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Difference between 10.5 and 11.0 cr #1283126 08/10/12 05:35 PM 08/10/12 05:35 PM
Joined: May 2004 Posts: 1,522 Ste-Sophie, Quebec, Canada W Wedgeman OP pro stock
Wedgeman OP pro stock W Joined: May 2004 Posts: 1,522 Ste-Sophie, Quebec, Canada	Hey...! My 408 has 10.5:1 cr...my 60ft is 1.47... I wonder if I could notice any difference in performance if I step up to thinner heads gasket and get 11.0:1 cr ? Speculate on that please Dan 67 Barracuda

Re: Difference between 10.5 and 11.0 cr [Re: Wedgeman] #1283127 08/10/12 06:40 PM 08/10/12 06:40 PM
Joined: Jan 2003 Posts: 6,591 Canton, Ohio S Sport440 master
Sport440 master S Joined: Jan 2003 Posts: 6,591 Canton, Ohio	You will notice a difference with a 1/2 point jump in comp. On my old 440 906 I saw 2 tenths with a .040 shave or about .7 comp jump. With your little 408 you will see less, but you will still see a gain.

Re: Difference between 10.5 and 11.0 cr [Re: Sport440] #1283128 08/10/12 07:10 PM 08/10/12 07:10 PM
Joined: Jan 2003 Posts: 11,711 Portage,michigan B B3422W5 I Live Here
B3422W5 I Live Here B Joined: Jan 2003 Posts: 11,711 Portage,michigan	It is well documented that the power difference regarding compression will be larger with lower compression to start with. In other words, you would gain more power going from 9 to 1 to 10 to 1 than you would going from 13 to 1 to 14 to 1. Hope that makes sense. 69 Dart GTS A4 Silver All steel, flat factory hood, 3360race weight 418 BPE factory replacement headed stroker, 565 lift solid cam Best so far, 10.40 @127 1/4 1.41 best 60 foot 6.60 at 103.90 1/8

Re: Difference between 10.5 and 11.0 cr [Re: Wedgeman] #1283129 08/10/12 07:47 PM 08/10/12 07:47 PM
Joined: Jun 2003 Posts: 52,972 Romeo MI MR_P_BODY Master
MR_P_BODY Master Joined: Jun 2003 Posts: 52,972 Romeo MI	A difference in heads will be a factor also... alum heads may see a bigger benefit due to alum heads like more compression to equal out to iron

Re: Difference between 10.5 and 11.0 cr [Re: Wedgeman] #1283130 08/10/12 08:02 PM 08/10/12 08:02 PM
Joined: Oct 2004 Posts: 8,165 Left Coast B BobR master
BobR master B Joined: Oct 2004 Posts: 8,165 Left Coast	Quote: Hey...! My 408 has 10.5:1 cr...my 60ft is 1.47... I wonder if I could notice any difference in performance if I step up to thinner heads gasket and get 11.0:1 cr ? Speculate on that please Dan 67 Barracuda Very little difference. Less than 10 HP.

Re: Difference between 10.5 and 11.0 cr [Re: Wedgeman] #1283131 08/10/12 08:37 PM 08/10/12 08:37 PM
Joined: Jan 2003 Posts: 16,925 NC 440Jim I Live Here
440Jim I Live Here Joined: Jan 2003 Posts: 16,925 NC	Depends on the cam, intake, headers, converter stall, etc. etc. But until you list that, I would say 2% more power. So if you are making 1000 hp that would be 20 hp. And a 12 second car adding 20 hp would be 0.2 seconds in the 1/4 mile. So it depends what you have and what it runs ...

Re: Difference between 10.5 and 11.0 cr [Re: 440Jim] #1283132 08/10/12 10:09 PM 08/10/12 10:09 PM
Joined: May 2004 Posts: 1,522 Ste-Sophie, Quebec, Canada W Wedgeman OP pro stock
Wedgeman OP pro stock W Joined: May 2004 Posts: 1,522 Ste-Sophie, Quebec, Canada	408 Indy headed I was hoping to gain .2 sec in the 1/8 mile... just by swaping to thinner head gaskets....cheap horsepower to me , go from 6.75 to 6.55.. Dan

Re: Difference between 10.5 and 11.0 cr [Re: Wedgeman] #1283133 08/10/12 10:23 PM 08/10/12 10:23 PM
Joined: Jun 2003 Posts: 52,972 Romeo MI MR_P_BODY Master
MR_P_BODY Master Joined: Jun 2003 Posts: 52,972 Romeo MI	Quote: 408 Indy headed I was hoping to gain .2 sec in the 1/8 mile... just by swaping to thinner head gaskets....cheap horsepower to me , go from 6.75 to 6.55.. Dan I think your asking alot for just the head gasket but thats... JMO

Re: Difference between 10.5 and 11.0 cr [Re: MR_P_BODY] #1283134 08/10/12 10:28 PM 08/10/12 10:28 PM
Joined: Mar 2007 Posts: 3,300 Northern Indiana Dunnuck Racing master
Dunnuck Racing master Joined: Mar 2007 Posts: 3,300 Northern Indiana	Depends on where your quench distance is now,and where it will end up after the swap. Not hard at all to gain 20 hp fixing a bad quench. Keith www.dunnuckracing.com

Re: Difference between 10.5 and 11.0 cr [Re: 440Jim] #1283135 08/10/12 10:46 PM 08/10/12 10:46 PM
Joined: Jul 2007 Posts: 1,682 Philadelphia R radar top fuel
radar top fuel R Joined: Jul 2007 Posts: 1,682 Philadelphia	I have read about the diminishing returns in torque from CR increases. That makes sense, but I also wonder how it could possibly fit into the 'whole picture' of matching parts. Like Jim said- depends on the other parts. I have 0 experience with race gas territory compression ratios but I suspect that if increases give diminshing returns then the primary reason for a 15:1 cr in a race setup would be to maximize the performance of a wild cam with lots of overlap. So if your CR is low for what your cam wants maybe your gains could be greater? I'm only guessing- I'd love to hear from someone that actually knows.

Re: Difference between 10.5 and 11.0 cr [Re: radar] #1283136 08/10/12 11:40 PM 08/10/12 11:40 PM
Joined: Jan 2008 Posts: 795 Glendale Az D Darryls-Demon super stock
Darryls-Demon super stock D Joined: Jan 2008 Posts: 795 Glendale Az	I think you should check your cylinder pressure, you may be able to bump it up one whole point if you find out your cylinder preesure is around say 150 pounds now.

Re: Difference between 10.5 and 11.0 cr [Re: Darryls-Demon] #1283137 08/11/12 12:33 AM 08/11/12 12:33 AM
Joined: May 2004 Posts: 1,522 Ste-Sophie, Quebec, Canada W Wedgeman OP pro stock
Wedgeman OP pro stock W Joined: May 2004 Posts: 1,522 Ste-Sophie, Quebec, Canada	Cylinder pressure is 180lbs.....may be the cam is asking for more ??? 255/263@ .050 solid roller.. Dan

Re: Difference between 10.5 and 11.0 cr [Re: Wedgeman] #1283138 08/11/12 01:03 AM 08/11/12 01:03 AM
Joined: Mar 2007 Posts: 3,300 Northern Indiana Dunnuck Racing master
Dunnuck Racing master Joined: Mar 2007 Posts: 3,300 Northern Indiana	What's the lsa ? Keith www.dunnuckracing.com

Re: Difference between 10.5 and 11.0 cr [Re: Dunnuck Racing] #1283139 08/11/12 02:15 AM 08/11/12 02:15 AM
Joined: May 2004 Posts: 1,522 Ste-Sophie, Quebec, Canada W Wedgeman OP pro stock
Wedgeman OP pro stock W Joined: May 2004 Posts: 1,522 Ste-Sophie, Quebec, Canada	lsa is 110........

Re: Difference between 10.5 and 11.0 cr [Re: Wedgeman] #1283140 08/11/12 04:31 AM 08/11/12 04:31 AM
Joined: Jan 2003 Posts: 6,591 Canton, Ohio S Sport440 master
Sport440 master S Joined: Jan 2003 Posts: 6,591 Canton, Ohio	Quote: 408 Indy headed I was hoping to gain .2 sec in the 1/8 mile... just by swaping to thinner head gaskets....cheap horsepower to me , go from 6.75 to 6.55.. Dan At your level of performance, you will not see a 2 tenths gain with a 1/2 point comp increase. Nope/No way! If your running 6.75,s now, with that 1/2 point bump, Id expect high 6.68,s or so.

Re: Difference between 10.5 and 11.0 cr [Re: Wedgeman] #1283141 08/11/12 11:52 AM 08/11/12 11:52 AM
Joined: Oct 2007 Posts: 4,206 New York polyspheric master
polyspheric master Joined: Oct 2007 Posts: 4,206 New York	http://victorylibrary.com/mopar/otto.htm Boffin Emeritus

Re: Difference between 10.5 and 11.0 cr [Re: Sport440] #1283142 08/11/12 12:22 PM 08/11/12 12:22 PM
Joined: Jan 2008 Posts: 795 Glendale Az D Darryls-Demon super stock
Darryls-Demon super stock D Joined: Jan 2008 Posts: 795 Glendale Az	Quote: Quote: 408 Indy headed I was hoping to gain .2 sec in the 1/8 mile... just by swaping to thinner head gaskets....cheap horsepower to me , go from 6.75 to 6.55.. Dan At your level of performance, you will not see a 2 tenths gain with a 1/2 point comp increase. Nope/No way! If your running 6.75,s now, with that 1/2 point bump, Id expect high 6.68,s or so. With 440sport, its not like your cylinder pressure is low now so I just can not see how a 1/2 point more will make that much difference.

Re: Difference between 10.5 and 11.0 cr [Re: Darryls-Demon] #1283143 08/11/12 04:53 PM 08/11/12 04:53 PM
Joined: May 2004 Posts: 1,522 Ste-Sophie, Quebec, Canada W Wedgeman OP pro stock
Wedgeman OP pro stock W Joined: May 2004 Posts: 1,522 Ste-Sophie, Quebec, Canada	Oh Thanks for all the good advice ! Dan

Re: Difference between 10.5 and 11.0 cr [Re: Wedgeman] #1283144 08/11/12 06:20 PM 08/11/12 06:20 PM
Joined: Jun 2007 Posts: 103 NEW JERSEY BIGSPEED member
BIGSPEED member Joined: Jun 2007 Posts: 103 NEW JERSEY	Little to no gain unless the tighter quench fixes something,maybe 10 hp.Bill C. Ceralli Racing Engines & Checkered Flag Machine Racing engines , CNC porting & induction development http://www.checkeredflagmachine.net/

Re: Difference between 10.5 and 11.0 cr [Re: BIGSPEED] #1283145 08/11/12 10:19 PM 08/11/12 10:19 PM
Joined: Jan 2009 Posts: 1,044 Victoria, Australia Ian super stock
Ian super stock Joined: Jan 2009 Posts: 1,044 Victoria, Australia	what is your complete combo/weight .your 2 tenths may be in advancing cam ,gear change ,stall etc 1.37 60 ft [email]6.0@113[/email] [email]9.57@141[/email] 408 glide 3550lbs new video http://www.youtube.com/watch?feature=player_embedded&v=Xvq3ZObywQE

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