much more, i dont think the kit matters too much, but what do I know, other than what i have read here on the list

I have to imagine the modex crank with more counter weights, and the lighter pistons and rods might make it rev faster and wear less under normal use.
by the way, is a modex much heavier than a stock crank? how much lighter are the carillo rods and JE pistons than the stock stuff?

mk

ShawnSmith

> how much lighter are the carillo rods and JE pistons than the stock stuff?

Lots lighter. I don't have the numbers, but I hefted factory-stock-968 pistons vs GB's aluminum custom ones and I'd guess GB's to be half the weight of stock. Rods are closer in weight. Don't know about the crank.

We're in agreement on the ballparks for hp assuming decent breathing for the larger motor.

bd0nalds0n

It's not just about rwhp. The strokers make gobs of torque at low levels.