NA Pistons in a Turbo

[suprra_girl]

actually.....
lol

i'm using 020" gte pistons... my compression was upped by lots of skims on head & block and using a thin head gasket

previous cc on engine with a 4mm hg was 7.98:1
i got a 1.8mm gasket which worked out to be 9.4:1 according to some calculations someone made

 

[Justin]

I imagine you would have slighly better gas mileage (a feature of high compression motors).
You would also get more power ("free") since that is also a feature of high compression motors (unless you are sacrificing boost).

I'm not to terriably worried about gas mileage.... If I wanted good milage I wouldn't have sold my Accord

That's what I'm torn between.... Fromhat I have gathered running 10-12 PSI would be awesome in terms of power... and I doubt I'd ever run more power than that till I could afford all sorts of tricky stuff.

I have also been thinking of using N/A pistons because if the N/As can be turbocharged with their pistons (assuming they use their original pistons), why can't I.

yah, I've been thinkin the same thing

My intended set-up may be different than yours though, Justin. I am only building very close to stock (my need for speed only gets quenched on 2 wheels).

I'm only going with all that hardware cuz I want my engine to be as bullet proof as I can afford... I'm not planning on making huge numbers, just want it to be solid.

actually.....
lol

i'm using 020" gte pistons... my compression was upped by lots of skims on head & block and using a thin head gasket

previous cc on engine with a 4mm hg was 7.98:1
i got a 1.8mm gasket which worked out to be 9.4:1 according to some calculations someone made

that's what the NA pistons are. one of the things i'm hesitant about is the fact the NA pistons are cast, nor forged.

how has your car been running, with the higher compression, anything note-worth?




coinball on SF said that he was building what i was thinking of... he predicted 14 PSI at 2500 RPM's... that would be awesome!!!

 

[suprra_girl]

well i was only running 9 psi with afr's at 11.7:1 stock fuel system
i guess for high compression lovers you would love the way my car responds, no lag just smooth full on power all the way to 6500rpm, rev limiter gets in the way at 6750 lol
pulled 278whp @ 9psi 9.4:1cr
and a 13.3 1/4 on a very cold night

im going back to 8.0:1 tho as more boost and kick you in the arse boost is more fun for me

 

[Furball]

Detonation is the lurking problem here. High comp can have a lot going for it if you take the necessary precautions when running higher boos levels (higher octane gas or something like a water injection system to cool things down). I remember seeing a video of a not yet fully tuned high compression ratio mkiii runing a T-70somthing turbo slapping around a Z06 Corvette and a Modified Mustang Cobra, with the mkiii running just 9 psi. That is just sweet.

 

[supradan22]

Same rods Natan.

Are they the same bearings too?

 

[IJ.]

Yep same same!

Not a lot of differences between the 2 motors excluding the oil squirters bypass oil cooler and block drilled for the oil return/supply for the turbo CPS in place of the NA Distributor and I think 1 cam!

 

[rakkasan]

Detonation is the lurking problem here. High comp can have a lot going for it if you take the necessary precautions when running higher boos levels (higher octane gas or something like a water injection system to cool things down). I remember seeing a video of a not yet fully tuned high compression ratio mkiii runing a T-70somthing turbo slapping around a Z06 Corvette and a Modified Mustang Cobra, with the mkiii running just 9 psi. That is just sweet.

John's car (JBL) I believe. :icon_lol:

 

[supradan22]

Yep same same!

Not a lot of differences between the 2 motors excluding the oil squirters bypass oil cooler and block drilled for the oil return/supply for the turbo CPS in place of the NA Distributor and I think 1 cam!

Thats good to know im in need of new bearings and rods and all I see on ebay are the 7mgte so just too be sure would this work with the 7mge http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&rd=1&item=7977714812&category=33619

 

[Justin]

Detonation is the lurking problem here. High comp can have a lot going for it if you take the necessary precautions when running higher boos levels (higher octane gas or something like a water injection system to cool things down). I remember seeing a video of a not yet fully tuned high compression ratio mkiii runing a T-70somthing turbo slapping around a Z06 Corvette and a Modified Mustang Cobra, with the mkiii running just 9 psi. That is just sweet.

That's what I'm tryin to do, find out all the precautions I would need to take. High Octane gas isn't that big of a deal, I'd maybe spend 20-40 more dollars a year

 

[IJ.]

Thats good to know im in need of new bearings and rods and all I see on ebay are the 7mgte so just too be sure would this work with the 7mge http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&rd=1&item=7977714812&category=33619

Don't know about all the hype but yeah they'll work in a GE!

 

[TONY!]

Since I have been intrigued by high compression engines for some time, I saved this thread before the site crash. It has some info on high compression engines and I believe it may be the set up that Genna laid 700+ RWHP. Enjoy.

NOTE: Since some of the following members are not here anymore, don't expect to get responses from them.

9.5:1 comp SP71, fully built w/ AEM

running off of the wg spring(10ish psi), 400 miles on motor, in auto mapping/learning mode on AEM, very conservativetiming......

this car pulled a stock Z06, modded '03 cobra and some others.........at 10 psi

boost hits so much earlier and harder, and I wouldn't be surprised if he puts down 430 to 450 rwhp at 10 psi...

some vids were taken against the Z06, hopefully they will be shared here.....

How about someone give up some more info on this Vette Slayer? And BTW... can someone explain what the PSI equivilant might be for this car if it had
standard 7M compression? What I mean is: The new Higher compression plus the 10psi is equivelant to standard compression plus ??psi....

I've always had the understanding that if one was to run a higher compression motor this would be advantageous in that one would be able to run lower boost (thereby maximizing the efficiency of the turbo and extending its life) all the while making more power at this lower boost setting. That being said, why do we find folks who already have the lower compression (standard) motors going with setups that lower the compression even more? Is it just to say that they can now run 30+psi and so on..? Or are there mechanical advantages to this as well? Given the choice, I would probably go with the higher
compression setup for the reasons stated above. What do you folks think?

How about someone give up some more info on this Vette Slayer? And BTW... can someone explain what the PSI equivilant might be for this car if it had standard 7M compression? What I mean is: The new Higher compression plus the 10psi is equivelant to standard compression plus ??psi....

I've always had the understanding that if one was to run a higher compression motor this would be advantageous in that one would be able to run lower boost (thereby maximizing the efficiency of the turbo and extending its life) all the while making more power at this lower boost setting. That being said, why do we find folks who already have the lower compression (standard) motors going with setups that lower the compression even more? Is it just to say that they can now run 30+psi and so on..? Or are there mechanical advantages to this as well? Given the choice, I would probably go with the higher
compression setup for the reasons stated above. What do you folks think?

if done correctly more boost on lower CR will always be more hp then lower boost on higher CR. PSI is a misleading measurment of power, but it is the only thing that we can measure in a practical mannor. lb/min is actually where the hp comes from. psi is just how hard the turbo is working to force XX lb/min into the motor.

Yeah, this is Genna's car, not mine…Another advantage of the high comp is that it spools like a much smaller turbo.

oh yeah, there are advantages to lower boost with higher CR. i'm doing it myself, but only 9.2:1CR but daily use i am only running 8psi on a stock CT. definetly make for nice street driven car.

would like to see his dyno numbers running 10psi on 9.5:1CR.

 

[TONY!]

I also joined DeanMarcum's forum to see what he thinks of all this. He sent a duplicate message to SF as he did to me in his forum. I hate to crosspost, but as I have heard drjonez twice say, "Dean is the man." So here is what he said:

With the ITS turbo I am running right now the car made over 500RWHP. Stock GE pistons (cast hypereutectic just like the turbo pistons), 550s, Rebic LC, head and manifold porting and a few other little things. I was able to hurt a N/A piston because of a failed Aeromotive fuel pressure regulator which dropped the pressure while on a 16psi run. The drop in pressure caused detonation which lead to a cracked ring land. Running the N/A pistons brings you closer to the raged edge and things do break if a minor system fails.

When running over 400RWHP you should really have a fuel pressure gauge with a warning light. I did not install it on the brown car because it is my "driver" and did not think I would ever look for over 300HP. But, things change, LOL. The block and crank were not hurt at all. The piston suffered 2 cracks on the #2 ring land. Easy to fix.

Anyhow, the GE pistons/comp ratio work fine with the GTE electronics. Just be sure to run good fuel and if you upgrade the turbo and/or start pushing over 14psi things must be monitored much more closely.

The brown Supra has become more of a "test bed" for new ideas on the 7M so I did not mind "breaking it". Gives me a reason to pull the motor and try something new since I can not get it to blow a head gasket.

The highest "safe" boost to run on the N/A pistons assuming that your fuel system is up to snuff is 12 psi. If you run a more efficient turbo or better intercooler then you can bump up to 14psi. Run a good fuel computer and larger injectors and the aforementioned you can see 16psi. Run some form of timing control along with athe aforementioned and you can see 18psi. Race gas and the aforementioned: 20psi.

Runnig 10psi or less and stock ignition timing should cause no problems.

 

[Mr.SelfDestruct]

I have a friend running a high compression GE in his cressida that hes building, do you think a turbo would be safe with the higher-than-stock compression?

 

[bluemax]

I didn't want to have problems when I did my NA>T , and I wanted better pistons anyway, so I went with forged 8.3:1 compression pistons.
I think it also depends on the weather conditions too. If you're in a dry hot area than you can't run too high boost. If you're in a cold wet area then you can boost much higher.
One thing good about the higher compression motors is that they are much more efficient, product more HP, and better fuel economy than equivalent lower compression motors. You just risk detonation. I've read going from N/A 9:1 down to N/A 8:1 you loose about 10% HP.