pistons

[st_anger5532]

ok sorry i dont have time to search im about to leave. but if i use 1.8l pistons in my 2.0 beta II engine. how much with the compression go up. wil it go up for am i just thinking of something else. if im rigth about the comp. going up this would be perfect for me. casue i want to go NA at first. just put thos in. and while the engine is put on a new intake manifold or get it ported. and maybe get a few more things done. but yeah. after than if i wanna go FI i can pull the engine again and put 1.8L rods in and that will lower compression right?

thanks.
andrew.

[Cypher]

1.8 pistons with 2.0 rods higher compression. don't know to what level but 1.8 rods and pistons = lower compression

[st_anger5532]

thanks, now i know what i want to do. now i just need to know if anyone knows the compression differences. doesnt KDMguy have 1.8L pistons and rods? maybe he will see this and help me out. but yea i really gotta get going.

thanks,
andrew.

[slow 2K2GT]

yes KDMguy has them in his engine right now for lowering compression levels. I know he sells them with the Stage 1 turbo kit thats hes offering, so just getting 1.8 pistons shouldnt be that tough. They are also available through Kspec.

[Cypher]

it lowers it too 8:1

[slow 2K2GT]

yes 8:1 for pistons and rods, pistons alone I belive is 11.5:1. I believe the figure was every point of raised compression was 14% hp gain, though there would need to be some good fuel control there to save your engine from ingniting and dying, though I imagine a set of 290cc injectors would be fine. Actually if the ECU can compensate for a little boost, than it should do just fine with a little extra compression.

[cbehage]

http://kspec.com/list.php?ac_id=85&ai_id=1480

[slow 2K2GT]

Thanks man I wasnt able to find that link. Pretty fair price for the gains you could see, even if you gain 4whp from this and are able to do your own work its a steal!

[Keyan]

So wait, upping the compression from 10.1:1 (stock) to 11.0:1 could show hp gains......?? how much and why haven't I done this yet?

[KeWLKaT]

Yep...

Welcome to the world of NA power, Keyan.

[Keyan]

shhhhhhh don't tell anyone.

how much hp am I looking to get?

if kspec is selling these for $139, and we're talking like 20hp, i am so in. hell maybe 10hp i'm in. But what kind of fuel tuning would i need? would a mafterburner work? hahaha. I am in the blank here, don't tell me you guys are as well.

[KeWLKaT]

WAIT

Slow down there though guys

Higher compression=higher risk of detonation

You would need to:

- Advance the timing (or)
- Use VERY high octane gas

Or both.

At that level timing and fuel becomes VERY VERY VERY important, so you always have to make sur your injectors are working 100%, your plugs too, and I would also recommend polishing the crap out of the head to clean it up.

At that level of compression it becomes very easy to break something.

[Keyan]

bah :'(

[ricerrx7]

You would need to:

- Advance the timing (or)
- Use VERY high octane gas



You mean retard timing right?

[KeWLKaT]

though it is questionable about the amount the risk you have at 11.0:1 compression.

i bet there is some one here who has first/second hand advice to give out.

i personaly havent known anyone with those pistons, so i cant tell you :(


Though on a serious note, are those 1.8l pistons and rods plug and play?

[Keyan]

they should be. from the looks of it, the only thing that makes that -.2L is the head of the piston. the diameter should be the same....someone PM kdmguy. he didn't have to un-bore his block to make it a smaller diameter or anything (haha) so i'm sure it's plug and play.

[KeWLKaT]

LOL


unBORE

hahahaa

[ricerrx7]

yep, plug and play.

[slow 2K2GT]

again this is only 1 point increase for compression fuel isnt a HUGE issue here, its the timing that would be a killer. I would imagine KDMguy knows the answers to our Qs. I actually posted the same issues over at his forum, when I get an answer I will post it here.

[KeWLKaT]

damn.... i think i might aswell go for this instead of the head spacer...

300$ for pistons vs 300$ for head speacer + 2x gaskets

[slow 2K2GT]

dont forget you will need rods as well...

[tharptroy]

You mean retard timing right?

I sure as hell hope thats what he means.

a point of compression isnt that big of a deal though, especially since the XD runs with 10:1 on 87 octane, 93 octane and stock timing curves would probably be fine.

you may pick up 5whp from the changing of the pistons, and once you realize how much work that entails to do it properly, then you'll likely spend your money elsewhere. (shaving cylinder head while its at the porting shop (usually no extra charge) cams, etc)

as for you guys wanting to change the pistons for boost, why not just buy forged pistons since you're going to have to spend the money to have the block machined anyway?

[kdmguy]

Well, again guys... If you change any hardware setting you gotta change the software to support or get the best performance out of it.
Compression ratio will change by replacing different size pistons but you will run into higher risk to blow your engine without any ECU tune.

[Keyan]

What type of ecu tune do you recommend kdmguy?

Would a mafterburner (catches the MAF signal and alters it to make the ECU spray more or less fuel) work or are we talking a complete ECU swap?

[cbehage]

You need ignition timing controll as well as fuel control. SMT-6 or 7, emanage.

kewl, you would need rods and pistons. Would probalby be cheeper to find an old 1.8 engine and take the rods/pistons.

I am thinking about doing this too. Or buying these:

http://kspec.com/list.php?ac_id=85&ai_id=799