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11.5:1 comp with pump gas? #477675 09/23/09 03:48 PM 09/23/09 03:48 PM
Joined: Jan 2007 Posts: 8,042 Mt Morris Michigan mopar dave OP master
mopar dave OP master Joined: Jan 2007 Posts: 8,042 Mt Morris Michigan	this has been talked about on here before, but my situation is alittle different. i will be pulling motor and trans soon for the 8" convertor install and thought it would be a good time to have the ports on the indys cleaned up better and shave the heads for more compression. i have a 408 with indy 360-1 heads with CP dish pistons that are ceramic coated on top and a solid roller cam 258/264@50-.650/.650 on a 108 and 45* of overlap. if i shave the heads .030" and use a .035" gasket this with give 11.5:1 compression, but do you think i will still be able to use pump gas? what would be the limit on pump gas with this combo? thanks http://www.youtube.com/watch?v=aIxaesJ190U http://youtu.be/lCZAaN7fFLg

Re: 11.5:1 comp with pump gas? [Re: mopar dave] #477676 09/23/09 04:28 PM 09/23/09 04:28 PM
Joined: Oct 2004 Posts: 8,165 Left Coast B BobR master
BobR master B Joined: Oct 2004 Posts: 8,165 Left Coast	Quote: this has been talked about on here before, but my situation is alittle different. i will be pulling motor and trans soon for the 8" convertor install and thought it would be a good time to have the ports on the indys cleaned up better and shave the heads for more compression. i have a 408 with indy 360-1 heads with CP dish pistons that are ceramic coated on top and a solid roller cam 258/264@50-.650/.650 on a 108 and 45* of overlap. if i shave the heads .030" and use a .035" gasket this with give 11.5:1 compression, but do you think i will still be able to use pump gas? what would be the limit on pump gas with this combo? thanks Detonation can be a silent killer. I wouldn't.

Re: 11.5:1 comp with pump gas? [Re: BobR] #477677 09/23/09 04:34 PM 09/23/09 04:34 PM
Joined: Jan 2003 Posts: 4,002 Joplin, Mo R rt66jim master
rt66jim master R Joined: Jan 2003 Posts: 4,002 Joplin, Mo	My 416 has 72cc W2's Wiseco flattops with 5cc valve reliefs. Calculators figure it at 11.2. It will run on pump gas if you pull the timing back to 30*. It has 185 lbs of cranking compression. Jim

Re: 11.5:1 comp with pump gas? [Re: BobR] #477678 09/23/09 04:40 PM 09/23/09 04:40 PM
Joined: May 2004 Posts: 12,401 Taxes & Virus's R-US, NY Dragula I Live Here
Dragula I Live Here Joined: May 2004 Posts: 12,401 Taxes & Virus's R-US, NY	I run 11.6:1 on the street with pump gas in my hemi and have never had an issue. I run 50/50 race gas when at the track. There is a discussion thread about quench and cranking pressure that can tell you where the sweet spot is if you do a search. I keep a good eye on the tune-up just because of the compression I run, but I would rather have the horse power than not have it. The pistons were the same price either way. '70 Cuda,...605 EFI Hemi Street Car (6.20 best pass, 1.33 60ft) https://www.youtube.com/watch?v=WYw6RA-k5Bk (6.25 at 108.75mph from inside car) https://www.youtube.com/watch?v=3zQEb9uxFng (6.25 at 108mph from outside car) https://www.youtube.com/watch?v=JCvfzsC4NgM (9.9) '66 Barracuda AWB Stretched nose Blown 440 Car in build stage '71 Duster Drag Car 400 Low Deck 512 best 6.002 at 115.44mph https://www.youtube.com/watch?v=Znuo3jMUXTk

Re: 11.5:1 comp with pump gas? [Re: rt66jim] #477679 09/23/09 04:43 PM 09/23/09 04:43 PM
Joined: Jan 2007 Posts: 3,695 nc E emarine01 master
emarine01 master E Joined: Jan 2007 Posts: 3,695 nc	I think you are real close, eather way ya need to take cranking compression and find what #s you make with that cam, it seems 175-180psi is the upper limit, a lot depends on fuel type and quench, with 12 to 1 and a long duration cam we made 185 psi and ran pump 93 just moving the truck around the shop and yard , we went race fuel under load, same motor with a smaller roller 260@ .50 makes 220 psi so no 93 anymore

Re: 11.5:1 comp with pump gas? [Re: emarine01] #477680 09/23/09 04:50 PM 09/23/09 04:50 PM
Joined: Apr 2007 Posts: 325 Greenville, WI B Big B enthusiast
Big B enthusiast B Joined: Apr 2007 Posts: 325 Greenville, WI	I've been running a 493/440 with 12.4:1 compresion for 4 years. Run the hell out of it. It's all about the cam. I have 266/271@.050 Here's the dyno sheet 5501204-dyno.jpg (213 downloads)

Re: 11.5:1 comp with pump gas? [Re: Big B] #477681 09/23/09 05:17 PM 09/23/09 05:17 PM
Joined: Jan 2003 Posts: 4,002 Joplin, Mo R rt66jim master
rt66jim master R Joined: Jan 2003 Posts: 4,002 Joplin, Mo	Quote: I've been running a 493/440 with 12.4:1 compresion for 4 years. Run the hell out of it. It's all about the cam. I have 266/271@.050 Here's the dyno sheet What heads are on that motor?

Re: 11.5:1 comp with pump gas? [Re: rt66jim] #477682 09/23/09 05:22 PM 09/23/09 05:22 PM
Joined: Oct 2003 Posts: 3,698 NE Oklahoma V Von master
Von master V Joined: Oct 2003 Posts: 3,698 NE Oklahoma	IMO, I think you will be fine. I have no quench at all (open chamber heads, .045 gasket, .005 out of the hole), compression comes out to 10.5. Cam is 259/259 duration at .050. I ran it on pump 91 for a year and a half, without any known issues. My cranking compression is only 145-150PSI. 72 RR, Pump gas 440, 452s, 3800 lbs, Corked, ET Radials,. 11.33@117.72. Same car, bone stock 346s, 9.5 comp, baby solid. 12.24@110.

Re: 11.5:1 comp with pump gas? [Re: Von] #477683 09/23/09 05:26 PM 09/23/09 05:26 PM
Joined: Mar 2008 Posts: 5,746 Ontario, Canada Dodgem master
Dodgem master Joined: Mar 2008 Posts: 5,746 Ontario, Canada	A good test will be to go to the garage and warm up a bit pull all the plugs and the carb (I like to do it this way) and do a compression test to get an idea where you are cranking now??

Re: 11.5:1 comp with pump gas? [Re: rt66jim] #477684 09/23/09 06:15 PM 09/23/09 06:15 PM
Joined: Apr 2007 Posts: 325 Greenville, WI B Big B enthusiast
Big B enthusiast B Joined: Apr 2007 Posts: 325 Greenville, WI	It has Indy-1's. Cranking psi is 195

Re: 11.5:1 comp with pump gas? [Re: Big B] #477685 09/23/09 06:28 PM 09/23/09 06:28 PM
Joined: Jan 2007 Posts: 8,042 Mt Morris Michigan mopar dave OP master
mopar dave OP master Joined: Jan 2007 Posts: 8,042 Mt Morris Michigan	heads are indy 360-1's with .039" quench, 10.75 comp and 190 cranking psi. been running pump gas with it for two seasons now without any problems and no black specks on plugs. i figure that maybe with an aluminum head with .035" quench and coated piston tops i might get away with pump gas at 11.5 comp. dunno? http://www.youtube.com/watch?v=aIxaesJ190U http://youtu.be/lCZAaN7fFLg

Re: 11.5:1 comp with pump gas? [Re: Big B] #477686 09/23/09 06:31 PM 09/23/09 06:31 PM
A Anonymous Unregistered
Anonymous Unregistered A	Quote: It has Indy-1's. Cranking psi is 195 if those are the actual #'s, you'll want a different cam. more static compression will just increase the cranking psi out of sight for pump gas.

Re: 11.5:1 comp with pump gas? #477687 09/23/09 06:52 PM 09/23/09 06:52 PM
Joined: Nov 2003 Posts: 6,293 Rock Springs Bob_Coomer master
Bob_Coomer master Joined: Nov 2003 Posts: 6,293 Rock Springs	What gains are to be had on raising compression, only to pull timing out to compensate for too low a octane fuel rating? Yes it will run on pump gas after timing changes... IMO this combo will be counter productive, and wont be optimal.. I wouldnt bother with shaving the heads.. I would rather run optimal timing with a half point to a point less in compression, than run the compression up there and pull timing out, and fight detonation. Have you thought about E85 which is a pump fuel? [color:"red"]65 Hemi Belvedere coming soon [/color] [color:"#00FF00"]557" Indy engine 1.07 60ft 144mph in the 8th 2100 lbs package [/color]

Re: 11.5:1 comp with pump gas? [Re: Big B] #477688 09/23/09 07:01 PM 09/23/09 07:01 PM
Joined: Jan 2003 Posts: 2,402 Wichita,KS B Blakcharger440 top fuel
Blakcharger440 top fuel B Joined: Jan 2003 Posts: 2,402 Wichita,KS	Quote: I've been running a 493/440 with 12.4:1 compresion for 4 years. Run the hell out of it. It's all about the cam. I have 266/271@.050 Here's the dyno sheet So what are the cam specs you are using to run 12.4:1 compression? And are you referring to 91 or 93 at the pump? The best gas they sell around here is 91 or else you buy race gas.

Re: 11.5:1 comp with pump gas? [Re: Blakcharger440] #477689 09/23/09 07:11 PM 09/23/09 07:11 PM
Joined: Jan 2007 Posts: 8,042 Mt Morris Michigan mopar dave OP master
mopar dave OP master Joined: Jan 2007 Posts: 8,042 Mt Morris Michigan	i'm currently using sunoco ultra 93. what size cam would i have to step up to? how much overlap? http://www.youtube.com/watch?v=aIxaesJ190U http://youtu.be/lCZAaN7fFLg

Re: 11.5:1 comp with pump gas? [Re: mopar dave] #477690 09/23/09 07:37 PM 09/23/09 07:37 PM
Joined: Jan 2003 Posts: 16,928 NC 440Jim I Live Here
440Jim I Live Here Joined: Jan 2003 Posts: 16,928 NC	Dave, There are no guarantees. But if I was going to increase your CR, I would add more duration to the cam at the same time. 1993 Daytona, 5.50 at 130mph (1/8) 1.19 sixty ft (PG). Link to 572 B1 - Part 1

Re: 11.5:1 comp with pump gas? [Re: 440Jim] #477691 09/23/09 07:57 PM 09/23/09 07:57 PM
Joined: Jan 2007 Posts: 8,042 Mt Morris Michigan mopar dave OP master
mopar dave OP master Joined: Jan 2007 Posts: 8,042 Mt Morris Michigan	ok, but what size should i be looking at? 268/274@50 on 108? this would be 10* more than i currently have. give me some ideas. http://www.youtube.com/watch?v=aIxaesJ190U http://youtu.be/lCZAaN7fFLg

Re: 11.5:1 comp with pump gas? [Re: mopar dave] #477692 09/23/09 08:58 PM 09/23/09 08:58 PM
Joined: Jan 2007 Posts: 8,042 Mt Morris Michigan mopar dave OP master
mopar dave OP master Joined: Jan 2007 Posts: 8,042 Mt Morris Michigan	i just figure while the engines out it will be a good opertunity to increase compression to get a few more ftlb of torque. if i cant do it with pump gas i'll just have to mix it. http://www.youtube.com/watch?v=aIxaesJ190U http://youtu.be/lCZAaN7fFLg

Re: 11.5:1 comp with pump gas? [Re: mopar dave] #477693 09/23/09 10:01 PM 09/23/09 10:01 PM
Joined: Mar 2008 Posts: 5,746 Ontario, Canada Dodgem master
Dodgem master Joined: Mar 2008 Posts: 5,746 Ontario, Canada	Quote: ok, but what size should i be looking at? 268/274@50 on 108? this would be 10* more than i currently have. give me some ideas. that would probably be the ticket but may need a 4800 stall or somewhere in between 264/270 ish??

Re: 11.5:1 comp with pump gas? [Re: Blakcharger440] #477694 09/23/09 10:26 PM 09/23/09 10:26 PM
Joined: Apr 2007 Posts: 325 Greenville, WI B Big B enthusiast
Big B enthusiast B Joined: Apr 2007 Posts: 325 Greenville, WI	I use 93 octane The cam is a Comp solid roller 266/271@50. 112 lobe sep 108 centerline .680 lift Pro-charger and fuel injection next

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