What is a good static compression ratio?
What is a good static compression ratio? With a healthy shot of spray? Was originally shooting for 12.5:1 but now thinking around 10.5-11:1. What do you all think?
TEA heads, ported intake, no cam ground yet
BTW a healthy shot is 2-300ish
For a weekend warrior track/street car, keeping it cool, and on pump gas, I'd target 12:1. You can push it higher, but your tuning window and safety margin disappear quickly.
For a daily driver, more like 11:1.
For a daily driver, more like 11:1.
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Joined: Jan 2013
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From: Las Vegas
The more juice u add the more room u have to make for it. Too much compression and too much juice will increase what they call pumping loses and power may even go down.
Plenty of info on setting up a NOx motor u just have to take the time to read it. If u add just a small plate sys then 11:1 ok but for a big 2 stage sys u would want more like 10:1. But ya gotta read for yourself because u want a nitrous cam to match - and u can rework your heads for dedicated nitrous also - and still run fine on the street also.
My 2 cents.
Plenty of info on setting up a NOx motor u just have to take the time to read it. If u add just a small plate sys then 11:1 ok but for a big 2 stage sys u would want more like 10:1. But ya gotta read for yourself because u want a nitrous cam to match - and u can rework your heads for dedicated nitrous also - and still run fine on the street also.
My 2 cents.
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nitrous LOVES compression. There are lots of medium shot(400-500) engines running in the 13-14:1 range. Don't let people fool you into thinking that the larger the shot the less compression you need.
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Verdad Gallardo The more juice u add the more room u have to make for it. Too much compression and too much juice will increase what they call pumping loses and power may even go down.
Plenty of info on setting up a NOx motor u just have to take the time to read it. If u add just a small plate sys then 11:1 ok but for a big 2 stage sys u would want more like 10:1. But ya gotta read for yourself because u want a nitrous cam to match - and u can rework your heads for dedicated nitrous also - and still run fine on the street also.
My 2 cents.
Plenty of info on setting up a NOx motor u just have to take the time to read it. If u add just a small plate sys then 11:1 ok but for a big 2 stage sys u would want more like 10:1. But ya gotta read for yourself because u want a nitrous cam to match - and u can rework your heads for dedicated nitrous also - and still run fine on the street also.
My 2 cents.
OK thanks, What about on pump gas, Is 12.5 ish:1 still a good figure, Or can it be pushed higher without detination?
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From: Las Vegas
Q: Is there an ideal compression ratio?
A: There is a relationship between the compression ratio, nitrous flow, and cubic inches. At competitive levels of one nitrous horsepower per cubic inch and greater, compression ratio should be at least a couple of points of compression lower than a naturally aspirated combination.
Q: Can high compression engines utilize nitrous oxide?
A: Absolutely. High or low compression ratios can work quite suitably with nitrous oxide providing the proper balance of nitrous and fuel enrichment is maintained. NS kits are used in applications from relatively low compression stock type motors to Pro-Modified, which often exceed 15 to 1. Generally, the higher the compression ratio, the more ignition retard, as well as higher octane fuel, is required.
And this from Nitrous Express: http://www.nitrousexpress.com/carbfaq.html
Q. What is the best compression ratio to run with nitrous?
A. Nitrous can be run successfully with almost any compression, however we have found that 14-1 is the highest ratio that has a reasonable “Window of Safety”. Ratios as high as 17-1 can be used, but only by elite tuners with years of experience. Using alcohol as an enrichment fuel will allow you to run higher compression ratios without fear of detonation.
Try this from Nitrous Supply w/s: https://www.nitroussupply.com/Tech.html
Q: Is there an ideal compression ratio?
A: There is a relationship between the compression ratio, nitrous flow, and cubic inches. At competitive levels of one nitrous horsepower per cubic inch and greater, compression ratio should be at least a couple of points of compression lower than a naturally aspirated combination.
Q: Can high compression engines utilize nitrous oxide?
A: Absolutely. High or low compression ratios can work quite suitably with nitrous oxide providing the proper balance of nitrous and fuel enrichment is maintained. NS kits are used in applications from relatively low compression stock type motors to Pro-Modified, which often exceed 15 to 1. Generally, the higher the compression ratio, the more ignition retard, as well as higher octane fuel, is required.
And this from Nitrous Express: http://www.nitrousexpress.com/carbfaq.html
Q. What is the best compression ratio to run with nitrous?
A. Nitrous can be run successfully with almost any compression, however we have found that 14-1 is the highest ratio that has a reasonable “Window of Safety”. Ratios as high as 17-1 can be used, but only by elite tuners with years of experience. Using alcohol as an enrichment fuel will allow you to run higher compression ratios without fear of detonation.
Q: Is there an ideal compression ratio?
A: There is a relationship between the compression ratio, nitrous flow, and cubic inches. At competitive levels of one nitrous horsepower per cubic inch and greater, compression ratio should be at least a couple of points of compression lower than a naturally aspirated combination.
Q: Can high compression engines utilize nitrous oxide?
A: Absolutely. High or low compression ratios can work quite suitably with nitrous oxide providing the proper balance of nitrous and fuel enrichment is maintained. NS kits are used in applications from relatively low compression stock type motors to Pro-Modified, which often exceed 15 to 1. Generally, the higher the compression ratio, the more ignition retard, as well as higher octane fuel, is required.
And this from Nitrous Express: http://www.nitrousexpress.com/carbfaq.html
Q. What is the best compression ratio to run with nitrous?
A. Nitrous can be run successfully with almost any compression, however we have found that 14-1 is the highest ratio that has a reasonable “Window of Safety”. Ratios as high as 17-1 can be used, but only by elite tuners with years of experience. Using alcohol as an enrichment fuel will allow you to run higher compression ratios without fear of detonation.
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Joined: Sep 2003
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From: Raleigh, NC
I've seen numerous street driven LT1 cars running 12:1 or higher compression and 200+hp of nitrous. With pump gas. People have literally been doing it ever since the LT1 motors came out.
No matter the SCR, it's always a decent idea to run some good gas when spraying, for the extra safety margin if nothing else. Not at all a requirement though, if the rest of your setup is up to the task.
That info on the nitrous companies' websites is highly generalized in nature and has little to no relevance in the LT1 world. Ignore them, actually from the couple of posts in this thread it appears you ought to ignore cardo0 altogether.
Nitrous is not the same thing as boost, you DO NOT have to lower your SCR to "make room" for it, nitrous bears it's own oxygen and acts as it's own intercooler so the combustion dynamic is very different than cramming a motor full of hot compressed air, as with forced induction. You just have to make sure your fuel system is bringing enough to the party and your components can handle the additional cylinder pressure. Running nitrous on a street car is not something for a guy who doesn't sweat details, pay attention and keep a regular eye on how everything is working.
No matter the SCR, it's always a decent idea to run some good gas when spraying, for the extra safety margin if nothing else. Not at all a requirement though, if the rest of your setup is up to the task.
That info on the nitrous companies' websites is highly generalized in nature and has little to no relevance in the LT1 world. Ignore them, actually from the couple of posts in this thread it appears you ought to ignore cardo0 altogether.
Nitrous is not the same thing as boost, you DO NOT have to lower your SCR to "make room" for it, nitrous bears it's own oxygen and acts as it's own intercooler so the combustion dynamic is very different than cramming a motor full of hot compressed air, as with forced induction. You just have to make sure your fuel system is bringing enough to the party and your components can handle the additional cylinder pressure. Running nitrous on a street car is not something for a guy who doesn't sweat details, pay attention and keep a regular eye on how everything is working.
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From: Las Vegas
Yea sure pay attention to the details and then whats his name doesnt have any to share. Plenty of trolls on this site that hate any legitimate information rather than the accepted hearsay. Like the nitrous companies dont know what their trying to explain but he (or it) does. And u can take his word for it ha ha, ho ho, thats real funny. But u cant use his c.r. "recommendations" because he doesnt provide any. Easy to read who u should ignore.
Yea sure pay attention to the details and then whats his name doesnt have any to share. Plenty of trolls on this site that hate any legitimate information rather than the accepted hearsay. Like the nitrous companies dont know what their trying to explain but he (or it) does. And u can take his word for it ha ha, ho ho, thats real funny. But u cant use his c.r. "recommendations" because he doesnt provide any. Easy to read who u should ignore.
You seem to be the only one who can't figure out who should be ignored
Whenever you decide to go see a shrink, just link him to this forum for a good background
TECH Regular
Joined: Sep 2003
Posts: 442
Likes: 3
From: Raleigh, NC
Yea sure pay attention to the details and then whats his name doesnt have any to share. Plenty of trolls on this site that hate any legitimate information rather than the accepted hearsay. Like the nitrous companies dont know what their trying to explain but he (or it) does. And u can take his word for it ha ha, ho ho, thats real funny. But u cant use his c.r. "recommendations" because he doesnt provide any. Easy to read who u should ignore.
Have you ever ran nitrous on anything, let alone anything LT1 powered? Do you have any understanding at all of how nitrous oxide injection works and the combustion dynamic it creates? Are you at all familiar with the LT1 motor's ability to run much higher than typical SCRs on pump fuel to begin with, whether nitrous is involved or not?
Go ahead and build your 10:1 nitrous LT motor and then come teach everyone in here a lesson about heresay
But since you jumped on someone about not providing a recommendation on SCR for a nitrous LT motor that will see street duty, if it were me, I would shoot for something between in the range of 11.5 to 12.0. Where the exact # ended up would be dependent upon a number of other factors.
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From: Las Vegas
So what are u basing your 11.5 to 12.0 comp ratio on? U have any real data to support it? Or just more hearsay. What size NOx shot? Oh, oh, thats right any size shot unhuh. Are they all the same to u?? Admit it u dont know! What are the sources of your information. Joe, Smoe and someone on the sidewalk? What are the "other factors" in choosing a c.r. - thats what the OP wants. So lets hear it. Ya, nitrous vendors cant touch that kind of help.
In your nearly empty profile i see a student. I can imagine how much time and $$$ a student has to spend proving NOx compression ratios. Plenty of time to troll the forums though. Get a real life.
In your nearly empty profile i see a student. I can imagine how much time and $$$ a student has to spend proving NOx compression ratios. Plenty of time to troll the forums though. Get a real life. 
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