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Old 11-23-2010, 11:58 PM   #1
dwill73
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Default Race Gas versus Alcohol on a dyno

For example, say you had a 850Hp SBC with a very well tuned gasoline carb then switched it over to a alcohol carb built for that same motor. How much more horsepower or torque is possible making such a switch? I've heard of E-85 having up to 50hp over race gas. I've only had experience at the track with both, but curious of a engine builders experience on a dyno between them.
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Old 11-24-2010, 08:09 AM   #2
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Default Re: Race Gas versus Alcohol on a dyno

If it were that easy everyone would do it.
The advantages of methanol and ethanol are there abiility to absorb heat and reduce the intake charge temp.
Depending on the application and engine combo will vary.
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Old 11-26-2010, 12:59 AM   #3
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Default Re: Race Gas versus Alcohol on a dyno

Alot depends on what race gas you are using and what the set up is, different combinations like different fuel, some setups will make more power on gas and some on alky, usually a Q16 gas setup will make more HP than a M1 alky deal but then agian you have M5 witch i have heard makes about the same as Q16 ,
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Old 11-26-2010, 10:18 AM   #4
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Default Re: Race Gas versus Alcohol on a dyno

Dynoed a sbf that made 800hp on gas and it maxed out the cylinder heads doing it. Switched to alky and lost 20hp, the theory was that since we were maxing the heads on gas the alky just took up room for the air and lost hp.

Don't know if this was true but i does make some since.
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Old 11-28-2010, 08:59 PM   #5
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Default Re: Race Gas versus Alcohol on a dyno

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Dynoed a sbf that made 800hp on gas and it maxed out the cylinder heads doing it. Switched to alky and lost 20hp, the theory was that since we were maxing the heads on gas the alky just took up room for the air and lost hp.

Don't know if this was true but i does make some since.
That sounds like a bunch of BS. Your dyno guy told you that? Sounds more like the wrong carb set up. Your gain should be 2-10HP and 40-50 foot LBS torque.
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Old 11-30-2010, 02:46 PM   #6
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Default Re: Race Gas versus Alcohol on a dyno

I've personally seen switching from gas to an alcohol carb most cars picked up .4 tenths on a iron headed motor and .3 tenths on a aluminum headed motor. In the quarter mile of course. I've read 4 to 10 percent more power on a dyno. The power being on the torque side.
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Old 12-21-2010, 11:17 AM   #7
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Default Re: Race Gas versus Alcohol on a dyno

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Originally Posted by Relentless View Post
Dynoed a sbf that made 800hp on gas and it maxed out the cylinder heads doing it. Switched to alky and lost 20hp, the theory was that since we were maxing the heads on gas the alky just took up room for the air and lost hp.

Don't know if this was true but i does make some since.
That is true. Typically alcohol engines require bigger heads because the extra fuel displaces air in the intake runner in the head for injection, and both intake and head for a carb. The guys that have seen HUGE gains with alcohol over gas probably had too big of a cylinder head with the gasoline and it worked perfect for the alky. With the same exact motor with same heads you will typically lose a little hp but gain torque. I run a 380cc head on my 560ci bbc with alcohol and since I am going to run a 2 stage nitrous system I probably could go even bigger on the head. I would love to try the big Brodix 16 degree head one of these days

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Old 12-21-2010, 12:12 PM   #8
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Default Re: Race Gas versus Alcohol on a dyno

We did a 540 BBC on E-85 and pump gas comparison. It made 745hp and 710tq on 93 octane pump gas, and 765hp and 731tq on E-85 and all the EGT's dropped by 100deg on the E-85 if that helps.
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Old 12-22-2010, 06:09 PM   #9
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Default Re: Race Gas versus Alcohol on a dyno

WE saw a 665 alum head motor make 1400 hp on gas with a tunnel ram and two carbs--took the intake off and put an alcohol injector on and lost 60 hp.
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Old 01-15-2011, 09:48 PM   #10
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Default Re: Race Gas versus Alcohol on a dyno

My experience is on a 418 cu in sbc. Ran 10.42 with a 1000cfm Holly 4150 tuned by Pro Systems with Brodix 11x heads. Switched to Enderle mechanical injection & no other changes and went 9.98>
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Old 01-22-2011, 09:42 AM   #11
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Default Re: Race Gas versus Alcohol on a dyno

Way back when (199, my car ran 9.95 to 10.02 on C 114 plus. It was a 482 BBO. I had Avanti Carbs do a 1050 Dominator up for me on alcohol and changed my fuel pump to a Product Engineering fuel system. No changes on anything except the carb and fuel pump. Right off the trailer the car went 9.68. Never looked back from that point on.

Last March i had my 434 SBO on BTR`s dyno and we broke the engine in with a Dale Cubic Dominator on VP Nos fuel. It made 816HP. After three pulls we switched over to my EFI set up on M5. It made 877HP.
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Old 01-22-2011, 01:48 PM   #12
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Default Re: Race Gas versus Alcohol on a dyno

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Originally Posted by 434 Olds View Post
Way back when (199, my car ran 9.95 to 10.02 on C 114 plus. It was a 482 BBO. I had Avanti Carbs do a 1050 Dominator up for me on alcohol and changed my fuel pump to a Product Engineering fuel system. No changes on anything except the carb and fuel pump. Right off the trailer the car went 9.68. Never looked back from that point on.

Last March i had my 434 SBO on BTR`s dyno and we broke the engine in with a Dale Cubic Dominator on VP Nos fuel. It made 816HP. After three pulls we switched over to my EFI set up on M5. It made 877HP.
Every car that I've seen make the switch always picked up on average 2 to 3 tenths. This was switching carbs only. I finally asked a alcohol carb builder the difference, since he has a dyno, and he said most motors pick up a lot more torque and maybe some Hp. But that extra torque is were you get the quicker ET from.
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Old 01-29-2011, 01:13 PM   #13
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Default Re: Race Gas versus Alcohol on a dyno

I know these are "shelf" motors, but look at what RM has on their web site.

565 "Super Series": 4.600 Bore/ 4.250 Stroke (w/o Vacuum Pump) Alcohol: 930/Gas: 950 Hp. Alcohol: 800/Gas: 790 Ft. Lbs

Those are awfully close but I bet the alky motor would lose less on a hot day though and be more consistent. Even using 2.5 times as much, alky is still cheaper than race gas (at least it is around here).
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Old 02-15-2011, 02:26 PM   #14
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Default Re: Race Gas versus Alcohol on a dyno

It all depends on the efficiency of the cylinder heads, burn rate in the chamber, optimum cam profile, etc. A very well sorted gas setup will make the same power as alky; in some cases make more power. But that is not typical in the conventional headed world. If you are talking big chief setups then cubic inches come into play if you are carb'ed, about 565-582 is the max for it on alky. You can go bigger with injection but it really helps to open the chambers up a little on the injected motors.

Alky motors are a lot more consistent, move less with the air change. Typically, gas cars can lose up to 4 tenths between mineshaft air and 100 degree humid days, alky motors might lose tenth to tenth and a half.
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Old 02-18-2011, 03:03 PM   #15
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Default Re: Race Gas versus Alcohol on a dyno

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Alky motors are a lot more consistent, move less with the air change. Typically, gas cars can lose up to 4 tenths between mineshaft air and 100 degree humid days, alky motors might lose tenth to tenth and a half.
Nitrous motors will loose 4 tenths going with the atmospheric extremes.. And nitrous spray in at like 100 degrees below zero..

All engines need oxygen to make power.. If the air isn't there, they arn't going to run.. No matter what they use for fuel..
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