Gtr Engine Rebuild. New Stock Crank?

[R32 TT]

I don't see why a crank collar properly fitted would not be good enough for 500hp.  It costs half as much or less 'but I might as well throw $500 in the river since I'm rebuilding the engine anyway'.  Note sarcasm - not rudely meant, just easier to use.

Also those pistons will not likely be lighter will they?  More likely the opposite.  Dunno about the rods.

<{POST_SNAPBACK}>

No offence taken. I don't really want to throw $500 away on anything either. It just seems to me that to go to all this trouble while the motor is out and so on, and then pop the 12yr old crank back in - which has had to be modified (possibly weakened at this point?) - in the scheme of things $500 was good insurance... but hey, that's exactly why I am asking the question - to see what others have done/think on this.

Pistons I thought were lighter going to the forged items over the stock cast ones -aren't they?

The crower rods are about 200g lighter than the stock rods. (recently another was done, and my engine builder weighed them both).. so all this means less stress on the crank I would think.

[R31Nismoid]

once you fit the collar etc its still gonna need to be machined before goin back into the motor.

thats where the new crank works out near enough to the same costings, without the wait of workshops

[Abo Bob]

The weak point on that crank is the oil pump drive which the collar deals with.

How is the crank getting weaker with age? A new crank is never perfect anyway, it still needs some machining.

Also please note I tied your 500hp power figure to my statement.

Forged pistons are generally heavier than cast but you are making up for it with those rods - whether you need them or not is another story.

[Swiper the Fox]

But I am not going as full on as someone building an outright race car either.

<{POST_SNAPBACK}>

if this is so....you dont really need the motec and cdi....i have a brand new power fc pro which may suit your application better....could do a swap perhaps. pm me for a chat if your keen to work something out with me.

Edited January 23, 2006 by DiRTgarage

[lwells]

How is the crank getting weaker with age?  A new crank is never perfect anyway, it still needs some machining.

<{POST_SNAPBACK}>

If cranks are anything like engine blocks, my understanding is that there are distinct advantages refreshing a used item from a metalurgy point of view, that is, the used item has already hardened and done any warping/etc.

Anyone more knowledgable then me (ha! that's not hard ) care to comment?

[R32 TT]

The weak point on that crank is the oil pump drive which the collar deals with.

How is the crank getting weaker with age?  A new crank is never perfect anyway, it still needs some machining.

Also please note I tied your 500hp power figure to my statement.

Forged pistons are generally heavier than cast but you are making up for it with those rods - whether you need them or not is another story.

<{POST_SNAPBACK}>

Fair enough. I suppose it was just my thought that perhaps the crank may have suffered some fatigue over that time. If not, and in keeping with what Lucien says about the metallurgy point of view - perhaps it is better to simply keep that one?

I'm all for saving the money if it really is no advantage.

[R32 TT]

if this is so....you dont really need the motec and cdi....i have a brand new power fc pro which may suit your application better....could do a swap perhaps. pm me for a chat if your keen to work something out with me.

<{POST_SNAPBACK}>

Cheers for that, but I guess I meant I am not a "no limit to budget, out and out race car". I still intend to be 'racing' as much as I can.

Part of the reason I have Motec and CDI is because that what my tuner is most familiar with, and secondly - he sponsored me. He probably wouldn't like me to give it away like that. But thanks for the offer anyhow. Now if you want to swap a veilside front bar for that nice stock one you have - that's something I'd be interested in!

[R32 TT]

Forged pistons are generally heavier than cast but you are making up for it with those rods - whether you need them or not is another story.

<{POST_SNAPBACK}>

I just weighed the stock pistons in at 440grams - and the JE replacements are 335grams according to the specs.

25% less, or 100grams per pot saving - using this particular piston. Got to be good.

Take another 200grams off per rod and the crank surely is having a better time of things at 8000rpm - not to mention the faster spin up time?

[Sinista32]

I just weighed the stock pistons in at 440grams - and the JE replacements are 335grams according to the specs.

25% less, or 100grams per pot saving - using this particular piston. Got to be good.

Take another 200grams off per rod and the crank surely is having a better time of things at 8000rpm - not to mention the faster spin up time?

<{POST_SNAPBACK}>

I notice your using JE pistons what made you choose these?

I ask because I have a dilema of using JE's which I got at a good price or sourcing Weisco's which have teflon coating from the factory, which apparently are a closer fit and less noisy from cold start.

All advice appreciated.

Edited January 24, 2006 by Sinista32

[Abo Bob]

I just weighed the stock pistons in at 440grams - and the JE replacements are 335grams according to the specs.

25% less, or 100grams per pot saving - using this particular piston. Got to be good.

Take another 200grams off per rod and the crank surely is having a better time of things at 8000rpm - not to mention the faster spin up time?

<{POST_SNAPBACK}>

Well that's interesting. Has anyone got a pic of the JE piston lying around?

Do they have short skirts?

I went for the wiseco's recently for the abovementioned reasons basically. Teflon coated skirts from factory, clearances are smaller than some, fairly quiet compared to some, nice long skirts for keeping square in the bore, not expensive.

This weight saving says to me you have even less reason to get a new crank.

Just my opinion.

[R32 TT]

Well that's interesting.  Has anyone got a pic of the JE piston lying around?

Do they have short skirts?

I went for the wiseco's recently for the abovementioned reasons basically.  Teflon coated skirts from factory, clearances are smaller than some, fairly quiet compared to some, nice long skirts for keeping square in the bore, not expensive.

This weight saving says to me you have even less reason to get a new crank.

Just my opinion.

<{POST_SNAPBACK}>

Yeah I hear what you're saying. Perhaps the JE are thinner and/or have shorter skirts. (I've always preferred shorts skirts.. not just in pistons either...)

I'll have to see if I can get hold of one and post some pics. I don't think the JE have any coatings like the Wiseco's either... I was thinking of having them ceramic coated - but thats just the top, not the skirts.. How much are the Wiseco's?

I notice your using JE pistons what made you choose these?

Frankly, it was just what my engine builder suggested. He's always had a like for the JE stuff. I once used them in a V8 too. But to be honest - I'm sure the Wiseco are probably just as good. And I like the sound of the teflon... I'll ask him about it and see what he thinks, but I know he did say that most 'good forged pistons' these days are all very good.

[Abo Bob]

About $1300ish a set.