parish8

iTrader: (6)

help me out here, i am a little confused. by looking at some compresor maps and turbo calculators i see

1291cfm = 93lb of air at 90deg

but only 71lb of air at 262deg

if a t76 is rated at 91lb of air max where is that measured because if the inlet temp is 90deg the output temp will be ~262deg and that is a way diferent weight of air.

i assume the cfm's are constant thru out the system, if the turbo can put our 90lb of air at the incresed temp then once intercooled it will put out alot more air.

does that make any sence, i am not even sure i understand the question but i am sure i would get alot more power with a really good intercooler.

Black Blown 02

Not sure if I understand the question correctly, but I know if you have a given amount of air and change the temperature, it is still the same amount of air it just takes up more or less space depending on the temperature.

Lets say the turbo takes in 90lb of air at 90 degrees.

It heats that air to 262 degrees and sends it to the intercooler.

The intercooler cools it back down to 100 degrees.

You should still have the 90 lbs of air you started with.

If I understand it right, when its 262 degrees, its the same amount of air, it just takes up way more space.

Black Blown 02

I think the only thing that is going to change the amount of air your engine sees is the temperature of the air at the inlet of the turbo.

Once you get the air past the turbo then the mass air the engine sees cannot be changed.

If you put ice in the intercooler on a 100 degree day and saw 50 degree IAT's going into the TB, you'd still have the same mass air reading, just cooler temps and more detonation resistance.

Its the 50 degree days that your mass air readings will get crazy!

parish8

iTrader: (6)

so you are saying the cfm's are not constant at all but the lb/min is. i guess that makes sence, a suck thru or a blow thru maf should read the same.

so the only benifit to an intercooler is the reduced IAT. it wont actualy see any more lb's of air?

parish8

iTrader: (6)

wait, just thought of something else, if there was a large loss of cubic feet as the charge was cooled wouldnt the presure go down. thru a good air to water intercooler there is only a slight loss of presure, like .2psi, if the lb/min reamined the same the cubic feet would have to go down ALOT, seems like that would reduce the presure alot too.

something here is over my head

Black Blown 02

Yes, exactly. seal up an empty soda bottle in a 70 degree room, and throw it into the freezer for 10 minutes.

You have the exact same amount of air in there, but you'll be amazed at the amount of space that air takes up at freezer temperature.

I've seen drag car setups running 22psi with no intercooler. It would be a flow restriction. They are able to run 116 octane race gas, so 350 degree IAT's don't cause it to detonate.

parish8

iTrader: (6)

lets just say the intake valve is the largest restriction and all the air is fighting to get thru there, if the same amount of air takes up more space when hoter then your not going to get as much air past that intake valve and into the cylinder.

if it was cooler you would be able to push more air past it at the same presure since it now takes up less space. so it seems to me just adding an intercooler as long as it wasn't too much of a restriction would allow you to flow more lb/minute at the same presure.

is there something wrong with that line of thought, it would explain alot for me.

let me get at the whole point of the discusion, i am buying tht turbo kit and the intercooler is TINY, it is rated by spearco for 500hp, i am going to guess that it will be at best 50% efficient at 15psi on a 409, if i put a huge air to air on there and was able to get the efficency up to 80% would i flow more air or just have a reduced chance of detonation. using the turbo charts at smoke em up leads me to believe it will flow more air.

Black Blown 02

Yeah, in maximum boost, Corky Bells book, theres an equation to figure intercooler loss. Intercooler inlet and outlet temp is figured in, so with a good temperature drop, I would imagine boost would drop a couple of psi too.

parish8

iTrader: (6)

goto this page http://www.smokemup.com/auto_math/airflow2.php

if i enter 409ci, 90%ve, 6000rpm, 15psi, 170deg. i get 1300cfm and 81lb/min

now if i enter the same but with 103deg i get 1300cfm but 91lb/min

i used another page on that site to calculate the intercooler output temps based on 70deg ambient air and 40%efficency for the 1st one and 80%efficency for the 2nd one.

going off that chart it looks like a monster intercooler could be worth 10lb/minute vs the tiny one that comes with the kit i am looking at. i could be way off on that 40%, wont know that till i try it and it will be while before i have a 409 and all the other stuff to even give this a try.

Black Blown 02

Yeah, that makes perfect sense. I think the cooler you get that air, it stands to reason that it would be easier to get it all in there.
With no intercooler at 20 psi you might see 15 psi intercooled same amount of air.

Black Blown 02

Do these temps refer to ambient outside air temps, or TB inlet temps?

Black Blown 02

Yeah, I think you better start looking for an intercooler rated for 1000 hp.

That one is probably going to be a serious restriction to flow.

parish8

iTrader: (6)

i am prety sure they are TB inlet temps

parish8

iTrader: (6)

it is a water to air unit, i dont think it will be much of a restriction at all, they have very little boost loss but i dont think it is going to do alot of cooling either once the cfm's get up there.

Black Blown 02

Do they rate their intercoolers in CFM on their site (spearco?)
I would like to know at what CFM certain intercoolers start to restrict flow.
Or do they just start to cool less, and not restrict too much??

parish8

iTrader: (6)

yes they do, and the restriction goes up with the flow BUT the air to air ones are like 1psi or so, the water to air ones are like .2psi, so even pushing it way past it's rating isn't going to end up with alot of boost loss.

go here http://www.binaryjungle.com/pdfs/Turbonetics2002.pdf
page 41, and look at the 2-231 at 700cfm there is only .1 psi loss but the cooling is droping off fast.

Black Blown 02

Good info! Thats cool about air/water intercoolers. Seems like with air/air theres alot more restriction to flow.

How many cfm are you looking at for your setup, 700rwhp?

parish8

iTrader: (6)

more like 1200cfm, but the intercooler in the kit is about the same size at that 2-231

Black Blown 02

The more I think about it, it makes sense if the air is cooler it will occupy less space and be easier to shove into the engine, increasing horsepower.

Black Blown 02

What do you think the flow looks like with that intercooler at 1200cfm?