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View Poll Results: How much nitrous will it take?
100 shot 3 12.00%
125 shot 0 0%
150 shot 5 20.00%
175 shot 1 4.00%
200 shot 16 64.00%
Voters: 25. You may not vote on this poll

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Old 01-26-2008, 05:24 AM   #21
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Ok, here's a pic of the graph I made in Excel, and the numbers I used in excel. I didn't know how to scale the x-axis for RPM, but I labeled it anyway. The dot's begin from the left at 1K RPMs, and increase in 500 RPM increments. This graph is for 270 flywheel torque. If 270 ft/lbs. was the limit on a stock engine, then a 100 shot would be safe at 3500 RPMs, a 150 shot by 5500, and a 200 shot by 6500. However, I'm pretty sure I can make more torque than that safely, which means a 200 shot is starting to look pretty possible. Waiting to hear a safe max flywheel torque value...
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Old 01-26-2008, 03:57 PM   #22
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So what's going on there? It's miata torque plus a constant amount of HP? Obviously not, since at low RPM the lines would look nothing the same. I think you're onto something, but explain it better please.

A car that made 250 hp wheel at 5200 rpm would be making about 300 ft-lbs. In the realm of reasonable. In the realm of reasonable who relies on this car to get them from point A to point B? I would definately say no.

But back up transportation if you're going to play with numbers like that. Things are over might quick in a system like that. I think you could do it, but the more you count on your car, the less of a good idea even something "safe" becomes. :-(
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Old 01-26-2008, 04:29 PM   #23
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It's miata hp plus nitrous HP at any given RPM, that would add up to 270 ft/lbs. of torque. I need to make better graphs, but I'm not very good at excel. I'll add a thrid line later that shows max HP the motor can make at any given RPM, if it makes 270 ft/lbs. of torque. That line would simply be the addition of the stock hp plus the nitrous HP.

I may be wrong, but I think I was told the motor could reliably make about 400 ft/lbs of torque with good tuning and not bend a rod.
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Old 01-26-2008, 05:38 PM   #24
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Quote:
Originally Posted by patsmx5 View Post
It's miata hp plus nitrous HP at any given RPM, that would add up to 270 ft/lbs. of torque. I need to make better graphs, but I'm not very good at excel. I'll add a thrid line later that shows max HP the motor can make at any given RPM, if it makes 270 ft/lbs. of torque. That line would simply be the addition of the stock hp plus the nitrous HP.

I may be wrong, but I think I was told the motor could reliably make about 400 ft/lbs of torque with good tuning and not bend a rod.
The max power it can make at a given RPM for 270 ft lbs is (RPM * 19.5). A straight line.

I'd like to see a plot of that line, minus the stock miata HP, and that will tell you how much of a shot you can handle at any rpm.
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Old 01-26-2008, 08:37 PM   #25
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Quote:
Originally Posted by AbeFM View Post
A car that made 250 hp wheel at 5200 rpm would be making about 300 ft-lbs.
Ummm, no, it would be making about 250 ft/lbs at 5200 RPM.

Now as far as a "safe" value... Running a 5 speed. I am going to suggest that with a staged progressive controller, a 150 shot is pushing it. You will begin to bust transmissions. With the six speed, a 200 shot is pushing it (but doable.)

As far as the motor goes. I think it's capable of handling 300 ft/lbs of torque (total; N2O plus stock torque) with solid tuning, but I would replace the rods just as a precaution. The rods are gonna take a beating and you want something stronger than stock. I don't like the stock rods with juice at these levels even though I suspect they would stay together.

And just because I think it will stick together don't mean ****... LOL, You are definitely looking at the outer rim of sensibility.

Mark

Last edited by Markp; 01-26-2008 at 09:00 PM.
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Old 01-26-2008, 08:45 PM   #26
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Quote:
Originally Posted by patsmx5 View Post
Well, marks post makes sense. However, I did some research a while back and a 100 shot at 800 RPMs will blow a miata headgasket. I've sprayed a [email protected] on a Honda 4cylinder forever, so I guess a 100 at 3K isn't much worse.
Well duh, that's because spraying a 100 shot at 800 RPM would make 656 ft/lbs of torque... of course it's gonna spit the damn gasket. Just as if you sprayed a 650 HP shot at 5200 RPM... It's gonna spit the freaking gasket. Care to guess what the cylinder pressures are on a 650 shot?

When you spray a 75 shot at 3,000 RPM it makes 131 ft/lbs of torque and at 5200 RPM it makes 75 ft/lbs of torque (and guess what, at 800 RPM it makes 492 ft/lbs of torque.) However it ALWAYS makes 75 HP.

Mark
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Old 01-26-2008, 09:22 PM   #27
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Quote:
Originally Posted by Markp View Post
Ummm, no, it would be making about 250 ft/lbs at 5200 RPM.
Heh, sorry, I shortcutted. What I meant to say was:
Give there are a number of reliable, 280 peak whp turbo cars out there, figure at 5200 rpm they are in the 250 hp range, and there are about 50 hp lost in the drivetrain, that's around 300 ft-lbs. So 300 ft-lbs at the crank is probably reasonable with a good tune.

Quote:
Originally Posted by Markp View Post
Now as far as a "safe" value... Running a 5 speed. I am going to suggest that with a staged progressive controller, a 150 shot is pushing it. You will begin to bust transmissions. With the six speed, a 200 shot is pushing it (but doable.)
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