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Pump gas friendly race motor
#1093478
10/12/11 09:51 PM
10/12/11 09:51 PM
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Joined: Nov 2003
Posts: 10,384
Upstate NY
Bigcube
OP
I Live Here
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OP
I Live Here
Joined: Nov 2003
Posts: 10,384
Upstate NY
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How much squeeze? It will be 572 cubes, figure an optimized cam for dealing with pump gas, will be a roller. Will see a shot of spray at the track with some better gas. Will see street time, must not be temperamental. What sort of compression should I shoot for... ballpark, I know it's a loaded question. I'm thinking 11:1 ish? Alum. heads and block. I have a few ideas rolling around in my head, have to see how things pan out over the winter. Looking for opinions of people who know pump gas stuff. Not looking to push the ragged edge. I figure if I can make 750ish HP I can easily spay it to 8.50's and run 9.20's on motor, plenty fast enough to go get ice cream.  And maybe start having fun with the car again at the same time...  
Jim
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Re: Pump gas friendly race motor
[Re: Bigcube]
#1093479
10/12/11 10:05 PM
10/12/11 10:05 PM
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Joined: Jun 2003
Posts: 9,225
Charleston
sixpackgut
Drag Week Mod Champion
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Drag Week Mod Champion
Joined: Jun 2003
Posts: 9,225
Charleston
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i'm at 12-1 with 185 cranking comp. that comp increase came from the indy heads. with rpm heads i was at 10.5-1 with 185 cranking comp.
credit goes to Dan @ Performance Only for specing the cam. it is more tame than the 590 mopar shaft i had before
Gen 3 power 6.22@110, 9.85@135
Follow @g3hemiswap on instagram
performance only racing, CRT, ultimate converter, superior design concepts, ThumperCarbs
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Re: Pump gas friendly race motor
[Re: Bigcube]
#1093482
10/12/11 10:30 PM
10/12/11 10:30 PM
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Joined: Mar 2004
Posts: 1,371
Tallmadge, Ohio
Butch
pro stock
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pro stock
Joined: Mar 2004
Posts: 1,371
Tallmadge, Ohio
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That's good news Jim. If you want to make the trip back to Norwalk for some icecream at next season I'll buy.  Butch
'74 Duster 440
'04 Hemi Quad Cab Ram
'06 Pacifica
'78 MGB
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Re: Pump gas friendly race motor
[Re: Bigcube]
#1093483
10/12/11 10:32 PM
10/12/11 10:32 PM
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Joined: Jun 2003
Posts: 52,972
Romeo MI
MR_P_BODY
Master
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Master
Joined: Jun 2003
Posts: 52,972
Romeo MI
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Quote:
Wow! 12:1? I guess it's all about the cam. I can see bleeding off cranking compression, but no ping under load? I never thought you could be safe at 12:1 with pump swill.... guess I have a lot to learn!
It ALL comes down to the dynamic compression... my
14.1:1 has 185 cranking pressure
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Re: Pump gas friendly race motor
[Re: Bigcube]
#1093486
10/13/11 12:14 AM
10/13/11 12:14 AM
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Joined: Aug 2003
Posts: 43,099
Bend,OR USA
Cab_Burge
I Win
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I Win
Joined: Aug 2003
Posts: 43,099
Bend,OR USA
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My 518 low deck motor with 440-1 CNC ported by MCH made 775 HP on Oregon pump gas with 10.8 to 1 compression and absolutely no quench to speak of.(at 4300 FT above sea level also, DTS dyno straight up no fudging  ) The pistons have a 22 CC dish because the motor originally had a set of ported 906 iron heads on it  I should replace the pistons to a set of reverse dome with some quench, I'm sure there is some power there It is way easir to turn up the squeeze HP than it is to start with to much compression Big motors(C.I.) make a lot of power without a bunch of compression  I'd shoot for 10.5 to 1 or lower
Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)
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Re: Pump gas friendly race motor
[Re: Bigcube]
#1093487
10/13/11 12:23 PM
10/13/11 12:23 PM
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Joined: Jan 2003
Posts: 13,351
Marion, South Carolina [><]
an8sec70cuda
I Live Here
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I Live Here
Joined: Jan 2003
Posts: 13,351
Marion, South Carolina [><]
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Jim, you know hemis are different than wedges, but I have about 11:1 in my hemi and it runs fine on pump 93...when I get the non ethanol stuff. It has 185 psi cranking. Summer time w/ ethanol blended 93 it will rattle and lose a noticeable amount of power. My 440 is 14.5:1 and has 185 psi cranking compression also, but it'll never see anything but race fuel. The pump 93 isn't what it was a few years ago, so I'd go conservative on the compression if it was me.
CHIP
'70 hemicuda, 575" Hemi, 727, Dana 60
'69 road runner, 440-6, 18 spline 4 speed, Dana 60
'71 Demon, 340, low gear 904, 8.75
'73 Chrysler New Yorker, 440, 727, 8.75
'90 Chevy 454SS Silverado, 476" BBC, TH400, 14 bolt
'06 GMC 2500HD LBZ Duramax
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Re: Pump gas friendly race motor
[Re: 383man]
#1093490
10/13/11 07:01 PM
10/13/11 07:01 PM
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Joined: Nov 2003
Posts: 10,384
Upstate NY
Bigcube
OP
I Live Here
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OP
I Live Here
Joined: Nov 2003
Posts: 10,384
Upstate NY
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Thanks everyone for the responses. Seems like 10.5-11.5ish compression with the correct cam should be fine. What do people do to pick a cam and have cranking compression end up where it needs to be? Is that adding more duration? Or overlap? Just curious what would be different in a pump gas cam compared to a high compression/race fuel cam? I would leave spec'ing the cam to the professionals, more just curious ow they would be different.
Jim
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Re: Pump gas friendly race motor
[Re: Bigcube]
#1093491
10/13/11 11:05 PM
10/13/11 11:05 PM
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Joined: Feb 2007
Posts: 6,295
U.S.
moparniac
master
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master
Joined: Feb 2007
Posts: 6,295
U.S.
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11.89 to 1 162 low 170 high cranking compression Races on junk 93 BaBy
Mopar Performance
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Re: Pump gas friendly race motor
[Re: Bigcube]
#1093492
10/14/11 09:10 AM
10/14/11 09:10 AM
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Joined: Jan 2003
Posts: 13,351
Marion, South Carolina [><]
an8sec70cuda
I Live Here
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I Live Here
Joined: Jan 2003
Posts: 13,351
Marion, South Carolina [><]
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Quote:
Thanks everyone for the responses. Seems like 10.5-11.5ish compression with the correct cam should be fine. What do people do to pick a cam and have cranking compression end up where it needs to be? Is that adding more duration? Or overlap? Just curious what would be different in a pump gas cam compared to a high compression/race fuel cam? I would leave spec'ing the cam to the professionals, more just curious ow they would be different.
Dwayne spec'd the cams in both of my motors. The 440's cam is a more radical profile...pretty much race only. Yet you see the compression difference.
My little 440 makes my Hemi sound like a 383, lol. 
CHIP
'70 hemicuda, 575" Hemi, 727, Dana 60
'69 road runner, 440-6, 18 spline 4 speed, Dana 60
'71 Demon, 340, low gear 904, 8.75
'73 Chrysler New Yorker, 440, 727, 8.75
'90 Chevy 454SS Silverado, 476" BBC, TH400, 14 bolt
'06 GMC 2500HD LBZ Duramax
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