Nitrous with 11.25 CR
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TECH Apprentice
Joined: Oct 2006
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From: Wichita, Ks.
Nitrous with 11.25 CR Just curious, but can you safely run a 75-100 shot on pump gas with 11.25 CR.
Haven't seen much discussed about higher compression ratios and spray.
If there is a link to more info please let me know.
Haven't seen much discussed about higher compression ratios and spray.
If there is a link to more info please let me know.
You shouldn't have a problem. Check the spark plug chart in the stickies to see what plug u should use. Run 93 octane, have it tuned for the timing pull and have fun. Make sure u have enough fuel also.
A #7 plug and the appropriate amount of timing pulled and you will be fine, a safe amount of timing to pull would be 1 degree for every 20 hp (5 for a 100 shot) and you shouldn't have any problems at all. That's probably conservative, but safe.
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11.25 to 1 isn't too high, you start pushing it into the high 11's and add nitrous, and you're going to be getting on the edge.
The #7 plug is colder then most will tell you to run, but will add a little safety, the timing, most will tell you 1 degree for every 25 hp, but at 5 for 100 you should be o.k., unless the tuneup is very agressive as it stands.
With a #7 plug, and about 18 degrees you should be fine, you may find that it will take 20 degrees, but starting a little low is always safer. Don't let it get too rich or lean, try to keep the a/f in the mid 12's and you should be fine.
A rule of thumb, that you can go by:
A stock motor with a 100 shot needs about 4 degrees pulled from an optimal tune which is probably about 26 degrees, and needs a #6 plug. Every 100 hp, or full compression point that you go up needs 1 step colder on the plug, and should have 4 degrees less timing.
Example, a cam only car will probably take 28 degrees n/a, put heads on it and bump the compression a full point, and you'll need about 24. Add 100 shot to that, and you'll find it needs about 20.
As power is added, continue this type of ratio, race fuel will allow more timing, but this is a somewhat safe rule.
The #7 plug is colder then most will tell you to run, but will add a little safety, the timing, most will tell you 1 degree for every 25 hp, but at 5 for 100 you should be o.k., unless the tuneup is very agressive as it stands.
With a #7 plug, and about 18 degrees you should be fine, you may find that it will take 20 degrees, but starting a little low is always safer. Don't let it get too rich or lean, try to keep the a/f in the mid 12's and you should be fine.
A rule of thumb, that you can go by:
A stock motor with a 100 shot needs about 4 degrees pulled from an optimal tune which is probably about 26 degrees, and needs a #6 plug. Every 100 hp, or full compression point that you go up needs 1 step colder on the plug, and should have 4 degrees less timing.
Example, a cam only car will probably take 28 degrees n/a, put heads on it and bump the compression a full point, and you'll need about 24. Add 100 shot to that, and you'll find it needs about 20.
As power is added, continue this type of ratio, race fuel will allow more timing, but this is a somewhat safe rule.
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Remember it's a guidline, not something that should be etched in stone.
Once you're over the 500 rwhp level, I would also run race fuel. Don't mess around, put 116 in the tank, the cost vs cheap race fuel isn't much, and that will certainly make for a good safe setup.
Of course, once you get to the point that you need a #9 or colder plug and are spraying more then 250, all bets are off, tuneup is wrong you can eat anything up if you don't know what you're doing.
Once you're over the 500 rwhp level, I would also run race fuel. Don't mess around, put 116 in the tank, the cost vs cheap race fuel isn't much, and that will certainly make for a good safe setup.
Of course, once you get to the point that you need a #9 or colder plug and are spraying more then 250, all bets are off, tuneup is wrong you can eat anything up if you don't know what you're doing.
Remember it's a guidline, not something that should be etched in stone.
Once you're over the 500 rwhp level, I would also run race fuel. Don't mess around, put 116 in the tank, the cost vs cheap race fuel isn't much, and that will certainly make for a good safe setup.
Of course, once you get to the point that you need a #9 or colder plug and are spraying more then 250, all bets are off, tuneup is wrong you can eat anything up if you don't know what you're doing.
Once you're over the 500 rwhp level, I would also run race fuel. Don't mess around, put 116 in the tank, the cost vs cheap race fuel isn't much, and that will certainly make for a good safe setup.
Of course, once you get to the point that you need a #9 or colder plug and are spraying more then 250, all bets are off, tuneup is wrong you can eat anything up if you don't know what you're doing.
That's when you put good fuel (116 of your choice, better if you can) in, and this is one way you can fight off detonation on a setup that's close to the boarderline for pump fuel to work. Or, it's a way to allow a degree or 2 more timing to be used, or another 50 to 100 hp worth of power on a setup like say a h/c stock bottom end.
It also gives you the ability to adjust the fuel pressure seperately from the main fuel system for tuning purposes, which is also helpful in getting the most out of a system.
If you are going to spray more then 200, you need a setup that is in each cylinder (fogger DP type) unless you're running a carb style intake with a plate, in that case you can take that a little farther. And, if you're spraying more then 200, you should be running a standalone.
It also gives you the ability to adjust the fuel pressure seperately from the main fuel system for tuning purposes, which is also helpful in getting the most out of a system.
If you are going to spray more then 200, you need a setup that is in each cylinder (fogger DP type) unless you're running a carb style intake with a plate, in that case you can take that a little farther. And, if you're spraying more then 200, you should be running a standalone.
Gotcha, thanks. So I should go with a DP fogger system right off the bat even though I'm going to start on a small shot? (Sorry if I'm threadjacking...) I guess that would make sense financially. Am I on the right track here?
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From: Wichita, Ks.
I'm also considering a direct port system for safety reasons more than anything else.
I want to keep it as safe as possible since I will run 91 octane and already at 526rwhp.
I want to keep it as safe as possible since I will run 91 octane and already at 526rwhp.
You can run a 100 shot thru a fogger, just have to take the jets out often, and make sure they're clean, the smaller they get the easier it is for something to clog one.
ssdave, at your power level you definitely need to go strait fogger, and definitely run the best fuel you can. (I assume that's on a built motor though, so the piston's should be alot better then stock and take alot more, but still that's alot of power on pump to be adding nitrous on top of)
ssdave, at your power level you definitely need to go strait fogger, and definitely run the best fuel you can. (I assume that's on a built motor though, so the piston's should be alot better then stock and take alot more, but still that's alot of power on pump to be adding nitrous on top of)
Thread Starter
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From: Wichita, Ks.
It is a LME built LS7 430, Wiseco pistons, and aftermarket lower end.
Dyno Dynamics dyno.
It is a heavy car, 3880 with me and 18 gals of gas.
I don't want anything crazy, but I would like to be in the 10's at full dress.
But safety is top priority.
Dyno Dynamics dyno.
It is a heavy car, 3880 with me and 18 gals of gas.
I don't want anything crazy, but I would like to be in the 10's at full dress.
But safety is top priority.
An ls7 430 is gonna need very little to nothing to get you into the 10's on motor I'd think... 3880 is heavy, but still I think that's going to run 10's anyway.
You probably could get away with a 100 shot and just put a standalone in the car for a regular behind the TB plate and be in the bottom 1/2 of 10's no problem like that.
But, with a motor like that, it will surly take 200 all day... so if ya think stepping up is a possibility, then I'd just go fogger right away
You probably could get away with a 100 shot and just put a standalone in the car for a regular behind the TB plate and be in the bottom 1/2 of 10's no problem like that.
But, with a motor like that, it will surly take 200 all day... so if ya think stepping up is a possibility, then I'd just go fogger right away
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Joined: Oct 2006
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From: Wichita, Ks.
Thanks, I'll look into a standalone.
That sounds simple and safe.
It's just motor on the street but a little spray push in the 1/4.
Nothing crazy, but ya know; horsepower is addicting.
Thanks for the straight up info.
That sounds simple and safe.
It's just motor on the street but a little spray push in the 1/4.
Nothing crazy, but ya know; horsepower is addicting.
Thanks for the straight up info.
I was gonna say 11.25 is high compression????? 
all good info in here as usual from JL and the rest....
can't expound on any of it cause it's so good..... 12:1 compression or 500 RWHP and higher and yes put 116 in it.......
You could probably get away with some tracktech 110 if you had to.... I've run that racegas that is obviously 110 octane making about 675 RWHP thru a TH400..... (about 750 at the crank)...
For the bigger shots I put C16 in it only....
all good info in here as usual from JL and the rest....
can't expound on any of it cause it's so good..... 12:1 compression or 500 RWHP and higher and yes put 116 in it.......
You could probably get away with some tracktech 110 if you had to.... I've run that racegas that is obviously 110 octane making about 675 RWHP thru a TH400..... (about 750 at the crank)...
For the bigger shots I put C16 in it only....