84mm Or 84.5mm Pistons?

[importimage]

I plan to rebuild the bottom end of my B20B this winter. I am going to get the block resleeved and upgrade the pistons.

My question is, should I go with the 84mm sleeve and piston combo? OR should I go with the 84.5mm sleeve and piston combo?

What pistons would you recommend for the B20B Vtec Turbo setup???

 

[E_SolSi]

if your resleaving anyway might as well go for the larger bore

 

[jamiedude]

Originally posted by E_SolSi@May 30 2003, 08:39 PM
if your resleaving anyway might as well go for the larger bore

wouldnt you be sacrificing top end? or rather the ability of the higher redline?

im just curious

 

[lsvtec]

Not with a larger bore.

 

[K2e2vin]

i think you are thinking the added reciprocating weight, which means it'll rev a little slower but the larger bore would probally eliminate that.

 

[importimage]

My head is built up already. I have the stainless steel valves, titanium retainers, high lift valve springs, 5 angle valve grind etc.....my point is I want a 8500 rpm redline tops. I get freaked out shifting that high so I usually cut her off at 8000 rpm.

I think I will go with the 84.5mm bore. I guess I will make more power with the larger bore if tuned right....duh!!

Any more feedback would be cool though!

Thanks all

 

[JDMilan]

go with the 84.5, shit I would go with 85, now that is yummy..........anyways, I say drop in a set of good cams and if you bottom is built properly then you can take it to 9k no problem even 10k and maybe higher, but just make sure your components are good.


Milan

 

[posol]

boost, i wouldn't go more than 84

 

[importimage]

Would you rev to 9k or 10k even with my the turbo? I figured I sould call it quits at 8500 rpm max with the turbo.

I suppose that staying with the 84mm bore would be a bit safer and stronger...even sleeved......I guess the high boost usage puts a lot of stress on all the components!!

 

[JDMilan]

I was talking about motor......but at the same token, why wouldn't you rev higher, if your making safe power up there with a turbo why not?


Milan

 

[posol]

pointless. you won't make power there

in order to make power up high, what do you need? High overlap cams.
what does boost like? high lift, stock duration.

as you can see, its pointless, and jsut puts unneeeded strees on your motor, all to SAY you can rev to 10 grand, when the guy revving to 8 just blew your doors off

 

[K2e2vin]

then how do f1 cars running boost make power all the way to 17,000?

 

[posol]

because they don't make ANY power below 10,000

on a street car, thats just stupid

 

[importimage]

I know this is off topic from my original post but if I go with the 84mm bore (Which I will) and keep the turbo with the b20/Vtec/Turbo setup...which cams should I use?

 

[kyleirwin]

Originally posted by importimage@May 31 2003, 07:26 PM
I know this is off topic from my original post but if I go with the 84mm bore (Which I will) and keep the turbo with the b20/Vtec/Turbo setup...which cams should I use?

crower b-series vtec turbo cams if you have the $$$. if not, stock GSR cams work well with boost.

 

[K2e2vin]

Originally posted by pissedoffsol@May 31 2003, 06:30 PM
because they don't make ANY power below 10,000

so how are the cams setup; it is known that high-overlap cams are good for high rpm in NA, but what about the case of turbo? it couldnt be lift alone, could it?

 

[importimage]

I am gonna go with the crower turbo cam stage 2. I am only able to do this with the bottom end being rebuilt. Otherwise the stock flat piston will hit the valve.

 

[posol]

Originally posted by K2e2vin+May 31 2003, 10:55 PM-->

pissedoffsol

@May 31 2003, 06:30 PM
because they don't make ANY power below 10,000

so how are the cams setup; it is known that high-overlap cams are good for high rpm in NA, but what about the case of turbo? it couldnt be lift alone, could it?

basically, at a certain rpm depending on the cam's duration, there will be overlap until it gets going real fast. wile its in this state of over lap, you're pushing boost right out the exhaust valves, never used to make power. now, when you hot say 9k rpms, that long duration allows you to still make power up top because its hapepening so fast and because of the overlap down low, it has the pyhsical "length" to allow the valve to be opened longer.

in the case of turbo, you want to get as much air (lift) as humanly possible in just enough time (duration) before it gets blown out the exhaust.

 

[posol]

Originally posted by importimage@May 31 2003, 11:23 PM
I am gonna go with the crower turbo cam stage 2. I am only able to do this with the bottom end being rebuilt. Otherwise the stock flat piston will hit the valve.

don't bother with cams. just use stock GSR cams.
after youre boosted and tuned, you will realize, that spending 800 bucks on cams, and a 1000 on retiners and springs, for 10-20 more horse is just plain stupid, when you can simply turn up your boost contorller 1 more psi for free.

 

[importimage]

Good call on not doing the cams. You provide good information...I like that.

.....I'm an idiot!!!!