lucas569

iTrader: (3)

or get the head milled....

mojambo

iTrader: (3)

if you get the head milled, would you need an engine management system? or would the piggy be sufficient?

ProjectR#69

iTrader: (6)

13:1 compression is too crazy, most V8's arent even running that high of a compression ratio.

Arithmetic

iTrader: (9)

bump.

anybody call? It's tuesday... also don't mention 13.1. Say 10.5.1 or 11.1

Jotun

Ok i would do some serious research on this because the reason the lancer guys stayed at 10.5:1 as the standard piston for upping your comp ratio is because when you go above 11.0:1 you will through a CEL and would have to run seriously high octane fuel not pump gas especially at 13:1. I used to build domestiic engines(V8's) and when we built an engine with any thing over 10.5:1 we told them they were required to run a minimun of 91 octane fuel.
N1te and I just put a set of Buschur racing pistons in his lancer and they are only 10:1 and we are expecting substatial gains in torque and an increased powerband especially with some sort of management computer.

gregivq

iTrader: (5)

I got high compression pistons in my Lancer OZ, not Ralliart. They are great but I'm running only 10.5:1 while stock is 9.5:1. Not a big change but still lots of horespower.

If you want to run 13.1:5 on your ralliart please don't drive near me. With my setup I have to stay with 13.1 Air Fuel Ratio! With a Mivec engine it would probably take some time to tune it so it will not blow up in the air + high octane gas + timing retard.
It is possible to run 13.1:5 but the gains would be to little for too much effort in tuning.
Go to google.com and do some research about compression. You will find out that one of the biggest errors people make is going too far with compression and then ending up with little gains because of all the things needed to be sacrificed in order to make things safe.

MitsuRalliArt

People run 12.0:1 in RSX's all day long. Engine management is the true key.

Arithmetic

iTrader: (9)

My friend has a non vTEC integra GSR and is running 12.5 compression on his b18. He was thinking about getting the vTEC head and just running stock compression, but he is much faster without vTEC. Also after hearing his engine revv its sounds sick... and with his other support mods he said he's smoking rsx-s left and right.

lucas569

iTrader: (3)

no, imo the piggy would be sufficient... all car companys have a limit of how far you can mill the head. the basics of it is that thay shave the head slightly giving it a slightly higher comp. sort of like what they do w/ brake rotors... theres a SAFE limit to how much it can be shaved down.

normally they shave em when the head gets slightly warped from blowing a head gasket or when rebuilding a high milage engine,etc....

or when you want to squeeze a few more ponies, on my cousins 88 crx si we were able to get an 8 whp increase at peak! not bad for just shaving the head, on my d16 sohc vtec we only got 3-5 whp at peak, still not bad....

i can only imagine the newer head was a more effient desing.

another little trick would be to get a thinner headgasket, same concept. i cant remember which company it was but back in my honda days i knew of a company that would make headgaskets for any car at the thickness you specify, even thicker if you so wanted it.

you could get a thicker hg to lower comp instead of changing pistons to run even safer w/ a turbo setup.

Boeturbolancer

iTrader: (26)

This is only true if your controlling timing as well... the timing curves on the ralliart are way to advanced to be running 13:1 on pump gas... even on Race gas you'd be running rich to compensate.

Timing at times is over 30 degrees advanced... on 13:1 you'll not likely be going for long on pump gas. The compression increase involved in Forced induction is not the same as on the NA setup. I don't want to go into detail only tell you that going past 11:1 on an NA setup isn't easy without race gas or timing control. If you have a way to control timing it's not as bad but 13:1 will be pushing it since the compression rate, even rich, will be more susceptable to spontanious combustion occurances(preignition). Not so much the detonation it's the preignition that will get you.

ProjectR#69

iTrader: (6)

you mess with 13:1 compression, your going to wind up with a rod in your oil pan and a broken crank. Unless you build everything up, then you should be okay.

Boeturbolancer

iTrader: (26)

not entirely... just need the right engine management. That's most important of anything. If you can have the same motor put over 200whp down it should be able to hold the compression increase as long as its controlled.

KreepaEvoX

At least get me 10.5 dammit. then we can get to 200 whp... Great for some grocery getting

Daddymac

iTrader: (2)

I wonder what the cost difference is between building a higher comp. motor vs. going FI is. What about the reliability. Say the goal is 200WHP. I'm willing to bet its probably cheaper an safer to attain that goal on the 4G69 motor buy going FI then NA (HC).

gregivq

iTrader: (5)

High compression is more reliable than boosting and you stay emission legal. Pistons are forged and more durable. The only thing you have to worry about is not get any crazy mods in without tunning the fuel maps. For example camshaft that would change your fuel delivery or something like that. You probably would not detonate but probably slowly melt away the combustion chamber.
Turbo is cool but always have to worry about the oil and then the fuel delivery and emission. There are few people with Lancer OZs that will be trying to catch up with the stage 1 turbo with just NA mods. Soon it will be possible and the costs will be a bit lower than turbo.