Stroker costs - anyone have a rough breakdown?
12-06-2004, 08:56 PM
#46
Rennlist Member
Greg Gray wrote:
The reason I went with this particular set up (HPC coating on used 968 pistons) is because at the time, it was really the only option available for using uncoated/unplated bores. I spoke with the folks at Powerhaus and they stated that this combo is really the only one that they have found to work. They hadn't been satisfied with any coated domestic piston, or any cylinder coating/plating. Using the HPC coating w/968 pistons allows you to retain the close factory tolerances.
Using 968 pistons you will still have the back up off the iron coating. Probably something to monitor while doing oil changes.
12-06-2004, 09:33 PM
#48
Race Director
I guess the bottom line is power costs money! Reliable HP costs even more....its a simple question "how fast do you want to go." Answer: "how fat is your wallet!"
12-06-2004, 09:43 PM
#49
Rennlist Member
Adam,
I'm attempting to build a 6.4 liter stroker. It's been a very interesting journey to date.
I had been sitting on a 928 International/Scat stroker crank for about 18 months, with no core blocks available. I finally broke down and purchased a complete '87 motor w/accesories for $2.5K. Upon tear down I discovered it was an earlier crank sprayer motor. Don't know if this is good or bad, but it will be interesting all the same. When I measured the cylinders, they were thinner than what it typically recommended for the 4mm overbore. I went for it anyway. My cars is an '88 A/T, so with the tall 2.20 gears I'm not looking to be winding it very high. Before boring I looked for pistons. Again, probably another 12 months before I decided on what to do. Mahle/KB's were no longer available, no one had really proven the nikasil/nichrome coatings. I was going to coat, but after alot of checking around wasn't comfortable with the skirt/cylinder clearances that had to be run with the domestic pistons, so used 968's were my choice. HPC coating is supposed to adhear well and last with this stock Alusil.
In the heads dept. I wasn't sure that GT cams would give the kind of powerband I wanted for the A/T. I got a set of GTS cams, and for kicks put in my 5 liter. There was a noticeable drop in low end grunt and top end run off. Good midrange hit from 3.5K to 5.5K. If I can get a free weekend, the plan is to dyno this set up, and then swap the GTS exhaust cams with the stock S4's. Louie Ott and I played with this on one of his dyno sims, and it produced some very nice numbers. Stock intake valves won't cut it on a stroker. I'm going with the 968's, and perhaps some mild porting.
The rotating assembly is almost done. I've got two more pistons to clearance, and then I'll be ready to balance them (once I get the new rings). Bought a .1gram scale, so I can balance them my self. Once that is done, the pistons will go out for coating. One last balance check on their return, then the crank, rods, pistons, balancer, and flywheel all go out for balancing. Lots of Mallory metal to get the whole thing to balance out. Once that is done, short block time.
On the intake side, I'll probably keep it stock until someone gets Louie's set up smog checked. If it clears, I may take the leap.
On the exhaust side, I'll definitely be ponying up for the Devek large primary stage II headers. I'll have to talk to the professor about what to do from the collectors back.
The engine is being built to be the ultimate daily driver. No aspirations to be a high winding race car, I just always want to be "on the pipe", regardless of rpm.
It's been a very fun, very maddening project so far. A lot of assembly, measure, cursing, unassembly, do it all over again.
I'm attempting to build a 6.4 liter stroker. It's been a very interesting journey to date.
I had been sitting on a 928 International/Scat stroker crank for about 18 months, with no core blocks available. I finally broke down and purchased a complete '87 motor w/accesories for $2.5K. Upon tear down I discovered it was an earlier crank sprayer motor. Don't know if this is good or bad, but it will be interesting all the same. When I measured the cylinders, they were thinner than what it typically recommended for the 4mm overbore. I went for it anyway. My cars is an '88 A/T, so with the tall 2.20 gears I'm not looking to be winding it very high. Before boring I looked for pistons. Again, probably another 12 months before I decided on what to do. Mahle/KB's were no longer available, no one had really proven the nikasil/nichrome coatings. I was going to coat, but after alot of checking around wasn't comfortable with the skirt/cylinder clearances that had to be run with the domestic pistons, so used 968's were my choice. HPC coating is supposed to adhear well and last with this stock Alusil.
In the heads dept. I wasn't sure that GT cams would give the kind of powerband I wanted for the A/T. I got a set of GTS cams, and for kicks put in my 5 liter. There was a noticeable drop in low end grunt and top end run off. Good midrange hit from 3.5K to 5.5K. If I can get a free weekend, the plan is to dyno this set up, and then swap the GTS exhaust cams with the stock S4's. Louie Ott and I played with this on one of his dyno sims, and it produced some very nice numbers. Stock intake valves won't cut it on a stroker. I'm going with the 968's, and perhaps some mild porting.
The rotating assembly is almost done. I've got two more pistons to clearance, and then I'll be ready to balance them (once I get the new rings). Bought a .1gram scale, so I can balance them my self. Once that is done, the pistons will go out for coating. One last balance check on their return, then the crank, rods, pistons, balancer, and flywheel all go out for balancing. Lots of Mallory metal to get the whole thing to balance out. Once that is done, short block time.
On the intake side, I'll probably keep it stock until someone gets Louie's set up smog checked. If it clears, I may take the leap.
On the exhaust side, I'll definitely be ponying up for the Devek large primary stage II headers. I'll have to talk to the professor about what to do from the collectors back.
The engine is being built to be the ultimate daily driver. No aspirations to be a high winding race car, I just always want to be "on the pipe", regardless of rpm.
It's been a very fun, very maddening project so far. A lot of assembly, measure, cursing, unassembly, do it all over again.
12-07-2004, 05:05 PM
#52
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Originally Posted by atb
400hp/425ft lbs.
12-07-2004, 05:31 PM
#53
Rennlist Member
Worf,
Yup, that's rear wheel horsepower I'm referring to. I don't know if my selected cam combo will get me there with regard to HP numbers. The tq numbers shouldn't be to tough to hit.
Yup, that's rear wheel horsepower I'm referring to. I don't know if my selected cam combo will get me there with regard to HP numbers. The tq numbers shouldn't be to tough to hit.
12-07-2004, 05:33 PM
#54
928 Collector
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Originally Posted by fst951
... one of the reason that we never went to the metric system, is because fractions actually make much more sense to computers and provide for faster clock speed and data calculations.
umm No . That is not why. Computers do not run on measurements Dude. So, computers never actually "think about" the terms we're discussing here. They simply receive an instruction and perform it, move the resulting decision to the output device and move on.In other words, asking a computer 1/64ths vs asking it .001mm .... makes no difference. Programs aren't written, and instruction sets don't contain, application-level information like that ... only data. Data are (or is it "is" by now) single inputs used to make decisions and provide output. In its simplest form, what comes into a computer is nothing but ON and OFF. In large volumes.
12-08-2004, 10:55 AM
#55
Race Director
Adam
Those numbers are very possible with the setup you are talking about....if not more, defintely more torque.... Either way it will be a huge improvement over a 5 liter.
Those numbers are very possible with the setup you are talking about....if not more, defintely more torque.... Either way it will be a huge improvement over a 5 liter.
12-08-2004, 04:21 PM
#56
Rennlist Member
Iceman, I'm hoping you're right.
The truth of the matter is, I've yet to see a dynograph of a non-Devek built stroker (except Mark A's) topple the 400hp mark. If there's one out there, I'd love to see it. Some have come close, some not so close, all of which might make it after they get their tuning issues sorted, but at this point I stil haven't seen one.
I think 400 RWH is doable with the GT cam, I don't know if the GTS cams have enough top end run out to make it there.
With regard to torque, I think your right, not aiming too high with the 425 figure.
We'll see.
The truth of the matter is, I've yet to see a dynograph of a non-Devek built stroker (except Mark A's) topple the 400hp mark. If there's one out there, I'd love to see it. Some have come close, some not so close, all of which might make it after they get their tuning issues sorted, but at this point I stil haven't seen one.
I think 400 RWH is doable with the GT cam, I don't know if the GTS cams have enough top end run out to make it there.
With regard to torque, I think your right, not aiming too high with the 425 figure.
We'll see.
12-09-2004, 10:23 AM
#57
Race Director
Adam
Also most of the numbers for Devek strokers is with 5 speeds...which will always have slightly higher RWHP numbers over the automatic. The engine that is in my car came out of another guys car at DEVEK who just installed a 6.5L stroker (plus everything else) in his 88 auto. It sounded sweet, had headers, two cats, full devek exhaust and "mild" head work (according to Susan) she said it would dyno around 380rwhp. That was with the stock S4 cams, so the GT cams with more aggresive valves/porting should be around 400whp even with an auto. It should be a fun project for you & you'll end up with a much more powerful 928!
Also most of the numbers for Devek strokers is with 5 speeds...which will always have slightly higher RWHP numbers over the automatic. The engine that is in my car came out of another guys car at DEVEK who just installed a 6.5L stroker (plus everything else) in his 88 auto. It sounded sweet, had headers, two cats, full devek exhaust and "mild" head work (according to Susan) she said it would dyno around 380rwhp. That was with the stock S4 cams, so the GT cams with more aggresive valves/porting should be around 400whp even with an auto. It should be a fun project for you & you'll end up with a much more powerful 928!
