JohnBradley

iTrader: (30)

What intake manifold, stock or Magnus or something? Timing sounds similar to what I was doing at 31psi on the stock intake manifold on 92 octane and 9:1. I squeaked in 9 but only past 7700 and rev'd to 8300 so not in there for long. On the Magnus I was able to dump more in since the VE had improved as well as scavenging to keep the cylinders clean.

Aaron

Mellon Racing

iTrader: (38)

FWIW I'm daily driving/racing on 93 octane with 10:1 at 30psi making 600awhp. The timing is only slightly lower than when I was on 9:1

EvoDan2004

iTrader: (94)

what else was changed when you went from 9.1 to 10.1? just the motor or was there other parts?

i ask this because my main question is what motor ''9.1/10.1'' will make the most power/trq at the same timing/boost/afr levels from one another.

BLKCarbonEVO

iTrader: (2)

I believe that there is a 4% difference in power between 9:1-10:1 with all things else being equal.

Mikey

4doorbullit

iTrader: (2)

Lol. Right on the money. Yeah its on a stock intake manifold. I also was able to run 9 degrees around 7800 rpm but thats pretty much the rev limit by then. I just turned it down to 8 degrees bec sometimes it would pull timing if the boost would creep a little higher. The 10:1 compression its pretty much perfect for 93oct but idk about 92 oct. I live in florida so we dont have that here.

Mellon Racing

iTrader: (38)

I went from FIC 1650's to FIC 2150's the rest was the same.

I used to run 32psi to get 600, now I run 30psi and a few degrees less timing to get 600awhp.

JohnBradley

iTrader: (30)

So really the 93 lets you run one point more then than I can on 92, basically. If your timing/boost isnt any different but you are making 3% or 4% on power due to compression. Everything being what I would suspect then is my car made 531whp with the same basic setup, 4% more would push it to 552ish. The fact that on average it looks like you can run 3-4* more timing normally would put it where I was after the Magnus (12-13*) out the top and made 574. All in all it seems the timing is worth more than compression at least in my case if all these numbers translate directly across like that.

Has this car been to the dyno at this level or the track?

aaron

EvoDan2004

iTrader: (94)

so it is making power easier then before. can that 10.1 motor run 32psi and that higher timing or does it not like it.

4doorbullit

iTrader: (2)

The car hasnt gone to a dyno yet. I did put the logs on the virtual dyno. The car was also weighed to make sure everything was accurate as possible. It put down 525whp on the new Vd dyno.

Mellon Racing

iTrader: (38)

It might make more on pump with more boost, but 600 was my goal and it was a long day. Stock ecu and stock maf for what it's worth. This was back in the 60-80 degree weather, it's ~ 30 degrees lately so I'm sure it's up on power due to that.

next up will be setting up the d2 coilovers and the e85 tune when I get the clutch back from tilton. our track was finally purchased after it's been shut down for years so maybe we'll get to race this spring.

03whitegsr

iTrader: (8)

I think the thing people miss is that you don't pick compression and work around it. You pick a turbo and the fuel you are going to run and select the compression based on that.

If raising the compression will make you "octane limited" before you max out the turbocharger, then you are likely better off using lower compression, provided maximum power is the goal. Contrary to that, if you can max out the turbo and reach MBT on the tune, bumping up the compression will likely show gains (unless you just happen to be at that sweet spot on compression). Thermal efficiency doesn't take a big hit until you start getting under 8:1. Like wise, thermal efficiency doesn't go up much past 11:1.

Eric, the 10:1 I was referring to was closer to 9.5-9.7:1. It's just the flat top -4cc valve pocket piston with zero deck height. They were called 10:1 at the time, like Aaron said though, some companies are catching on and calling them 9.6:1 pistons.


"Dynamic compression" is a joke though. You have so much inertia charging, exhaust reversion and other dynamic effects going on that "dynamic compression" tells you almost nothing. I guess it gives you an idea of the cranking compression at very low engine speeds...

JohnBradley

iTrader: (30)

I think I mathed it out to show that ESPECIALLY if the car in question is really only making 525whp.

I look at it like this, Honda guys dont rebuild their turbo motors at 10:1 and go. Almost all of them drop it 8.5:1 or 9:1 and go. 9:1 vs 10:1 in my car really doesnt seem to make a difference. Its great for making records on a given turbo, or if you have a methanol car and are going crazy anyway. Or if you are a rally guy (again more along the lines of a record for a given turbo size) and need to maximise the squish for the amount of air going in.

If I wanted a "pumpgas" record I'd go the other way most likely and drop compression. If I wanted an E85 record I'd still probably go no more than 10:1. If I want a DSM and auto to come up on the converter without nitrous then maybe I'd think about high compression. Tried it, mixed results, not likely to do high compression again.

The rally project is a different story...not one I am going to talk about in public

aaron

saxon

iTrader: (10)

since I am coming from a built 11:1 k24 turbo motor id say its the opposite anymore, most stay around 10:1 or 11:1 if your a k series, but then again the head flow, variable cam timing etc do help out

i really need to look into these setups and see what really works, it seems there are so many different setups ranging from 2.0 to 2.4 with every version having a "long rod" variant it seems impossible to say any compression is the "right" compression

JohnBradley

iTrader: (30)

For sure. On E85 or racegas and high boost I would say its okay. Tony1 took that S2k and put like a 3.0mm HG in it when he made 700whp on a stock bottom end. On the 10:1 and 11:1 K series though, how much boost are they running? Do they run what most of us Mitsu guys consider normal? Or what we consider WG line? I am asking cuz I am curious btw, not wanting to sound like a dick

cij911

iTrader: (14)

Aaron - I thought most pump timing maps were more like 15* at redline (for 9) and much higher for the 8 IIRC. Why were you only able to run 8 * ? Thanks!