eg:R

I plan On getting a set of arias 84mm flat top piston, but the compression they have for my application will be 10:8(gsr 84mm). Just wondering if this will be ok. I had 9:2 before and since a rebuilt needed and i wanted to try somthing with higher compression. I wanted at least 10flat compression, but the closes was 10:8. Arias piston brand is what I'm only trying to get. Im trying to make around 500-550hp on e85 or pump 91. Meth Injection can be used if needed for pump gas.

EsotericImage

iTrader: (8)

Is this a sleeved 84mm block?

Muckman

iTrader: (2)

Yes on E85!

eg:R

Yes

mechanix619

You mean 10.8:1 and 9.2:1 correct?

You'll be okay with 10.8:1 and E85 is too debatable of a topic to even get started.

turbohatch96y7

iTrader: (15)

E85 is the way to go especially if you have gas stations with pumps in your area..
I have NEVER seen a thread pop up where someone using e85 got a bad batch of gas and blew they're motor.. NEVER! ALWAYS A BUNCH OF HE SAID SHE SAID BS..
If e85 was so inconsistant why do they produce flex fuel vehicles?? Don't listen to the haters ^^^
Run e85 and save your motor.

eg:R

Yes, I didn't want to be too technical. I was sure everyone here knows. I guess I will look into getting the flat top 10:8:1 pistons.

EsotericImage

iTrader: (8)

Whats the CC on these pistons? If theyre flat tops, then i doubt their 10.8.. but i could be wrong.

whats the specs on these?

Gunmetal_B20_Hatch

iTrader: (9)

they should be around a -3cc piston. I have a set of flat top Wiseco's for my 84mm LS. Im using a P8R head with the 47cc chamber, so I get a final CR of around 10:1 flat.

What head are you using?

You can also go with a thicker HG if you want to drop the CR a bit.

mechanix619

I didn't give my opinion on E85, I simply stated that it's a debatable topic. It's not polite to accuse without having the facts straight.

eg:R

Motor is a stright gsr bored out 84mm. Arias Pistons are for gsr motor with 84mm bore. The bigger bore size bump up the compression. Arias part # 3310000 is what I'm looking at.

turbohatch96y7

iTrader: (15)

I apologize

Hidenplanvew

That compression will be very nice in and out of boost... E85 will be good on a set up like that.

mechanix619

Gunmetal_B20_Hatch

iTrader: (9)

No.

eg:R

Ok, please tell me why a bigger bore would'nt bump any compression.

yzracer323

iTrader: (3)

10.8:1 is fine. For your 550 whp goal, use e85 or race gas,

It would be a grenade on 91 if you were able get that power with it.

Dc4LsTeG

iTrader: (7)

I believe it will, maybe not much

Gunmetal_B20_Hatch

iTrader: (9)

Bore size has ABSOLUTLEY nothing to do with compression ratio...

Dc4LsTeG

iTrader: (7)

Are you sure? That's what I thought to, until I found this

" Compression ratio is the ratio of cylinder volume with the piston in the bottom of the bore divided by the cylinder volume with the piston at the top of the bore.When you bore the cylinder it's volume is larger. Your volume increases when the piston is at the bottom of the bore a lot more than it increases with the pistion at the top of the bore. If the piston comes to deck height or higher then the volume with the piston at the top of the bore does not increase, but the volume with the piston at the bottom is larger. That makes the compression ratio higher with a bored cylinder."

Also if you use a compression calculator for an engine and change nothing but the bore, the compression does go up

EsotericImage

iTrader: (8)

hmm, so comparing an 81mm LS and an 84mm B20, the compression raises just cuz of the bigger bore?

The Stroke,Piston CC and comp height will def come into play.

eg:R

Yes

mechanix619

Umm...

'' Compression ratio is the volume of the cylinder when the piston is at the bottom of the cylinder compared to where it is when the piston is at TDC. A 100 cubic inch cylinder would have its volume squeezed into 10 cubic inches with a 10:1 ratio. The easiest way to keep track of it is to think of every thing as volumes that are stacked on top of one another. The factors that stack up are the displacement of the cylinder (bore and stroke), the volume of the deck clearance (getting back to the zero-deck issue from before), the volume of the gasket (which is basically a short-round cylinder), and the volume of the combustion chamber. The net combustion chamber volume means you must subtract dome volume add the dish volume. Use the formula (bore x bore x stroke x .7854 x 16.4) to get the volume for a cylinder in cc's. Stack up the cylinder + the deck volume + the gasket volume + the net chamber volume---take this number and call it A…Stack up the deck, the gasket, and the net chamber volume and call it B….. Take the big number A and divide it by the small number B and it will give you the compression ratio.''

eg:R

There's a lot of misleading info. Here on Honda-tech.

mechanix619

At least there is never a dull moment around here.