Fastest928

Just to be clear, are you saying that the GTS cranks cost less to produce than a stock 6cwt crank?

TexasDude74

Once you make the leap to billet, why stop at the block? Billet heads would allow whatever bore spacing you wanted. I've never heard of a full billet 32 valve build. Full billet pushrod setups in the 6-800 inch range are usually around $60k. What do you think a 500 cube 928 engine would cost? $100K?

ptuomov

First of all, I don't in reality have much idea what it costs to make crankshafts in high volume.

What I think (but do not know) is that they had certain design constraints for the GTS crank, such as the stroke, bob weight, the rod big end sizing, and the distance from the oil pan bottom. My speculation is that within those constraints, they picked the crankshaft design that was the cheapest to forge. It may have been more expensive to make than the stock S4 crank, because the S4 stroke is shorter. I am merely speculating that the GTS crank was cheaper to make than a six (or eight) counterweight crank that met the design constraints but aligned the counterweights in a way that produces lower main bearing loads.

Just an opinion, and a speculative at that.

Jim Devine

The car in my avatar was the first to run the 390 block- it was a team Mclaren m8d driven by Denny Hulme . First time in a race & he won - Laguna 1970.
The 390 block evolved from a need to beef up the blocks- the conventional sleeved blocks would crack between the cyls when used at 494 cu in.
& up. the 390 blocks eliminated the sleeves, allowing for more meat in the cyl / deck area.
The only bad thing was if you broke a rod, the conventional sleeve motor could be welded & repaired. The 390 blocks with the high silicone
content would have cracks everywhere from the shock. We broke a rod & the only visable damage was in the area of the pan rail, but when it was disassembled & crack checked, the lifter bore area was cracked everywhere- not repairable. Good & bad points to each type of block material.

danglerb

Once you are talking about a non Porsche block, why is making it like a Porsche block a consideration?

As I understand it in racing blocks are well understood, and selected for the type of heads and crank you want to use, with the edge of the art activity mostly about heads. If its important to keep the 928 heads, why not pick an existing known good block design and adapt it to use 928 heads?

GregBBRD

And those are cheap!

the flyin' scotsman

Its been over a year and was curious if there was further progress.

Sure like to re-open the topic and hopefully keep the side bar MK chat to a min.

Rob Edwards

There's a 'new' GTS crank and a Nikasiled block over there somewhere with my name on it, I have been beating Greg about the face and neck with a quartet of camshaft blanks to get him to do something interesting with them. Got sidetracked by the intake thing, and work/life in general. Hoping to have a drysumped, intaked, screamer-type engine that's worthy of the Zombie.

Ducman82

I can't wait to see the cam shaft beatings in person.... (Sips coffee)

the flyin' scotsman

Would you know if anyone has installed a new crank, bearing, rod, w.pin assembly into an existing engine?

I have a very early GTS and hve been thinking long and hard re. the above using existing pistons and new rings.....essentially a rebuilt bottom end

GregBBRD

They exist. They are in running vehicles.

I make them in 5.0, 5.4, and 6.5 (95.25mm) liter strokes.

I try to keep them in stock.....along with the appropriate size and length connecting rods.

GregBBRD

Joseph Fan has one, here locally, in his GTS.

the flyin' scotsman

great to hear Greg.....hopeful Joe is a member and can share his experience.

My GTS engine currently runs well, burns zero oil but am aware of the shortcomings of the stock components particular to this MY.

IcemanG17

where did I put that lottery ticket......

The sad part.....IF I had the money for one of these custom built beasts, you gotta go big for the full 6.5L....BUT that would bump he into GTS5 or GTSU and racing against GT3 Cup's or silly power custom turbo's doesn't sound like fun to me, but beating them (Anderson style) would be fun...

Currently in my class I need about 313whp......almost 50 more than I have now!!!

GregBBRD

Sorry, didn't see that you were talking about the stock stroke 5.4 crankshaft. I have not assembled an engine with one of these cranks and rods, although I do have all the pieces.....just not enough time.

Edwards and I are going to build one of these for his track car, with some other of my new pieces and see if we can spin one up, a bit more, while still making good low end torque.

I intentionally made these crankshafts, rods, and associated pieces to work with the stock pistons. As a matter of fact, the cranks are already balanced for an "average" GTS piston....and they will work with any of the stock piston weights, without any changes.

I'm not using 928 rod bearing sizes. While the "soft" stock 928 rod bearing does a great job absorbing debris without damaging the crankshaft, the softness becomes an issue when the bearings are used for other than just pure street driving. The bearings I'm using are a far harder and far superior bearing, for "more spirited use".

If you are interested, I'd love for someone to build an engine out of these pieces and would work with you, both technically and on the price of the pieces.

I would certainly want to "mock" the pieces up and make sure that dimensionally everything is correct, before moving forward. This is very easy for me to do here, to confirm that dimensionally everything is correct.