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Question on mixing race gas and premium fuel #1115106
11/16/11 04:23 PM
11/16/11 04:23 PM
Joined: Feb 2005
Posts: 2,158
God's Country - Etowah, TN.
A34 Offline OP
top fuel
A34  Offline OP
top fuel

Joined: Feb 2005
Posts: 2,158
God's Country - Etowah, TN.
Hey Guys,

I have a new engine for a street car that's sporting 11.25:1 compression. It's a iron headed 440 with stock intake and exhaust manifolds, running a pure stock cheater cam and 800 avs edelbrock carb. Stock reproduction coil and factory dual point converted with pertronix ignition kit. Total timing set at 38.

On initial break-in we mixed 110 octane with 93 so it wouldn't ping. I was wondering if any of you guys have had experience mixing race gas with premium. Someone told me the stock coil doesn't put out enough voltage to properly burn the race gas and I should try and run it on 93 if possible, stating that with alcohol added it is more like 96 octane. I'm not up on that stuff, so not sure what is a old myth or real. I would appreciate any input from guys that have experience mixing this stuff.

I don't mind adding race fuel if needed for it not to ping. I want to understand better how they act when mixed and if the stock coil is a limiting factor.

Thanks !


God Bless America, Our Troops and Their Families !

DEO VINDICE
Re: Question on mixing race gas and premium fuel [Re: A34] #1115107
11/16/11 04:39 PM
11/16/11 04:39 PM
Joined: Aug 2003
Posts: 43,007
Bend,OR USA
C
Cab_Burge Offline
I Win
Cab_Burge  Offline
I Win
C

Joined: Aug 2003
Posts: 43,007
Bend,OR USA
Quote:

Hey Guys,

I have a new engine for a street car that's sporting 11.25:1 compression. It's a iron headed 440 with stock intake and exhaust manifolds, running a pure stock cheater cam and 800 avs edelbrock carb. Stock reproduction coil and factory dual point converted with pertronix ignition kit. Total timing set at 38.

On initial break-in we mixed 110 octane with 93 so it wouldn't ping. I was wondering if any of you guys have had experience mixing race gas with premium. Someone told me the stock coil doesn't put out enough voltage to properly burn the race gas and I should try and run it on 93 if possible, stating that with alcohol added it is more like 96 octane. I'm not up on that stuff, so not sure what is a old myth or real. I would appreciate any input from guys that have experience mixing this stuff.

I don't mind adding race fuel if needed for it not to ping. I want to understand better how they act when mixed and if the stock coil is a limiting factor.

Thanks !



Stock coil doesn't have enough voltage to burn race gas Another urban myth The coil(any coil) will produce enough voltage to jump the gap, regardless of pump swill or race gas being in the motor Your pushing the limits on compression with the iron heads and exhaust sytem and total timing What spark plug brand and heat range(part #) are you running? The cheater cam may help a tiny bit as far as the compression but I would be very careful on detonation, if it starts pinging(when it gets hot outside)lift up the throttle and get some better fuel I have treid mixing race gas and pump swill years ago, the race gas is a different specific gravity than the pump swill so they ended up seperating when the car sat overnight, I think Try getting a clear gas jar, as big as possible, and mix the two fuels together % like your going to use, shake them up and let the jar sit for a while, at least two hours or more. If the two fuels seperate in the jar you know it will seperate in the car Let us know if you test it and what it does


Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)
Re: Question on mixing race gas and premium fuel [Re: A34] #1115108
11/16/11 04:52 PM
11/16/11 04:52 PM
Joined: Mar 2007
Posts: 3,275
West Coast, USA
jbc426 Offline
master
jbc426  Offline
master

Joined: Mar 2007
Posts: 3,275
West Coast, USA
38 total seem a bit much. I'v always had luck with 35 total.

How much do you drive it? Around here, there's a handful of places that sell 100 octane unleaded at the pump for $7.25 a gallon. One place is even open 24hours. You could put a 1/4 tank of that and top off with pump premium. I run straight 100 unleaded, but I have almost 13 to 1. My car loves the stuff!

For longer road trips, I plan on fitting a small 10 or 15 gallon fuel cell filled with leaded 110 that's plumbed to be partially drained into my custom main tank.

I figure I can add 5 gallons of the good stuff just before I fill up with premium unleaded and with the fuel cell, be able to mix up 2 or 3 batches of decent fuel out on the road.


1970 Plymouth 'Cuda #'s 440-6(block in storage)currently 493" 6 pack, Shaker, 5 speed Passon, 4.10's
1968 Plymouth Barracuda Convertible 408 Magnum EFI with 4 speed automatic overdrive, 3800 stall lock-up converter and 4.30's (closest thing to an automatic 5 speed going)
Re: Question on mixing race gas and premium fuel [Re: jbc426] #1115109
11/16/11 06:54 PM
11/16/11 06:54 PM
Joined: Jan 2005
Posts: 716
Indiana
6
65dragnet Offline
super stock
65dragnet  Offline
super stock
6

Joined: Jan 2005
Posts: 716
Indiana
My 499 lowdeck 12 to 1 cr I do 60% 110 and 40% 93. 38 degrees timing locked MSD , Indy EZ Aluminum heads !


E. Williams 65 Coronet 500 3400lbs w/d, 446, Indy EZ'S, A&A transbrake,Comp 650 lift cam, 6.50 @ 105 mph 1/8th 10.25 @ 130mph 1/4
Re: Question on mixing race gas and premium fuel [Re: jbc426] #1115110
11/16/11 06:55 PM
11/16/11 06:55 PM
Joined: Mar 2009
Posts: 1,058
bigfork mn
D
dragram440 Offline
super stock
dragram440  Offline
super stock
D

Joined: Mar 2009
Posts: 1,058
bigfork mn
Quote:

38 total seem a bit much. I'v always had luck with 35 total.

How much do you drive it? Around here, there's a handful of places that sell 100 octane unleaded at the pump for $7.25 a gallon. One place is even open 24hours. You could put a 1/4 tank of that and top off with pump premium. I run straight 100 unleaded, but I have almost 13 to 1. My car loves the stuff!

For longer road trips, I plan on fitting a small 10 or 15 gallon fuel cell filled with leaded 110 that's plumbed to be partially drained into my custom main tank.

I figure I can add 5 gallons of the good stuff just before I fill up with premium unleaded and with the fuel cell, be able to mix up 2 or 3 batches of decent fuel out on the road.



Wow is all that worth running a little extra compression. If you got rid of the extra weight it would probly be just as fast with a little less compression and 13.1 on 100 octane doesnt seem like much. Most people on here told me to run 110 octane with 12.5 to 1 on my 499 unless maybe just idleing around town.


67' charger 499 RB 10.57 at 127
Re: Question on mixing race gas and premium fuel [Re: dragram440] #1115111
11/16/11 07:30 PM
11/16/11 07:30 PM
Joined: Mar 2008
Posts: 216
still waiting on 684
K
Kiner Offline
enthusiast
Kiner  Offline
enthusiast
K

Joined: Mar 2008
Posts: 216
still waiting on 684
Don't know but if you start mixing. Hope this helps.
http://www.motorsportsracingfuels.com/OctaneCalculator.html

Re: Question on mixing race gas and premium fuel [Re: Kiner] #1115112
11/16/11 08:31 PM
11/16/11 08:31 PM
Joined: Feb 2003
Posts: 911
London, England
mopar_mark Offline
super stock
mopar_mark  Offline
super stock

Joined: Feb 2003
Posts: 911
London, England
Kiner,
Thanks for the handy Octane link

Re: Question on mixing race gas and premium fuel [Re: jbc426] #1115113
11/16/11 08:40 PM
11/16/11 08:40 PM
Joined: Oct 2003
Posts: 1,170
Westbury, NY
B
bumps440 Offline
super gas
bumps440  Offline
super gas
B

Joined: Oct 2003
Posts: 1,170
Westbury, NY
Quote:

38 total seem a bit much. I'v always had luck with 35 total.




it amazes me that people still do that. I was once a fool too that believed the false information that mopar "BIBLE" gave every one. causes more problems with main cap walk and lower ends. 35* is more than enough.

you can use that chart to help figure out the octane you need.
EVER CONSIDER E-85?
would solve all of your problems with out very many of its own.
good luck

Re: Question on mixing race gas and premium fuel [Re: A34] #1115114
11/17/11 12:21 AM
11/17/11 12:21 AM
Joined: Oct 2003
Posts: 7,506
Az
Crizila Offline
master
Crizila  Offline
master

Joined: Oct 2003
Posts: 7,506
Az
Quote:

Hey Guys,

I have a new engine for a street car that's sporting 11.25:1 compression. It's a iron headed 440 with stock intake and exhaust manifolds, running a pure stock cheater cam and 800 avs edelbrock carb. Stock reproduction coil and factory dual point converted with pertronix ignition kit. Total timing set at 38.

On initial break-in we mixed 110 octane with 93 so it wouldn't ping. I was wondering if any of you guys have had experience mixing race gas with premium. Someone told me the stock coil doesn't put out enough voltage to properly burn the race gas and I should try and run it on 93 if possible, stating that with alcohol added it is more like 96 octane. I'm not up on that stuff, so not sure what is a old myth or real. I would appreciate any input from guys that have experience mixing this stuff.

I don't mind adding race fuel if needed for it not to ping. I want to understand better how they act when mixed and if the stock coil is a limiting factor.

Thanks !



If you mix 50 /50 of 110 and 93 you will end up with 102 and that should keep you out of detonation - even at 38 degrees timing. If you have a fuel seperation issue, you got water in the fuel, which will cause the ethanol to fall out of suspension. I have raced with that blend in a 11.52:1 motor ( 195 cranking compression ) with no problems. I might add I was running a pretty tight quench though ( .038").

Last edited by Crizila; 11/17/11 12:23 AM.

Fastest 300
Re: Question on mixing race gas and premium fuel [Re: A34] #1115115
11/17/11 01:00 AM
11/17/11 01:00 AM
Joined: Dec 2008
Posts: 415
Peru
cbarracuda Offline
mopar
cbarracuda  Offline
mopar

Joined: Dec 2008
Posts: 415
Peru
tolueno and 93

Re: Question on mixing race gas and premium fuel [Re: dragram440] #1115116
11/17/11 11:17 PM
11/17/11 11:17 PM
Joined: Mar 2007
Posts: 3,275
West Coast, USA
jbc426 Offline
master
jbc426  Offline
master

Joined: Mar 2007
Posts: 3,275
West Coast, USA
Quote:

Quote:

38 total seem a bit much. I'v always had luck with 35 total.

How much do you drive it? Around here, there's a handful of places that sell 100 octane unleaded at the pump for $7.25 a gallon. One place is even open 24hours. You could put a 1/4 tank of that and top off with pump premium. I run straight 100 unleaded, but I have almost 13 to 1. My car loves the stuff!

For longer road trips, I plan on fitting a small 10 or 15 gallon fuel cell filled with leaded 110 that's plumbed to be partially drained into my custom main tank.

I figure I can add 5 gallons of the good stuff just before I fill up with premium unleaded and with the fuel cell, be able to mix up 2 or 3 batches of decent fuel out on the road.



Wow is all that worth running a little extra compression. If you got rid of the extra weight it would probly be just as fast with a little less compression and 13.1 on 100 octane doesnt seem like much. Most people on here told me to run 110 octane with 12.5 to 1 on my 499 unless maybe just idleing around town.




I'm running a high quench/ aluminum head combo with coated pistons that came out to 12.8 to 1. The thing dynoed at 684 hp at 5500 rpm running an easy-on-the-vavletrain 550 lift hydraulic roller cam.

I love the feel, snappiness and sound of high compression. I've had low compression 440's before and missed all that. For me it's WELL worth it. I will never go back to low compression unless i'm running a blower or turbo.

My tank gives me a range of over 225 miles, and 100 octane unleaded is readily available around here. It smells great and keeps my motor nice and clean too.

I don't really plan on using the car for cross country road trips, so I really haven't messed with adding an additional fuel cell as of yet, but the tank is plumbed for it should the need arise. I figured if I need to, adding a 15 gallon tank of 110 leaded could extend my range close to 1000 miles by blending 5 gallons a tank with with pump gas.

Last edited by jbc426; 11/17/11 11:18 PM.

1970 Plymouth 'Cuda #'s 440-6(block in storage)currently 493" 6 pack, Shaker, 5 speed Passon, 4.10's
1968 Plymouth Barracuda Convertible 408 Magnum EFI with 4 speed automatic overdrive, 3800 stall lock-up converter and 4.30's (closest thing to an automatic 5 speed going)
Re: Question on mixing race gas and premium fuel [Re: jbc426] #1115117
11/18/11 08:44 AM
11/18/11 08:44 AM
Joined: Jan 2003
Posts: 21,050
Niles , Ohio
T
therocks Offline
oh wait.but hey.lets see.oh yeah.
therocks  Offline
oh wait.but hey.lets see.oh yeah.
T

Joined: Jan 2003
Posts: 21,050
Niles , Ohio
I can run my 12.5 aluminum headed 440 on 93.Just can really hammer it or it pings.Just normal driving its great.When I want to pound it I add about 4 gallons of 110 to 12 of 93.At the track I run almost straight 110.Rocky


Chrysler Firepower
Re: Question on mixing race gas and premium fuel [Re: Cab_Burge] #1115118
11/20/11 12:06 AM
11/20/11 12:06 AM
Joined: Feb 2005
Posts: 2,158
God's Country - Etowah, TN.
A34 Offline OP
top fuel
A34  Offline OP
top fuel

Joined: Feb 2005
Posts: 2,158
God's Country - Etowah, TN.
Quote:

Quote:

Hey Guys,

I have a new engine for a street car that's sporting 11.25:1 compression. It's a iron headed 440 with stock intake and exhaust manifolds, running a pure stock cheater cam and 800 avs edelbrock carb. Stock reproduction coil and factory dual point converted with pertronix ignition kit. Total timing set at 38.

On initial break-in we mixed 110 octane with 93 so it wouldn't ping. I was wondering if any of you guys have had experience mixing race gas with premium. Someone told me the stock coil doesn't put out enough voltage to properly burn the race gas and I should try and run it on 93 if possible, stating that with alcohol added it is more like 96 octane. I'm not up on that stuff, so not sure what is a old myth or real. I would appreciate any input from guys that have experience mixing this stuff.

I don't mind adding race fuel if needed for it not to ping. I want to understand better how they act when mixed and if the stock coil is a limiting factor.

Thanks !



Stock coil doesn't have enough voltage to burn race gas Another urban myth The coil(any coil) will produce enough voltage to jump the gap, regardless of pump swill or race gas being in the motor Your pushing the limits on compression with the iron heads and exhaust sytem and total timing What spark plug brand and heat range(part #) are you running? The cheater cam may help a tiny bit as far as the compression but I would be very careful on detonation, if it starts pinging(when it gets hot outside)lift up the throttle and get some better fuel I have treid mixing race gas and pump swill years ago, the race gas is a different specific gravity than the pump swill so they ended up seperating when the car sat overnight, I think Try getting a clear gas jar, as big as possible, and mix the two fuels together % like your going to use, shake them up and let the jar sit for a while, at least two hours or more. If the two fuels seperate in the jar you know it will seperate in the car Let us know if you test it and what it does




Thanks Cab. I'm running the ever popular Champion J12Y plugs. I'm gonna take her out on a long cruise tomorrow and see how she acts running on straight 93.


God Bless America, Our Troops and Their Families !

DEO VINDICE
Re: Question on mixing race gas and premium fuel [Re: Kiner] #1115119
11/20/11 12:08 AM
11/20/11 12:08 AM
Joined: Feb 2005
Posts: 2,158
God's Country - Etowah, TN.
A34 Offline OP
top fuel
A34  Offline OP
top fuel

Joined: Feb 2005
Posts: 2,158
God's Country - Etowah, TN.
Quote:

Don't know but if you start mixing. Hope this helps.
http://www.motorsportsracingfuels.com/OctaneCalculator.html




This rocks, thanks !


God Bless America, Our Troops and Their Families !

DEO VINDICE
Re: Question on mixing race gas and premium fuel [Re: A34] #1115120
11/20/11 03:36 AM
11/20/11 03:36 AM
Joined: Aug 2003
Posts: 43,007
Bend,OR USA
C
Cab_Burge Offline
I Win
Cab_Burge  Offline
I Win
C

Joined: Aug 2003
Posts: 43,007
Bend,OR USA
Quote:

Thanks Cab. I'm running the ever popular Champion J12Y plugs. I'm gonna take her out on a long cruise tomorrow and see how she acts running on straight 93.


If it pings you might want to try colder plug like a J10Y or a RJ10YC, even better if you can find them would be a RC7YC or a RC6YC or the equivalent heat range plugs in Autolite or NGK. I had a boat motor,(inboard out board SB 350 Chevy ) that would ping with J12Y but not ping with J11Y or J10Y back when you cuold still buy them at parts store Autolite AR73 or AR72 would work to but they are expensive now since they added the AR prefix(Autolite Racing) Autolite resitor number 83 and 82 are the same plug in resitors at a much lower price, they work well also


Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)






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