Found my 8000 fuel cut
My ECU should be here soon.
Originally Posted by SR20DEN
Sure, don't be concerned about someone elses engine. Why don't you do something constructive and blow up your own engine first. Then you tell us all about it.
Originally Posted by Stephen Max
Be aware that this assumes that pi = 3. Kinda rough, but easy to use when figuring out piston speed in your head.
Originally Posted by IceY2K1
My ECU should be here soon.
By the way, I am waiting for you to return that composite manifold back to Dixit so he can send it to me for study & modification.
How would one go about documenting or measuring if float is actually or has occured? Seeing as power #'s have never been tested that high it would be difficult to discern where the valves begin floating unless power on the dyno drops from 200 to 0 in 1 RPM. A drop in the power band at 7900 could just be because the MEVI falls out of reasonance much more quickly than the stock manifold. Just wondering.
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Joined: Oct 2003
Posts: 334
Originally Posted by SR20DEN
I suppose now would be as good a time as any to throw some un-needed gas into the fire.
The VQ20DE used the same 73.3mm crank as the VQ30DE, however the new VQ23DE uses a 69mm crank. If someone with too much time and money on their hands wanted to try something different they could put the VQ23 crank in a VQ35 and get a 2966 cc engine that would rev to 8500 rpm to reach 3848fpm.
The equation for calculating feet per min is:
Metric:
FPM = (stroke x rpm) / 152.4
ex: (81.4mm x 7200) / 152.4 = 3845.67 (VQ35DE)
Inches:
FPM = (stroke x rpm) / 6
ex: (3.0" x 6500) / 6 = 3250 (Ford 302)
Also, the 3850fpm is just an example. It may or may not be the max allowable average piston speed on these engines. Stock SR20DEs can go to 4514fpm all day. (86mm x 8000)
http://www.poweredbynissan.com/Engin...ngineSpecs.htm
The VQ20DE used the same 73.3mm crank as the VQ30DE, however the new VQ23DE uses a 69mm crank. If someone with too much time and money on their hands wanted to try something different they could put the VQ23 crank in a VQ35 and get a 2966 cc engine that would rev to 8500 rpm to reach 3848fpm.
The equation for calculating feet per min is:
Metric:
FPM = (stroke x rpm) / 152.4
ex: (81.4mm x 7200) / 152.4 = 3845.67 (VQ35DE)
Inches:
FPM = (stroke x rpm) / 6
ex: (3.0" x 6500) / 6 = 3250 (Ford 302)
Also, the 3850fpm is just an example. It may or may not be the max allowable average piston speed on these engines. Stock SR20DEs can go to 4514fpm all day. (86mm x 8000)
http://www.poweredbynissan.com/Engin...ngineSpecs.htm
Out of curiosity, why's it over 6? And what did Stephen mean when you said it assumes pi is 3? How is pi involved at all? Nobody is doing anything with circles, spheres. Why wouldn't it be over 12, since there are 12 inches in a foot? I assume the earlier thing I saw with 3000+ fps was a typo, since you're now using fpm? 3800 fps or whatever is more than 3 times the speed of sound.
fps...fpm...picky picky.
Still shows a VQ35 at 7200rpm has the same mean piston speed as a VQ30 at 8000rpm. Take the lighter internals of the VQ30 into account and he's going to run into valve float or something else limiting power.
Still shows a VQ35 at 7200rpm has the same mean piston speed as a VQ30 at 8000rpm. Take the lighter internals of the VQ30 into account and he's going to run into valve float or something else limiting power.
Senior Member
Joined: Oct 2003
Posts: 334
Originally Posted by SR20DEN
If you want to use 12" you have to change the equation. It's been simplified.
fpm= (2*stroke*rpm)/12
And we are dealing with circles. The rotating crank offset.
fpm= (2*stroke*rpm)/12
And we are dealing with circles. The rotating crank offset.
Originally Posted by SR20DEN
Everywhere I look I see that equation. I havent found any that use pi. This equation is for mean piston speed. To determine maximum piston speed it would require pi.
Originally Posted by Eric425
Where does the 2 come from? You're calculating the stroke in inches * rpm which would be the total distance in inches over 1 minute. Then divide that by the number of inches in a foot to find how many fpm, right? That's the equation I saw in the first post. It looks like an extremely simple equation, like what 10 year olds do in their math class. The rotating crank shouldn't have any effect unless it somehow fits into the equation, which it doesn't seem too. Like we don't throw in pi somewhere in every equation just because we're on a planet that's spherical. Or is there a different version?
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