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Old 01-23-2008, 10:56 AM   #1
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Default Max boost for compression

how much boost can you run on 11:5:1 compression intercooled with just C16 race fuel.
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Old 01-23-2008, 11:17 AM   #2
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why, you can run some but it wont be optimal
it will depend on how the engine is tuned how much timing ect. there are still some variables.
not sure to many have done it cause its not worth it, now if you were running acholol it would be different.
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Old 01-23-2008, 11:19 AM   #3
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'Only' C16?

Interesting read here:

http://www.musclemustangfastfords.co...tio/index.html
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Old 01-23-2008, 11:40 AM   #4
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yes just c16
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Old 01-23-2008, 12:59 PM   #5
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i run as much as 40psi on 10.5 comp with torco 118 with no problems,not sure how much yuor engine can take but i think you could run 20psi on c16 with the proper tune
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Old 01-23-2008, 02:45 PM   #6
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Cool article link Kevin, thanks for posting that up.

Anyone want to buy an 8:1 348ci LS6 shorty?
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Old 01-23-2008, 03:06 PM   #7
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yo shawn @ VA speed, do you have any video's of your car? That setup and horsepower is pretty insane i would love to see it go, or even just what it looks like.
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Old 01-23-2008, 03:27 PM   #8
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why not run E85? Cheaper and will be more friendly
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Old 01-23-2008, 03:47 PM   #9
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Cool article link Kevin, thanks for posting that up.

Anyone want to buy an 8:1 348ci LS6 shorty?
Yes, that was a great article but race only of course. There is no way that it could apply to a street car on running lower octane fuel. John I wouldn't go that far of wanting to sell your engine after reading that article. I think that was a joke b/c you have a stout setup in my mind. It all depends on the setup really, but many say around 9.0 and a bit higher is a happy medium.
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Old 01-23-2008, 04:06 PM   #10
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Yes, that was a great article but race only of course. There is no way that it could apply to a street car on running lower octane fuel. John I wouldn't go that far of wanting to sell your engine after reading that article. I think that was a joke b/c you have a stout setup in my mind. It all depends on the setup really, but many say around 9.0 and a bit higher is a happy medium.
Of course its a race setup in the article, I would think since the OP was asking about running C16 it applies to him very well.
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Old 01-23-2008, 04:13 PM   #11
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yo shawn @ VA speed, do you have any video's of your car? That setup and horsepower is pretty insane i would love to see it go, or even just what it looks like.
Here's a couple pics for you bro,no video online right now.


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Old 01-23-2008, 04:20 PM   #12
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Very nice, good way to fill up all that space up front on a 2nd gen
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Old 01-23-2008, 06:25 PM   #13
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Of course its a race setup in the article, I would think since the OP was asking about running C16 it applies to him very well.
You are correct Kevin, I was generalizing of course and being at work my mind was somewhere else. He's definetly beyond normal and pure race car, my bad

Again though, great article none the less, I know it did that but not to that effect!
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Old 01-23-2008, 07:51 PM   #14
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You are correct Kevin, I was generalizing of course and being at work my mind was somewhere else. He's definetly beyond normal and pure race car, my bad

Again though, great article none the less, I know it did that but not to that effect!
No problem man, I thought that was interesting article..
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Old 01-23-2008, 08:45 PM   #15
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Originally Posted by stroked_408 View Post
how much boost can you run on 11:5:1 compression intercooled with just C16 race fuel.
Depends on your Cam. We run 26lbs on 11-1 comp. with C-16 and rev to 8000rpm.
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Old 01-24-2008, 03:35 PM   #16
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Here's a couple pics for you bro,no video online right now.
Where are the vids? I bet that thing is psychotic to drive!

To the original poster, it depends. Are you running on the stock non forged internals? Or is your setup forged?

Again, as mentioned before, its not a good idea to run boost on a high CR engine. You can get away with doing so by raising the octane level and or intercooling it, but you're still kind of going against what ideally you want for boost, and that is a lower CR.

Even with C16, I wouldn't run more than 10#'s of boost, especially if you are still on stock internals. The amount you're going to spend on fuel alone should make you think about just getting some forged lower CR pistons.
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Old 01-25-2008, 09:16 AM   #17
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Another general observation, but the class racers tend to find the limits of various combinations, so that's why guys in like SSO have experimented with various compression levels. I'm sure a number of those guys have found out what is too much compression for their car, they can be changing engines and components quite a bit if they need to and have the funds.
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Old 01-25-2008, 09:42 AM   #18
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Who keeps spreading this BS. Compression is fine. Intercooling and Octane are you friends. Adding compression make the engine more thermally efficient,make more hp and tq and also makes the power adders work better.

This whole argument is retarded. I geuss Tim Lnych and Steve Petty should run low compression engines in SSO etc etc etc.

For that matter lets all hop on the lemming bus and go over the cliff.


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Where are the vids? I bet that thing is psychotic to drive!

To the original poster, it depends. Are you running on the stock non forged internals? Or is your setup forged?

Again, as mentioned before, its not a good idea to run boost on a high CR engine. You can get away with doing so by raising the octane level and or intercooling it, but you're still kind of going against what ideally you want for boost, and that is a lower CR.

Even with C16, I wouldn't run more than 10#'s of boost, especially if you are still on stock internals. The amount you're going to spend on fuel alone should make you think about just getting some forged lower CR pistons.
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Old 01-25-2008, 11:04 AM   #19
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Who keeps spreading this BS. Compression is fine. Intercooling and Octane are you friends. Adding compression make the engine more thermally efficient,make more hp and tq and also makes the power adders work better.
Shops that sell engines dont like to see a lot of static compression, cant blame them since enough people blow their **** up at 8.5:1. Its easy enough to throw too big of a turbo or blower on to make up for it anyhow, but you pay with more parasitic loss and slower spool/higher compressor air temps. Nothing is for free

IMO if you know what you are doing I wouldnt be scared of some higher compression in a race car thats intercooled running C16.

But sooner or later you will reach a point where the increased compression wont leave enough room to pack the amount of a/f in you want or the heat it creates just makes detonation impossible to control. Lot of that depends on intake port, camshaft, chamber design and exhaust efficiency as well.

Last edited by kp; 01-25-2008 at 11:11 AM.
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Old 01-25-2008, 11:54 AM   #20
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Quote:
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IMO if you know what you are doing I wouldnt be scared of some higher compression in a race car thats intercooled running C16.

But sooner or later you will reach a point where the increased compression wont leave enough room to pack the amount of a/f in you want or the heat it creates just makes detonation impossible to control. Lot of that depends on intake port, camshaft, chamber design and exhaust efficiency as well.
This is exactly what I am talking about. If you look into doing some more research you will find that to run higher boost levels the ideal way is to lower the CR. This also allows you to run on pump gas without detonation.

If you don't believe me and refuse to do more research, start a poll in the FI forum and just ask others in here on what the ideal CR is for a high boosted motor. I garuntee the ones with experience from doing it a while or from learning the hard way from a blown engine will tell you that if you plan on high boost, you don't want a high CR.

Simply stated, high CR + high boost = detonation. You can help your chances of staying away from detonation to a certain extent by raising the octane level, but it will only go so far to help you before detonation cannot be contained.
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