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Old 02-26-2001, 03:57 PM   #1
Xscreamer
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Post Kevin Thomas Got a Nitrous Question???

Can a stock EJ25 handle a 75 shot every once in awhile??? I have intake, pulley, exhaust, with a S-AFC. Im putting my car on a dyno on the 9th down in maryland. Since i have to dyno for a hour and half when im done tuning my s-AFC I want to have charts with the my bolt-ons, 55 shot, 65 shot, and 75 shot... Can the motor handle it???
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Old 02-26-2001, 05:06 PM   #2
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When in doubt, don't do it.
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Old 02-26-2001, 07:46 PM   #3
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I dont really doubt it, I just dont know enough about NOS to make a good judgement...

~Brandon
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Old 02-26-2001, 09:14 PM   #4
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Kevin doesn't have a 2.5 He has an Outback Sport with the 2.2 liter.

Imprezinator has a NOS kit on his car, but I don't think it was a 75 shot. I think it is closer to a 50.
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Old 02-27-2001, 08:12 AM   #5
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I am plannin on using the 55 shot for daily driving, but for the dyno can i bump it up to 75 with out breaking something...

~brandon
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Old 02-27-2001, 04:16 PM   #6
Kevin Thomas
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AaronB is right. I own a 1997 2.2ltr Impreza Outback Sport Wagon. I am now running a 60 shot with 5psi of non-intercooled turbo boost. I don't know what that would equate to with just using Nos alone.

Any of you engineers hear care to figure this out? Question: What shot of Nos is equal to the power output of a turbokit using 5psi of non-intercooled boost with a 60 shot of Nos? Maybe the answer lies within that? *shrug* I take it that a 70 shot would be the limit based on there being a general agreement that 7psi of boost (which I take would be around 70hp in a Minnam Stage II) is the max your injectors can handle. I'm just using common sense but maybe someone has a formula to figure this out.

As far as Nos not breaking anything, if you have enough fuel pressure the engine should be fine, at a 70 shot. Your tranny is another issue. I'd look out for that if not anything else.

[This message has been edited by Kevin Thomas (edited February 27, 2001).]
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Old 02-27-2001, 06:44 PM   #7
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FPR if you plan on a lot of 75 shots cheap insurance..not exactly the best solution..but it will help
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Old 02-28-2001, 06:16 AM   #8
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I have a S-AFC that has been Dyno tuned so i think it will be a little better than a FPR...

~Brandon
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Old 02-28-2001, 06:25 AM   #9
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How does the SAFC have anything to do with nitrous? I didn't know it had a function to increase fuel when the nitrous is on?

Most nitrous kits have some way to increase fuel when on the juice. Usually they increase fuel pressure or injector on-time. If you tune the SAFC for nitrous won't it run WAY rich the 99.999999% of the time you're not using the nitrous?

Tony
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Old 02-28-2001, 11:13 AM   #10
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I have MY99 with intake, pulley, and exhaust so once i hit the hit rpms it leans out real bad. So my S-AFC will be tuned to run the correct A/F ratio at each rpm. Yes the Zex kit does boost the fuel, but that doesn't mean that it will be to keep the internals in tact...

~Brandon
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Old 02-28-2001, 11:20 AM   #11
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I have no idea if your internals will be ok but I suspect they'll be fine if you have enough fuel.

My point was the usefulness of the SAFC for nitrous. You either tune it for N/A or you tune it for nitrous, either way your a/f ratio will be incorrect when you're running the car in the mode you didn't tune for. I would use the dyno to tune in the SAFC for N/A and make sure the zex kit boosts the fuel up enough to keep your ratios correct for nitrous.

Tony
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Old 02-28-2001, 11:30 AM   #12
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If you really want to be safe, get a good fuel pump. An FPR isn't a bad idea, either, but I found that mine ran a bit lean with the stock fuel pump. Got a Holley 255LPH pump in there, and all was well. That didn't solve my other problems with the ZEX kit though. But I have already explained those in enough depth, I think.
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Old 03-01-2001, 04:06 PM   #13
Kevin Thomas
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I didn't mention it earlier (I think I should have) but fuel pressure in the Nos Kit that I use *#5122* goes up from 38-45psi to 60-70psi. No fuel pressure risers or additional fuel controlling device is needed. That's not to say that these devices can not be used. It specifically states that fuel flow is accomplished by increasing the fuel pressure and fuel flow rate. Just some food for thought!
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Old 03-01-2001, 04:20 PM   #14
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Ok, regular air is 3 parts nitrogen, and 1 part oxygen. NOS is 2 parts nitrogen, and 1 part oxygen. When your engine is running, it is burning the OXYGEN and the FUEL. So, when you run NOS you need to add fuel to the mixture (the reason alot of people have bad luck with dry systems). Get yourself a AFR guage and monitor it a WOT (if that is where you are going to us it). If you are running rich, it will be safe to add nos, but if you are lean, you are driving a bomb. NOS is very same and doesn't do damage to the engine IF DONE PROPERLY!!! My co-workers drag car runs 1000HP of NOS, and he runs all seans before he rips into the motor. Just remeber to add fuel. You will probably run into driveline problems (clutch slipping, wheels spinning, etc) before engine problems if you make sure you have enough fuel. Just run short busts and check you plugs until you find the magic number you need.
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Old 03-01-2001, 06:27 PM   #15
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Make sure you run a wet system. If you jet the fuel and nitrous correctly you should be ok. Then you can tune your car on the dyno without NOS and when you use NOS the wet system will add the necessary fuel.
MAKE SURE YOU HAVE A PROFESSIONAL TUNE IT!!!
You might also need to retard your timing?
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