Blocking off coolant to plenum

[flyin ryan]

Originally Posted by secondchance

I came accross an interesting calculator that calculates relative horsepower based on air temp, atmospheric pressue and relative humidity:

http://www.anycalculator.com/enginehorsepower.htm

Based on this 100 degree to 90 degree (10 degree differential) holding air pressure at 31 and relative humidity at 30% for both shows 102.2% and 104% respectively - translating to .18% hp differential per degree.

If this is true, for a motor of 350 hp, per 10 degree drop of intake air should result in 6 hp gain roughly.

That's the general factor we use for 'Intake Air'.

[LGAFF]

Can air coming in heat that quickly passing through the plenum?

[Locobob]

Don't expect big power gains from blocking off the coolant to the plenum and TB. I have mine blocked off and rerouted through the tops of the coolant pipes - to help bleed air from the system. I also have the phelonic spacers between the plenum and injector housings. All of this amounts to a 10-15 degree difference in plenum temps. This will help cool the inlet charge somewhat but not to the full 10-15 degrees. The benefits of this mod are 1. easier plenum pulls 2. less chance of leaks 3. a small performance gain - not much but a little here and there adds up.
I did an article on this subject for HOTB a year or two ago - check it out.

[XfireZ51]

Originally Posted by LGAFF

Can air coming in heat that quickly passing through the plenum?

That would be my question also. I think the "isolators" are not worth it from an insulating point of view. Now if you use a intercooler...

[Paul Workman]

Originally Posted by XfireZ51

That would be my question also. I think the "isolators" are not worth it from an insulating point of view. Now if you use a intercooler...

Dom, you're right. Considering the mass of the intake and the IHs, and the specific heat of aluminum, compared to the mass of air taken in at WOT in the quarter mile, it is easy to see that the temp of the TB/Plenum is pretty small potatoes. First, the air temp is going to snatch the heat out of the intake etc like a candle in the wind; quickly gone for any practical concern over heating of the air. And second, the surface area of the plenum/IHs, etc are tiny compared to the core of an intercooler - a very inefficient heat exchanger, is my point. The heat transferred to the air is going to be minimal at WOT.

If we really want to take advantage that cooling the air (read: air density) provides, the intercooler seems like it might make sense. But, to get meaningful cooling of ambient air (e.g. down from say 85º to 30ºF) for a NA engine at WOT means the core is going to have to operate well below freezing al la -20 or -30ºF. Unfortunately, the water vapor would condense and freeze when coming in contact with a core that cold. It is one thing to bring supercharger air at over 200ºF down to 110º with the intercooler, but to keep from freezing ambient air/moisture, the IC core is going to have to remain above freezing, and that means much less efficiency.

But, still a 30º drop from 85º ambient would still mean around a 15 hp gain to a 400 hp base engine. The question is net gain, or in other words, how much power does the weight of the intercooler and coolant and coolant handling equipment cost in HP offset?


After doing the math, I've reconsidered bypassing the TB for any other reason than to make pulling the plenum easier. But, the intercooler...that intrigues me. (How 'bout a bottle of super-chilled water forced thru the intercooler beginning at the launch? Just thinking "out loud"...)

P.

[Aurora40]

How would you use coolant to bring an intercooler's core temp down below ambient temperature? Wouldn't you need a refrigerant?

It would seem like using the A/C on the intake charge. My guess is the power lost to run the compressor would offset any gain.

What about some kind of water/alcohol injection? You could presumably cool the solution ahead of time, keep it in a cooler on the way to the track, then fill the reservoir up before you make a run. I dunno...

Edit: I guess I skimmed your post, I missed the part about the cold water for the I/C.

[secondchance]

Originally Posted by Aurora40

How would you use coolant to bring an intercooler's core temp down below ambient temperature? Wouldn't you need a refrigerant?

It would seem like using the A/C on the intake charge. My guess is the power lost to run the compressor would offset any gain.

What about some kind of water/alcohol injection? You could presumably cool the solution ahead of time, keep it in a cooler on the way to the track, then fill the reservoir up before you make a run. I dunno...

Edit: I guess I skimmed your post, I missed the part about the cold water for the I/C.

I agree running compressor would negate any gain.
Water/alcohol injection would work. If I remeber correct, Turbo Mustangs back in early to mid- 80s had water injection (I can't recall whether factory or aftermarket). I heard those cars were running into rusted spark plug problems.

[flyin ryan]

Originally Posted by Locobob

Don't expect big power gains from blocking off the coolant to the plenum and TB. I have mine blocked off and rerouted through the tops of the coolant pipes - to help bleed air from the system. I also have the phelonic spacers between the plenum and injector housings. All of this amounts to a 10-15 degree difference in plenum temps. This will help cool the inlet charge somewhat but not to the full 10-15 degrees. The benefits of this mod are 1. easier plenum pulls 2. less chance of leaks 3. a small performance gain - not much but a little here and there adds up.
I did an article on this subject for HOTB a year or two ago - check it out.

Robert's right, gains will be small. If you want to do it for the sake of doing it, go for it...just don't have un-realistic expectations .

[Locobob]

Originally Posted by Aurora40

It would seem like using the A/C on the intake charge. My guess is the power lost to run the compressor would offset any gain.

Didn't Ford do something like this on the supercharged Lightning pickup truck?

[diamond zr1]

twin turbos mounted in the back,pushing forward thru a intercooler in front of the radiator,cooled with carbon dioxide bottles is the answer on my twin turbo car/check it out in the jan 09corvette mag.Hennessey uses a warer spray over the innercooler on his 09zr1/messey