How much peak timing for 1.4-bar of boost?

Tippy · 05:59 PM

Was running 22* but I think I heard a minor ping for a split-second.

Turned it down to 20 but wondering if I'm still too advanced.

On a side note, was running 28* at 1.1-1.2-bar before, before the Pelican brain trust told me that's too hot. Boy did it run good though!

Using fully programmable ignition, 93 octane, and single plug 3.4, 7.5CR.

b930 · 01-27-2014, 07:57 PM

22 is probably on the edge if other factors such as mixture and inlet air temps etc are not spot on. I run 20 with 1.2 bar but use a big intercooler with a GT35 and fat mixtures and it seems to be fine. Never heard recorded any knock on the SDS, but I am not using a different EMS without knock control so I just go with 20 at ~1.2bar to be safe.

Tippy · 09:45 PM

I'm running around 11.4-11.5 AFR's with a big IC too. Running a 58mm Holset vs your 62mm GT35R. Manifold temps are about 15 over ambient so far. Haven't used in summer temps yet.

Raceboy · Raceboy's Garage

Single plug requires at least 20 degrees of advance, especially with the large combustion chamber of 3.4 but with pump fuel you will be knock-limited.

I would prefer running lower boost but closer to MBT which would create less heat and more power.
Also if you did get knock in current temperatures (in Tx that is, here it is -17C at the moment) you will damage the engine for sure in summer.

The best solution is to add toluene or xylene to gas (no more than 30%) which would let you run 5-6 degrees more advance over current setup easily at 1.4 bars and make much more power without fearing of detonation (though cylinder pressures will be high as they supposed to be at those power levels).
My guestimate would be that engine makes ~700hp @ 1.4 bar and 28 degrees of advance with higher octane fuel.

Tippy · 01-28-2014, 06:55 AM

Remember I'm running the 58mm/8-blade HX40 so it would probably max at 600??

philip j · 01-28-2014, 07:14 AM

Quote:

Originally Posted by Raceboy

Single plug requires at least 20 degrees of advance, especially with the large combustion chamber of 3.4 but with pump fuel you will be knock-limited.

I would prefer running lower boost but closer to MBT which would create less heat and more power.
Also if you did get knock in current temperatures (in Tx that is, here it is -17C at the moment) you will damage the engine for sure in summer.

The best solution is to add toluene or xylene to gas (no more than 30%) which would let you run 5-6 degrees more advance over current setup easily at 1.4 bars and make much more power without fearing of detonation (though cylinder pressures will be high as they supposed to be at those power levels).
My guestimate would be that engine makes ~700hp @ 1.4 bar and 28 degrees of advance with higher octane fuel.

Has anyone ever run Toluene in a injection system? I always wondered about this? I think is is pretty hard on plastic parts though.

Philip

JFairman · 01-28-2014, 07:22 AM

Quote:

Originally Posted by philip j

Has anyone ever run Toluene in a injection system? I always wondered about this? I think is is pretty hard on plastic parts though.

Philip

Good point.
CIS fuel heads have some rubber o-rings in them and the aluminum lambda head has a more flexible synthetic diaphram that might not like toluene.
EFI fuel rails and injectors should handle it so as long as the fuel pressure regulator you use will tolerate toluene it should be ok.

jbrown · 01-28-2014, 09:29 AM

I run 25 degree timing on mine with 1.1 bar of boost.. For a little safty I run a meth injection kit. I have it plummed into the outlet of the intercooler pipe. After I do quick run I ck the temp at the output of the intercooler and it is cooler than temp outside.. It has worked great for me for 2 years.
I have single plug ignition and xdi ignition system....

xbmwguy · xbmwguy's Garage

Tippy, are you pulling timing at the onset of your power curve then adding back up top? I was at 26* at 6400 on e85

Tippy · 01-28-2014, 05:15 PM

No, but I need to. I think it probably had the slight ping at peak torque.

Raceboy · Raceboy's Garage

Oh, yeah, with 58mm HX40, it will make maximum ~600 whp..

We have used toluene on BMW E30 that had M30B35 fully built engine in it and Holset HX40 Super. At 1.7 bars it made 730 hp with 19 degrees of advance. It was scary to drive. Toluene did not cause any issues but the mixtures need some adjustment.

Remember, 1980's turbo-era F1 engines ran on pure toluene so it has been used with some success

WERK I · WERK I's Garage

Tippy,
What cams are you using?

Tippy · 01-29-2014, 03:46 PM

Stock Carrera 3.2 which are identical to SC cams.

aspemo · 01-30-2014, 09:54 AM

I have used xylene 20% mixture and it was no problem with 1.3-1.4 bar. Then I tried metanol but it choosed to abandon that solution, due too many factors that could fail. So now I use etanol.
The car seemed more easy on the trottle, more responsive, with 20% xylene. But with etanol I can increase the turbo pressure. LOL