To bore or not to bore...that is the question...

[Glamis400ex]

Hey guys,

I know this horse has been beat to death, but I got a little different spin on it this time.

My 99 400ex is in despeate need of more HP. It runs fine, no smoke or blow by. Last time I checked the compression it was around 118 psi, last year.


My question is, would you or would you not bore it to a 416 if it didn't need it? I know the only difference in price with the kits is the bore job, so money really ins't an issue here.

I want to keep as many bores as possible, preventing premature re-sleeving. So, if all she needs is a hone, who says just drop in a hi comp standard bore and who says go ALL THE WAY with a 416?
(I will be adding a hotcams stage 2 also reguardless if I bore it or not, possibly a 39fcr)

Thanks for your views on this,

Glamis

[trailburner]

I have a hard time ripping into the motor if it does'nt need it ...
But as soon as mine starts to lose compresion 416!!!NO DOUBT

[RAPTORAZ]

The power difference between a standard bore high compression piston and a 416 high compression piston will be very little. I'd just go with a stock bore high compression piston for now if you'd like to keep as many bores as possible for the future.

[quadfamily]

check with an engine builder. I was wondering about that one time too. I was thinking that I shouldn't bore it to it's max so that there would be more left to bore it again later down the road. But then I talked with Mickey Dunlap at 4 stroke tech and he said he's got so many stock standard sleeves laying around from people who had bigger sleeves installed that he would only charge $15 for a standard stock sleeve. So It's not worth worrying about saving you're sleeve.

[Hoodeye3]

And if you want to keep as many overbores as possible dont forget the 406 (1mm over stock)

[Glamis400ex]

Excellent input from everyone...thank you

Glamis

[Bunkerking217]

hot cam stage 2 and a 406(1 bore over) with a 11:1 HC piston and a curtis sparks flywheel key. it will fly!

[bmw500hp]

Originally posted by Glamis400ex

My question is, would you or would you not bore it to a 416 if it didn't need it? I know the only difference in price with the kits is the bore job, so money really ins't an issue here.
Glamis

This link will reference DYNO readings with the 400ex "stock bore" vs "stock bore with intake and exhaust mods". The link also posts various other bore and mod combinatons. Print and table the data for accurate evaluation.

http://www.geocities.com/gtthunder.geo/400ex.html