Who's running the most compression... - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Spray-Bomb · 09-09-2007, 10:24 PM

On the street ???

If you have a sound / vid clip that'd be great

67_C-30 · 09-09-2007, 10:44 PM

I'm running 22 : 1 in my '67 C-30...

But it's a Diesel!

BCOWANWHEELS · 09-09-2007, 10:52 PM

10.1 with iron heads and dist. 36deg. full advance you,ll have to run at least 93 oct. for sure as thats what my 383 is. it will valve rattle like crazy if you dont. 11.1 with alumin heads same thing. 9.1 is all around best for street i think.

67_C-30 · 09-09-2007, 10:53 PM

I've run as high as 10- 10.3 : 1 on a cast-iron headed SBC with a carburetor, but that's pushing it. I'm running a 12.2 : 1 CR 383 in my '82 Z28, but obviously, I'm running race fuel.

Walts_restoration · 09-09-2007, 10:55 PM

8.5 to 1 on the maro, oh wait highest? i lose haha

DieselEater · 09-09-2007, 10:56 PM

My current pulling engine is going into my 68' SWB project.....11:1 on 91 octane w/out problems........but I'm at 7000 feet elevation

840 rectangles, 800 Q-Jet, RPM air gap.

Spray-Bomb · 09-09-2007, 11:07 PM

Cool, anybody run'n propane (LP) ???

yenko427 · 09-09-2007, 11:21 PM

Hey everyone I'm new to performace stuff. How do you measure comp ratio I have a comp. gauge that I got from a friend.

DieselEater · 09-09-2007, 11:30 PM

Find your chamber size of your heads with your casting number......Go to Mor-Tec.......Then you must know what size/type pistion you're running.

example.....840 BBC iron heads have a 107cc combustion chamber + my L2349F TRW pistons spec sheet says that with 106.9 chambers I'll be around 11:1. If you don't know what piston you have, but the engine is stock, you can get an Idea of what piston was used from some GURU types around the net.

72 CustomCamper · 09-10-2007, 12:05 AM

Quote:

Originally Posted by 67_C-30

I'm running 22 : 1 in my '67 C-30...

But it's a Diesel!

That's what mine was when I had the 6.2 in my 72...

Chuck

bb1979 · 09-10-2007, 04:59 AM

I'm running propane I think my motor has something like 10:1 compression, and it runs great I've been told that 13:1 is acceptable with propane without any issues

**special-K** · 09-10-2007, 06:04 AM

18:1 in my 6.5TD.They actually can be made to run better by lowering from 22:1,sounds silly,right?
I`m picking up my fresh 327 today.It will be about 9.5 to 9.7:1 w/iron heads.I may get away with regular.It will be awhile before it sees service to find out.

bad6772 · 09-10-2007, 06:13 AM

9.5 but im going to a vortec S trim over the winter, my lower end is basically stock ZZ3 but i have had a ton of head work,( port polish port matched to my intake three angle vavle job dual springs, 2,02 1.60 valves and ported and ploshed my intake lil bigger cam (roller) , and of course my erson (extremly loud ) gear drive ,< i think it steals ponies though.... lol but it sounds awsome.........oh i lose

67_C-30 · 09-10-2007, 08:02 AM

Quote:

Originally Posted by special-K

18:1 in my 6.5TD.They actually can be made to run better by lowering from 22:1,sounds silly,right?

Not silly at all. You can turn the boost on up with the 18:1's w/o blowing head gaskets and melting holes in pistons!

djracer · 09-10-2007, 09:54 AM

I have 14 to 1 pistons in my junk but I run race gas! I will run as low as 112octane without the spray but only 116 to 118 when its on the bottle!

crazy longhorn · 09-10-2007, 10:04 AM

I run 9.8 on my alum headed 383, with 34 degrees of mechanical advance ,all in @ 2700 & 12 additional degrees in the advance can. Its fine on 91 octain fuel, but will ping a trace on 89 pulling a steep hill.

L

jkade · 09-10-2007, 02:24 PM

I will be running about 11.5:1 on my iron ls1.

snj8198 · 09-10-2007, 03:53 PM

8.9 cr in my MKIV block. a bit low for aluminum heads but im building a decent amount of cylinder pressure to make the best of my lower duration cam and flattop pistons.

Spray-Bomb · 09-10-2007, 04:10 PM

Quote:

Originally Posted by bb1979

I'm running propane I think my motor has something like 10:1 compression, and it runs great I've been told that 13:1 is acceptable with propane without any issues

What system are you running ??? Holley Pro-Jection ???

Are you LP only or can you still run off gas when you need too ???

djracer · 09-10-2007, 04:22 PM

my buddy had a 13 to 1 440 in a 70 duster but we had to mix av gas and super! It was one fast car for the street!

mark's68 · 09-10-2007, 06:10 PM

I've got a 388 with 10.6-10.7, sportsman heads but it lives on 100 octane low lead avgas. It realy likes it.

kelsfine69 · 09-10-2007, 07:01 PM

454 BBC LS7 12.25:1 crate engine with port and polished heads/matching intake and a 850 Holley. Premium and avegas 60/40 mix or premium and octane boost when the drum runs dry.

Kind of a crappy clip

http://www.youtube.com/watch?v=5ru1cCe62JQ

Scott68-93-97 · 09-10-2007, 07:53 PM

Quote:

Originally Posted by bb1979

I'm running propane I think my motor has something like 10:1 compression, and it runs great I've been told that 13:1 is acceptable with propane without any issues

You can run propane at 13 to or 14 to 1 no problem in fact it will help maximize power to fuel consumption raising compression, propane is 105 octane and loves high comp.

bryanw1968 · 09-10-2007, 08:25 PM

10:1, no problems on pump gas at 12 degrees initial. I can bump up the timing some with some 104 race fuel in it.

raceman29 · 09-10-2007, 09:19 PM

i had a det of 601 heads off a 305 and put them on my 355 race engine. ran 11:1 ran super unleaded and av fuel 50/50 around 32 degrees advance. dirt cirlce 6500 rpm. hottest would run was 230 degrees no problems. combustion chambers were 55cc and flat top 2 brow pistons.

09-09-2007, 10:24 PM	#1
Spray-Bomb Texas Big Wig Join Date: Jan 2007 Location: Mineola, Texas Posts: 5,620	Who's running the most compression... On the street ??? If you have a sound / vid clip that'd be great __________________ Just not low enough... ----------------------------- Sinister Killer

09-09-2007, 10:44 PM	#2
67_C-30 I have a radical idea! Join Date: Jan 2005 Location: Sweet Home Alabama! Posts: 6,513	Re: Who's running the most compression... I'm running 22 : 1 in my '67 C-30... But it's a Diesel! __________________ '67 C-30 Dually Pickup 6.2 Turbo Diesel, NP435 ‘72 C-10 SWB , 350 4bbl, TH350 '69 C-10 SWB , 250 L6, 3 OTT '69 GMC C3500, dump truck, 351 V6, NP435 '84 M1009 CUCV Military Blazer 67 C-30 Turbodiesel build thread http://67-72chevytrucks.com/vboard/s...d.php?t=254096 My trucks http://s226.photobucket.com/albums/d...ediafilter=all Member of the 1-Ton Club!

09-09-2007, 10:52 PM	#3
BCOWANWHEELS Registered User Join Date: Nov 2006 Location: KINGSPORT,TN. Posts: 3,035	Re: Who's running the most compression... 10.1 with iron heads and dist. 36deg. full advance you,ll have to run at least 93 oct. for sure as thats what my 383 is. it will valve rattle like crazy if you dont. 11.1 with alumin heads same thing. 9.1 is all around best for street i think. __________________ I BELIEVE IN JOHN 3:16

09-09-2007, 10:53 PM	#4
67_C-30 I have a radical idea! Join Date: Jan 2005 Location: Sweet Home Alabama! Posts: 6,513	Re: Who's running the most compression... I've run as high as 10- 10.3 : 1 on a cast-iron headed SBC with a carburetor, but that's pushing it. I'm running a 12.2 : 1 CR 383 in my '82 Z28, but obviously, I'm running race fuel. __________________ '67 C-30 Dually Pickup 6.2 Turbo Diesel, NP435 ‘72 C-10 SWB , 350 4bbl, TH350 '69 C-10 SWB , 250 L6, 3 OTT '69 GMC C3500, dump truck, 351 V6, NP435 '84 M1009 CUCV Military Blazer 67 C-30 Turbodiesel build thread http://67-72chevytrucks.com/vboard/s...d.php?t=254096 My trucks http://s226.photobucket.com/albums/d...ediafilter=all Member of the 1-Ton Club!

09-09-2007, 10:55 PM	#5
Walts_restoration Real Projects never die Join Date: Jan 2007 Location: Lawrence, kansas Posts: 1,508	Re: Who's running the most compression... 8.5 to 1 on the maro, oh wait highest? i lose haha __________________ Ill put it this way, ive got a few lawn ornaments My name tag says Ryan KansasTwister On other forums

09-09-2007, 10:56 PM	#6
DieselEater Registered User Join Date: Dec 2006 Location: Trinidad, Colorado Posts: 642	Re: Who's running the most compression... My current pulling engine is going into my 68' SWB project.....11:1 on 91 octane w/out problems........but I'm at 7000 feet elevation 840 rectangles, 800 Q-Jet, RPM air gap. __________________ 69' 3/4 4X4 470ci BBC 700 HP.... D60/14bolt 205/465 http://profile.myspace.com/index.cfm...ndid=127691959

09-09-2007, 11:07 PM	#7
Spray-Bomb Texas Big Wig Join Date: Jan 2007 Location: Mineola, Texas Posts: 5,620	Re: Who's running the most compression... Cool, anybody run'n propane (LP) ??? __________________ Just not low enough... ----------------------------- Sinister Killer

09-09-2007, 11:21 PM	#8
yenko427 Registered User Join Date: Jun 2007 Location: Sweeny,Texas Posts: 96	Re: Who's running the most compression... Hey everyone I'm new to performace stuff. How do you measure comp ratio I have a comp. gauge that I got from a friend.

09-09-2007, 11:30 PM	#9
DieselEater Registered User Join Date: Dec 2006 Location: Trinidad, Colorado Posts: 642	Re: Who's running the most compression... Find your chamber size of your heads with your casting number......Go to Mor-Tec.......Then you must know what size/type pistion you're running. example.....840 BBC iron heads have a 107cc combustion chamber + my L2349F TRW pistons spec sheet says that with 106.9 chambers I'll be around 11:1. If you don't know what piston you have, but the engine is stock, you can get an Idea of what piston was used from some GURU types around the net. __________________ 69' 3/4 4X4 470ci BBC 700 HP.... D60/14bolt 205/465 http://profile.myspace.com/index.cfm...ndid=127691959

09-10-2007, 04:59 AM	#11
bb1979 Registered User Join Date: Apr 2007 Location: NSW, Australia Posts: 205	Re: Who's running the most compression... I'm running propane I think my motor has something like 10:1 compression, and it runs great I've been told that 13:1 is acceptable with propane without any issues __________________ 1979 C20 pickup 454 big block turbo 400, 4.56 gears

09-10-2007, 06:04 AM	#12
special-K Special Order Join Date: Nov 2004 Location: Mt Airy, MD Posts: 85,852	Re: Who's running the most compression... 18:1 in my 6.5TD.They actually can be made to run better by lowering from 22:1,sounds silly,right? I`m picking up my fresh 327 today.It will be about 9.5 to 9.7:1 w/iron heads.I may get away with regular.It will be awhile before it sees service to find out. __________________ "BUILDING A BETTER WAY TO SERVE THE USA"......67/72......"The New Breed" GMC '67 C1500 Wideside Super Custom SWB: 327/M22/3.42 posi.........."The '67" (project) GMC '72 K2500 Wideside Sierra Custom Camper: 350/TH350/4.10 Power-Lok..."The '72" (rolling) Tim "Don't call me a redneck. I'm a rough cut country gentleman" R.I.P. ~ East Side Low Life ~ El Jay ~ 72BLUZ ~ Fasteddie69 ~ Ron586 ~ 67ChevyRedneck ~ Grumpy Old Man ~

09-10-2007, 06:13 AM	#13
bad6772 Official Site Guitar Shredder Join Date: May 2006 Location: Oz Posts: 3,955	Re: Who's running the most compression... 9.5 but im going to a vortec S trim over the winter, my lower end is basically stock ZZ3 but i have had a ton of head work,( port polish port matched to my intake three angle vavle job dual springs, 2,02 1.60 valves and ported and ploshed my intake lil bigger cam (roller) , and of course my erson (extremly loud ) gear drive ,< i think it steals ponies though.... lol but it sounds awsome.........oh i lose

09-10-2007, 09:54 AM	#15
djracer Registered User Join Date: Feb 2001 Location: Wetumpka, Al, U.S. Posts: 8,891	Re: Who's running the most compression... I have 14 to 1 pistons in my junk but I run race gas! I will run as low as 112octane without the spray but only 116 to 118 when its on the bottle! __________________ Kevin Special Thanks to All who have helped on the TRUCK! My Pass Time Show http://s129.photobucket.com/albums/p...Chapter1-0.mp4 So Far my best Times are: Motor only: 6.44 1/8 @ 104.13 10.39 1/4 @ 125.83 Nitrous Times: 5.785 1/8 @ 118.65 with a 1.336 60ft 9.168 1/4 @ 142.58 with a 250 shot dead out of the hole!

09-10-2007, 10:04 AM	#16
crazy longhorn Fabricate till you "puke" Join Date: Jun 2002 Location: Ill Posts: 9,402	Re: Who's running the most compression... I run 9.8 on my alum headed 383, with 34 degrees of mechanical advance ,all in @ 2700 & 12 additional degrees in the advance can. Its fine on 91 octain fuel, but will ping a trace on 89 pulling a steep hill. L __________________ 69 longhorn,4" chop,3/5 drop, 1/2 ton suspension/disc brakes,1 1/2" body drop,steel tilt clip, 5.3/Edelbrock rpm intake/600 carb, Hooker streetrod shorties,2 1/2" exhaust/ H pipe/50's Flows , 6 spd Richmond trans,12 bolt/ 3.40 gears....

09-10-2007, 02:24 PM	#17
jkade Senior Member Join Date: Nov 2005 Location: AL Posts: 2,519	Re: Who's running the most compression... I will be running about 11.5:1 on my iron ls1.



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09-10-2007, 03:53 PM	#18
snj8198 Registered User Join Date: Feb 2007 Location: Star Valley, WY Posts: 2,038	Re: Who's running the most compression... 8.9 cr in my MKIV block. a bit low for aluminum heads but im building a decent amount of cylinder pressure to make the best of my lower duration cam and flattop pistons. __________________ Steve 1971 GMC Longbox. Full Roller Stroker 489 w/ FiTech EFI, Chris Straub Cam/NV4500/205/D60/14B w. Grizzly Locker and 4.11's. 2" Lift on 33's

09-10-2007, 04:22 PM	#20
djracer Registered User Join Date: Feb 2001 Location: Wetumpka, Al, U.S. Posts: 8,891	Re: Who's running the most compression... my buddy had a 13 to 1 440 in a 70 duster but we had to mix av gas and super! It was one fast car for the street! __________________ Kevin Special Thanks to All who have helped on the TRUCK! My Pass Time Show http://s129.photobucket.com/albums/p...Chapter1-0.mp4 So Far my best Times are: Motor only: 6.44 1/8 @ 104.13 10.39 1/4 @ 125.83 Nitrous Times: 5.785 1/8 @ 118.65 with a 1.336 60ft 9.168 1/4 @ 142.58 with a 250 shot dead out of the hole!

09-10-2007, 06:10 PM	#21
mark's68 Registered User Join Date: Aug 2007 Location: greenville,ms. Posts: 47	Re: Who's running the most compression... I've got a 388 with 10.6-10.7, sportsman heads but it lives on 100 octane low lead avgas. It realy likes it.

09-10-2007, 07:01 PM	#22
kelsfine69 18 Till I Die Join Date: Mar 2005 Location: Alberta, Canada Posts: 1,522	Re: Who's running the most compression... 454 BBC LS7 12.25:1 crate engine with port and polished heads/matching intake and a 850 Holley. Premium and avegas 60/40 mix or premium and octane boost when the drum runs dry. Kind of a crappy clip http://www.youtube.com/watch?v=5ru1cCe62JQ __________________ 2011 GMC Acadia 1969 GMC BBC LS7 2007 GMC Crew Duramax 1987 Camaro Iroc 350 Tuned Port Injection 42000Km 1987 Chevrolet Silverado 350 TBI 1987 Chevrolet Silverado 350 TBI(yes 2) Take me drunk, I'm too home...

09-10-2007, 08:25 PM	#24
bryanw1968 Senior Member Join Date: Jul 2006 Location: Leander, Texas Posts: 850	Re: Who's running the most compression... 10:1, no problems on pump gas at 12 degrees initial. I can bump up the timing some with some 104 race fuel in it.

09-10-2007, 09:19 PM	#25
raceman29 Registered User Join Date: Jul 2007 Location: new mexico Posts: 10	Re: Who's running the most compression... i had a det of 601 heads off a 305 and put them on my 355 race engine. ran 11:1 ran super unleaded and av fuel 50/50 around 32 degrees advance. dirt cirlce 6500 rpm. hottest would run was 230 degrees no problems. combustion chambers were 55cc and flat top 2 brow pistons.

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