Landjet

Does anyone know how much of a temp drop across the intercooler it takes to gain a 1 HP?

95ONE

based on percentages. So it's different for everyone. But the general runle is . For every 10 degree F drop. you get a 1% increase.

fast951

Hi Craig, there are other variables involved. The same intercooler will have different effect based on humidity and barometric pressure.

Rough figures, to give you an idea:

- Each 5deg F (5F) change in temps from 60F will affect air density by 1%. ex: 70F = 98% Air Density, 50F = 102% Air Density
- The higher the humidity the less dense the air.
- Barometric pressure - If it goes up the air density goes up etc...
- Air Density affects HP roughly 10:7 ratio. Ex: Air Density goes up 10%, HP increses roughly 7%.

To figure out the HP change you must calculate the Air Density Change, so 3 variables must be taken into consideration.

The intercooler will lower the temps, which will increase the air density. However, unless you are conducting the test under the same barometric and humidity the HP increase will vary.

It's good to note that the temp has the most effect on HP. As a rule, each drop of 10F will change the air density by 2% and the HP by roughly 1.2-1.4%. Most simplify it further and go with 10F decrease in temp results in 1% HP increase.

I know, more than you asked for, hope it helps.

RolexNJ

Craig, I think there have been a lot of other threads on this topic, if I can find them I will post them soon. Anyway, this should be a very interesting thread. John @ VR may have some data on this too.

95ONE

Ok.. general rule or John's super specific NASA version!!! LOL.

fast951

LOL - I edited it! But you had to know what I'm working on to post such a "NASA" response.

95ONE

I wouldn't want anything less!

Basically, what I got out of your post is, it depends on so many variables and determinations that its extremely difficult to generalize a specific amount. Absolutely. I understand what you work on most of the time rely's on those numbers. I'm kinda a numbers geek myself. That's why I found such humor in it!

Landjet

Ok as soon as I blink again I will start to comprehendaaaaaa John. Great answers guys that is what I was looking for. I am going to start testing some materials soon to try and keep heat soak down on different parts so this will give me some what of a guideline on possible HP change when on the dyno testing.

anders44

are you still running stock IC craig?

Mike1982

Thanks for that great write up John, I have always wondering about the humidity as well. I have heard the 10 degrees lower gives 1% more HP, which is close to what you said, but always wonder how the humidity would directly effect the HP.

fast951

While I'm over complicating matters and confusing the issues, let's see if I can explain the humidity vs. HP



- Based on the temperature, the humidity affects air density differently (and of courseHP).

We assume base air density at 60F and 0% humidity.
The hotter it is, the % humidity has a greater effect.

ex: at 90F temp, 50% humidity reduces air density by approx 1.9-2.1% (or a reduction of approx 1.4% HP). While at 60F, 50% humidity reduces air density by approx. 1% (or a reduction approx 0.7% HP) (The HP loss is for what the humidity caused. You add to it the loss (or gain) based on the temp differential).
So the same 50% humidity yields different results based on the temperature.


So if you are making 100HP at 60F and 0% humidity at 90F and 50% humidity you will lose (3% due to heat + 1.4% due to humidity) or approx: 4.5% of your power and you will end up with 95.5HP output.

disclaimer: all of the percentages are approximate figures.

Landjet

anders44 Yes I am still running the stock intercooler. I am going to take temp readings with it before I upgrade and will post the results. I will do temp into the intercooler, and out into the TB. I am also looking at ways to reduce heatsoak in the intake and other areas. More info to come.

John, so a long as I keep track of temp and humidity on all of my testing even on different days I can always calculate gain or loss. Those are the ratio's I was looking for. Video should be there anytime.

blown 944

vey timely thread for me as I am looking at sizing the proper IC for my supercharged car.

I will be taking some reading tonight witha thermo gun.

If I post the results maybe some could help me i I'm am off with my figures?

Currently I am getting by using A LOT of methanol to cool it down but It is extremely hot!!

I am surprised I havn't killed it yet.

I'll post some results soon GTG

--Sid

blown 944

Well I just got donen doing a little testing using a thermo gun. Here are my results

on the 951 after running up to about 18psi and 15 on the top end then pulling over immediately (numerous times with same results~5 degree) and testing the hard pipes:

max temp on the turbo exit pipe was ~190 deg
on the pipe to the TB was ~90 deg

then on the 944 s/c car (I feel like a complete moron for posting this). After just running it up to 15 psi in the garage a couple of times.....the transfer pipe between the blower and intake was ...(scared of the flaming) 230 degrees. This is just in the garage.

I went ahead just for testing and took it out and ran it through 1st and second pulled over real quick and the temp was ...255 degrees..OH my I think I'm living on borrowed time at this point with this thing.

The belt is coming off tonight until I get the I/C on it. It does go to show however how well methanol can work

Now the question is, how big of an I/C am I going to need to get the temps back down to around 90 from probably around 290? (guessing here considering now I won't take it out and try to kill it again)

--Sid (big dummy)

95ONE

I used to see temps like that all the time on supercharged anything. An NSX I supercharged a few months ago was running 10psi at 255 deg. intake temps. My old jakson racing supercharged Prelude had around 260 deg. All the comptech and JR Supercharged RSXs. It's just how hot it gets.