Diablo - Octane - Elevation

**C4ME2** · 11-21-2007, 03:48 PM

When I buy a tool like the Diablo Predator I want to be able to use it to its full capability. There is not 93 octane gas available in my area (Salt Lake City) and believe me I have looked. Highest available is 91, during my search I came across this excerpt from the Utah government website:

"Many people coming from the lower altitudes of the United States are somewhat worried because the octane levels found in Utah are not as high as what they are accustomed to. This is not really a problem and the reason why will shortly be explained.
The number found posted on the gasoline pumps is a Relative Anti-Knock rating This means that the gasoline will burn rather than detonate in the cylinders of your car. When a car engine begins to knock, supposing the engine is in good condition, it is because the fuel and air mixture is exploding before the pistons can reach the top of their stroke. This is extremely inefficient and can soon ruin an engine. Today's cars are governed by a computer so the possibility of knocking has been greatly reduced but does sometimes occur. At lower altitudes, there is a need to have a higher Relative Anti-Knock rating due to the increased air pressure. Less pressure is required by the pistons in the engine to produce the most efficient power output. At the higher altitudes, a lower Relative Anti-Knock rating is necessary to achieve the same results. Due to the decrease of air pressure the engine's pistons provide the necessary pressure to get an efficient burn and subsequent power output."

I guess what I want to know is if I can run the 93 tune with minimal detonation on 91 gas at this elevation? The easy answer is get the Diablo install 93 tune and log some runs. However, I was wondering if this had already been contemplated and tested. I asked Mike at Diablo about it and he had never heard of this before.

I know there are a bunch of members at elevation and was curious of their experience and satisfaction with the 91 tune from Diablo and whether they have tried the 93.

Thanks

**mullens** · 11-21-2007, 04:35 PM

I'm in Vegas with high elevation and poor 91 fuel (oxygenated to boot). The 91 CAI canned tune ran great, but had KR in excess of 5. Even adding fuel didn't do much good. I finally got a cmr tune from Promotion and they just about have it dialed in. I'm telling you that's the way to go. I'll post my results when the tune is complete.

**Mike@Diablosport** · 11-21-2007, 04:45 PM

The bigger issue I see with elevation is that there is less O2 available in the air, meaning that cars tend to run a bit on the rich side.
This extra fuel may help to cover up some of the ill effects of low octane gas (KR) but at a slight loss of power.
Like you said, installing the tune and logging is the only real way to know for sure, and I would also suggest a good in car wideband to go along with it.

Thanks
Mike

**C4ME2** · 11-21-2007, 05:25 PM

Originally Posted by mullens

I'm in Vegas with high elevation and poor 91 fuel (oxygenated to boot). The 91 CAI canned tune ran great, but had KR in excess of 5. Even adding fuel didn't do much good. I finally got a cmr tune from Promotion and they just about have it dialed in. I'm telling you that's the way to go. I'll post my results when the tune is complete.

Is ProMotion in Vegas or were you able to do this over email?

Makes me wonder what the B&G stage 2 is doing regarding KR..... Guess I need to bite the bullet and get the Diablo!

**C4ME2** · 11-21-2007, 05:34 PM

[quote=C4ME2;1220530]Is ProMotion in Vegas or were you able to do this over email?

I should have known better...just a little searching and I would have my answer, I can be so lazy sometimes....

**mullens** · 11-21-2007, 06:26 PM

I'm doing it by e-mail, but they do travel and dyno tune cars off site. They'll be in Texas for the next week. IMO, get the Diablo. There's so many things you can do with it.

**magnuman** · 11-21-2007, 09:57 PM

What's your elevation in S.L.? I am in Boise at about 3000 ft. and the 93 tune works fine here with the cold weather. Don't know how it will do in the hot summer though.
I have a Dashhawk to monitor Knock Retard, and it will sometimes give me 2 degrees under heavy load. Around town and easy driving is no problem. I am also running 2% richer at low RPM WOT.

**UK CHRYSLER 300C** · 11-23-2007, 09:22 AM

sorry to butt in on your thread,but I am looking to buy either the predator or flashpaq,but I'm in the UK,now the question I want to ask is..we only have 95 ron fuel,will this be ok to run with the predator or will I have to do some other mod??thanks for your time

**C4ME2** · 11-23-2007, 12:14 PM

Originally Posted by magnuman

What's your elevation in S.L.? I am in Boise at about 3000 ft. and the 93 tune works fine here with the cold weather. Don't know how it will do in the hot summer though.
I have a Dashhawk to monitor Knock Retard, and it will sometimes give me 2 degrees under heavy load. Around town and easy driving is no problem. I am also running 2% richer at low RPM WOT.

magnuman, SLC average elevation is 4300 feet, are you using the 93 tune with 91 pump gas? If yes, sweet, exactly what I had in mind.

**mullens** · 11-24-2007, 12:12 AM

Originally Posted by UK CHRYSLER 300C

sorry to butt in on your thread,but I am looking to buy either the predator or flashpaq,but I'm in the UK,now the question I want to ask is..we only have 95 ron fuel,will this be ok to run with the predator or will I have to do some other mod??thanks for your time

Is that 95 octane? Sorry not familiar with "ron" designation. There's no comparison with the Predator and Flashpaq. The Predator blows SC away in almost every aspect, features, customer service, etc.

**UK CHRYSLER 300C** · 11-24-2007, 07:21 AM

Thanks i'll bear that in mind,but will it be ok to use it with 95 octane fuel,cos thats the lowest we have in the UK,cheers

**mullens** · 11-24-2007, 08:20 PM

Originally Posted by UK CHRYSLER 300C

Thanks i'll bear that in mind,but will it be ok to use it with 95 octane fuel,cos thats the lowest we have in the UK,cheers

Absolutely. Just use the 93 tune or get a cmr. With that high octane I'd go for the custom tune. I wish I could get 95 octane here. (I'd settle for 93!)

**UK CHRYSLER 300C** · 11-26-2007, 08:14 AM

when you say use the 93 tune,is the diablo tunable to different octanes then,and what is cmr?

**Mike@Diablosport** · 11-26-2007, 11:25 AM

Originally Posted by UK CHRYSLER 300C

when you say use the 93 tune,is the diablo tunable to different octanes then,and what is cmr?

The predator has specific 91 and 93 octane tunes.
CMR is our custom tuning software which allows you to modify and edit tunes to suit any need.

Thanks
Mike

**UK CHRYSLER 300C** · 11-26-2007, 03:59 PM

Originally Posted by Mike@Diablosport

The predator has specific 91 and 93 octane tunes.
CMR is our custom tuning software which allows you to modify and edit tunes to suit any need.

Thanks
Mike

thanks,tell me more

what exactly do i need as far as the diablo goes,dont want cia,noisy exhausts,I have always had street sleepers but in my day

electronic witchcraft was not around.
All I need is more grunt at the bottom end and mid range (loads of it)
not bothered about top end speed,155mph is fast enough,need more acceleration,thanks.Ray

oh by the way,where the hell can I get a cmr tune in the UK??