11 to 1 compression
Thread Starter
Safety Car
Joined: May 2005
Posts: 4,176
Likes: 7
From: Jennings LA
11 to 1 compression
anyone running compression of 10.9 or 11 to 1 on pump gas. thinking of getting flat tops in my new 383 stroker, compression will be 10.9 to 1. we have 93 octane available in our area and several guys are running 11.3 to 1 without problems. I would like to have the higher compression for the power, it is not a daily driver.
Le Mans Master
Joined: Oct 2002
Posts: 5,714
Likes: 6
From: Silver City NM
St. Jude Donor '05-'07
If you need a boost in octane you can get this stuff. One of the few that is supposed to actually work.
http://www.maxlead2000.com/
http://www.maxlead2000.com/
Racer
Joined: Dec 2001
Posts: 328
Likes: 0
From: Dallas County Texas
You're right on the edge, with perfect timing, no lean
conditions, no weird spark riser parts in the combustion chamber, etc., with 11.25:1 with aluminum heads. Someone else was posting some very interesting stuff on quench volume and such, especially in that case relative to head gasket thickness/volume and head cc's.
With iron, drop 10 points - it localizes heat more than aluminum and so causes hot spots to start ignition events.
People generally feel safe with real world engines that see a lot of miles (oil fumes also cause increase in knocking - from worn rings and valve guides and such) with 10.75:1 on aluminum and 9.8 with iron, but more is doable.
With iron, drop 10 points - it localizes heat more than aluminum and so causes hot spots to start ignition events.
People generally feel safe with real world engines that see a lot of miles (oil fumes also cause increase in knocking - from worn rings and valve guides and such) with 10.75:1 on aluminum and 9.8 with iron, but more is doable.
Race Director
Joined: Dec 1999
Posts: 11,096
Likes: 990
From: Sierra Foothills CA
Originally Posted by DJ Dep
If you need a boost in octane you can get this stuff. One of the few that is supposed to actually work.
http://www.maxlead2000.com/
http://www.maxlead2000.com/
Racer
Joined: Dec 2001
Posts: 328
Likes: 0
From: Dallas County Texas
Wow DJ - that's the STUFF!!!
That's 200 gal of $2.50/gal 93 octane JUNK at $500 turned into 201 gal of 100 octane (REAL GAS!!!) for $530!!! 117 octane race gas is $7-8 per gallon, which you can water slightly past averaging with 93 (25% should get about 100) - so that would be 250 gal for $900!!!
$2.64/gal vs $3.60? Wow. ....and you wouldn't have to store large amounts of volatile fuels or have your own parking spot at your favorite real parts house.
While it sure isn't low-tox, either, it's nowhere near as plutonium like deadly as aniline, either. (Aniline is one of the few non-organometallic cheap-enough things that affect octane in a concentrated way, but it's stunningly poisonous.)
I wouldn't mind if somebody wouldn't package some concentrated versions of the manganese-based stuff (I think the commercial term is MMC? MMT? whatever....it's too dilute in the 104 Octane type products.) It's effective and doesn't trash emmissions stuff, but more expensive and for some reason, not sold in concentrated form.
------------
I notice their ad copy could use some work....ALL gas was leaded and "ethyl" did not refer to it - that referred to the term used earlier than "gasahol", meaning it contained some ethanol (ethyl alcohol) - for octane reasons at lower cost, not oxygenated fuel reasons.
$2.64/gal vs $3.60? Wow. ....and you wouldn't have to store large amounts of volatile fuels or have your own parking spot at your favorite real parts house.
While it sure isn't low-tox, either, it's nowhere near as plutonium like deadly as aniline, either. (Aniline is one of the few non-organometallic cheap-enough things that affect octane in a concentrated way, but it's stunningly poisonous.)
I wouldn't mind if somebody wouldn't package some concentrated versions of the manganese-based stuff (I think the commercial term is MMC? MMT? whatever....it's too dilute in the 104 Octane type products.) It's effective and doesn't trash emmissions stuff, but more expensive and for some reason, not sold in concentrated form.
------------
I notice their ad copy could use some work....ALL gas was leaded and "ethyl" did not refer to it - that referred to the term used earlier than "gasahol", meaning it contained some ethanol (ethyl alcohol) - for octane reasons at lower cost, not oxygenated fuel reasons.
Last edited by WayneLBurnham; Jul 19, 2005 at 01:18 AM.
Race Director
Joined: Jan 2003
Posts: 15,176
Likes: 88
From: State of Confusion
I'm running 10.4 with iron heads, on SUNOCO-94, and have no problem.
A buddy put a 10.8:1 stock-car motor on the dyno once before it was ever put in the car, and fired it on pump-gas, just to ensure no leaks, oil pressure was OK, etc.:
just for giggles, they made a 'full-pull', and recorded the numbers.....
The next morning, on CAM2, it made the same power!
I'd be scared to run that CR, but just relaying what he found.
A buddy put a 10.8:1 stock-car motor on the dyno once before it was ever put in the car, and fired it on pump-gas, just to ensure no leaks, oil pressure was OK, etc.:
just for giggles, they made a 'full-pull', and recorded the numbers.....
The next morning, on CAM2, it made the same power!
I'd be scared to run that CR, but just relaying what he found.
Burning Brakes
Joined: Jun 2005
Posts: 1,131
Likes: 106
From: laingsburg MI
2020 C3 of the Year Finalist - Modified
I run 11.2:1 with alum. heads on the street. mine will run fine on 94 sunoco. But, the motor must be built correctly to do this. (piston design, combuston chamber design, appropiate cam, gears, converter, cooling system etc.
Pro
Joined: Oct 2002
Posts: 708
Likes: 0
From: somewhere south of normal
I just finished putting my 383 short block together this week, with all forged parts. I have flat pistons with 5cc valve relief. If I use aluminum heads that have 72cc chambers my cr will end up around 10.9:1. This works for me really well on the street using 93 octane fuel.
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Le Mans Master
Joined: Apr 2000
Posts: 7,562
Likes: 9
From: B'Ville NY
Cruise-In III Veteran
St. Jude Donor '05
Im running 11:1 with 93 oct and no problems with detonation, but if I did it over, I would probably be closer to 10:1 . Why worry about detonation for a mere 10-30 more hp on a street car? If this were a race only car we were talking about, then I would say the extra HP may be worth it from the higher compression. My2C's
Le Mans Master
Joined: Oct 2002
Posts: 5,714
Likes: 6
From: Silver City NM
St. Jude Donor '05-'07
Originally Posted by SmokedTires
Why worry about detonation for a mere 10-30 more hp on a street car?
"I would like to have the higher compression for the power, it is not a daily driver."
So it's NOT a "street" car. Racing gas is not readily available in some parts of the country, so additives like Maxlead2000 become a good alternative. A "mere 10-30 hp"!!!!! People are spending $300 for roller rockers to squeeze out 5-7 horsepower. 10-30 sure ain't "mere" to most folks.
You must be a VERY young guy Wayne. "Ethyl" was the term used before "Premium" came in vogue for "high test" (also another term for Premium) gasoline. It was used in the late 50s through the 60s.
Dep
Burning Brakes
Joined: Apr 2000
Posts: 1,012
Likes: 0
From: Minnesota
Originally Posted by DJ Dep
The original poster said:
You must be a VERY young guy Wayne. "Ethyl" was the term used before "Premium" came in vogue for "high test" (also another term for Premium) gasoline. It was used in the late 50s through the 60s.
Dep
You must be a VERY young guy Wayne. "Ethyl" was the term used before "Premium" came in vogue for "high test" (also another term for Premium) gasoline. It was used in the late 50s through the 60s.
Dep
Was thinking the very same thing
For some of us pumping "Ethyl", checking the oil, and washing the windows was our high school summer job.SEMPER FI--1970 Dave
Le Mans Master
Joined: Apr 2000
Posts: 7,562
Likes: 9
From: B'Ville NY
Cruise-In III Veteran
St. Jude Donor '05
Originally Posted by DJ Dep
The original poster said:
"I would like to have the higher compression for the power, it is not a daily driver."
So it's NOT a "street" car. Racing gas is not readily available in some parts of the country, so additives like Maxlead2000 become a good alternative. A "mere 10-30 hp"!!!!! People are spending $300 for roller rockers to squeeze out 5-7 horsepower. 10-30 sure ain't "mere" to most folks.
"I would like to have the higher compression for the power, it is not a daily driver."
So it's NOT a "street" car. Racing gas is not readily available in some parts of the country, so additives like Maxlead2000 become a good alternative. A "mere 10-30 hp"!!!!! People are spending $300 for roller rockers to squeeze out 5-7 horsepower. 10-30 sure ain't "mere" to most folks.
Melting Slicks
Joined: Jan 2004
Posts: 2,672
Likes: 1
From: New Cumberland PA
Originally Posted by DJ Dep
A "mere 10-30 hp"!!!!! People are spending $300 for roller rockers to squeeze out 5-7 horsepower. 10-30 sure ain't "mere" to most folks.
Dep
Dep
Le Mans Master
Joined: Oct 2002
Posts: 5,714
Likes: 6
From: Silver City NM
St. Jude Donor '05-'07
Originally Posted by SmokedTires
But that $300 for the roller rockers may not be a bad deal if it gets you that added power you're looking for. Yes the higher compression will give you more power, but the added cost of fuel may add up to be pretty expensive over time, best example is nitrous; it doesn't cost a whole lot for the added power you get from it, but if you use it from every stop, the cost to keep refilling that bottle will add up quickly
mandm1200: Compare the 350/300 horse 1969 engine with the 350/350 horse engine. Not a lot of difference but more cam/compression and FIFTY more horsepower. Stop reading those stoopid advertiser-sponsored articles!!!
Dep
Melting Slicks
Joined: Jan 2004
Posts: 2,672
Likes: 1
From: New Cumberland PA
Originally Posted by DJ Dep
mandm1200: Compare the 350/300 horse 1969 engine with the 350/350 horse engine. Not a lot of difference but more cam/compression and FIFTY more horsepower. Stop reading those stoopid advertiser-sponsored articles!!!
Dep
Dep
Racer
Joined: Jan 2005
Posts: 492
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From: Birmingham AL
As I was on a road trip vacation I passed through many a state that you could only get 91 octane pump gas and in the upper mid-west in many places it was 90 octane because of the addition of ehtanol which drops the octane rating.
With gas prices going in the direction they are, the fuel mixture of pump gas we are used to today is going to change just because of simple economics as bio fuels become cheaper and hence added to our fuels. I've heard the reasoning before that "it's not a driver", but consider that more carefully. Are you saying that I'm primarily going to race it and street it some time or is it 100% race and NO street. If there is any street use planned I can't see the logic in going the route of depending on 93 or higher pump gas. My prediction is that in under 2 years you will not be able to find 93 octane outside of a few boutique gas stations that will exact a hefty price for it.
Trust me, I like the idea of great strip numbers for my setup. But I'm not willing to sacrifice the option of a weekend road trip in the Vette to put down a faster strip number. I won't even approach the topic of whether a C3 is the best choice of a strip machine anyway....that would open too much of a can of worms.
With gas prices going in the direction they are, the fuel mixture of pump gas we are used to today is going to change just because of simple economics as bio fuels become cheaper and hence added to our fuels. I've heard the reasoning before that "it's not a driver", but consider that more carefully. Are you saying that I'm primarily going to race it and street it some time or is it 100% race and NO street. If there is any street use planned I can't see the logic in going the route of depending on 93 or higher pump gas. My prediction is that in under 2 years you will not be able to find 93 octane outside of a few boutique gas stations that will exact a hefty price for it.
Trust me, I like the idea of great strip numbers for my setup. But I'm not willing to sacrifice the option of a weekend road trip in the Vette to put down a faster strip number. I won't even approach the topic of whether a C3 is the best choice of a strip machine anyway....that would open too much of a can of worms.
Thread Starter
Safety Car
Joined: May 2005
Posts: 4,176
Likes: 7
From: Jennings LA
cam
the cam is a 292/292 500 lift camshaft. I am going to order a 383 shortblock and you have your choice of pistons. dished or flat tops,
my heads are 64cc wich will give it 10.9 to 1 with flat tops.
here is the short block
http://cgi.ebay.com/ebaymotors/ws/eB...RK%3AMEWA%3AIT
decisions, decisions
my heads are 64cc wich will give it 10.9 to 1 with flat tops.
here is the short block
http://cgi.ebay.com/ebaymotors/ws/eB...RK%3AMEWA%3AIT
decisions, decisions
Le Mans Master
Joined: Oct 2002
Posts: 5,714
Likes: 6
From: Silver City NM
St. Jude Donor '05-'07
Originally Posted by gator79
the cam is a 292/292 500 lift camshaft. I am going to order a 383 shortblock and you have your choice of pistons. dished or flat tops,
my heads are 64cc wich will give it 10.9 to 1 with flat tops.
here is the short block
http://cgi.ebay.com/ebaymotors/ws/eB...RK%3AMEWA%3AIT
decisions, decisions
my heads are 64cc wich will give it 10.9 to 1 with flat tops.
here is the short block
http://cgi.ebay.com/ebaymotors/ws/eB...RK%3AMEWA%3AIT
decisions, decisions
"I have never had a customer come back and say " dang I wish I had gone with a 350. That 383 is just way to much!' These are AWSOME torque. If you are building a truck and putting on mudder tires this is a MUST DO!!"
I have a new name for the 383!!! The MUDDER ENGINE!!!
Dep
Le Mans Master
Joined: Oct 2002
Posts: 5,714
Likes: 6
From: Silver City NM
St. Jude Donor '05-'07
So I found this article on compression ratios and how they affect power. And, of course, the person referencing this article LEFT off a key point:
"The rule of thumb for the compression ratios run in most street engines is: for every point change in the compression ratio your power output will change by 2%. Using this rule of thumb on an engine that produces 400 hp, every 1 point change in compression ratio will result in approx. a 8hp change in output.
Note the bold section.
http://www.bnol.com/troberts/oldsfaq/ofcrc.htm
Dep
"The rule of thumb for the compression ratios run in most street engines is: for every point change in the compression ratio your power output will change by 2%. Using this rule of thumb on an engine that produces 400 hp, every 1 point change in compression ratio will result in approx. a 8hp change in output.
Note the bold section.
http://www.bnol.com/troberts/oldsfaq/ofcrc.htm
Dep
Melting Slicks
Joined: Jan 2004
Posts: 2,672
Likes: 1
From: New Cumberland PA
Originally Posted by DJ Dep
So I found this article on compression ratios and how they affect power. And, of course, the person referencing this article LEFT off a key point:
"The rule of thumb for the compression ratios run in most street engines is: for every point change in the compression ratio your power output will change by 2%. Using this rule of thumb on an engine that produces 400 hp, every 1 point change in compression ratio will result in approx. a 8hp change in output.
Note the bold section.
http://www.bnol.com/troberts/oldsfaq/ofcrc.htm
Dep
"The rule of thumb for the compression ratios run in most street engines is: for every point change in the compression ratio your power output will change by 2%. Using this rule of thumb on an engine that produces 400 hp, every 1 point change in compression ratio will result in approx. a 8hp change in output.
Note the bold section.
http://www.bnol.com/troberts/oldsfaq/ofcrc.htm
Dep
The hp gain by increasing/decreasing compression is not something I am capable of determining. For rough estimates, there are charts that will give an approximation.