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Old 12-05-2002, 02:41 PM   #1
dcoty
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Default 11:1 compression and nitrous, need advice.

Hey everyone!

Im building my block up right now and was planning on running a 100 shot of nitrous, but i also want 11:1 compression ratio (coated for nitrous use) to go full N/A.

I have been told that I can do a 100 shot with my block being built up on 11:1 by some people, but I have also been told that 50 shot is the max I can go on 11:1. I was told I need to do 10:1 compression to be able to do a 100 shot.

So which is it? Is it safe to do 100 shot form a wet kit on 11:1, or should I only do a 50 on 11:1?

Also, which kit should I use? Im planning on using a 4 fogger form nitrous express. Its this the best route? Should I do a single fogger wet kit?

I hope we can come to a real descision here, because I dont want my car breaking again (broken valve and spun bearing). I really want to be sure about what Im going to be doing.

This is what is happening to my block:
Custom connecting rods (increased length by 4mm)
Custom pistons and rings (nitrous coated,11:1 CR)
Custom wrist pins
Sleeving the block
Closed deck
Knife edged crank shaft

So tell me what you guys KNOW will be ok, I've heard all kinds of things so far. Thanks for your help i really appreciate it.

Dan
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Old 12-05-2002, 05:29 PM   #2
Eric SS
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Just curious, if you are going to run nitrous, why do you want ot go with 11.0:1 anyway? The jump from 10:1 to 11:1 will be worth less than 10% power. Not worth it in my oppinion. I would go with the 10.0:1 and not more than 10.5:1. Any higher and you also start ahving to worry about running higher octane gas and higher cylinder pressures.

In other words, let your nitrous take care of your extra horspower and not your CR

Eric
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Old 12-05-2002, 05:30 PM   #3
Eric SS
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Oh yeah, use a Wet kit and go with the Nitrous Express kit. The Solenoids are MUCH better than the NOS pieces and carry a lifetime warranty.

Eric
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Old 12-05-2002, 05:33 PM   #4
2002whitewrx
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that would put your car at about 13.5:1 compression when you hit the nitrous you will need some kind of msd box to retard the timing when you hit it or it will detonate, definately go wet if your going the nitrous route I myself would just put a turbo on alot less problems there!
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Old 12-05-2002, 05:39 PM   #5
Eric SS
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Quote:
Originally posted by 2002whitewrx
I myself would just put a turbo on alot less problems there!
I must respectfully disagree with you. I have never blown a motor using Nitrous, but have blown 2 turbo motors in a year

Eric
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Old 12-05-2002, 05:49 PM   #6
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just want to add that turbo's blow motors (see sidebar)
dcoty- where are you getting your rods and pistons? what brand, how much?

~Brian
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Old 12-05-2002, 07:05 PM   #7
Rob K
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Dcoty's brother here. The con rods are made by Oliver, and I think the pistons are made by CP.

More than 99% of his driving is done without Nitrous. It's a street car that will see both road course and 1/4 mile racing. All driving is on 94 octane, and he can switch maps with the unichip to a N20 map with less ignition advance for added safety. Maybe I'll set the N20 up on his car with a separate fuel system, so he can run some VP 116 race fuel when he uses the N20, but that's a lot of extra work and complexity.
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Old 12-05-2002, 07:48 PM   #8
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Road Course+ Closed deck= very bad results....

do you have a link to where he bought the pistons and rods?
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Old 12-05-2002, 10:27 PM   #9
Section 8
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Quote:
Road Course+ Closed deck= very bad results....
Tell us about this statement. Do you mean that with a completely closed block that since you are cutting off the water from the head, you will have problems, or something else?

cheeRS,

Greg
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Old 12-05-2002, 11:44 PM   #10
kturner
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Haven't you learned your lesson yet? Are you the guy rebuilding his motor from the last nitrous experiment? Anyway, my free advice would be to start at lower shot levels and work up, if the kit allows. Monitor everything possible, check plugs, etc. But, I am timid and actually detuned my 55 shot kit due to clutch slippage. I am very happy right about 40.
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Old 12-06-2002, 02:51 AM   #11
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if you plan to use a 100 shot of nitrous get 9.5:1 pistons...well unless you plan on putting a rod thru the brain pan. the problem is your compression is going to end up sky high and you are going to end up detonating on one cylinder which will load up the next and squeeze the rod bearing and you are right back where you started. If you are building the motor why not go with a low 100 shot 4 fogger NX system and later add a lower pressure turbo kit @ 9:1 you'd have a VERY fun and VERY driveable car...well then again that's all based on if you are after a NA beast or a driveable car.

and i'm with eric turbo's on stock bottom ends do end up breaking cars, engine management and boost greed are what determine when

jeremy
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Old 12-06-2002, 11:37 PM   #12
dcoty
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Thanks for the replies!

I am going for a driveable N/A car and I am planning on staying that way for sure. I guess a 50 shot is all i can do form what i've heard.

And yes, I am the one who broke a valve from my last nitrous experiment

I am not willing to sacrifice a 11:1 compression ratio for a shot of noirous once in a while, i would rather just stick with a total n/a build up.

Anyway, my ears are open to other responses, so keep them commin! I dont want to break my engine for the 3rd time .

Thanks guys, i appreciate it. Im starting to finally see what can and cant be done, becuase Ive hard different things from places all over, including cobb.

Dan
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Old 12-06-2002, 11:48 PM   #13
Eric SS
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Quote:
Originally posted by dcoty
Thanks for the replies!

I am going for a driveable N/A car and I am planning on staying that way for sure. I guess a 50 shot is all i can do form what i've heard.

And yes, I am the one who broke a valve from my last nitrous experiment

I am not willing to sacrifice a 11:1 compression ratio for a shot of noirous once in a while, i would rather just stick with a total n/a build up.

Anyway, my ears are open to other responses, so keep them commin! I dont want to break my engine for the 3rd time .

Thanks guys, i appreciate it. Im starting to finally see what can and cant be done, becuase Ive hard different things from places all over, including cobb.

Dan
Trust me, you will be much more happy with a 10:1 motor that you can squeeze more nitrous with than an 11:1 motor that you can squeeze less nitrous with. Why?? I'll try to make it short and sweet

Nitrous = TONS OF TORQUE!!

Say you go 11:1 with a 50hp shot. say for example that you have 250hp and 225lb/ft of torque off the nitrous and 300hp and 300lb/ft of torque with the nitrous

BUT, from 11:1 down to 10:1 CR you will lose about 8-10% power.

So, you will have 225hp and say 200lb/ft of torque off the nitrous. BUT, on the nitrous (with a 75hp shot) you will have 300hp but probably over 325lb/ft of torque!!! AND it will be in a more usable powerband.

I'll take the 10:1 motor that can run on pump gas all the time and have more torque instead of the 11:1 motor that relies on AWESOME tuning to run on pump gas with less torque.

Just make sure you always have nitrous... besides, if you are gonna race, won't you always use the nitrous? I know I did

Eric
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Old 12-07-2002, 03:10 AM   #14
HndaTch627
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Quote:
Originally posted by dcoty
I am not willing to sacrifice a 11:1 compression ratio for a shot of noirous once in a while, i would rather just stick with a total n/a build up.
everyone i ever knew that has run nitrous has said once in a while, yet the bottle heater is ona nd the bottle is open ANY time the car is running...kinda funny how that works
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Old 12-07-2002, 11:09 AM   #15
dcoty
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Jeremy, I see your point, and agree with it 100%. But I would prefer to have higher hp when Im not spraying since I really wouldnt use the nitrous very often at all (honest). I really want to go all the way on the n/a build, and losing compresion to run more nitrous which constitutes roughly 5% of my driving... id rather have the extra horses for the other 95% of my driving. But I see the torque sacrifice when using the nitrous when doing this.

But, you are sure I would be able to run a 50 shot from a nitrous express 4 fogger? Ive been told by a nitrous shop (dont know how reputable they are) to go with a single fogger kit from nitrous express. I really need to know what exact kit, style and shot I can handle(50 seems to be it), Ive heard so many different answers so far.

Good guess on the hp #s too, thats what we are shooting for, all i need now is a custom intake manifold (mines ported and polished) and Ill be set.

Dan

PS: Am I stubborn or what?
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Old 12-07-2002, 02:42 PM   #16
HndaTch627
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dan- the reason they prolly told you to runa single fogger is because of the shot you are looking for. Normally a 50shot isn't enough to worry about an individual fogger system. Now with the way a subaru manifold is designed i think it's the only accurate way to get even nitrous distribution to all 4 cylinder w/o the risk of puddling. Plus going with the 4 fogger system is safer then running a single nozzle especially if you plan to maybe bump the shot once in a while at the track....well good luck boys, but make sure you have some engine management that can pull timing because you are going to need to pull about 2-3 degrees away if you want to run a 100 shot.

Good luck

jeremy
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Old 12-07-2002, 04:44 PM   #17
dcoty
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Well, I figured a 4 fogger would be the best ption for me. The Unichip will be able to pull timing on a seperate map when I use nitrous.

It seems to worry a lot of people running nitrous on an 11:1 compression ratio engine, so Ill stick with a 50 shot and maybe consider tweaking it up a little more if im SURE nothing will break.

Anyway, it will be about 3-4 weeks before i get my car back, but I should be squeezing as much n/a hp out of it as possible until I go with a better intake manifold or even individual throttle bodies. Thanks for the help Jeremy (every time i put up a thread!). Anyone else?

Dan
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