Pump gas vs. Torco 114

Is anyone running 2 seperate tunes for pump gas vs. racing gas and if so, on average, what is the difference in timing??? Do you have any dyno and/or track time to compare the difference in H.P. or E.T.?

Hard to believe that no one has run some higher octane race gas thru their motors. Timing and/or boost increases would certainly net some noticable performance numbers.

Hard to believe that no one has run some higher octane race gas thru their motors. Timing and/or boost increases would certainly net some noticable performance numbers.

IMHO there is not that much extra power to be made using extra timing and race gas or torco. I fool around with my timing all the time and don't see any drastic increases or decreases adjusting timing. I see large increases in power when the AFR is exactly right.:)

There's plenty of power to be made with more timing.....

I've gotten rid of the car (94 Z/28) but back when I first put the P600Bb on the car and it just made 7lbs of boost and I switched between 24* and 28* of timing it averaged about 15rwhp and 20rwtq throught the powerband. I know that's relatively small but it did make a differnce at the track and also was easy to do.

Now after that motor met it's maker (on the pump gas tune & 24*) I rebuilt it to a 383 w/ D1 19#'s and this is where timing made a huge difference.

The below are all rear wheel numbers from a dynojet.

24*- 571 hp / 535 tq
26* - 604 hp / 552 tq
28* - 630 hp / 562 tq
30* - 654 hp / 581 tq

I drove the car on the street and ran between 22-24 degrees and at the track I used to run it in the 28* range and it ran 10.0 @ 136

The motor did not like 29* or above as it munched a few head gaskets while trying to reach for glory (aka - 9's)

Whatever it was fun while it lasted ;)

Marc

There's plenty of power to be made with more timing.....

I've gotten rid of the car (94 Z/28) but back when I first put the P600Bb on the car and it just made 7lbs of boost and I switched between 24* and 28* of timing it averaged about 15rwhp and 20rwtq throught the powerband. I know that's relatively small but it did make a differnce at the track and also was easy to do.

Now after that motor met it's maker (on the pump gas tune & 24*) I rebuilt it to a 383 w/ D1 19#'s and this is where timing made a huge difference.

The below are all rear wheel numbers from a dynojet.

24*- 571 hp / 535 tq
26* - 604 hp / 552 tq
28* - 630 hp / 562 tq
30* - 654 hp / 581 tq

I drove the car on the street and ran between 22-24 degrees and at the track I used to run it in the 28* range and it ran 10.0 @ 136

The motor did not like 29* or above as it munched a few head gaskets while trying to reach for glory (aka - 9's)

Whatever it was fun while it lasted ;)

Marc

What kind of heads do you have on your 383? AFR? I just can't figure out why your combo likes so much timing.

24*- 571 hp / 535 tq
26* - 604 hp / 552 tq
28* - 630 hp / 562 tq
30* - 654 hp / 581 tq

Marc

Those are the kind of numbers I would expect as I've never seen a blower motor (or most any motor for that matter) not like additional timing providing it has the appropriate octane fuel to safely support the added timing.

Marc - What kind of fuel were you running when it started eating the head gaskts? I would imagine with some 114 or 116, 28 to 30* of lead and 18-19lbs. of boost, the motor would be relatively happy:D, providing you didn't lug it.

97pilot - I was running stock LT1 heads that were ported by CNC.

Before and after pics of the heads are here:
http://www.geocities.com/marc94z28/cncheads.html

Click on the pics for more pics ;)

Boosted - I was running the highest unleaded gas I could get. Don't recall if it was 104 or 107 but somewhere in that range.

I considered running leaded C16 but I was running a FAST system and wide band 02 sensors were not cheap, in hindsight they would probably have been cheaper than doing head gaskets (downtime, parts, headaches etc...)

There are times when I miss the Tomato (the 94 Z) but my 73 Z/28 with an LS1 is not too shabby either :D Looks better and goes good.

Uncle Marc

EDIT....one more thing....when I put the combo together I went with 9.3:1 compression and I was planning on running between 14-15#'s of boost but I started eating blower belts due to the high quality tensioner that ATI provides so I went to SD Concepts (only 2½ hours away from me) and let them do their spring loaded tensioner on the car....well, when I got it back the boost went up to 19 due to no belt slippage and I could never justify spending $85 for a bigger pulley to go slower

Very interesting before and after pics. It really shows how much a good port will clean up lt1 heads.:)

I find that boosted cars need far less timing than NA. I have yet to hear a good explanation. About all I can come up with is that there must be a lot of turbulence in a boosted motor and this increases the burn rate. Centrifugally SC LT1's, other SBC's and SB Fords seem to make max hp with ~26 degrees regardless of fuel used. But the AF ratio must be right. Lean will make more power to a point, going beyone will take out the head gaskets or worse due to detonation. We did an experiment yesterday with my buddies low CR/high boost SBF. We ran it w/o the blower. Power was pitiful - it lost over 400rwhp. It needed a lot more timing. Boosted, max hp is with 24 degrees but w/o boost it wanted 36. My BBC NA alcohol motor wants 40 degrees. High compression BBC's have crappy combustion spaces due to the large dome needed and alcohol burn slow. So, there is an obvious explanation.

Rich

My motor peaks out at 26 degrees when boosted and 34 when the belt is off and I run it normally aspirated. I've taken it up to 30 degrees boosted with no appreciable gain. When my AF ratio goes from 11.8 to 10.5 it feels like I'm losing 100hp. This is street tuning at a local airport.

Was that intercooled?

IMHO there is not that much extra power to be made using extra timing and race gas or torco. I fool around with my timing all the time and don't see any drastic increases or decreases adjusting timing. I see large increases in power when the AFR is exactly right.:)

So then why does my buddies Supra make 600whp on pump gas and 850whp on race gas???

So then why does my buddies Supra make 600whp on pump gas and 850whp on race gas???

Because he is cranking up the boost?

Rich

Because he is cranking up the boost?

Rich

And upping the timing.

So then why does my buddies Supra make 600whp on pump gas and 850whp on race gas???
It doesnt matter because he'll run a 12.4 1/4 either way

Higher octane fuel won't give you more power. It takes away the chance of detonation which gives you the ability to run more timing, or more boost allowing more power. I don't know many guys having 2 seperate tunes for supercharged applications for the reason that we can't really change up our boost on the fly, so the one tune is really all we have. Some guys who have track only cars I know run only on, and are tuned for race gas. Now, some turbo guys I know (very popular on Supra's) are known for having 2 tunes that you are talking about (one for the pump gas, and another higher boost setting for the race gas).

Honestly, the best way to go IMO, is to go with one tune on methanol injection. Running methanol injection will cool your IAT's allowing you to run more boost and timing just as running race gas would, only the methanol injection comes on only under boost, and therefore costs MUCH less. I ragged the hell out of my car this year and I only went through about 7 gallons of methanol. The whole year cost me an extra $18 in methanol. Thats pennies compared to all the extra money you'd have to spend on race gas every fill up (let alone finding a pump on a regular basis that offers race gas).

It doesnt matter because he'll run a 12.4 1/4 either way

You should come run him then.

Internet racing is the ghey. Especially when it isn't even your own car.

Rich

Was that intercooled?

Intercooled and spraying meth.

So then why does my buddies Supra make 600whp on pump gas and 850whp on race gas???

Above 26 degrees power was down a little. Below 26 degrees power falls off quick at 15psi. The less boost I run the more timing it wants. At zero boost it likes 34 and at max boost it likes 26. Its pretty linear. At 7 pounds it likes 30 degrees. So I'm sticking with my opinion that race gas and more timing does not gain you much appreciable power.

Now if your adding another 10psi due to the extra octane then hell yes your gonna make a ton more power.

Is that 26 in the cells or 23 plus the 3 the pcm adds?

Hal

Holy old threads batman. 26 in the cells. I'm not sure what you mean by the PCM adding 3.

??? I thought it was commonly considered that the pcm adds 3 degrees. Now you want to see old threads you should check some of the threads in 00/01? when we were talking about how the pcm must be adding advance.

Well I just checked and for some reason posts only go back to 2003 (used the term "powerdyne"). There was a lot of info before this period on FI and tuning. Weird this info is now gone (or at least is unsearchable).

Hal