I am really thinkin about that RPW shim..... It's just hard for me to do that because I know for a fact that double gasketing is never a good idea..... But, never know right?? I want to decompress the motor a bit just so I can raise to about 10psi, and with a decomp that creates about the same internal temps as 7-8psi. I may try it out, Im not worried about it blowin, just some unwanted leaking. I wish the company that invented the heat ring made one for our lancer..... what it is is a special o-ring placed right around the cylinder on the inside edge of the HG..... It is pressurized to 500psi and even if the head lifts, you still get a total and complete seal, which, they say, also equals more power because no gases can slip through like an MLS can..... too bad they dont make one for ours......

 

Using double gaskets is not a good idea, however using a decomp shim is different. Plus, as per RPW, the shim and head gasket are sealed with Hylomar to create the strongest seal possible. Steel has the same expansion rate as the block and as such does not need to be periodically re-torqued like a copper headgasket does. RPW has been dealing with the 4G9x engines for more than a decade. I trust every word they say. This is why Australians have some of the sickest 4G9x powered cars.

If by "heat ring" you're referring to o-ringing the block go to any machine shop. My engine build has been o-ringed by the machine shop doing my work. It's not application based, its size based. I'll be running an OEM stock head gasket and ARP studs with my new turbo kit at 25-30psi. My pistons are 9.0:1 so I'm not gonna run any decomp gasket.

 

not trying to bash you or anything, u have done as much, if not more reading on 4g9x motors as i have... but i dont see u pushing 30psi out of your t3 or the gt3xx that u said u would be upgrading to.. unless you have basically unlimited funds to work with and dont plan on having a motor that will last very long. the abuse your talking about for a block like ours just wont hold up long.. what are you looking into or your block? u got someone building u a forged block and crank?
cast iron blocks can go a long way, but your talking about some serious abuse..

- sorry was a little off topic from the thread - pm me senate

 

Higher compression creates a lower combustion temp since its more efficient. Also, really dont think 10psi on 9:1 is going to be any safer than 8psi on 9.5:1.

Stick with the stock gasket since it will seal correctly and use proper fasteners, OEM or ARP will be fine.

In the end, a higher compression boosted car is much more pleasant to drive than a low compression motor with more psi.

My TT has been stroked by 227cc and increased compression from 9.5:1 to 10.16:1 and it is such a better motor in every way

 

Hey dude not trying to say you don't know your stuff, and I say with respect that you should read up a bit. Compression ratio has to do with squeezing the air/fuel ratio farther, as in, the same amount of air/fuel mixture just squeezing it even harder. This creates heat. Heat is where an engine gets its power, the power stroke depends on the expansion of gasses to force the piston down. But, heat of course has its side effects, and I shouldn't have to list them, but the most obvious is pre-ignition, or detonation. This as I'm sure you know can pop a hole right through a piston. Lowering the compression ratio squezes the air/fuel mixture less, creating less heat. Compressing air creates heat, and at 7psi air temp will raise about 110-150 deegrees, depending on humidity and elevation. This is what destroys a boosted car, the heat, not the pressure. So by decreasing compression you are lowering temps, but with the added 3psi or so of boost, you get reletively the same amount of heat (just a bit more), but more air and fuel. This allows more mixture to be burned, providing a "longer" burn, to give you more power. This is why I want a Decomp gasket or shim. I'm going with the RPW shim, from the other guys said up there, they have a decade of knowledge on the 4G9 series, which is good news to me..... THANKS GUYS!!!!! Also, you need ARP headstuds, OEM just won't cut it as you say they will. You can't tecnichely "blow" a MLS (Multi Layered Steel) head gasket the same way as a composite, your OEM studs stretch, causing a leaking head gasket. ARP are a must for any boosted car, to prevent the head from lifting off the block. Hope this helps ya out a bit, not trying to be a smart *** but I do have a fair understanding of how an engine is affected by small yet effective changes. Thanks guys!!

 

Higher compression is better in a way. The reason we can't run high compression is because we don't have direct fuel injection, like higher end cars such BMW and Audi.

I wouldn't mind loosing low end power, our cars are FWD anyways. Too much low end torque will get us no where. Then again, I do plan on staying on stock compression, or maybe even 9.0:1

 

You are right in a sense, but thats not the problem. Lets forget about fuel and air delivery for a second. Remember in 1st grade, when we all thought it was so cool when our teacher put a little piece of tissue paper in a suringe. He would plug the one end then compress the piston, and the tissue would start to smoke. It was the air being compressed that created the heat, the harder you pushed, the hotter the inside air got. This applies the exact same way to the internal combustion engine. It doesnt matter how you deliver fuel, or how you deliver air, a higher compression ratio IS going to create more heat. This heat cannot be ignored, nor can it be eliminated. All that direct injection does is battle the side effects of the higher compression, and you can therefore get away with it. Our cars can handle just as much compression, you just need to do other things to compensate for the added heat, and these things may be too drastic to accomplish. It doesnt matter what you do, that air is still getting squeezed the same amount. You just don't increase compression with a turboed car.... sure you can, but you are losing in the long run. By adding a forced induction system, you are increasing that amount of air, just as you would with a higher compression ratio. This creates more heat, and with heat come pre-ignition and detonation. Pre-ignition is when the air/fuel mixture ignites on its own BEFORE the nucleus of flame (spark) happens, causing severe engine damage. Detonation is when the air/fuel mixture ignites AFTER the Nucleus of flame (spark), but at a different part of the combustion chamber, or before the propagation has reached that point, disrupting the controlled burn into something uncontrolled, causing engine damage also. All direct injection does is help control pre-ignition and detonation, but it doesnt solve the problem, it is just easier to keep a higher compression ratio without drastic measures. DI is extremely expensive and requires MUCH more caution when working with, as the pressures involved will literally cut you in half if something goes wrong. As I stated before, when using forced induction a lower compression ratio allows MORE air/fuel mixture be used becasue it is being FORCED into the engine, not DRAWN in. Actually some companies and techs willl tell you that it is NECESSARY to lower the CR when installing a forced induction system, though many do not because it does require tuning to correct for the loss in compression, and as we ALL know our cars definitely run good without lowering the CR. But, lowering it WILL allow for more boost safely, and more boost equals more air, more air equals more fuel, more air/fuel equals more power. Hope this sets everyone straight, not trying to act like a know it all.

 

found out something kida neat yesterday... Played around with some settings in ecuflash.... Increased the MAF size, increased latency a bit, increased maf scaling, increased idle rpms to get it to idle better and guess what. got more of that low end much like she had before i boosted her. The throttle doesnt lag any more and is much more responsive. I think the latency is what makes most of the difference cuz I got the most results from changing those values... just a slight increase, maybe .200 ms was perfect...

 

Hey thats awesome man.... I will really get the idle good once i get my parts. I ordered a stock MLS head gasket, ARP head studs, and the RPW Decomp. Shim @ 1.00mm thick..... can't wait to share my results when i get it in, I'll be sure to post on this thread so you can all join my glory, or defeat (hopefully the first one!!!!) No but seriously the only thing that I know will suck...... I didn't have the money to get it tuned yet, but I had it raod tuned quite well, a little rich up top under boost but it really did run good, now im gonna have to play with my fuel curve, but i know ill have fun doing it.... Thanks for the help guys, glad that you helped me make my final decision. Later.....

 

AWWWW crap..... RPW is away for the holidays and they don't get back till the 20th of jan...... I need my lancer running by the 24th of jan....... I hope they will do overnight or 2 day shipping..... we will see

 

overnight shipping from austrailia?!

well, whenever you get it, let us know how it goes. I may go with with the metal shim also along with ARP studs of course

 

Yeah, seems like the best choice.... I would of course like to go with decomp. forged pistons, but they don't exactly grow on trees, even though I wish they did. LOL But yeah I'll be sure to let everyone know, I sent them an email asking if they would give me a call to discuss shipping, They should be able to 2 day it at the least..... I hope haha.

 

dude just get a cometic gasket they have different trims so you get to pics what thickness you want...

 

Oh its all good dude, RPW's shims come in .80mm, 1.00mm, 1.50mm, and 2.00mm. I chose the 1mm for about a .5 drop in CR. Plus I looked around and couldnt find our engine under Cometic's website. I think RPW will work, and plus it's already ordered lol. Anyways, I'm hittin the sack

 

All right guys, just keepin you updated. I sent the money tonight, and with express shipping it cost me 450AUD for the ARP's, the shim/glue, and express shipping. Comes out to about 300 bucks..... not bad considering I was willing to spend 410 bucks on it before I knew everything is in Austrailian dollars lol. Anyways, I'll keep everybody informed, The parts shouldnt take that long, shipping was 100 dollars so I'm hoping it was a good extra investment.