Explain why the cooling effect of N2O wouldn't negate the need for a FMIC

sizemoremk

Registered User
Hey guys!

Just pondering some things here about FMICs and N20... FMIC not being an option...

I guess I have some other underlying questions as well...

I understand that that the ACT temp sensor will retard timing when the heat goes up. Why does this need to happen?

I also read that for every 50 HP of N20 that you need to retard the timing a degree or two... why is this required?

If hot = less dense = a need to retard the timing?
then why does
N20 = more dense = a need to retard timing?


Is it the heat itsef, and not just the density of the air as a result of heat, that creates a need to retard timing?

I wouldn't think a 200ish degree air charge "temperature itself" would make much of a diffrence inside the comnbustion chamber (other than density)... My understanding is the the reason my SC hauls so much more A$$ on a cool night, is the density of the air charge, not necessarily the temprature of it; understanding that the two are related.


From what I read the FMIC would allow you to keep the timing more advanced via the ACT temp already.

My question is why would cooling by FMIC, and the cooling effect of N2O be any different?

By the way, I am not talking about a spray onto the IC N2O setup, I am talking about into the intake N2O :D Mine is in the lower IC tube before the ACT sensor.

My understanding is that the N2O just releases extra O2 to be burned, and that the cooling is more of a side effect as it is being released.

Which creates the more dense charge?
The extra O2 released by N2O creating a more dense air charge.
OR
The FMIC

I found a few plaes that said N20 come out the bottle at about -125 degrees F. I know the N20 is only a small percentage of the air charge, but I read a few differnt places that the entire air charge, generically speaking, would be between 60-75 degrees cooler, meaning 6-7% more HP correct, and that is just from the temp change...

But even 50 degrees cooler seems to me. I would think that the cooling effect of N20 would be very close, perhaps even better than the cooling effect of the FMIC. I know that FMIC would be an "all the time mod," and also, the pressure drop is better on the FMIC, but my car is quick enough on the street, I only need the power every once in a blue moon when I get to the dragstrip...

Any clarifications to make???

Thanks for looking!
 
Yeah, that is a VERY good point....someone please chime in...as I am thinking of a 30 shot after the IC.....
 
sizemoremk said:
I understand that that the ACT temp sensor will retard timing when the heat goes up. Why does this need to happen?

Prevents detonation.

sizemoremk said:
I also read that for every 50 HP of N20 that you need to retard the timing a degree or two... why is this required?

I believe, N20 gives you more combustion, which will make more heat, retarding the timing reduces that, which keeps your pistons from melting.

sizemoremk said:
If hot = less dense = a need to retard the timing?
then why does
N20 = more dense = a need to retard timing?

Hot intake temps=less dense=EEC pulls timing.
N20 = more dense= more combustion = more heat = need to retard timing


sizemoremk said:
Is it the heat itsef, and not just the density of the air as a result of heat, that creates a need to retard timing?

?? :confused:

sizemoremk said:
I wouldn't think a 200ish degree air charge "temperature itself" would make much of a diffrence inside the comnbustion chamber (other than density)... My understanding is the the reason my SC hauls so much more A$$ on a cool night, is the density of the air charge, not necessarily the temprature of it; understanding that the two are related.

I think that makes sense. :confused: Your car will run better on a cool night. Density is also relevant to elevation.

sizemoremk said:
My question is why would cooling by FMIC, and the cooling effect of N2O be any different?

N20 cools alot more.
 
So the ACT retards timing when hot sue to heat, and not the density of the air charge.

So a difference of 50 degree s ro so DOES make a difference in the combustion chamber temp?

I would think that 50 degrees hotter in a 2000+ degree combustion chamber would be a drop in the bucket.

Is the intake temp exponetially increased in the combustion chamber?

As a guestimate, does say a 75 degree intake temp produce a 2200 degree combustion templ and a 125 degree intake temp produce like a 2500 degree combustion temp?

I would also have thought that the less dense air as a result of the higher temp would kinda cancel out the temp change...

I guess I am not quite understanding the relationship of temperature/density in relatino to combustion temps....

Any more explanations?

Thanks guys!
 
Running a 25HP shot of N20 would be about equal to a good FMIC. Because both are creating a denser charge of air. Only the N2O gives you a denser charge because it is so cold...and you also get a lil sumn sumn from the oxygen injection when the molecules split.

BUT....consider $1400 for a FMIC vs. $400 for a N20 Kit. You save $1000, but you never run out of FMIC vs. a bottle that you need to refill. It costs about $35 to fill a 10# bottle. So once you've filled the bottle 28 times you could have paid for a FMIC. If you are using the N20 constantly like you would a FMIC then you will probably go through several bottles before you know it.

Therefore....I don't think it would be a good idea to use N20 ONLY at 25HP for the cooling purposes. But rather you could use a 50-75HP jet and not only get the cooling, but an actual increase in performance that would cost thousands of dollars extra in performance parts to achieve. At that point, it starts to make more sense.

You still have to worry about something that is not constantly on tap though. With N20 you need full bottles, fuses and solenoids that may crap out...you have to pay attention to bottle temperature and may invest in a heater and thermostat + bottle cover? Purge system? Then you are spending a few hundred over your innitial costs.

I toyed around with a CO2 system for my stock intercooler last year. The kit was very nice and cost $350. I could not get the hobbs switch to work though and had to manually purge the CO2. Stupid me kept forgetting to turn the Co2 back off which is why at last years Shootout I popped like 4 fuses. I also burnt a 20 ft Nitrous line on my battery terminal. I smoked a solenoid. The bottle was never big enough and needed filled constantly. Even in rough condition the system put 7+ RWHP down so I'm sure it could have produced 15 RWHP............but for me...........I got tired of dealing with the annoyances that came with it.

I ditched the CO2, built my own FMIC for $700...and have the constant power gains with no hassle.

Micah
 
I am running the 50 shot of N2) right now, and will be gonig to the 75 maybe more :D when I get time to play with my EEC tuner.

But from what I gather, for 1/4 mile purposews, the FMIC gains would be negligible if you are running NOS while at the track. The pressure drop could be better with the FMIC, but is that even a factor with a 50-75 shot of N2O?


Thanks guys!
Just wanting to make sure I am understanding all of this right!
 
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