race gas revisited, why and when? Options

[scotty914]

sorry miles i am just doing my job here, and trekkor sorry for the high jack

miles instead of buying new music stuff how about sending another brad check (IMG:http://www.914world.com/bbs2/html/emoticons/hide.gif)

[redshift]

You take guitars?

(IMG:http://www.914world.com/bbs2/html/emoticons/huh.gif)


M

[Type 4 Unleashed]

The thing about AV Fuel, you have to remember where it's used. It has alot of additives, which some are, deicing agents, and other agents, for the higher altitudes, where the air is thin and cold.

Even though it has a higer octane, running it at sea level, will not get the same results, that race gas would provide. Even mixing it, would provide little or no benefit.

Anyone that ran AV Fuel, what was the color of your tail pipe? And if you say white, that speaks for it self. (IMG:http://www.914world.com/bbs2/html/emoticons/aktion035.gif)

[Trekkor]

Point of interest:

Topped off with pump gas, and the car seems a bit underpowered and has some pinging I never noticed before. (IMG:http://www.914world.com/bbs2/html/emoticons/dry.gif)

It pings a little on idle, mid range and when accelerating. Also after a good hard run it pings and dings on hard decel coming off 6k down to idle.

My mix is 2.5 gallons 110 octane fuel and the rest 91 octane Chevron pump gas. What is that like 16-17% juice?

KT

[lapuwali]

QUOTE (trekkor @ Apr 8 2005, 03:41 PM)

Point of interest: Topped off with pump gas, and the car seems a bit underpowered and has some pinging I never noticed before. (IMG:http://www.914world.com/bbs2/html/emoticons/dry.gif) It pings a little on idle, mid range and when accelerating. Also after a good hard run it pings and dings on hard decel coming off 6k down to idle. My mix is 2.5 gallons 110 octane fuel and the rest 91 octane Chevron pump gas. What is that like 16-17% juice? KT

It pings at IDLE? It pings on DECEL? I think you're hearing something you think is ping and it's really something else.

On an engine where octane is marginal, ping will only happen under load, usually at lower revs. If it happens at high engine speeds, the octane isn't "marginal", it's way too low, and you'll eventually have a holed piston. If it happens at very light loads or no load at all, then something is very seriously wrong. Ping should always get worse going uphill, and will typically go away if you drop down a gear going up that hill.

Does adding the 110 octane make this noise go away? If so, then I don't understand what's going on.

[Trekkor]

Right now the concentration of high octane in the tank is low. And now is when I notice it pinging.

QUOTE

It pings a little on idle, mid range and when accelerating. Also after a good hard run it pings and dings on hard decel coming off 6k down to idle.

I should have said little pinging while hard accelerating off idle and mid-range.

It's not major. Just faint. If I put more super sauce in the tank and it goes away, I know it needs it. Right?

remember folks, this motor came out of a tube frame desert racecar. Guy said that it had too much power for the car...he put in a 1835cc type 1 instead (IMG:http://www.914world.com/bbs2/html/emoticons/wacko.gif)

Said it was airborne too much...

KT

[ArtechnikA]

QUOTE (trekkor @ Apr 8 2005, 07:16 PM)

...If I put more super sauce in the tank and it goes away, I know it needs it. Right?

what's your ignition advance again?

what's the curve like ?

could be that you have way too much initial advance. could be that the advance comes in too quick.

could be that you could retard the cams a few degrees.

if you don't know their grind, and you don't know how they're timed, and you don't know the actual compression ratio, you're really tuning by symptom. (simetimes it's the best we can do...)

you might try for a different emulsion tube arrangement if you're experiencing leanness in the transition. (no way to know without AFR vs load curves from a dyno...)

colder plugs might be a short-term Band-aid if you can keep them from fouling.

[Trekkor]

This dizzy gives me 35 degrees advance at 6k.

KT

[Trekkor]

You all should know what a freak I really am.
I put some race fuel in my lawn mower and weed whacker, too. (IMG:http://www.914world.com/bbs2/html/emoticons/unsure.gif)

When I'm working in the yard the smell makes me think of racing instead. (IMG:http://www.914world.com/bbs2/html/emoticons/wink.gif)

KT

[nebreitling]

that's sick trekkor... just sick. (IMG:http://www.914world.com/bbs2/html/emoticons/screwy.gif)

[Trekkor]

QUOTE

You all should know what a freak I really am.

OK, "Sick Freak", I really am... (IMG:http://www.914world.com/bbs2/html/emoticons/burnout.gif)

KT

[J P Stein]

I've never heard my 6er ping, but have felt it...back when I was workin' on the tune.

According to B. Anderson, pinging in a 911 motor can be nearly inaudible....which would lead one to assume that if you can hear it clearly, it's not light.

I'd back off the timing till you get it worked out or you'll be a sick freak with holed pistons.

[grantsfo]

QUOTE (trekkor @ Apr 9 2005, 09:26 AM)

You all should know what a freak I really am. I put some race fuel in my lawn mower and weed whacker, too. (IMG:http://www.914world.com/bbs2/html/emoticons/unsure.gif) When I'm working in the yard the smell makes me think of racing instead. (IMG:http://www.914world.com/bbs2/html/emoticons/wink.gif) KT

LOL!

I'll have to treat my weed wacker to some race gas since I have 2 acres of waist high weeds. Maybe it will make me go faster! (IMG:http://www.914world.com/bbs2/html/emoticons/biggrin.gif)

Only car I can run race gas and really feel improvement is my 1.8 T A4 that has been chipped. That car easily puts out another 10 hp with 104 octane as opposed to 91 premuim we get here in CA. My wife always knows when I put race gas in that car. She'll come home and say wow the Audi was really fast today what did you do to the car?

[ArtechnikA]

QUOTE (trekkor @ Apr 8 2005, 07:41 PM)

This dizzy gives me 35 degrees advance at 6k.

E and S are specified for 30* BTDC @ 6000

as important as total advance is when it comes in; there's a curve it's supposed to follow that approximately matches the cam. a broken or weak spring will bring in the advance way too early and cause pinging. watch how the advance comes in some time and see if it's a relatively smooth linear progression or if it all comes in in one jump...

[Trekkor]

The acceleration is smooth then the power COMES ON after about 4500rpm's in a BIG STRONG way. (IMG:http://www.914world.com/bbs2/html/emoticons/clap.gif)

Drove it out to the track today. I only noticed a little popping and sneezing out the carbs on cruising speed. Say 3000rpm's

KT

[ArtechnikA]

QUOTE (trekkor @ Apr 9 2005, 08:17 PM)

The acceleration is smooth then the power COMES ON after about 4500rpm's in a BIG STRONG way. (IMG:http://www.914world.com/bbs2/html/emoticons/clap.gif) Drove it out to the track today. I only noticed a little popping and sneezing out the carbs on cruising speed. Say 3000rpm's KT

cool. that's where your cams come in.
but it has nothing to do with your ignition advance curve...

this is not a seat-of-pants thing.

the best way to find out what you've got (besides probably 5* too much advance) is to pull the dizzy and have it checked out by someone with a distributor machine. the correct curves are published in the factory workshop manuals; if you have the distributor number (ideally, the Porsche number although the Bosch number isd better than nothing...) we can track down what the curve *should* be.

lacking that, the best thing to do it watch the timing marks with a timing light, which i understand is a PITA on a /6 (BTDT). the next time i install an engine in a /6 i'm going to put different-colored paint dots every 5 degrees from Z1 to 35* si can see right away what it is i'm looking at... anyway - you need to verify that the advance comes in -relatively- smoothly. there are a couple of little bumps but basically it's pretty smooth. what it should *not* do is come in very quickly at too low rpm (like the dizzy in my E does - it's basically all in by 2500 and i have to be pretty careful with lugging. i'll fix it when the engine comes out...)

the popping and sneezing sounds you have a bit of the standard transition-to-mains Weber flat spot. i would try to go up a couple of steps richer on the emulsion tubes.

[Trekkor]

Thanks very much for the good advice, once again. (IMG:http://www.914world.com/bbs2/html/emoticons/wink.gif)

I've been putting off pulling out the distributor anyway, as I need to get the part # for the Pertronix upgrade.

KT