Difference Between 8.5:1 CR and 10.1:1 CR

Techniq · February 18th, 2010, 11:17 AM

Just Curious as to what the New 5.0 w/ 8.5:1 CR will run like in Comparison to the Stock 4.6 w/ 10.1:1 CR. I'm mostly concerned with Gas Mileage and Driveablity. Noticeable Power Difference is something im expecting but how much? Just curious Since I've decided not to go with Boost, (Other Expenses), for a little while longer... Like 1-3 years longer.

Mach Boy · February 18th, 2010, 12:40 PM

I could be wrong but I thought the new 5.0 was closer to 11 CR.

rk_2000_Z/28 · February 18th, 2010, 01:00 PM

I'm not sure what the new motors have, but 8.5:1 is LOW for a n/a motor. I think that's what the supercharged Cobras come with.

Trick Tuners · February 18th, 2010, 01:01 PM

Low compression = bag mpg, and low power, but is good for high boost.

Reloaded · February 18th, 2010, 01:58 PM

's

mustanginky · February 18th, 2010, 02:39 PM

That low compression without a blower will be a dog. BetteR get some 4.30's.

bitemark46 · February 18th, 2010, 02:55 PM

Originally Posted by Mach Boy

I could be wrong but I thought the new 5.0 was closer to 11 CR.

<Ed Macmahon voice> "Yes, you are correct sir" </>

mustanginky · February 18th, 2010, 06:21 PM

I think he's talking about a 5.0 stroker for his car

NO_PI_NO_POWER · February 18th, 2010, 08:52 PM

Nothing is exact, but given the same motor, if the only thing changed is compression, a guideline is 4 percent power gain for every full point of compression added.

Techniq · February 19th, 2010, 09:56 AM

Originally Posted by Mach Boy

I could be wrong but I thought the new 5.0 was closer to 11 CR.

Sorry,it's a stroker Shortblock build. I went with Cast iron block , forged internals , but a boosted format. So CR is somewhere between 8.5:1 - 9.1:1.

Techniq · February 19th, 2010, 10:00 AM

Originally Posted by mustanginky

That low compression without a blower will be a dog. BetteR get some 4.30's.

Lol, I hear you there. I was considering 4.10's

03_StangGuy · February 19th, 2010, 01:10 PM

With compression that low your gonna need a big PD blower

Techniq · February 19th, 2010, 09:08 PM

My original intent was to go with a decent size Procharger Kit.

Techniq · February 21st, 2010, 11:18 AM

As for functionality it won't do any harm to the motor itself will it?

Doc8224 · February 21st, 2010, 03:38 PM

no it's just not gonna have any power at all.

03_StangGuy · February 22nd, 2010, 09:26 AM

Too high of compression could be a problem. But a motor with 8.5:1 compression is goni to be a dog with out a BIG roots/screw type blower. Even with a procharger your not gonna make boost soon enough to offset the low compression. Usually u would run 9.0:1 compression with a roots/screw blower and around 9.5 with a centri.

Techniq · March 1st, 2010, 12:33 PM

Originally Posted by NO_PI_NO_POWER

Nothing is exact, but given the same motor, if the only thing changed is compression, a guideline is 4 percent power gain for every full point of compression added.

I've used a couple different calculators but for some reason I'm getting the feeling there not very accurate.

86er · March 2nd, 2010, 11:54 PM

Originally Posted by 03_StangGuy

With compression that low your gonna need a big PD blower

as in Powerdyne?

those belt driven book case ends?

Those are the worst thing to put on a car if you are serious about power.

not worth the material they are cast out of

03_StangGuy · March 3rd, 2010, 10:25 AM

Originally Posted by 86er

as in Powerdyne?

those belt driven book case ends?

Those are the worst thing to put on a car if you are serious about power.

not worth the material they are cast out of

PD or positive displacement blower refers to any manifold type blows, Whipple and Kenne Bell included.

Techniq · March 5th, 2010, 02:35 PM

Originally Posted by 86er

as in Powerdyne?

those belt driven book case ends?

Those are the worst thing to put on a car if you are serious about power.

not worth the material they are cast out of

Lost me there.

February 18th, 2010, 11:17 AM	#1
Techniq Regular 2004 Mustang Mach 1 Will Run After Build! Join Date: Nov 2008 Location: Belleview, FL Posts: 364 iTrader: 0 reviews	Difference Between 8.5:1 CR and 10.1:1 CR Just Curious as to what the New 5.0 w/ 8.5:1 CR will run like in Comparison to the Stock 4.6 w/ 10.1:1 CR. I'm mostly concerned with Gas Mileage and Driveablity. Noticeable Power Difference is something im expecting but how much? Just curious Since I've decided not to go with Boost, (Other Expenses), for a little while longer... Like 1-3 years longer. __________________ 5.0L Cast Iron block/Forged internals-Melling Oil Pump w/Billet Gears-BBK Twin 65mm Throttle Body-BBK Longtube Headers-BBK O/R "x" Pipe- Maganflow Cats-B&M Sport Short Throw-Eibach Drag-Launch Springs-And Some More...Hope to run new set-up soon.

February 18th, 2010, 12:40 PM	#2
Mach Boy MM's Orangest 2004 Mach 1 Mustang Join Date: Sep 2007 Location: Indy Posts: 2,846 Blog Entries: 1 iTrader: 1 reviews	I could be wrong but I thought the new 5.0 was closer to 11 CR. __________________ Looking for 03/04 4V ABS Wiring Harness Connector/Incomplete Wiring Harness (with ABS connector)

February 18th, 2010, 01:00 PM	#3
rk_2000_Z/28 Forever in our hearts travis_afx 2003 SVT Cobra Join Date: Apr 2007 Location: Enid, OK Posts: 4,311 iTrader: 0 reviews	I'm not sure what the new motors have, but 8.5:1 is LOW for a n/a motor. I think that's what the supercharged Cobras come with. __________________ 03 Cobra-Slow 02 SS, 00 Z/28-Gone Rest In Peace Travis Billings

February 18th, 2010, 01:01 PM	#4
Trick Tuners MM Fanatic KB'd GT Join Date: Nov 2006 Location: San Diego Posts: 4,467 iTrader: 3 reviews	Low compression = bag mpg, and low power, but is good for high boost. __________________ Check out my forums for stuff on troubleshooting, tuning, etc We teamed up with Socal Performance Racing to bring dyno tuning to San Diego. Be friends with us on FB

February 18th, 2010, 02:39 PM	#6
mustanginky MM Fanatic 2000 gt Join Date: Feb 2009 Location: La grange, KY Posts: 4,254 iTrader: 2 reviews	That low compression without a blower will be a dog. BetteR get some 4.30's. __________________ Procharged 2000 5 Speed BAB GT, built motor, blower cams, speedy dyno tune 412 hp, 450 rw tq HARDCORE CREW BRIGHT ATLANTIC BLUE CREW #1 MEMBER

February 18th, 2010, 06:21 PM	#8
mustanginky MM Fanatic 2000 gt Join Date: Feb 2009 Location: La grange, KY Posts: 4,254 iTrader: 2 reviews	I think he's talking about a 5.0 stroker for his car __________________ Procharged 2000 5 Speed BAB GT, built motor, blower cams, speedy dyno tune 412 hp, 450 rw tq HARDCORE CREW BRIGHT ATLANTIC BLUE CREW #1 MEMBER

February 18th, 2010, 08:52 PM	#9
NO_PI_NO_POWER Granny Shifter 1997 Mustang GT 12.297@113.47 Join Date: Jul 2008 Location: Greeley, CO Posts: 752 iTrader: 0 reviews	Nothing is exact, but given the same motor, if the only thing changed is compression, a guideline is 4 percent power gain for every full point of compression added. __________________ 1997 GT 2.6L Kenne Bell Build Thread 1989 LX Last edited by NO_PI_NO_POWER; February 18th, 2010 at 08:56 PM.

February 19th, 2010, 01:10 PM	#12
03_StangGuy I Poop Entirely Way Too Much Blown 03 GT Join Date: Jun 2007 Location: Long Island NY Posts: 6,913 iTrader: 0 reviews	With compression that low your gonna need a big PD blower __________________

February 19th, 2010, 09:08 PM	#13
Techniq Regular 2004 Mustang Mach 1 Will Run After Build! Join Date: Nov 2008 Location: Belleview, FL Posts: 364 iTrader: 0 reviews	My original intent was to go with a decent size Procharger Kit. __________________ 5.0L Cast Iron block/Forged internals-Melling Oil Pump w/Billet Gears-BBK Twin 65mm Throttle Body-BBK Longtube Headers-BBK O/R "x" Pipe- Maganflow Cats-B&M Sport Short Throw-Eibach Drag-Launch Springs-And Some More...Hope to run new set-up soon.

February 21st, 2010, 11:18 AM	#14
Techniq Regular 2004 Mustang Mach 1 Will Run After Build! Join Date: Nov 2008 Location: Belleview, FL Posts: 364 iTrader: 0 reviews	As for functionality it won't do any harm to the motor itself will it? __________________ 5.0L Cast Iron block/Forged internals-Melling Oil Pump w/Billet Gears-BBK Twin 65mm Throttle Body-BBK Longtube Headers-BBK O/R "x" Pipe- Maganflow Cats-B&M Sport Short Throw-Eibach Drag-Launch Springs-And Some More...Hope to run new set-up soon.

February 21st, 2010, 03:38 PM	#15
Doc8224 N/A 4v Guru 2003 Mach 1 Join Date: Oct 2007 Location: Afghanistan Posts: 3,463 Blog Entries: 2 iTrader: 1 reviews	no it's just not gonna have any power at all. __________________ Military Crew U.S. Army Aviation Apache's Lead The Way

February 22nd, 2010, 09:26 AM	#16
03_StangGuy I Poop Entirely Way Too Much Blown 03 GT Join Date: Jun 2007 Location: Long Island NY Posts: 6,913 iTrader: 0 reviews	Too high of compression could be a problem. But a motor with 8.5:1 compression is goni to be a dog with out a BIG roots/screw type blower. Even with a procharger your not gonna make boost soon enough to offset the low compression. Usually u would run 9.0:1 compression with a roots/screw blower and around 9.5 with a centri. __________________

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