Race gas timing, hearing a different opinion.

[B3422w5]

Don, have you considered a session on a chassis dyno?

My engine is only 11.2-1 and made the most power at 34° on an engine and chassis dyno. It also made 30 more HP on pump 93 than it did on 98 race gas, it was built for pump 93 though. You may not need as much octane as you think you do.

nothing is readily available other than pump , and then 110. Nothing in between.
at 12.4 to 1, I feel extremely comfortable ( and safe)knowing 110 is the correct fuel.
it may not run any better with more timing, and I already have it correct, but when a guy as sharp as Chris Hardy gives me some pointers, I am gonna heed them and try what he says. If for no other reason because it doesn’t hurt to try.

 

[B3422w5]

Don, have you considered a session on a chassis dyno?

My engine is only 11.2-1 and made the most power at 34° on an engine and chassis dyno. It also made 30 more HP on pump 93 than it did on 98 race gas, it was built for pump 93 though. You may not need as much octane as you think you do.

I don’t doubt any of that. But none of it has anything to do with my original post

 

[justinp61]

I don’t doubt any of that. But none of it has anything to do with my original post

One would think that testing timing on a chassis dyno would show what you needed to run. I certainly apologize for my intrusion, please carry on.

 

[B3422w5]

One would think that testing timing on a chassis dyno would show what you needed to run. I certainly apologize for my intrusion, please carry on.

You are more than good with me my friend. Chassis dyno would help, but for that same 200 bucks they want, I can get an even more accurate result at the track for a 35 dollar test and tune. I can bump timing around couple times on same evening in same or similar air and see what it likes
gonna likely get at least one such outing before first time I plan to race memorial weekend..lord willing

 

[furrystump]

I run VP blue or c12 at 12.2, at 34 degrees, over all the years it never has like more or less timing and I have played with it a BUNCH! I played with the idea of tuning for track conditions with total timing. (Never really paid off) I’m also sure I don’t need all the octane I’m running, but it’s been “safe” for 8-9 years for me. It’s almost like all the crap you carry in your wallet. You know you don’t need it, but you can’t get yourself to throw any of it away. . Plug gap changed a bit after going from 10:1 to 12.2:1.

 

[TT5.9mag]

Exactly. Race fuel can effect a low compression motor in a negative way.

not what my original post is about. My motor is 12.4 to 1, requires race gas.
my point is will it like more timing than if it was say 10 to 1 running on pump gas.

Ok so the new question is, same engine but with 12.4:1 on race gas vs 10:1 on pump gas, will the timing requirement change. If the compression was the only change, and you got there by not altering the combustion chamber, I’d say the timing requirement will be the same if not very similar. You said you milled the heads so a small change in combustion chamber shape/size. So maybe a couple degrees different at max power/max timing. And I’d say it will go from your original 34 degrees to something like 32-33 degrees.

 

[B3422w5]

Ok so the new question is, same engine but with 12.4:1 on race gas vs 10:1 on pump gas, will the timing requirement change. If the compression was the only change, and you got there by not altering the combustion chamber, I’d say the timing requirement will be the same if not very similar. You said you milled the heads so a small change in combustion chamber shape/size. So maybe a couple degrees different at max power/max timing. And I’d say it will go from your original 34 degrees to something like 32-33 degrees.

I had Eddie heads milled to 61 cc’s previously on the 360, compression was 10 to 1 ish
now have bloomer heads at 61cc… the chambers will be/ are extremely similar. A negative to these LA heads, be they Eddie’s, bloomers, or speed master, etc.
same cam, just more cubes, more compression and single plane instead of air gap.
Chris was telling me you can run into a large “ numb” area regards timing not doing anything. The aim is to creep up on the timing till just short of detonation to see the biggest difference.
I suspect with the 110, detonation is out of the realm of possibility on my motor, with just a few degrees timing adjustment.
so I may see little or nothing, but it’s worth trying, before I hadn’t even thought of going past where I am.

 

[TT5.9mag]

In my experience, engines that are numb to timing adjustment’s typically have a very lazy combustion chamber with low compression or a large dome piston in them. When I say numb I mean that they don’t respond negatively or positively to changes in timing typically from 35 or so up to like 39 degrees. Mostly big block chevys. If that’s the case my go to tuning is to start on the high end and back the timing off until the car slows down. Then add a degree. Yours, with flat tops and a small closed chamber will slow down on both sides of optimal timing I guarantee it.

 

[RustyRatRod]

nothing is readily available other than pump , and then 110. Nothing in between.
at 12.4 to 1, I feel extremely comfortable ( and safe)knowing 110 is the correct fuel.
it may not run any better with more timing, and I already have it correct, but when a guy as sharp as Chris Hardy gives me some pointers, I am gonna heed them and try what he says. If for no other reason because it doesn’t hurt to try.

What's your cylinder pressure? 110 seems a little lacking for a true 12.4 IMO. I would have gone straight to 114.

 

[B3422w5]

What's your cylinder pressure? 110 seems a little lacking for a true 12.4 IMO. I would have gone straight to 114.

Chris Hardy told me it would probably like around 105 best. If anything 110 is a bit much, but it’s safe
I ran 110 for years on that W5 deal, 13.1 to 1, zero issues.
new owner runs 112 now, but it’s a bit over 14 to 1( new pistons)
went 9.54 with it couple weeks ago.

 

[LO23M8B]

Run what gives you the best mph. I would think about 36 should be about right but the test and tune is the best way.

 

[RustyRatRod]

Chris Hardy told me it would probably like around 105 best. If anything 110 is a bit much, but it’s safe
I ran 110 for years on that W5 deal, 13.1 to 1, zero issues.
new owner runs 112 now, but it’s a bit over 14 to 1( new pistons)
went 9.54 with it couple weeks ago.

Well, I admit my comparison I'm sure is a bad one. I had a 327 chebbie in a 67 Chevelle I drove on the street in the mid 80s that was blueprinted just north of 12:1. I ran 114 in it, mainly because where I worked sold it and it was relatively cheap then. I'm sure with some tuning it probably would have run on less, but that was it. lol

 

[B3422w5]

Well, I admit my comparison I'm sure is a bad one. I had a 327 chebbie in a 67 Chevelle I drove on the street in the mid 80s that was blueprinted just north of 12:1. I ran 114 in it, mainly because where I worked sold it and it was relatively cheap then. I'm sure with some tuning it probably would have run on less, but that was it. lol

you mention that 327
Guy I keep mentioning, Chris Hardy, recently( think it was last year) got involved with a SS/HA Nova. He did the heads on it, not sure what else, but it really stepped this guy’s program up. His name is Pinoski.
10 to 1 327, quadrajet( of course) 164 cc head, 1.94 valve, weighs 3360.
It’s been 9.89. Think the guy lives
in Montana maybe. Been 10.30’s there at high altitude. 9’s in California.

 

[Rat Bastid]

First of all, you NEED a curve. Unless you are setting your timing at shift RPM you don’t have a clue what your timing actually is.

So find someone who can test your complete ignition system to figure out how much retard you have and where it happens and correct the curve for it.

I can run 12:1 on pump gas. You can buy 98 octane race gas. Before I did that I would run pump gas and use Torco Accelerator in that. It’s cheaper than race gas and it works. Start at 2 ounces per gallon and back it down 1/2 ounce per gallon. You may only need 1/2 ounce per gallon.

Of course, it’s easier to test for this on a dyno, so like mentioned above I’d be looking for a chassis dyno to test it.

And get a curve in your distributor.

 

[MOPARMAGA]

Thought everybody knew..lol
i am not running race gas for my health. It’s 8.50 a gallon.
I have zero deck flat tops. I had bloomer actually mill my heads to get it to 12.4. Thought the little extra squeeze might help a heavy car.
and honestly, it’s not like I drive it 15,000 miles a year. So I live with the fuel costs

****, it's $17.00 in my area

 

[TT5.9mag]

you mention that 327
Guy I keep mentioning, Chris Hardy, recently( think it was last year) got involved with a SS/HA Nova. He did the heads on it, not sure what else, but it really stepped this guy’s program up. His name is Pinoski.
10 to 1 327, quadrajet( of course) 164 cc head, 1.94 valve, weighs 3360.
It’s been 9.89. Think the guy lives
in Montana maybe. Been 10.30’s there at high altitude. 9’s in California.

Rich Pinoski. Lives in Northern California races in the pacific division in super stock.

 

[B3422w5]

Rich Pinoski. Lives in Northern California races in the pacific division in super stock.

yea, guess he sometimes races at elevation too, Montana, Idaho.
I see he lives in California after looking it up. Anyhow nice running 327.
my buddy back here in Michigan now does his heads for his stuff.

 

[Hysteric]

The better the mixture quality wise the faster the burn speed is the less timing it needs. Lean mixtures burn slow.......

 

[A body]

Always interesting….. our best dyno numbers were at locked at 32. 13.5-1 running VP C-12. Have never changed it at the track. 6k stall shift at 7500 trap at 8.

 

[B3422w5]

Always interesting….. our best dyno numbers were at locked at 32. 13.5-1 running VP C-12. Have never changed it at the track. 6k stall shift at 7500 trap at 8.

I think your running a better chamber than an Edelbrock type head like I currently run has. Makes sense it would need less timing.

When I had my W5 combo, it was the fastest with 32 degrees( locked out). Moved it all over the place, actually even running it at 30 was only marginally slower.
Most of the racy Gen 3 stuff seems to like under 30. Buddy ran his class car at 26 with Gen 3 power
Dont know why Chris has seen what he has seen, but
I certainly don’t question his credentials. Kinda why I put this post up…to see what others think, and why

 

[Rat Bastid]

The better the mixture quality wise the faster the burn speed is the less timing it needs. Lean mixtures burn slow.......

And the burn rate of the fuel isn’t related to octane. I suspect that the guy running all the timing on race gas is using a fuel with a relatively slow burn rate.

 

[TT5.9mag]

I think your running a better chamber than an Edelbrock type head like I currently run has. Makes sense it would need less timing.

When I had my W5 combo, it was the fastest with 32 degrees( locked out). Moved it all over the place, actually even running it at 30 was only marginally slower.
Most of the racy Gen 3 stuff seems to like under 30. Buddy ran his class car at 26 with Gen 3 power
Dont know why Chris has seen what he has seen, but
I certainly don’t question his credentials. Kinda why I put this post up…to see what others think, and why

N/A LS engines are the same way. They make best power around 29 degrees.

 

[MoparLeo]

+ octane = slower burn time
more advance timing = more time to burn
lower octane = less timing
Nitro timing ? a lot..........

 

[Hysteric]

From Rocket Racing Fuels:

Flame Speed, Octane Number, & Horsepower Relationship

"Flame speed is determined by the hydrocarbon components in the gasoline. It is critical to making max power, but not related to octane quality. Our Rockett Scientists pay close attention to these factors."

"The octane number of a gasoline has little to do with how fast it burns or how much power the engine will make. Octane number is the resistance to detonation."

The more timing you need the more negative work the engine is doing. Ie if the piston is still rising while the pressure is rising dues to combustion then that energy is not transferred to the crank as positive pressure. The less timing the better

 

[famous bob]

I have locked out dizzy, running timing at 34 degrees. In fact, when I had my 13+ to 1 W5 deal, it seemed to like 32 degrees best.
Was talking to Chris Hardy at RET engine development this morning. Via a mutual friend, he and I have become friends.
I was asking him about possible jet changes going to these new bigger headers.
He asked me about timing, after some jetting tips.
When I told him 34, he said no way running race gas. Said he had never seen anything like less than 38 on race gas, and yes, pump gas definitely less.
I told him these heads had been on a dyno and liked 34 degrees. He said, “ was it race or pump gas” I said pump gas, he says..see!
Goes on to say he has had TONS of motors running race gas on his dyno, and nothing liked what timing I am running.

Thoughts?
Thinking I will get a baseline at current 34 with new headers when I get car out, then start bumping it up and see what happens.
I haven’t played with it from 34, just played with jetting some, thinking 34 is kinda a default sweet spot

hi octane race gas , burns slower than lesser gas...