Hmm. 100 octane Heffner program didn't add power.. any ideas?


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peiserg

GT Owner
Aug 15, 2010
284
Phoenix, az
I have my custom 2.7" pulley, and am using the SCT loaded 91 octane program (with 100 octane in tank). I got 620 rwhp on 91 setting, 634 on 93 setting, and 640 on 100 octane program. Am i expecting too much of the jump from 93 to 100 octane? We let the car cool down for a while after the (relatively) dissapointing 100 octane run, but the repeat gave exactly the same numbers. I don't know jack about timing or fuel, but was expecting a big jump over the 93 setting.

On the plus side... this will definitely save me money, since i now know the 100 octane doesn't make any more power than 93... no race gas for me.
 
Your not gonna see much difference. The reason People with turbo cars get 150+ more hp on race gas is because they increase the boost along with the fuel and timing. Your not changing your boost levels by just running higher octane fuel and using the Heffner 100 tune which is just increasing your timing.
 
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Point one consult with Jason directly first and foremost since the calibrations your referencing are his and he can dictate the exact differences. If we could also see the dyno sheets or run sensor datalogs that would explain the rest of it in totality

Point two if you have the octane headroom you can indeed make power with more spark advance when using race gas, at times around 10WHP +/- per degree.
 
I'd love to assist you in any way that I can or at the very least answer any questions that you have. If you'd like, give me a call or pm me your contact info and I'll give you a call.

As Shelby said, when you are changing the tune in this type of application the primary difference is ignition timing. As such, there is only so much ignition timing that I can add in a mail order tune without risking engine damage. There are also several other pieces of data that need to be collected such as air / fuel ratio, manifold pressure, air inlet temperature and whether you are using leaded or unleaded 100 octane fuel.

I'll look forward to helping you out.
 
Torrie and Heff are definitely the two people that can help you the most with this. :)
 
Torrie and Heff are definitely the two people that can help you the most with this. :)
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Yeah, these knuckleheads might know a thing or two that could be useful. :biggrin

Those are all very good numbers, IMO for "just" a pulley & tune. With more information, the dudes above could determine if you have more headroom for more timing or not. The other good point made here is that all fuels are not created equal and depending on the type/brand of fuel, you could see very different A/F results. As such, these out of the box tunes try to keep your engine safe. There's no doubt in my mind that this is the trade-off that you would want.
 
nota4re said:
Those are all very good numbers, IMO for "just" a pulley & tune. .
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+1

I did not know that much RWHP was available with just a pulley and tune.
 
Your not gonna see much difference. The reason People with turbo cars get 150+ more hp on race gas is because they increase the boost along with the fuel and timing. Your not changing your boost levels by just running higher octane fuel and using the Heffner 100 tune which is just increasing your timing.

I realized the boost wasn't going to change, and I know that adds a big kick in the tq/hp. I wasn't sure if the timing/fuel were close to maxxed out on 93 vs 100. I guess that's the main thrust of the question for me. Since i saw a decent bump from 91 to 93, I was thinking i would see an even greater jump with an additional 7 pts of octane built into the tune. I don't know if there is simply a point of "diminishing returns," or if without bumping boost along with octane one would simply not benefit much.. I'm not trying to come off as complaining, since 634 was quite impressive.


I'd love to assist you in any way that I can or at the very least answer any questions that you have. If you'd like, give me a call or pm me your contact info and I'll give you a call.

As Shelby said, when you are changing the tune in this type of application the primary difference is ignition timing. As such, there is only so much ignition timing that I can add in a mail order tune without risking engine damage. There are also several other pieces of data that need to be collected such as air / fuel ratio, manifold pressure, air inlet temperature and whether you are using leaded or unleaded 100 octane fuel.

I'll look forward to helping you out.

I was using 109 unleaded (10 gallons) with about 5 gallons of 91 left in the tank. AMbient temp was maybe 60F, and it was pouring rain outside.
I'm not here to complain.. i was just wondering if I should "expect" a bigger bump. Either way, i'm pretty satisfied with 620 rwhp/590 rwtq at 91 octane and 14.8 psi. I'll give you a hollor in the next little while, since it's faster than writing messages.
 
peiserg,

Do you have headers and an accufab throttle body?
 
Only other power adder would be my Bob Ida exhaust. But from what i've heard, it actually doesn't add much if any power. I didn't do a before/after dyno, that's just what the cognesceti here have stated. Sure sounds kick ass tho. That's why i bought it.
 
Race gas will allow you to run more boost and more timing. If you are not able to increase boost then timing is it. The power gains are usually in the mid range power and torque. Dont expect any tripple digit power gains. 30-40 rw hp & tq would be a lot. Figure about 10 rw per degree of timing increase.
 
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