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Compression ratio and nitrous


Crash1647545504

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spray loves compression....

 

the higher you go the more torque its going to make, you also increase the cylinder pressure alot so if you up the ratio don't skimp on bottom end parts like piston pins, rings, and rod bolts, the initial shock load from nitrous is very high.

 

it does also help to know what your trying to build. if its under 400 cubes I wouldn't go over 250 hp on a stock shortblock, if your over 400 cubes 350 hp would not be out of the question.

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I would also say lower it, not quite as much as for a boosted application. By running nitrous you are adding more "stuff" in the cylinder ,when compared to a non-nitrous setup, like a boosted application. I would imagine that a nitrous setup would be similar to a small boost level. I would be interested a true answer.
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Q: Can high compression engines utilize nitrous oxide?

A: Absolutely. High or low compression ratios can work quite suitably with nitrous oxide provided the proper balance of nitrous and fuel enrichment is maintained. NOS kits are used in applications from relatively low compression stock type motors to Pro-Modifieds, which often exceed 15 to 1. Generally, the higher the compression ratio, the more ignition retard, as well as higher octane fuel, is required. For more specific information talk to one of our technicians.

 

this is right From Nitrous Oxide Systems website.

 

http://www.holley.com/HiOctn/TechServ/TechInfo/NOSTech5.html

 

compression makes power, regardless of your engine combination.

 

you have to have your air fuel mixture right and your timing down.

 

most people are scared of compression becuase you can't make mistakes and its always right out on the ragged edge, but with a good tune and a stout shortblock the skies the limit.

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Nitrous does not have the same detonation issues that forced air does. Many people Up the compression for nitrous like dave said it is just a matter of tune and if your pistons, rods, crank, and rings can hold the cylinder pressures.

 

What kind of compression are you thinking of? And how large is the shot gonna be?

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Sorry shoulda been more specific.

 

The car im going to buy is a honda, 4 cyl. the factory c/r is 9.3 or 9.2, I found JE SRP pistons for this motor that either upped the ratio to 10.0 or dropped it to 9.0 but nothing with stock ratio. I also have a kit with rods, pins, rings, ect... the plan is for a NX 125-150 shot wet, direct port.

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You will have to get pistons that are setup for nawws, otherwise your wasting your time filing the rings for nitrous. You can go sky high with the compression and sky high with the nitrous. Compression isn't the issue when using nitrous, most of the time it's fuel or lack there of. Just be sure your car/engine can handle the amount of nitrous you want to run.
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Aw MANg! and i was hopping filing the rings was all i had to do!!!! tongue.gif

 

Fuel shouldnt be an issue with my nice beafy fuel pump I have in my garage and some nice timing. and the fact its a direct port wet kit.

 

screw dry kits i learnd my lesson when i blew my last 4 banger up on a 100 shot... man that thing was bullet proofe for 1 1/2 years tho.

 

and iv already got my list of Forged pistons rods and other internal parts... now all i need to do is wait for mike to fix the CRX so i can buy the civic smile.gif .... oh and sell the beretta, and then actually get goin with this.

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Guest racinbird

heres a good link that helped me, http://www.go-fast.org/z28/new_to_nitrous.html

 

I always perfered a dry system, with a good fuel system the computer would adjust everything and no need to add fuel lines/solenoids to the system, less to go wrong, seems safer to me.

 

You will need a good tune, plugs, safety devices, and strong running sealed engine.

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This isnt my first dealing with nitrous.

 

Dry kits are a mistake, especially when dealing with small motor aplications. Say I went with a dry kit. I spray through a single nosel before the MAF. But the problem is the same amount of nitrous isnt going into each cylinder, less nitrous may be going into number 4 than say number 1 or 2 but the MAF is adjusting to increase the same amount of fuel into each cyl. So now you may have cyl 1 and 2 running a nice air fuel, but cyl 4 is running ritch.

 

So say I go direct port so that the same about of nitrous is going into each cyl. But witch a large amount like 150shot now my stock injectors cant handle the increase now i have to spend money on new injectors... and now im also not spraying through the MAF and i have to find another way to increase my fuel

 

With a wet kit. The right amount of fuel is delivered with the nitrous. No upgrade in injectors or worries about some cylinders being ritch or lean and others being even.

 

Dry kits are suposed to be the new technology in nitrous but IMO they are only safe up to what your stock fuel system can handle.

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Guest racinbird

Thats all true, Ive just heard of more problems arising from the fuel side of wet kits acting up rather than dry kits not being even throughout the cylinders.

 

Rich is always better than lean when dealing with WOT!!

 

If the one of the fuel solenoids goes out it would only take a fraction of a second to destroy the cylinder...Im not a nitrous expert by any means, I just did a lot of research last year when I was thinking of installing a kit on my Z

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waoh waoh waoh... since when is 10:1 "HIGH"??? Dude just do the rings and besure to watch the mix. Your not going to tear up anything but driveshafts and tires.

 

Your best bet is to run a second fuel line from a secondary fuel cell... like a 1 or 2 gallon, and fill it with some 100 octane or somethin like that. Use an inline pump, and inject that into the wet side of the nitrous nozzels. Do a direct port so your not getting a "hot" cylinder. Youd be surprised how awesome and powerful nitrous can be wen set up properly and tuned finely.

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Originally posted by racinbird:

Thats all true, Ive just heard of more problems arising from the fuel side of wet kits acting up rather than dry kits not being even throughout the cylinders.

 

Rich is always better than lean when dealing with WOT!!

 

If the one of the fuel solenoids goes out it would only take a fraction of a second to destroy the cylinder...Im not a nitrous expert by any means, I just did a lot of research last year when I was thinking of installing a kit on my Z

Yea, its cool thats just why i dont like dry now, I had those problems gettin good A/F on my last Dry kit, till i blew a chunk in my #4 cyl

 

this will be my first wet kit so lets hope it goes well

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Guest rperry74
Be very careful when ready to use your system. Make sure all fuel feed line have been bled and there are no air bubbles. When nitrous has no fuel to burn it will burn up whatever it can for fuel, ie; pistons, rings and in really bad cases, cylinder walls and heads. Also, a nitrous backfire due to a lean fuel condition is UGLY. I know, it's what killed my mustang. I have heard of sheared intake bolts and wasted heads after a nasty backfire. In my case it was both (2 stage 500 fogger system, backfired on intialization of second stage at 1/8 mile. BOOM!) As far as compression ratio goes, like the website says, the higher the better. Buddy in Cali had an 89 camaro pro streeted with a 409 cube small block and 14.5:1 compression. With roughly a 400 shot the car was good for 8.20s. Also, the more efficient the engine set up, the more power you will see from your system. N.O.S. have seen tests where a 250 horse plate system with really good heads and the like delivered over 300 horses, so efficiency is also key. Good Luck.
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Ben, one of the things that you will need to watch with the EFI motor and spray is how the computer limits RPM, some drop fuel others drop spark. If you are dropping spark, then no problem, but if you are dropping fuel, you're gonna go lean when you hit the limiter. You might consider a window switch, and drop the spray a few hundred RPM short of the limiter.

 

I figure that you already knew about this, but I figured I would mention it anyway.

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