stroker survey

[rhjames]

please participate if you have a stroked 928 engine.


16V or 32V?

What size do you have? (6.0, 6.4, etc)

Is your engine turbo-ed, supercharged, or naturally aspirated?

What configuration are you using? (pistons, rods, etc)

What block configuration are you using? (overbore w/ Nikasil, sleeves, etc)

What pistons are you using? (Porsche, custom, SBC based, etc)

What rods are you using? (steel, titanium, SBC based, custom, etc)

How many miles do you have on the engine since the build?

How do you drive it? (track only, hard street driving, or just putting around)

what is the maximum rpm's you turn this engine?

Have you had any rod failures? (bent, broken, etc)

Have you had any piston failures? (broken, skirt scuffing, etc)

Have you had any cylinder failures? (scuffed walls, gouging, etc)



This survey is an effort to put together data for various combinations and reliability. I will be putting this data on a spreadsheet and reporting back my findings.


Your time is appreciated.

Thanks-







--Russ

[rhjames]

interesting, 6 days and only one participant (R-list).


I was hoping that there would be more participation with this for the benefit of all.







--Russ

[john928]

The real reason for the low response is the lack of strokers. There just aren't that many and some are owned by non-internet people.

[m21sniper]

My 4.7 "may" be a stroker. It has been suggested by others to explain the freakish amount of horsepower my 83 US has.

[N2O-SHARK]

More talk then action. The few who have stroked, have spread tales of $20K+ to do it thier way. Scares most of us off.

I'm going to stroke this summer. Hope my wife doesn't catch me...
Figure I'll order the crank this spring from Scat or Carl. I plan on keeping my stock cylinders and 5.0L pistons (Flycut). 6.0L is fine for me. The extra .2L or .3L is twice the cost or more having to have the block prepared and new pistons. I just need to research what my rod options are. I'm hoping there is a stock rod that may work with a little change in compression instead of ordering custom rods.

6.0L with a little boost added someday should be decent and allow me to ditch the N2O.

[Danglerb]

Guessing that nobody that spent $15k to $30k on a stroker that didn't turn out as expected wants to talk about the details.

[redrider044]

Maybe I missed something but comming from an old hotrodder, if you increase the stroke on a motor, Porsche or any other brand, you need new pistons with the wrist pin hole moved closer to the top of the piston. If not, the pistons will ride too far up in the bore up past the block deck & hit the cylinder head. The only thing flycutting pistons will do is give you more piston to valve clearance. Please don't misunderstand, I'm not trying to be a know it all. Like I said, maybe I missed something.

[Danglerb]

Three elements, stroke, rod length, piston pin to top distance, some strokers do all three, some just a couple. Custom parts are expensive, so compromises are sometimes made to allow the use of some standard part, piston or rod.

Use a Porsche factory piston and you can skip the cost of Nikasil on the block.

The "standard" stroker that Greg builds uses a custom Moldex crank, custom Carillo rods, and I forget who makes the custom pistons in the larger bore, all fitted to a punched out nikasiled block.

[Normy]

Susan at Devek told me one trueism:

"The pre-'87 engines CANNOT be reliably bored beyond 100mm". This is because the company that Porsche used to cast the bores prior to 1987 did a lousy job of making sure the sand cores were in the correct place. An early '78 who's block was crafted just right can be bored out to 104 mm with no problems. But that is hit or miss, and you have 8 bores to get right. She basically told me over the phone that if I wanted a 6.4 liter engine, then I should try to buy an S4 block on eBay and send it to them. The chances of sucessfully boring an S4 block to 104 mm were pretty good, but the chances of my original M28-21 block making it through their bore process were NOT.

The early blocks can be bored to 100 mm. I am thinking about doing this in the next few years, if I decide to keep my current 928, which is now 24 years old. If I keep it, as opposed to buying a GTS...then I will look for some sort of forced induction. Erik wants me to buy a Murph kit, but I LOVE the way that a turbocharger comes online- a huge wave of torque all of a sudden. Kuhn's work comes to mind.

[all contingent on the economy; If I get furloughed in June then I'll be serving drinks in a bar and trying to make my house payment. My 928 will be parked and I'll be riding my bicycle to work~]

N!

[rhjames]

Originally Posted by john928

The real reason for the low response is the lack of strokers. There just aren't that many and some are owned by non-internet people.

probably something to that----


I had hoped for more responses, but it sure seems there's a lot to be desired.





--Russ

[Stan.Shaw]

Originally Posted by N2O-SHARK

Figure I'll order the crank this spring from Scat or Carl. I plan on keeping my stock cylinders and 5.0L pistons (Flycut). 6.0L is fine for me. The extra .2L or .3L is twice the cost or more having to have the block prepared and new pistons. I just need to research what my rod options are. I'm hoping there is a stock rod that may work with a little change in compression instead of ordering custom rods.

I do not believe you can single order stroker cranks from Scat, in the past they required a minimum of 6. You can order a single crank from Moldex.

It isn't an extra .2 or .3, it is an extra .4 or .5, presuming you go 104mm. So an additional 50% increase over just stroking. You will need custom rods regardless, so the cost difference is just the cost of pistons, presuming you using stock material pistons (commonly 968 or 944S2 pistons as I recall).

Originally Posted by Normy

Susan at Devek told me one trueism:

"The pre-'87 engines CANNOT be reliably bored beyond 100mm".

Interesting, as most stroker motors I know of, specifically source 85/86 blocks due to their thicker cylinders. At least that is what my research determined before I sourced the blocks for my projects.