You're supposed to run low compression with a turbo

"YSI-what can brown do for you" (ysi-what-can-brown-do-for-you)
08/22/2014 at 12:08 • Filed to: None

1015rwhp, 11.5:1 compression. That thing is going to explode!!!

DISCUSSION (35)

Biased Plies > YSI-what can brown do for you
08/22/2014 at 12:10

When it sounds this awesome, who cares if it occasionally explodes?

That said, it seems like a very short powerband, almost uselessly so.

Brian Silvestro > YSI-what can brown do for you
08/22/2014 at 12:10

How has that not broken yet.

mcseanerson > YSI-what can brown do for you
08/22/2014 at 12:11

What Octane? I don't have time to watch.

Edit: Also how much Boost?

Textured Soy Protein > YSI-what can brown do for you
08/22/2014 at 12:11

Probably running some kind of water/meth injection to keep cylinder temps down.

RazoE > YSI-what can brown do for you
08/22/2014 at 12:11

I had non-turbo pistons swapped on my 7MGTE for a higher compression. I was only pushing 12 psi, though.

The Tunnel > YSI-what can brown do for you
08/22/2014 at 12:12

Low compression is like using your home vaccum machine, Wen needs tons of compression!

YSI-what can brown do for you > mcseanerson
08/22/2014 at 12:12

E98 Fuel, so if E85 has a 100 to 105 octane rating, this probably around 115 to 120.

briannutter1 > YSI-what can brown do for you
08/22/2014 at 12:13

I build turbo pistons for a lot of people and you'll be surprised at how many are in this area and even higher if they are required to run restrictors :)

mcseanerson > YSI-what can brown do for you
08/22/2014 at 12:13

That helps, how much boost?

Grindintosecond > YSI-what can brown do for you
08/22/2014 at 12:14

Two schools of thought. low comp with high boost, or high comp with low boost. the internal pressure is all we really need to worry about in the end. the high compression with boost helps take care of the zero low end torque to start with, ie: helps mitigate the lag before the boost hits and also helps it spool up a bit sooner. The low comp with high boost means just that, big boost power. I suspect this engine will be very flexibile instead of just a big boost rev-limit drifting and you-tube bikini girl ride-along video car. Look at how much more rpm it has to use after the boost is on for the rest of the pull.

Saracen > YSI-what can brown do for you
08/22/2014 at 12:14

Running race gas, so that would help eliminate the chance for detonation.

Though imo, this is a waste of an E46 M3.

YSI-what can brown do for you > RazoE
08/22/2014 at 12:14

Well on the FRS people run 450hp on the stock engine internals. It has 12.5:1 compression ratio. . . it is ridiculous that they haven't exploded yet.

YSI-what can brown do for you > mcseanerson
08/22/2014 at 12:16

26psi, so it isn't at like 50 or something, but it is still quite a bit of boost.

mcseanerson > YSI-what can brown do for you
08/22/2014 at 12:17

Yeah 26 is a lot with that much compression, even on 115 octane.

YSI-what can brown do for you > Biased Plies
08/22/2014 at 12:18

I was trying to look at the dyno graph and it seems torque is held about mid way through the rev range, I honestly couldn't tell though.

YSI-what can brown do for you > Textured Soy Protein
08/22/2014 at 12:18

He is using E98 as fuel, so that probably helps.

YSI-what can brown do for you > Brian Silvestro
08/22/2014 at 12:18

Magic I tells yah!

YSI-what can brown do for you > Biased Plies
08/22/2014 at 12:20

Nope nevermind, it is about 70% through the revs before the torque curve peaks and flattens.

Yowen - not necessarily not spaghetti and meatballs > YSI-what can brown do for you
08/22/2014 at 12:21

What sort of boost do they run though?

YSI-what can brown do for you > Saracen
08/22/2014 at 12:21

I agree, not really meant for outright power, but hey, to each their own!

YSI-what can brown do for you > Yowen - not necessarily not spaghetti and meatballs
08/22/2014 at 12:22

I can't remember off the top of my head, but it is between 15 and 25. I know not real specific. The crawford BRZ uses 27 psi, so I am assuming it is somewhere around there.

Yowen - not necessarily not spaghetti and meatballs > YSI-what can brown do for you
08/22/2014 at 12:24

My EcoBoost 3.5 runs 10:1 compression and 12psi stock, after I get it tuned I'll be running more boost.

No matter what, with 1015 hp you will severely limit engine life no matter what you do and the only way to get to these numbers is with insane compression coupled with boost or low compression coupled with insane boost.

Zipppy, Mazdurp builder, Probeski owner and former ricerboy > YSI-what can brown do for you
08/22/2014 at 12:24

I occasionally drive a car that has a 19:1 compression and currently puts out 15psi boost.

Brian Silvestro > YSI-what can brown do for you
08/22/2014 at 12:27

There is no other explanation.

RazoE > YSI-what can brown do for you
08/22/2014 at 12:35

yeah, but the M series engines date back to the 60s..=D

Plus direct injection does wonders.

YSI-what can brown do for you > Zipppy, Mazdurp builder, Probeski owner and former ricerboy
08/22/2014 at 12:37

No way. I can't believe that shiz! Don't F1 cars have like a 17:1 comp ratio?

YSI-what can brown do for you > RazoE
08/22/2014 at 12:38

Bingo! It acts like a diesel engine. . . kind of. Really helps improve compression and thus performance.

jlmounce > YSI-what can brown do for you
08/22/2014 at 12:41

A lot more at play than just boost and compression. You're talking about static compression, but what really counts is dynamic compression. Remember, the intake and exhaust valves are only closed for so long. You can reduce dynamic compression by keeping the exhaust values open longer in relation to the intake stroke.

To reach that type of power, there's more going on with the setup then just throwing a large turbo and lots of pressure at it. There's likely custom ground cams for the setup which is a big part of it living. It's also likely running on a high octane fuel as others have mentioned.

As long as you can control combustion chamber heat and keeping your fuel pre-ignition level managed through proper quench and combustion chamber heat management, you can throw lots of boost at a high compression motor.

You're basically adopting diesel principles to a gasoline engine. Modern trucks for example run north of 17:1 compression and see boost near 40psi. Physics doesn't change in a diesel engine, so you can certainly do the same with a properly prepared gasoline engine.

julienjj > YSI-what can brown do for you
08/22/2014 at 12:44

Direct injection also give a non negligible cooling boost.

Zipppy, Mazdurp builder, Probeski owner and former ricerboy > YSI-what can brown do for you
08/22/2014 at 12:51

Better believe it.

It's a turbodiesel.

YSI-what can brown do for you > Zipppy, Mazdurp builder, Probeski owner and former ricerboy
08/22/2014 at 12:51

Oh well then. . . I thought it was a standard gasoline engine.

n54 & s38 > YSI-what can brown do for you
08/22/2014 at 12:53

Is that an E46 M3? Damn! Those engines are high strung as it is....

Rock Bottom > YSI-what can brown do for you
08/22/2014 at 13:25

As long as you have nice, tall ring lands and you don't cheap-out on things like fuel management and charge cooling, it can live. No problem.

Yowen - not necessarily not spaghetti and meatballs > julienjj
08/22/2014 at 13:37

haha non-negligible, I like that word.

Jordan and the Slowrunner, Boomer Intensifies > YSI-what can brown do for you
08/22/2014 at 14:03

I think it all depends on how strong the internals are, diesels run super high compression and some run over 36 psi stock.