low octane vs high octane in your 1971& older vette

[Domenic T.]

Re: low octane vs high octane in your 1971& older vette

Mark,
modified was a drag race class for cars that went over the limits of bore and mill that was allowed in a stock class. This was in the 60's.


Hey, if you happy with 93 thats good then you don't need to do any thing but use it.

You said it correctly, "just fine"

This is for those that are not happy with "just fine".

DOM

[Michael W.]

Re: low octane vs high octane in your 1971& older vette

Michael, I understand what you and Duke have generally said in this and the other octane thread and your assertions make the most sense to me.

But in Kurt's detonation case, didn't the increased octane address the detonation issue, by being more resistant to detonation, and thus in a roundabout way "made" more power because the engine now operates correctly with combustion, not detonation?

I thought you all had said that you normally don't need the higher octane unless you have detonation, like Kurt did. Did I misunderstand?

Yes that's right, no misunderstanding. Another way of expressing it would be to say that the engine was suffering a loss in power and economy due to the detonation.

This means that if Kurt's engine was not suffering from detonation in the first place, higher octane would be of no benefit.

[Mark K.]

Re: low octane vs high octane in your 1971& older vette

Mark,
modified was a drag race class for cars that went over the limits of bore and mill that was allowed in a stock class. This was in the 60's.


Hey, if you happy with 93 thats good then you don't need to do any thing but use it.

You said it correctly, "just fine"

This is for those that are not happy with "just fine".

DOM

"Just fine" means that it is operating right within the design parameters as specified by GM engineering. "Just fine" does not mean substandard performance - it means factory performance.

If it is your intent to exceed factory Horsepower and Torque specifications, fine, but then there will be trade-offs - cost, economy, driveability, fuel availability (if higher octane is need by a significant increase in compression). However, you no longer have a stock engine. And if you no longer focusing on stock engines, why are you blowing all that smoke about 327/365HP engines losing power on pump gas? I think you need to re-read Duke's posts and realize you need to go back to start with respect to your understanding of the impact of fuels on spark ignition engines.

[Pat M.]

Re: low octane vs high octane in your 1971& older vette

Yes that's right, no misunderstanding. Another way of expressing it would be to say that the engine was suffering a loss in power and economy due to the detonation.

This means that if Kurt's engine was not suffering from detonation in the first place, higher octane would be of no benefit.

Gotcha, thanks.

[Domenic T.]

Re: low octane vs high octane in your 1971& older vette

"Just fine" means that it is operating right within the design parameters as specified by GM engineering. "Just fine" does not mean substandard performance - it means factory performance.

If it is your intent to exceed factory Horsepower and Torque specifications, fine, but then there will be trade-offs - cost, economy, driveability, fuel availability (if higher octane is need by a significant increase in compression). However, you no longer have a stock engine. And if you no longer focusing on stock engines, why are you blowing all that smoke about 327/365HP engines losing power on pump gas? I think you need to re-read Duke's posts and realize you need to go back to start with respect to your understanding of the impact of fuels on spark ignition engines.

Mark,
NO, you are not understanding what I am saying.

The engines I am talking are bone stock.

These ARE STOCK engines that need to run the way they were ENGINERRED to.

Yours is NOT stock or at stock specs when you ALTER from STOCK settings.

There are experts in this field and the reading is free.

you can believe any thing you want but I would caution you on 6500RPM with 93 octane, thats a good way to pop things.

I believe I posted test results that were done by qualified experts using a 200K engine, not a parker pen.

I can say that you never tried av-gas or another good fuel.

the ones that cant get it support the only fuel they can get.

Mark,
Did you EVER try 104 in your engine?
I can answer that for you NO!

Did I ever try it , Yes with great results. It would scare you.

DOM

[Mark K.]

Re: low octane vs high octane in your 1971& older vette

Mark,
NO, you are not understanding what I am saying.

The engines I am talking are bone stock.

These ARE STOCK engines that need to run the way they were ENGINERRED to.

Yours is NOT stock or at stock specs when you ALTER from STOCK settings.

There are experts in this field and the reading is free.

you can believe any thing you want but I would caution you on 6500RPM with 93 octane, thats a good way to pop things.

I believe I posted test results that were done by qualified experts using a 200K engine, not a parker pen.

I can say that you never tried av-gas or another good fuel.

the ones that cant get it support the only fuel they can get.

Mark,
Did you EVER try 104 in your engine?
I can answer that for you NO!

Did I ever try it , Yes with great results. It would scare you.

DOM

Oh please. I raced in both Ralt RT-5s and Swift DB-1s back in the 80s in SCCA road racing events. I know what a good performing car is supposed to feel like. I also had a 64 327/365 that I picked up back in '81. I experimented with av gas, added tetra-ethyl lead, and other high octane boosters. They never did anything to my STOCK engine from a performance perspective. And av gas was a pain in the neck when it came to resetting float levels.

My current L71 is also STOCK (including all settings), is completely original (at 32K miles even with the original paint) and has never had any problems with pump 93 octane - and I've had the car for 16 years. It DOES run the way it was engineered to run.

As far as working with experts in the field, I was a powertrain business planning manager at one of the big three for the majority of my career. I've had close working relationships with plenty of hard core engine engineers in North America, Europe, and Japan. The idea that performance can be improved by increasing octane once detonation is not an issue is ludicrous.

If you actually want to learn something about internal combustion engines, I suggest you start where the professionals start. The following book is a reference guide for all base engine engineers:
http://www.amazon.com/Internal-Combu...7330391&sr=1-1

[Duke W.]

Re: low octane vs high octane in your 1971& older vette

Wow, textbooks are getting EXPENSIVE! A few years ago I was interested in adding Prof. Heywood's book to my library, which includes Obert (who was one of my profs as the U. of Wisconsin Engine Research Center) and Taylor's two volume, 1350 page tome since Heywood's book is now the most common used in upper division and graduate level IC engine courses, so I sent him an email at MIT.

He replied that one was in the works, but there was no firm completion date. It looks like the original 1988 version is still what's available, and my hope is that if a new revision ever comes out it will include a chapter on modern electronic engine management, which is about all that is really new since the 1960s.

I consider Taylor's set (which is still available in soft cover for about $100 for both volumes) to be THE BIBLE for any serious student of IC engines.

A lot of the "hot rod tricks" that most of you have been reading about all your lives were developed under the supervision of Prof. Taylor at the Sloan MIT automotive engine labs and were first used on the big reciprocating aircraft engines developed in the 1930s and 1940s, so most of those ideas have been around for longer than most of us have.

Guys like Smokey Yunick were smart enough to get copies of those old NACA papers that discussed research results, and that's where they learned most of their "tricks", but they never admitted that most of their basic ideas for improving engine performance were not their own. But by applying the basic ideas to automotive engines, they started and sustained a whole new industry.

Duke

[Domenic T.]

Re: low octane vs high octane in your 1971& older vette

Mark,
WOW can I get your autograph or are you going to play the "mine is better than yours game"?
If that's all you have done especially starting as late as the 80's, I don't expect you to understand a thing I was trying to do here.

I may have forgotten more than you know about this.

DOM

[Joe C.]

Re: low octane vs high octane in your 1971& older vette

This discussion will have no resolution!

People always "hear" what they want to hear. Some people have skulls so thick that there's no way to make them see the light.

Mister Tallarita is wrong. Dead wrong and is (possibly unknowingly) editing every post he reads, in his mind's eye, so that it somehow conforms with his own misconceptions. A little bit of knowledge is dangerous.

I don't have the patience to read all of these absurd posts, but before I quit rereading some of these inane posts, I noticed another misguided and hapless fellow, in post # 20 explains how much of a difference that a mix of 100LL and 93 PON made in the performance of his outboard motor. Finally, and almost as an afterthought, he mentions that as a result of the increased octane "..........the knocking went away......." Well.................DUH!

The following is a dyno sheet from a recently built up L76 engine. It is fully optimized with maximum and ideal spark timing, and burns 93 PON pump hi-test. The vitals on the engine:

1965 "870" block using ported (183/69 cc) 461 "big valve" heads, crossovers filled
Speed Pro L2166NF with 0.035" quench, 66 cc chambers
Static compression verified @ 11.2:1 plus/minus 0.1
0.030" overbore for 331 cubic inch displacement
248/254, .018/.018, 106/110/114, .385/.389
ported LT1 intake with 750 dual inlet carb, no choke horn
1966-67 327 Corvette 14" x 3" air cleaner with paper filter element
Hedman 1 5/8" primaries into 3" collectors
Very low restriction mufflers under GM issue sidepipe covers
Base timing 20* BTDC, 18* cent adv all in by 2300RPM, 14* vac advance @ 7.5 in-hg
stock "202" ignition coil, wires and ballast resistor, AC R45 spark plugs
## prior to bypassing ballast, installation of low impedance ignition coil and 8.5mm secondary wires, opening plug gaps to 0.045"....early 9/2011
\\ prior to installation of MSD 6AL ignition module..........late 9/2011

## The installation of the upgraded coil, bypassed ballast resistor, spiral wound wires, and increased spark plug gaps have caused the idle speed to increase by about 100 RPM, have cured a persistent plug fouling issue, and have made a significant SOTP difference in the performance of the engine.

\\ The installation of the MSD module has made another significant improvement in the engine's output, particularly between 6000 - 7500 RPM.

DYNORUNS were done before the noted improvements were made. They were done with the stock, and apparently substandard ignition components.

Pay particular attention to runs 1 and 3, where you can see the difference between running with open headers and thru the mufflers:

[Jim D.]

Re: low octane vs high octane in your 1971& older vette

Mark,
WOW can I get your autograph or are you going to play the "mine is better than yours game"?
If that's all you have done especially starting as late as the 80's, I don't expect you to understand a thing I was trying to do here.

I may have forgotten more than you know about this.

DOM

Gee Dom, I started racing in the mid 60's and I agree 100% with the above posts that show that you're full of *****. There is great, accurate info. in this thread and then there's the garbage you post. Sorry, but there are many here that know more than you could ever imagine putting into your pea sized brain.

[Domenic T.]

Re: low octane vs high octane in your 1971& older vette

jim& joe.

This pea sized brain was chosen to fly Betty & Gerry ford for 8 years.

My thurst for this hobby is what I was trying to share with this forum.

Now maybe you and the others that think I am full of BS can challenge the government agency that chose me and..... knows my blood type, what I did, and every thing else about me.

No,I am not a paper mechanic. I twisted a wrench for chevy and did more engines than you can fit in your garage amongst every thing else that has to do with a car,
I started and did very good in the 50's. Fuel went away in the early 70's while you and some others were spitting pablum.

I chose not to teach aviation mechanics at Long Beach city College which by the way will show the burn rates of low & high octane fuel and the advantages.

But the real Pea brains are to proud to listen becaus they read books that said different.

All my learning was trial & error and came from the school of hard knocks.

As duke said less than 1% races on this forum, he is SOOOOOOOO right.

PEA BRAIN

[Pat M.]

Re: low octane vs high octane in your 1971& older vette

This discussion will have no resolution!

People always "hear" what they want to hear. Some people have skulls so thick that there's no way to make them see the light.

Mister Tallarita is wrong. Dead wrong and is (possibly unknowingly) editing every post he reads, in his mind's eye, so that it somehow conforms with his own misconceptions. A little bit of knowledge is dangerous.

I don't have the patience to read all of these absurd posts, but before I quit rereading some of these inane posts, I noticed another misguided and hapless fellow, in post # 20 explains how much of a difference that a mix of 100LL and 93 PON made in the performance of his outboard motor. Finally, and almost as an afterthought, he mentions that as a result of the increased octane "..........the knocking went away......." Well.................DUH!

The following is a dyno sheet from a recently built up L76 engine. It is fully optimized with maximum and ideal spark timing, and burns 93 PON pump hi-test. The vitals on the engine:

1965 "870" block using ported (183/69 cc) 461 "big valve" heads, crossovers filled
Speed Pro L2166NF with 0.035" quench, 66 cc chambers
Static compression verified @ 11.2:1 plus/minus 0.1
0.030" overbore for 331 cubic inch displacement
248/254, .018/.018, 106/110/114, .385/.389
ported LT1 intake with 750 dual inlet carb, no choke horn
1966-67 327 Corvette 14" x 3" air cleaner with paper filter element
Hedman 1 5/8" primaries into 3" collectors
Very low restriction mufflers under GM issue sidepipe covers
Base timing 20* BTDC, 18* cent adv all in by 2300RPM, 14* vac advance @ 7.5 in-hg
stock "202" ignition coil, wires and ballast resistor, AC R45 spark plugs
## prior to bypassing ballast, installation of low impedance ignition coil and 8.5mm secondary wires, opening plug gaps to 0.045"....early 9/2011
\\ prior to installation of MSD 6AL ignition module..........late 9/2011

## The installation of the upgraded coil, bypassed ballast resistor, spiral wound wires, and increased spark plug gaps have caused the idle speed to increase by about 100 RPM, have cured a persistent plug fouling issue, and have made a significant SOTP difference in the performance of the engine.

\\ The installation of the MSD module has made another significant improvement in the engine's output, particularly between 6000 - 7500 RPM.

DYNORUNS were done before the noted improvements were made. They were done with the stock, and apparently substandard ignition components.

Pay particular attention to runs 1 and 3, where you can see the difference between running with open headers and thru the mufflers:

Gee Dom, I started racing in the mid 60's and I agree 100% with the above posts that show that you're full of *****. There is great, accurate info. in this thread and then there's the garbage you post. Sorry, but there are many here that know more than you could ever imagine putting into your pea sized brain.

[Joe C.]

Re: low octane vs high octane in your 1971& older vette

jim& joe.

This pea sized brain was chosen to fly Betty & Gerry ford for 8 years.

My thurst for this hobby is what I was trying to share with this forum.

Now maybe you and the others that think I am full of BS can challenge the government agency that chose me and..... knows my blood type, what I did, and every thing else about me.

No,I am not a paper mechanic. I twisted a wrench for chevy and did more engines than you can fit in your garage amongst every thing else that has to do with a car,
I started and did very good in the 50's. Fuel went away in the early 70's while you and some others were spitting pablum.

I chose not to teach aviation mechanics at Long Beach city College which by the way will show the burn rates of low & high octane fuel and the advantages.

But the real Pea brains are to proud to listen becaus they read books that said different.

All my learning was trial & error and came from the school of hard knocks.

As duke said less than 1% races on this forum, he is SOOOOOOOO right.

PEA BRAIN

Domenic, I know that you're gonna be sore at me for posting this......................but..................... .....this is why the federal government is in so much trouble.

[Domenic T.]

Re: low octane vs high octane in your 1971& older vette

Joe
sorry but I didn't see what you posted but if we can agree on one thing it's that we ( the gov) are in trouble.

PEA BRAIN

[Clem Z.]

Re: low octane vs high octane in your 1971& older vette

all stock engine carbs are jetted for sea level and above sea level you are running rich which will help keep you out of detonation. the new corvette engines with 11:1 CR run on pump gas because the computer richen the fuel system up at the higher RPM full throttle to prevent detonation. they can do this because all the govt test for emissions and fuel mileage are done at low RPMs. when tuners work on these new corvettes they lean out to top end for more power but you have to be careful with your gasoline. these engines do have "knock" sensor and they will back up timing to prevent damage BUT the timing stays backed up till you refill the tank and then it goes back to normal.