Matronics Email Lists Forum Index Matronics Email Lists
Web Forum Interface to the Matronics Email Lists
 
 Get Email Distribution Too!Get Email Distribution Too!    FAQFAQ   SearchSearch   MemberlistMemberlist   UsergroupsUsergroups   RegisterRegister 
 ProfileProfile   Log in to check your private messagesLog in to check your private messages   Log inLog in 

Auto Engine - compression ratio vs. octane

 
Post new topic   Reply to topic    Matronics Email Lists Forum Index -> Engines-List
View previous topic :: View next topic  
Author Message
bk_maynard(at)yahoo.com
Guest





PostPosted: Wed May 13, 2009 7:24 am    Post subject: Auto Engine - compression ratio vs. octane Reply with quote

  Would someone have a rough idea of what compression ratio I could run on my chevy auto<?xml:namespace prefix = o ns = "urn:schemas-microsoft-com:office:office" />

Conversion if I run 100LL instead of regular unleaded?

Specs for my 3.4 V6 are 9.0:1 for regular.



Thanks, Brad

[quote][b]


- The Matronics Engines-List Email Forum -
 

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

http://www.matronics.com/Navigator?Engines-List
Back to top
s_korney(at)hotmail.com
Guest





PostPosted: Wed May 13, 2009 8:18 am    Post subject: Auto Engine - compression ratio vs. octane Reply with quote

At least 10:1 with 100LL

Best... Steve

Date: Wed C 13 May 2009 08:17:42 -0700
From: bk_maynard(at)yahoo.com
Subject: Auto Engine - compression ratio vs. octane
To: engines-list(at)matronics.com
            Would someone have a rough idea of what compression ratio I could run on my chevy auto
Conversion if I run 100LL  instead of regular unleaded?
Specs for my 3.4 V6 are 9.0:1 for regular.
 
Thanks C   Brad
Quote:
http://www.matronics.com/N========================http://www.matronics.com/contrib===============
HotmailŪ has a new way to see what's up with your friends. Check it out. [quote][b]


- The Matronics Engines-List Email Forum -
 

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

http://www.matronics.com/Navigator?Engines-List
Back to top
jrccea(at)bellsouth.net
Guest





PostPosted: Wed May 13, 2009 8:34 am    Post subject: Auto Engine - compression ratio vs. octane Reply with quote

Theoretical limit is 11.2:1 with premium autofuel. I don't think I'd go that high. I do know from experience that 9.5:1 is OK on premium with 28 degrees advance on an O-200, but I have trouble on shutdown with regular.
JimC
[quote] ---


- The Matronics Engines-List Email Forum -
 

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

http://www.matronics.com/Navigator?Engines-List
Back to top
MONTY(at)bpaengines.com
Guest





PostPosted: Wed May 13, 2009 8:53 am    Post subject: Auto Engine - compression ratio vs. octane Reply with quote

I don't think I would use 100 LL in an auto engine for a couple of reasons.
1. Avgas burns at a slower rate
2. One of the products of combustion with leaded fuel is lead bromide, which is somewhat corrosive and abrasive.
Aircraft lubricating oil has an additive package to deal with lead bromide whereas motor oil does not.

an interesting side note. I rebult a Ford Flathead for a 46 Coupe I have and the engine is considerably pumped up. I ran it on the dyno here in the BPE shop and ran it on 100 LL. mixture was not quite right and during the process of straightening out power valves, jetting, etc. I also tested with 91 Oct mogas. The CR on this engine is 9.25:1 which is quite a bit for a flathead. The engine made slightly more power on mogas with the timing not changed. FYI

Monty Barrett
Barrett Precision Engines
[quote]
--


- The Matronics Engines-List Email Forum -
 

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

http://www.matronics.com/Navigator?Engines-List
Back to top
GrummanDude



Joined: 15 Jan 2006
Posts: 926
Location: Auburn, CA

PostPosted: Wed May 13, 2009 8:59 am    Post subject: Auto Engine - compression ratio vs. octane Reply with quote

If compression were the only consideration, it would be so simple. It
isn't that simple.

Cam design plays more of a roll in detonation limits than compression
alone. You can easily make 8.5:1 compression produce 145 pounds
cranking pressure if you know what you're doing. Likewise, 11:1 can
produce less than 140 pounds with the right lobe separation angle.

I recommend measuring the cranking pressure. 145 pounds cranking
pressure is easy with 100LL. 155 would be a little on the edge.
Anything in the 130 range (125 to 135) is a piece of cake.
--


- The Matronics Engines-List Email Forum -
 

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

http://www.matronics.com/Navigator?Engines-List

_________________
Gary
AuCountry Aviation
Home of Team Grumman
Back to top
View user's profile Send private message Send e-mail Visit poster's website
frank.hinde(at)hp.com
Guest





PostPosted: Wed May 13, 2009 9:13 am    Post subject: Auto Engine - compression ratio vs. octane Reply with quote

Interesting..And seems to be evidence that mogas is better for an aircraft engine too, assuming its not a turbo'ed 540.

I know my IO 360 loves mogas and runs well even with 10% Ethanol blends...Although I have not flown it above 15000ft so cannot attest to vphase seperation, water fallout predictions.

Frank

From: owner-engines-list-server(at)matronics.com [mailto:owner-engines-list-server(at)matronics.com] On Behalf Of Monty Barrett Sr
Sent: Wednesday, May 13, 2009 8:41 AM
To: engines-list(at)matronics.com
Subject: RE: Auto Engine - compression ratio vs. octane

I don't think I would use 100 LL in an auto engine for a couple of reasons.
1. Avgas burns at a slower rate
2. One of the products of combustion with leaded fuel is lead bromide, which is somewhat corrosive and abrasive.
Aircraft lubricating oil has an additive package to deal with lead bromide whereas motor oil does not.

an interesting side note. I rebult a Ford Flathead for a 46 Coupe I have and the engine is considerably pumped up. I ran it on the dyno here in the BPE shop and ran it on 100 LL. mixture was not quite right and during the process of straightening out power valves, jetting, etc. I also tested with 91 Oct mogas. The CR on this engine is 9.25:1 which is quite a bit for a flathead. The engine made slightly more power on mogas with the timing not changed. FYI

Monty Barrett
Barrett Precision Engines
[quote]

[b]


- The Matronics Engines-List Email Forum -
 

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

http://www.matronics.com/Navigator?Engines-List
Back to top
larry(at)macsmachine.com
Guest





PostPosted: Wed May 13, 2009 9:35 am    Post subject: Auto Engine - compression ratio vs. octane Reply with quote

Hi Frank,
I've used 87-octane with 10% ethanol for the last two years and only on
one occasion did "phase separation" occur. The aircraft had set for 4 months
with less than a gallon in the tank after the pre winter annual
inspection. The small amount of fuel did look nearly opaque and gray. I
drained the remaining
and added new fuel when flying weather returned. No telling how long the
gas had set in the retailers tank before I got it.

Larry McFarland 601HDS at www.macsmachine.com

Hinde, Frank George (Corvallis) wrote:
Quote:
Interesting..And seems to be evidence that mogas is better for an
aircraft engine too, assuming its not a turbo'ed 540.

I know my IO 360 loves mogas and runs well even with 10% Ethanol
blends...Although I have not flown it above 15000ft so cannot attest
to vphase seperation, water fallout predictions.

Frank

------------------------------------------------------------------------
*From:* owner-engines-list-server(at)matronics.com
[mailto:owner-engines-list-server(at)matronics.com] *On Behalf Of *Monty
Barrett Sr
*Sent:* Wednesday, May 13, 2009 8:41 AM
*To:* engines-list(at)matronics.com
*Subject:* RE: Auto Engine - compression ratio vs. octane

I don't think I would use 100 LL in an auto engine for a couple of
reasons.
1. Avgas burns at a slower rate
2. One of the products of combustion with leaded fuel is lead
bromide, which is somewhat corrosive and abrasive.
Aircraft lubricating oil has an additive package to deal with lead
bromide whereas motor oil does not.

an interesting side note. I rebult a Ford Flathead for a 46 Coupe I
have and the engine is considerably pumped up. I ran it on the dyno
here in the BPE shop and ran it on 100 LL. mixture was not quite
right and during the process of straightening out power valves,
jetting, etc. I also tested with 91 Oct mogas. The CR on this engine
is 9.25:1 which is quite a bit for a flathead. The engine made
slightly more power on mogas with the timing not changed. FYI

Monty Barrett
Barrett Precision Engines



*
*


- The Matronics Engines-List Email Forum -
 

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

http://www.matronics.com/Navigator?Engines-List
Back to top
frank.hinde(at)hp.com
Guest





PostPosted: Wed May 13, 2009 11:14 am    Post subject: Auto Engine - compression ratio vs. octane Reply with quote

Good input Larry..Sounds like the remaining fuel absorbed the water from condensation.

Fit for the lawnmower only after 4 months is a certainty now..Smile

Thanks

Frank



--


- The Matronics Engines-List Email Forum -
 

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

http://www.matronics.com/Navigator?Engines-List
Back to top
Ed Anderson



Joined: 10 Jan 2006
Posts: 475

PostPosted: Wed May 13, 2009 1:53 pm    Post subject: Auto Engine - compression ratio vs. octane Reply with quote

Given that the lower the octane rating, the more energy a specific volume of gasoline has, I am not surprised that with auto fuel you got more power than with 100LL. The higher octane fuel has less energy content and only real purpose is prevent detonation with high compression engines. Many believe that higher octane means more power than lower octane fuels, but only if you are able to run higher compression or forced induction systems (which in effect increase compression ratio).

100LL contains approx 120,000 BTU/Gallon whereas 87 Octane contains approx 125,000 BTU/Gallon or about 4% more energy.

Ed

Ed Anderson
Rv-6A N494BW Rotary Powered
Matthews, NC
eanderson(at)carolina.rr.com
http://www.andersonee.com
http://www.dmack.net/mazda/index.html
http://www.flyrotary.com/
http://members.cox.net/rogersda/rotary/configs.htm#N494BW
http://www.rotaryaviation.com/Rotorhead%20Truth.htm[url=http://www.dmack.net/mazda/index.html][/url]


From: owner-engines-list-server(at)matronics.com [mailto:owner-engines-list-server(at)matronics.com] On Behalf Of Monty Barrett Sr
Sent: Wednesday, May 13, 2009 11:41 AM
To: engines-list(at)matronics.com
Subject: RE: Auto Engine - compression ratio vs. octane


I don't think I would use 100 LL in an auto engine for a couple of reasons.

1. Avgas burns at a slower rate

2. One of the products of combustion with leaded fuel is lead bromide, which is somewhat corrosive and abrasive.

Aircraft lubricating oil has an additive package to deal with lead bromide whereas motor oil does not.



an interesting side note. I rebult a Ford Flathead for a 46 Coupe I have and the engine is considerably pumped up. I ran it on the dyno here in the BPE shop and ran it on 100 LL. mixture was not quite right and during the process of straightening out power valves, jetting, etc. I also tested with 91 Oct mogas. The CR on this engine is 9.25:1 which is quite a bit for a flathead. The engine made slightly more power on mogas with the timing not changed. FYI



Monty Barrett

Barrett Precision Engines
[quote]
--


- The Matronics Engines-List Email Forum -
 

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

http://www.matronics.com/Navigator?Engines-List

_________________
Ed Anderson
Rv-6A N494BW Rotary Powered
Matthews, NC
eanderson@carolina.rr.com
Back to top
View user's profile Send private message
andrew(at)oc384.net
Guest





PostPosted: Wed May 13, 2009 3:12 pm    Post subject: Auto Engine - compression ratio vs. octane Reply with quote

In that case is there an aviation oil including the additive that can be run in auto conversion engines? Or can the additive be bought and added when filling up with 100LL? If you’re flying into places w/out mogas it sounds like you need it.

-Andrew


From: owner-engines-list-server(at)matronics.com [mailto:owner-engines-list-server(at)matronics.com] On Behalf Of Monty Barrett Sr
Sent: Wednesday, May 13, 2009 10:41 AM
To: engines-list(at)matronics.com
Subject: RE: Auto Engine - compression ratio vs. octane



I don't think I would use 100 LL in an auto engine for a couple of reasons.

1. Avgas burns at a slower rate

2. One of the products of combustion with leaded fuel is lead bromide, which is somewhat corrosive and abrasive.

Aircraft lubricating oil has an additive package to deal with lead bromide whereas motor oil does not.



an interesting side note. I rebult a Ford Flathead for a 46 Coupe I have and the engine is considerably pumped up. I ran it on the dyno here in the BPE shop and ran it on 100 LL. mixture was not quite right and during the process of straightening out power valves, jetting, etc. I also tested with 91 Oct mogas. The CR on this engine is 9.25:1 which is quite a bit for a flathead. The engine made slightly more power on mogas with the timing not changed. FYI



Monty Barrett

Barrett Precision Engines
[quote]
--


- The Matronics Engines-List Email Forum -
 

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

http://www.matronics.com/Navigator?Engines-List
Back to top
dean.psiropoulos(at)veriz
Guest





PostPosted: Thu May 14, 2009 7:49 pm    Post subject: Auto Engine - compression ratio vs. octane Reply with quote

The big automotive engines of the 1960s took compression ratios to their
ultimate state of the art with premium leaded auto gas. Ratios from 10.5 to
11.5 to 1 were common place with 100 octane auto fuel. Since the unleaded
mandate, computer analysis has advanced the state of the art in combustion
chamber technology so that 9.5 to 1 ratios are possible on regular unleaded
fuel (87 octane) without detonation. If you use computerized engine control
with knock sensing you could probably go even higher. And with avgas being
the equivalent of somewhere around 110 octane autofuel, the sky should be
the limit (not quite but it would be an interesting exercise to see how high
one could go using a modern auto engine with avgas).

Dean Psiropoulos
RV-6A N197DM
Struggling with erratic idle on 0-360


- The Matronics Engines-List Email Forum -
 

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

http://www.matronics.com/Navigator?Engines-List
Back to top
Float Flyr



Joined: 19 Jul 2006
Posts: 2704
Location: Campbellton, Newfoundland

PostPosted: Fri May 15, 2009 5:58 am    Post subject: Auto Engine - compression ratio vs. octane Reply with quote

I had a friend who regularly ran his 426 Hemi Charger on high octane Avgas
before the advent of 100 LL.

Noel

--


- The Matronics Engines-List Email Forum -
 

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

http://www.matronics.com/Navigator?Engines-List

_________________
Noel Loveys
Kitfox III-A
Aerocet 1100 Floats
Back to top
View user's profile Send private message Send e-mail
Display posts from previous:   
Post new topic   Reply to topic    Matronics Email Lists Forum Index -> Engines-List All times are GMT - 8 Hours
Page 1 of 1

 
Jump to:  
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum
You cannot attach files in this forum
You can download files in this forum


Powered by phpBB © 2001, 2005 phpBB Group