Learning to make fast go fast!

[05stroker]

Have any of y'all seen a chart or diagram that shows the safe limit of Effective Compression Ratio vrs octane, or the max safe ECR for a 3v block?

Everything I find just shows I was insane to try 12:1 C/R.

 

[travelers]

I'm not sure if you can use any of these Billy but does make for some interesting reading.

http://mechanics.stackexchange.com/...hy-does-higher-effective-compression-not-requ

http://www.modularfords.com/threads/69722-Max-safe-PSI-and-Timing-for-93-pump-gas

The idea that higher octane gas = more power is a complete myth that is spread by oil companies looking to sell you a more expensive product. They do it with their advertising and by giving the high octane fuels decieving names like Shell's 'V-Power'.

The reality is, high octane gas has less potential energy than 87 gas because it contains proportionally less gas (energy) and more octane (filler). The sole purpose of octane is to make it harder to ignite the gas, which is required in some high performance engines with their crazy compression ratio's etc because the gas can ignite too early and damage the engine. It is not some highly explosive additive that creates a bigger bang. You will get peak performance out of your bike by using the lowest octane rating you can get away with. If you go too low then your fuel may start to pre-ignite (aka 'ping') which is very hard on your engine because the air/fuel mix ignites while the piston is still on it's way up which can blow a hole through your piston. Honda did a lot of testing on our engines to find out which octane level is lowest we can safely use and this is what you want to run. The only performance advantage of high octane gas is that it saves weight by lightening your pockets.

Actually, the only advantage of premium fuels is that some high octane fuels also contain additional additives to keep your engine cleaner. I don't know which high octane fuels do and which don't and realistically this a very minor issue but this is the only logical reason people can give for using higher octane gas when it's not required by the manufacturer.

To sum it up: Some fast vehicles need high octane fuels but the high octane fuels aren't what makes them fast. High octane fuels are just required to keep these cars from blowing up.

 

[weather man]

I'm not sure if you can use any of these Billy but does make for some interesting reading.

http://mechanics.stackexchange.com/...hy-does-higher-effective-compression-not-requ

http://www.modularfords.com/threads/69722-Max-safe-PSI-and-Timing-for-93-pump-gas

The idea that higher octane gas = more power is a complete myth that is spread by oil companies looking to sell you a more expensive product. They do it with their advertising and by giving the high octane fuels decieving names like Shell's 'V-Power'.

The reality is, high octane gas has less potential energy than 87 gas because it contains proportionally less gas (energy) and more octane (filler). The sole purpose of octane is to make it harder to ignite the gas, which is required in some high performance engines with their crazy compression ratio's etc because the gas can ignite too early and damage the engine. It is not some highly explosive additive that creates a bigger bang. You will get peak performance out of your bike by using the lowest octane rating you can get away with. If you go too low then your fuel may start to pre-ignite (aka 'ping') which is very hard on your engine because the air/fuel mix ignites while the piston is still on it's way up which can blow a hole through your piston. Honda did a lot of testing on our engines to find out which octane level is lowest we can safely use and this is what you want to run. The only performance advantage of high octane gas is that it saves weight by lightening your pockets.

Actually, the only advantage of premium fuels is that some high octane fuels also contain additional additives to keep your engine cleaner. I don't know which high octane fuels do and which don't and realistically this a very minor issue but this is the only logical reason people can give for using higher octane gas when it's not required by the manufacturer.

To sum it up: Some fast vehicles need high octane fuels but the high octane fuels aren't what makes them fast. High octane fuels are just required to keep these cars from blowing up.

A nice post, but has zero applicability to his issue. It really only applies to stock cars. Anyone modding need the higher octane to live.

 

[RocketcarX]

stock vehicle propaganda

Fixed it

 

[Department Of Boost]

A nice post, but has zero applicability to his issue. It really only applies to stock cars. Anyone modding need the higher octane to live.

I think the big question is how much pre-ignition (PI) protection you need. And how you get that. For example you can get race fuel up to what? 116 octane? Is the octane level completely representative of the PI properties? Or are there other ingredients?

Then you look at e85. It doesn't have a ton of octane, but it does have lot of PI properties.

So silly rough math/thinking/made up stuff here:

You have 93 octane pump gas. Let's call that our base "zero". That will give you X protection.

Then you throw 116 octane race fuel at it. That gives you 23 more octanes (which is a huge percentage of "zero"). So X + 23. Is all of the PI protection it provides due simply to octane? Or are there other goodies in there that aren't measured/called out that add to the PI protection?

Now you throw e85 at it. I'm seeing 100-105 octane. But we know that it will give PI protection way beyond that. So is it just the cooling properties that is making this happen? And if so how is that accounted for when figuring actual detonation resistance? What is your X factor with e85?

I have a hard time believing that e85 can't handle some very high cylinder pressures/heat. I know alcohol is not the same as ethanol. But they do have similar properties. And alcohol WORKS!!! Tom Bailey's Drag Week car makes about 4000hp at 55-60lb of boost on alcohol........................with no intercooler!!!!!!! At an absolute minimum you're looking at a 600deg IAT. And 55-60lb of boost!!!! Holy crap!!!!!! Even if e85 is half as good as alcohol, you would think it still has PLENTY of headroom.

IDK. I'm in full speculation mode here.

 

[TheBlackPearl]

^^^what he said

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[46addict]

Have any of y'all seen a chart or diagram that shows the safe limit of Effective Compression Ratio vrs octane, or the max safe ECR for a 3v block?

Everything I find just shows I was insane to try 12:1 C/R.

I was wondering the same thing and made a thread about ECRs before reading this post. Unless you know for sure detonation is what caused your engine to blow, I'm not sure if ECR is a critical variable for you unless you plan on turning up boost or static compression. If E85 and 31:1 ECR has been working for you, I don't see how it would suddenly be an issue..unless your fuel supplier did not blend the ethanol correctly.

I think the issue (if there is an issue) of crank support/harmonics should be ruled out first. Starting with the basics, is the belt tensioner in good working order? Any play in the idler/drive pulleys?

I'm just speculating here. I've never built anything fast.

 

[05stroker]

I think the big question is how much pre-ignition (PI) protection you need. And how you get that. For example you can get race fuel up to what? 116 octane? Is the octane level completely representative of the PI properties? Or are there other ingredients?

Then you look at e85. It doesn't have a ton of octane, but it does have lot of PI properties.

So silly rough math/thinking/made up stuff here:

You have 93 octane pump gas. Let's call that our base "zero". That will give you X protection.

Then you throw 116 octane race fuel at it. That gives you 23 more octanes (which is a huge percentage of "zero"). So X + 23. Is all of the PI protection it provides due simply to octane? Or are there other goodies in there that aren't measured/called out that add to the PI protection?

Now you throw e85 at it. I'm seeing 100-105 octane. But we know that it will give PI protection way beyond that. So is it just the cooling properties that is making this happen? And if so how is that accounted for when figuring actual detonation resistance? What is your X factor with e85?

I have a hard time believing that e85 can't handle some very high cylinder pressures/heat. I know alcohol is not the same as ethanol. But they do have similar properties. And alcohol WORKS!!! Tom Bailey's Drag Week car makes about 4000hp at 55-60lb of boost on alcohol........................with no intercooler!!!!!!! At an absolute minimum you're looking at a 600deg IAT. And 55-60lb of boost!!!! Holy crap!!!!!! Even if e85 is half as good as alcohol, you would think it still has PLENTY of headroom.

IDK. I'm in full speculation mode here.

Okay so, let's speculate a little more. If ECR is not limited by E85 in my case , at what point does ECR become to much for the components I was using? We all know that they all seem to come with HP ratings, but the same HP can be made with more boost and less CR resulting in a lower ECR.

Seems to me that a lower CR and a larger power adder would have been a safer bet with the info in the link I posted.

 

[weather man]

Okay so, let's speculate a little more. If ECR is not limited by E85 in my case , at what point does ECR become to much for the components I was using? We all know that they all seem to come with HP ratings, but the same HP can be made with more boost and less CR resulting in a lower ECR.

Seems to me that a lower CR and a larger power adder would have been a safer bet with the info in the link I posted.

The great thing about E85 is that it vaporizes much more uniformly than gas and it produces no soot. If you introduce oil into the cylinder, that goes out the window.

That said, you were running healthy compression for sure.

 

[Department Of Boost]

Okay so, let's speculate a little more. If ECR is not limited by E85 in my case , at what point does ECR become to much for the components I was using?

If I'm following you (I may not be) e85 is a non issue and you're way far away from the limits of it's detonation threshold (an assumption). Then the only thing left to break parts is load. And load is cylinder pressure. And X cylinder pressure yields Y HP. So HP rating is what you're left with at that point.

There is of course RPM's and harmonics. But I think we can all agree you're not pushing that stuff very far. There are 10,000rpm 4.6's out there. That is some serious rod loading.

We all know that they all seem to come with HP ratings, but the same HP can be made with more boost and less CR resulting in a lower ECR.

But ECR boils down to cylinder pressure. If you're making 1000hp with 12:1 and 25lb of boost or 1000hp with 8.5:1 and 35lb of boost aren't the cylinder pressures the same? Or really close?

Of course the IAT's would be wildly different But taken one step further how much different would the in cylinder temps right before ignition be if they have the same cylinder pressure????

Seems to me that a lower CR and a larger power adder would have been a safer bet with the info in the link I posted.

Yes, and more efficient.

You need a 8.5:1 motor with a R-Spec on top running a 4.5L Whipple.

 

[retfr8flyr]

It's always been my understanding in a race application, that at equal cylinder pressures, a lower compression ratio and higher boost level will produce higher HP than the higher compression and lower boost setup. This is due to the larger volume of A/F mixture allowed with the lower compression motor.

 

[BruceH]

Billy, is the same cylinder that the sleeve dropped the same one the rod broke in? Anything that stops or impedes the piston movement is going to transfer stress into everything else. If the rod was the weakest link then it would be the first thing to go.

Your piston top doesn't look like it was shot with a shotgun, it's not melted, none of the signs we usually see with a cylinder firing out of order or going lean. The spark plug tip could break just from the free wheeling piston hitting it after the rod broke.

Have you thought of looking up Mihovitz and asking if he would look at them? He used to frequent ModFords until too many dipshits started commenting on some of his achievements. What I'm getting at is he would know what happened and rumor has it that he likes to help mod motor hot rodders. IMO you are pushing the envelope farther than any of us have and entering uncharted territory with how much abuse parts will take. It's time to reach out to someone who makes gobs more power than you are and see if they will share anything they went through along the way.

 

[05stroker]

I decided to just go back to basics for now. I dropped the used 3v block off this morning to be checked over and bored to 3.582, also dropped off the stock stroke Kellogg to be checked and polished. I ordered a set of .030 Manley pistons and a new set of Total seal SS ring. Looks like I'm going with a 285 CID 9.8:1 CR build this time and spin some rpm. I will be using the lightweight series Manley Billet I Beam rods this time and no crank support. I plan to start of with the 3.9 pulley back on the blower and turn 7500 rpm again. Then add more boost and lower the rpm to see what works best for me. I can't run anything more then the 3.9 with out lowering rpm to keep from over spinning the blower. Just need to figure out bearings now and I'll be back in business.

 

[01yellerCobra]

Sometimes reading this thread makes me feel like a wuss for selling my last car because I was going on the third rebuild. Glad to see you not giving up Billy.

 

[05stroker]

Sometimes reading this thread makes me feel like a wuss for selling my last car because I was going on the third rebuild. Glad to see you not giving up Billy.

Or that you are just smarter then I am! Lol

 

[swflastang05]

I decided to just go back to basics for now. I dropped the used 3v block off this morning to be checked over and bored to 3.582, also dropped off the stock stroke Kellogg to be checked and polished. I ordered a set of .030 Manley pistons and a new set of Total seal SS ring. Looks like I'm going with a 285 CID 9.8:1 CR build this time and spin some rpm. I will be using the lightweight series Manley Billet I Beam rods this time and no crank support. I plan to start of with the 3.9 pulley back on the blower and turn 7500 rpm again. Then add more boost and lower the rpm to see what works best for me. I can't run anything more then the 3.9 with out lowering rpm to keep from over spinning the blower. Just need to figure out bearings now and I'll be back in business.

What size crank pulley do you have for the 12 rib? If it's 7.5" like mine is you would be spinning the blower almost 78k rpm with 7500 rpm engine speed, the F-1A's max out at 74k. Or do I remember something about you installing different bearings in your blower a while back?

 

[05stroker]

What size crank pulley do you have for the 12 rib? If it's 7.5" like mine is you would be spinning the blower almost 78k rpm with 7500 rpm engine speed, the F-1A's max out at 74k. Or do I remember something about you installing different bearings in your blower a while back?

7.65 crank pulley, and yes, ceramic bearings in this blower.

 

[swflastang05]

7.65 crank pulley, and yes, ceramic bearings in this blower.

Cool, how much would you anticipate that increased the max blower rpm?

 

[05stroker]

Cool, how much would you anticipate that increased the max blower rpm?

I wouldn't guess much. Not sure really.

 

[TheBlackPearl]

Here's a picture of an air to water intercooler I saw for the procharger kits for our cars.

Just thought I'd throw it out here.

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