333pg333

That's a good price for a custom billet crank. I would just wonder what they would actually design and deliver? Looks like they've been around for some time so they should know their business. If it's an 8 week turnaround time that's probably faster than you'll get anyone to convert a stock crank anyway. Worth considering. Or just stick with stock offset.

PDX-944

they were highly recommended by a long time engine builder.
they are also the ones that would be doing the offset grind if I go that direction. so likely similar times.

I wont stick with stock offset because at this point, its go big or go home. im looking to run pikes peak in the next 3 or 4 years. now or never. those credits cards aren't gonna run up themselves!!

333pg333

Billet crank could be nice! The stock crank is really heavy. Wonder what their target weight is. Also be aware that these motors suffer from some pretty serious harmonic issues, hence the balancers. I'd be curious what they would design?

rlm328

Why?

rlm328

True about the weight, knifing the edges reduces the weight considerably.

Just out of curiosity why would you chose billet over forged? Forged is normally considered stronger.

Have you looked at milledge's cams?

http://jonmilledgeengineering.com/pr...arged-2-valve/

333pg333

Sorry, I mistyped. I mean billet crank. Now corrected in post#18. I think you have a knifed crank but I would steer clear of them. Moderately lightening the stock one up to a point. A custom crank could be interesting but I just don't know what they'd produce. Note the crank going into the RP968 4ltr billet motor. No sign of knifing there.

GPA951s

FYI I Ran a Darton wet sleeved block this summer, and Blew the HG at the track had a 3 layer cometic... The block was done by someone else who I assumed knew what they were doing.. I had a custom 5 layer made because the piston was coming out of the hole about .014 Ran it on the street for a bit then back to the track were after 3 sessions the HG went again.. The block is going in the scrap... Im done with sleeves.. I have three other turbo blocks in stock form to choose from so I am going to go with Nickasil coating, Aluminum and Steel have different expansion rates, and mating the two in an engine that is going to be beat on at the track makes for a sketchy combo IMHO, Maybe people have done it successfully but your going to pay top dollar for a shop to Do it right.. This one was NOT And BTW all failures were on NO 1 cyl... So Im out all the Time and money put into this thing.. a set of 4.100 JE Pistons that I will never use again.. all the money to goto the track hotel and putting the engine in / out twice..all that at only 14psi of boost... Im done banging my head against a wall...
-Im actually at work today and should be a WGI doing about 130...and its 70 degrees and sunny..

PDX-944

I haven't looked at cams yet... the problem is I don't think many people have enough experience with this size motor to make anything worth pulling the trigger on.
That being said, stock cam wouldn't be great would it...?

because I like to stroke... and because with the 2.5 I cant offset it as much as I need. so I either have to use the 3.0 and offset that, or have one built from scratch.

that im not sure. but, honestly I don't think its worth the roll of the dice, and I don't think it would be that much better regardless, for the cost.

that, is definitely a bummer... I hate to hear that youre giving up on it already. Did you have it decked after sleeving? Did you partially fill the block?

PDX-944

I jumped on that spec stage 3 clutch in the classifieds... I figure that will save me a buck later on and should be plenty for now.

I have located a 3.0 crank, and a place to do the offset grind to 94mm.
Also I have 944enhancement that can do the wet sleeving/boring to 106mm, and supply custom pistons with gapped rings.

but I need to figure out which rods and bearings to get.

someone said mitsu, and another said small block chevy for bearings... but im struggling to figure that out.

the mitsu someone recommended was 150mm length (1.3" pin height), but that lands me .005 over deck height, with 9.3x:1 CR

if I calculate with 149mm rods (1.26" pin height) I end up at .07 deck clearance, 8.37:1 CR
That looks much better right? but how to I get 149mm rods? do I want to go with mitsu or other? I have to decide before I send the crank for grinding.

Deck height 9.05"
Bore 4.17" (106mm)
Stroke 3.7" (94mm)
Rod Length 5.87" (149mm)
Chamber Vol 56cc
Gasket Thickness .039"
Piston Dome -32cc
Pin Height 1.26" (32mm)

Equals deck clearance .07"
CR 8.37:1
Engine size 3.31L
Rod Ratio 1.59:1
Max Rod Angle 18.37 Degrees

Ideas on rods and bearings?

V2Rocket

seen you mention a few times now...what made you dislike the offset grind build?

V2Rocket

the Chevy I-6 rod suggestion was offered as a means of keeping the crank stiffer with larger rod journals, but i don't know that they'd actually fit with the long stroke into a 3.0 block due to girdle clearance.

you seem to be doing a lot of math and i'm wondering why.
if you're OK paying $3500+ for "sleeve enhancement" why not have some custom pistons made to suit your build by the same folks? especially since the bores need to be finish-machined to match the pistons anyways.

use Mitsubishi rods and grind the crank to fit...

PDX-944

hm, "sleeve enhancement"... lol. no other way I know to get 106mm out of them.

that does include custom wossner pistons with the wet sleeving. so does that mean they should be able to move the pin location to make up for the 1mm piston length?

and me math-ing a lot... im using the eagle engine calculator so that I have a known viable build....

V2Rocket

They can put the pin wherever you want, make the piston dish any cc you want, move the rings around, etc.

PDX-944

gotcha, never had custom pistons before =D

ill call him tomorrow and confirm all that, and then start the spending. im not excited to spend all this, but I race a LOT. its about all I do. and I might as well do it right. esp if im looking to run Pikes in 2020!

rlm328

I don't see what it gets you. Porsche is known for its bearing durability, so why go to a smaller bearing. I have been running stroked 2.7L or 3.0L+ engines for over 11 years now. I have had engine failures but never due to a bearing failure.

The 2.5L stroked to 2.7L engines just requires a change in rods for the crank end of the rod to clear the block at the crank. I have heard of people clearancing the block in order to get sufficient room for the bolts to clear. With the offset grinds you are going through some extra steps in order to save a little money on rods (?) and I do not see the benefit.

I am presently running a 3.1L Darton MID. It is set up for mid range power so the turbo is considered by many to be under powered but it is still making around 525 hp at the crank at 16 psi and about the 500 ft lbs for torque. The biggest problem I am having with this set up is trying to get rid of the heat. Over sized coolant and oil radiators, shrouded fans, etc.