How much boost…..
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Jul 28, 2022, 08:19 AM
Race Director
Joined: Mar 2011
Posts: 13,262
Likes: 3,151
From: SW Florida
2021 C6 of the Year Finalist - Modified
KingtalOn ....
The OP asks a simple question, and the best you can do for him is to muck-up your response with a bunch of meaningless numbers.
If you even own a boosted LS engine that you run on the street with pump gas, how about simply telling the OP how much boost you have been able to safely run.
You turn every one of these threads you post on, into a damned science class (without ever answering the OPs original question).
The OP asks a simple question, and the best you can do for him is to muck-up your response with a bunch of meaningless numbers.
If you even own a boosted LS engine that you run on the street with pump gas, how about simply telling the OP how much boost you have been able to safely run.
You turn every one of these threads you post on, into a damned science class (without ever answering the OPs original question).
Race Director
Joined: Mar 2011
Posts: 13,262
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From: SW Florida
2021 C6 of the Year Finalist - Modified
About the max boost I can run while using just 93 octane pump gas (and not get any knock retard) is 7.5 PSI
That's with 17° max spark timing during WOT ... that's 17° all the way to my 6,400 rpm shift.
'11 GS
That's with 17° max spark timing during WOT ... that's 17° all the way to my 6,400 rpm shift.
'11 GS
Safety Car
Joined: Oct 2007
Posts: 4,222
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From: South Florida
Boost is irrelevant. What you actually need is knowledge of the HP bottom end capacity for the engine, fuel quality variability, compression ratio, and compressor efficiency range for flow volumetric rate. These are the minimum information.
For example if the engine can only handle 600-700rwhp then that is your limit. Doesn't matter how much boost it takes, will be different for every engine, cam, head, etc...
other example if the compressor volumetric flow rate is capped out 800CFM then you cannot exceed that limit or risk over-spin and damage.
other example if the compression ratio is high or fuel quality is limited you will carefully tune around that, it takes experience, and settle on some safe limitation which isn't based on boost pressure but rather ambient and racing conditions worst case scenario.
The reason boost pressure is meaningless is because the boost is insignificant pressure. For example Compression is 1000psi, or 1200psi or something. The reason engines become damaged or explode from boost pressure is because of uncontrolled 1000+psi of compression, not the 30psi or 50psi of boost pressure or whatever.
For example if the engine can only handle 600-700rwhp then that is your limit. Doesn't matter how much boost it takes, will be different for every engine, cam, head, etc...
other example if the compressor volumetric flow rate is capped out 800CFM then you cannot exceed that limit or risk over-spin and damage.
other example if the compression ratio is high or fuel quality is limited you will carefully tune around that, it takes experience, and settle on some safe limitation which isn't based on boost pressure but rather ambient and racing conditions worst case scenario.
The reason boost pressure is meaningless is because the boost is insignificant pressure. For example Compression is 1000psi, or 1200psi or something. The reason engines become damaged or explode from boost pressure is because of uncontrolled 1000+psi of compression, not the 30psi or 50psi of boost pressure or whatever.
Race Director
Joined: Mar 2011
Posts: 13,262
Likes: 3,151
From: SW Florida
2021 C6 of the Year Finalist - Modified
KingtalOn ....
The OP asks a simple question, and the best you can do for him is to muck-up your response with a bunch of meaningless numbers.
If you even own a boosted LS engine that you run on the street with pump gas, how about simply telling the OP how much boost you have been able to safely run.
You turn every one of these threads you post on, into a damned science class (without ever answering the OPs original question).
The OP asks a simple question, and the best you can do for him is to muck-up your response with a bunch of meaningless numbers.
If you even own a boosted LS engine that you run on the street with pump gas, how about simply telling the OP how much boost you have been able to safely run.
You turn every one of these threads you post on, into a damned science class (without ever answering the OPs original question).
Platinum Supporting Vendor
Joined: Jul 2011
Posts: 2,077
Likes: 227
Then if you have more octane from Meth, E85, or race gas stay at or below 700 rwhp on stock pistons. Some guys have gone higher with success and some have failed pushing the limits.
Boost is just a measure of restriction so I prefer to gauge based on power made. Also I tell guys to speak to your Tuner and see what they feel comfortable pushing the power up to based on their experience.
Thx,
Josh
Race Director
Joined: Mar 2011
Posts: 13,262
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From: SW Florida
2021 C6 of the Year Finalist - Modified
Typical rule of thumb if running pump gas only stay at or below 600 rwhp on stock pistons. Sometimes you can get away with a little more with good pump 93 octane.
Then if you have more octane from Meth, E85, or race gas stay at or below 700 rwhp on stock pistons. Some guys have gone higher with success and some have failed pushing the limits.
Boost is just a measure of restriction so I prefer to gauge based on power made. Also I tell guys to speak to your Tuner and see what they feel comfortable pushing the power up to based on their experience.
Thx,
Josh
Stock pistons
.
Last edited by Turbo6TA; Jul 28, 2022 at 03:47 PM.
Safety Car
Joined: Oct 2007
Posts: 4,222
Likes: 1,078
From: South Florida
KingtalOn ....
The OP asks a simple question, and the best you can do for him is to muck-up your response with a bunch of meaningless numbers.
If you even own a boosted LS engine that you run on the street with pump gas, how about simply telling the OP how much boost you have been able to safely run.
You turn every one of these threads you post on, into a damned science class (without ever answering the OPs original question).
The OP asks a simple question, and the best you can do for him is to muck-up your response with a bunch of meaningless numbers.
If you even own a boosted LS engine that you run on the street with pump gas, how about simply telling the OP how much boost you have been able to safely run.
You turn every one of these threads you post on, into a damned science class (without ever answering the OPs original question).
2. every engine makes different number of boost so the question is impossible to answer directly, stock engine that make 7psi will make 0psi with a head/cam/intake mod same power. No matter what boost number you give it will be WRONG. And I am never wrong.
3. so far 'best' other answer in this thread has been exactly same as mine , no boost number given
Yet somehow you are not happy with my response which explains directly how to arrive at these conclusions.
Try to use your brain instead of complain about being asked to use it?
Race Director
Joined: Mar 2011
Posts: 13,262
Likes: 3,151
From: SW Florida
2021 C6 of the Year Finalist - Modified
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Melting Slicks
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Some get 1000whp out of SBE stuff for years, others manage to blow them up at half that. Really just depends, with good fuel and a good tuner you can make decent power for a long time.
I would agree with 600whp on straight 93 pump so you can beat the absolute crap out of it and be ok. I've done 600whp builds that are going on 10 years now of being boosted as peoples daily drivers.
With E85 you can lean a bit harder and have easily got away with 800-900 whp for a long time, keeping it at 700whp on E85 would essentially let it run forever.
I would agree with 600whp on straight 93 pump so you can beat the absolute crap out of it and be ok. I've done 600whp builds that are going on 10 years now of being boosted as peoples daily drivers.
With E85 you can lean a bit harder and have easily got away with 800-900 whp for a long time, keeping it at 700whp on E85 would essentially let it run forever.
Safety Car
Joined: May 2016
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From: Erlanger, Kentucky
KingtalOn ....
The OP asks a simple question, and the best you can do for him is to muck-up your response with a bunch of meaningless numbers.
If you even own a boosted LS engine that you run on the street with pump gas, how about simply telling the OP how much boost you have been able to safely run.
You turn every one of these threads you post on, into a damned science class (without ever answering the OPs original question).
The OP asks a simple question, and the best you can do for him is to muck-up your response with a bunch of meaningless numbers.
If you even own a boosted LS engine that you run on the street with pump gas, how about simply telling the OP how much boost you have been able to safely run.
You turn every one of these threads you post on, into a damned science class (without ever answering the OPs original question).
Safety Car
Joined: Oct 2007
Posts: 4,222
Likes: 1,078
From: South Florida
Engines are science and engineering. Sorry thats just the way it is. You can put 7psi to an engine and then modify it and wind up with -2psi using the same drive ratio for the blower and make the same power. Boost is meaningless. Im sorry you guys don't understand that. What confuses me however is when somebody else says the same exact thing I did you agree with them
Thread Starter
Instructor
Joined: Nov 2021
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KingtalOn ....
The OP asks a simple question, and the best you can do for him is to muck-up your response with a bunch of meaningless numbers.
If you even own a boosted LS engine that you run on the street with pump gas, how about simply telling the OP how much boost you have been able to safely run.
You turn every one of these threads you post on, into a damned science class (without ever answering the OPs original question).
The OP asks a simple question, and the best you can do for him is to muck-up your response with a bunch of meaningless numbers.
If you even own a boosted LS engine that you run on the street with pump gas, how about simply telling the OP how much boost you have been able to safely run.
You turn every one of these threads you post on, into a damned science class (without ever answering the OPs original question).
Drifting
Joined: Sep 2021
Posts: 1,302
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From: NoVa
2022 C6 of the Year Finalist - Modified
haha This would never happen. There may be slight differences from engine to engine, but his setup is nothing novel; given the variables he relayed, as others mentioned as well, ~7ish psi/conservative timing (16-18 degrees)/<600rwhp on 93. Your response is overly complicated (and incorrect, as highlighted above) and is of no benefit to the OP.
Thread Starter
Instructor
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haha This would never happen. There may be slight differences from engine to engine, but his setup is nothing novel; given the variables he relayed, as others mentioned as well, ~7ish psi/conservative timing (16-18 degrees)/<600rwhp on 93. Your response is overly complicated (and incorrect, as highlighted above) and is of no benefit to the OP.
make more than 600whp??
Safety Car
Joined: Oct 2007
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From: South Florida
haha This would never happen. There may be slight differences from engine to engine, but his setup is nothing novel; given the variables he relayed, as others mentioned as well, ~7ish psi/conservative timing (16-18 degrees)/<600rwhp on 93. Your response is overly complicated (and incorrect, as highlighted above) and is of no benefit to the OP.
2. It isn't important whether you can go from 20psi to 0psi or whatever. What is important is the point: that given some specific blower drive ratio, boost will change based on variables such as ambient temperature & engine breathing mods, so quoting some specific boost # is ridiculous and nobody with the knowledge and experience necessary to utilize forced induction will ever give a specific boost number.
Drifting
Joined: Sep 2021
Posts: 1,302
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From: NoVa
2022 C6 of the Year Finalist - Modified
1. I could make it happen very easily and I have in the past
2. It isn't important whether you can go from 20psi to 0psi or whatever. What is important is the point: that given some specific blower drive ratio, boost will change based on variables such as ambient temperature & engine breathing mods, so quoting some specific boost # is ridiculous and nobody with the knowledge and experience necessary to utilize forced induction will ever give a specific boost number.
2. It isn't important whether you can go from 20psi to 0psi or whatever. What is important is the point: that given some specific blower drive ratio, boost will change based on variables such as ambient temperature & engine breathing mods, so quoting some specific boost # is ridiculous and nobody with the knowledge and experience necessary to utilize forced induction will ever give a specific boost number.
OP apologies for hijacking the thread. When I tune cars, I take a prudent/judicious approach on pump gas (93).
Thread Starter
Instructor
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