its a 77mm stroke not bore
engine spesc

I thought the A14/A15 which revs higher also had to do with the stroke length.

I suppose, with roller rockers, double valve springs, everything lightened and balanced, the difference in stroke length may not manifest until you hit some really crazy rpms.

what can be done to stabilize the valve train??

So is what being said, all A series have about the same max rpm, when built out, some achieve higher in stock form, but mechanically, they're all pretty capable?

If this is a street car, I'd tend to say A15, it's nice to not have to work so hard driving around town.

Go for the A15. The thing is a monstor in anything you do with it. Road Racing, Time Attack, Rally, Off-road racing,etc., it stands the test of time and is bulit to take abuse.

Quote:All things being 'EQUAL', the engine with the greater displacement will have more to offer.

'Building it right' infers that one engine is of inferior build quality to another, but when comparing engines that are, as yet, unbuilt, this doesn't help the comparison argument at all.
It's best to compare apples to apples when making this kind of call.

So here's the deal.
In this instance, when comparing the highly modified A14 to the A15, 'all things being equal', then the additional displacement of the A15 will give it the edge.

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Now when you come from the Apple capital of the world ,Thus being Washington State and with the given info that I had

I am correct, am I not?

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Yes of course you are, if you have two engines and everything else being equal excepting for one having more cubes I would always lay my money on the one with more cubes.

Is there any relationship to stroke length and RPM?
I vaugely remember from my Skyline days that the stroker kits people put in RB engines were a little determintal to RPM power - which I assume meant the torque dropped off at a lower RPM.

definately go the A15, more cubic inches=more fun ty

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Well what people have been finding out from using spintrons(this is like a dyno for your valve train) is that areas you dont think would have any influence on valve train stability do.Things like push rod dia and rocker arm weight.

When I say valve train stability I'm really just talking about valve spring stability.(Your whole valve train adds to the stability of your valve springs) So what your trying to do is stop your valve springs going in to bounce.Because it kills power.So the more stable your valve train is the higher you can make power the the rpm range and the more power you will make.

It's hard for us because we dont have a spintron to use so we just have to going on what other people that do learn.

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They all have the same valve train so they can make there max power at the same point.However thats where the bore stroke ratio comes in so that being is I think there will be a cross over point where an a14 makes more power than an A15 even with the A15 have a bigger engine.That being said I dont think we would see this untill over 10,000rpm so it doesnt come in to play with most engines.

I try to follow pro stock as these are the closest high performance valve trains that we can learn from being the same type of style.Plus I just love pro stock.However people dont really like to give away what they learn so it's hard.

so shimming things so there is very little play, what about pushrod girdles? I look at the hotrod catalog and ponder, why don't we have more of these goodies?

maybe for the wiki someone will explain what has to be done to add double valve springs to a standard A15.
I really don't need em, I'd do better with the roller rockers.