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2V head: cheap and easy; clearly reasonable power.
4V head: more of a challenge, but way more power and takes you beyond 70's technology. What's missing in the 2V approach is top end power! Ever ride a 4V sport bike and take it to redline? OMG.
If you don't do it now, you'll probably do it later.
Why worry about non-interference?
Michael, always a pleasure to hear and learn from you. My approach to this build would be similar to Sid and Shawn, start slow and work my way up. I see the 2.7 head as being an "easier" and a bit cheaper way of building such engine.
I personally do not have as much experience with the 16V heads. Not that it intimidates me, but my comfort level is lower. Being that the chamber volume is much lower, how do 16V turbo engines compensate for the ride in CR? Custom pistons, leaving clearance at the deck? Would love to learn more...
I have plenty to research here on the forums regarding the 16V turbos, but I feel at this point, starting with the 2.7 head will make the build more obtainable for me. Plus, as you say, it leaves the opportunity to move up to the 16V head down the road.
Last edited by Will Feather; 11-20-2014 at 04:51 PM.
What happened to that motor and why is the crank out of it and for sale?
Motor went kaboom on #4. The piston melted and the sleeve even cracked. Probably something to do with tuning (guessing). This was a properly done motor with 106mm bore, sleeved, trick head with titanium valves, over $20k invested in the short block. Started with a brand new block from Germany, no expense spared.
Happened at Daytona while doing a warm up lap. I purchased the car from my friend because he lost interest and now have all these trick parts. Its a complete setup with intake/exhaust/plumbing and I know all this has to be worth something to someone.
I have no use for any of these parts as I have a 2 valve 968 turbo S motor in my car and I have no plan to ever change that.
Circle recently moved from Brockton to Berkley. Shortly after that I noticed that their webpage changed. The page appears to only have Jon's contact info now?
Meeting up is cool by me!
You still driving your 951 or is it asleep for winter? I have to replace a ball joint on mine otherwise Id be driving it. Once the salt hits the ground Ill put her in hibernation.
She's tucked away in my shop for now. I have a lot of parts to throw at the 2.5 in it this winter..
This 3.0 engine build will be a separate effort. I am looking to challenge myself, and now that my other projects are nearing an end, I would really like to build a 3.0 motor. May even throw it in a different car so my 86' has no downtime.
I am not a big believer in the 2.7 head. A modified turbo head can be made to flow essentially the same and you can retain the exhaust liners. Sid has a turbo head on his motor that uses 47mm valves (from SI Valves, $27/each). He self ported it and had Dave Sonos at SCH Cylinder heads do the valve job. Dave flowed Sid's head on a Superflow and the results are below. My neighbor has several 944 race cars and is building a 3L motor with a 2.7 head which his former mechanic said flowed close to a 4V head which is far from accurate. He had the 2.7 head ported professionally (very nice work) and it was not cheap! A local shop did the valve work and we had it flow tested and the results were not great (230 cfm at 0.5") We then sent the head to SCH and had the valve grind reworked and the results are below.
I am not a big believer in the 2.7 head. A modified turbo head can be made to flow essentially the same and you can retain the exhaust liners. Sid has a turbo head on his motor that uses 47mm valves (from SI Valves, $27/each).
Shawn, I dont disagree with you. But basing this engine on the 3.0 block, to stay 8V, I would need to go to a 2.7 head as it has the correct water outlet passage.
I have a turbo head on the shelf I may modify for my current 2.5 engine, using the 47mm valves sid used.
Motor went kaboom on #4. The piston melted and the sleeve even cracked. Probably something to do with tuning (guessing). This was a properly done motor with 106mm bore, sleeved, trick head with titanium valves, over $20k invested in the short block. Started with a brand new block from Germany, no expense spared.
Happened at Daytona while doing a warm up lap. I purchased the car from my friend because he lost interest and now have all these trick parts. Its a complete setup with intake/exhaust/plumbing and I know all this has to be worth something to someone.
I have no use for any of these parts as I have a 2 valve 968 turbo S motor in my car and I have no plan to ever change that.
Eeek...That must have been VERY disappointing for your friend! Sounds like some interesting parts you have. I'd take pics and post them up if you want to sell them.
2V head: cheap and easy; clearly reasonable power.
4V head: more of a challenge, but way more power and takes you beyond 70's technology. What's missing in the 2V approach is top end power! Ever ride a 4V sport bike and take it to redline? OMG.
If you don't do it now, you'll probably do it later.
Why worry about non-interference?
For me:
1- simplicity of having all parts needed easily available (native 2.5 stuff so other could repeat)
2- the challenge of it
3- pistons are cheap and on the shelf
4- money already invested in 2v parts
At this point, I could go either way on 2vs4 valve. My c as r is making way more power than the drivetrain can handle. I'm running very close to 10 seconds (which was well beyond my goals ) and there is still a lot more in it.
I'm currently working on an extreme head that may flow close to 280cfm when done.
So tbh, I don't really see a need for it unless you're looking for 700 hp or more.
I understand why, and that it seems foolish, but I'm very happy with how fast my car is even in the current state of build. Honestly, there isn't much that can touch it short of big power drag cars and really built exotics.
Got the 3.0 motor stripped down over the weekend. This particular motor has seen much better days. It originated as an engine fire car from the PO trying to replace his own injector seals. The next owner parted the car out, and took the head off. Unfortunately he left the car to the elements with the cylinder head off the block, resulting in some pretty nasty build up in the cylinders, that has prevented me from removing the pistons just yet. I also noticed a ding on the head gasket surface, about 0.5mm deep, that should be taken off with an 0.030 deck of the block.
The bottom end is in excellent shape, with the rod and mains bearings showing minimal wear. Engine came apart with no broken studs, only casualty will have to be the power steering/balance shaft carrier, as the sleeve was seized to the b-shaft and took some damage when prying it.
Still trying to nail down a machine shop that can do the work. Hoping to make some more progress with this motor.
Geez Will, that thing looks like it was in a fire, and a flood! ;-)
I drank Sid's kool-aid too. I am hoping to get sleeved block and stroked crank back this week after loooong stints at machine shops. Car hasn't run since May and I am really starting to miss it.
I agree that the 8v is old school tech and far surpassed by a 16v motor, but I still think for most people the stroker 8v is a great way to go. Not entirely sure I'd spend a heap of money (again) on one for the racetrack, but for a road based car I can see why people would go this way instead of the 16v. It's a shame that the 16v is somewhat more difficult to build.
11-20-2014, 04:20 PM
