Nitrous and head cfm

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Brooks James

Brooks James

VET, CPT, Huey Medevac Pilot
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I may be way off base, but Im thinking that
Nitrous can somewhat "go around " the notmally aspirated rules of head CFM and how much hp it will produce.
Example:
Say a 360 magnum @400 hp has a 200 shot of nitrous on it. The heads flow 220 CFM and will allow 450 horsepower. How much beyond 450 would the nitrous add, the heads being limited in flow ?? Theorhetically , of course
 
Only one way to find out, put a turbo and No2 on it, that way you have the best of both worlds, forced induction and thermo expansion of juice….:lol:
 
There it that. Had to give ya a smart *** Anwser. But it was also truthful. Juice is not going to change the flow of a head, it only help with the O2 concentration level in the air sucked through the head. Now, forced induction like a turbo will “go around” this due to air being forced into the chambers…
 
Scody21 said:
There it that. Had to give ya a smart *** Anwser. But it was also truthful. Juice is not going to change the flow of a head, it only help with the O2 concentration level in the air sucked through the head. Now, forced induction like a turbo will “go around” this due to air being forced into the chambers…
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Are you saying that 150. Hp worth of spray would be wasted ??
 
Episode 13 of engine masters, available on you tube. They ran nitrous on a 360hp 305 Chevy with vortex heads (pretty good heads). Made 200 more hp on a 150 shot, a 250 shot made 619hp, right on rated.
They blew it up with a two stage 300 hp shot, but Nitrous guru Monte Smith (sadly passed away) said it should have survived, and would have, if they had taken enough timing out.
There is a lot more to making power with nitrous than bolting a system on.
 
Brooks James said:
Are you saying that 150. Hp worth of spray would be wasted ??
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Nope. Just saying that your question about how juice could “go around” head CFM is not how juice works. Juice works on thermo expansion in the cylinder by adding more O2 once fired. That’s why I used the turbos as an example, as forced air don’t care about CFM as it forced into the hole, while only so much juice on N/A can be sucked into the hole limited by your CFM.
 
Forgot to mention that the enginemasters test used 118 octane fuel. For giggles, i just checked current prices. A 5 gallon pail is $110, so,$22/gal.
 
33IMP said:
Forgot to mention that the enginemasters test used 118 octane fuel. For giggles, i just checked current prices. A 5 gallon pail is $110, so,$22/gal.
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I just watch one and they had a 400 horse BP crate with 10/1 compression and they ran 87, 91, 110, 116 and E85. All the fuels ran within 5 HP of each other and e85 was 10-15 HP higher. I’ll see if I can find the link..
 
33IMP said:
Forgot to mention that the enginemasters test used 118 octane fuel. For giggles, i just checked current prices. A 5 gallon pail is $110, so,$22/gal.
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That test about octane is good.

I used to race in a very limited class for engine mods. Most guys were spending money on the 110 fuel. We tested it against the pump 87 and the 87 made more power. The other kicker was fuel checks. We would buy 87 at the local AM/PM or whatever. Test it for specific gravity. Quick run on the calculator for the max tested SG allowed, a dash of 8-14% nitromethane, and right at the top of the scale. Never got caught! But my exhaust sure smelled funny and idled crisper than the rest of them! When I quit racing I told the others about the AM/PM fuel, and how the 110 was a waste of money. Never said a word about Nitromethane.
 
crackedback said:
That test about octane is good.

I used to race in a very limited class for engine mods. Most guys were spending money on the 110 fuel. We tested it against the pump 87 and the 87 made more power. The other kicker was fuel checks. We would buy 87 at the local AM/PM or whatever. Test it for specific gravity. Quick run on the calculator for the max tested SG allowed, a dash of 8-14% nitromethane, and right at the top of the scale. Never got caught! But my exhaust sure smelled funny and idled crisper than the rest of them! When I quit racing I told the others about the AM/PM fuel, and how the 110 was a waste of money. Never said a word about Nitromethane.
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Agree. I think they used the 118 for two reasons: They wanted to make darn sure when it blew up, it wasn't from detonation, and they had it.( at Westech for forced induction testing)
I think that 305 test engine might have made more power on 110, and maybe even 91, but it would have blown up sooner on 91.
 
Long story, short version...Long time ago I ran a 318 in Colorado with ported J heads and a 150 shot, it ran 13.9 at Bandimere (~9500' DA). Same engine about a week later with ported 302 heads the car ran a best of 14.5 on a 150 shot (also ~ 9500' DA). So yes, head flow does matter.
 
Jeremiah said:
Are you doubting me, fact checking, or both? My car has a 4 speed and the engine dyno number follow the chassis dyno numbers which follow the track performance. Cab Burge has used the same dynos and raced at the same track with predictable results.

Maybe fact check a fellow bracket racer? Lol!
Click to expand...

People around here like ETs because it tells a lot more than just a big ticket dyno number.

It's not about suggesting anyone is a liar, more a curiosity to help make useful comparisons to other known performance benchmarks.
 
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