I have a 4wd P10 With avenir motor in it. Currently using a 520mm X 200 MM with 2.5" end pipe/core size Intercooler. I am collecting parts for my GT28R set up.

I just brought a new intercooler kit which is more suited for my 4wd (different cross member mounting compared to fwd) and the GT28R. But when i was ordering it online i didn't notice the size.

The new cooler is 600x280 with 3" end pipe/core (but uses 2.5" reducers) which is quite a bit larger than my current cooler. I want my car to be nice and peppy and try dodge anything that will create lag.

Is this too big for a GT28R? I am going to install it on my T25 First so i can sell my old kit, will i have any noticeable lag even with the t25?

heres an image comparing the 2.

http://img27.imageshack.us/img27/8881/sdc10663m.jpg

Everything I have read on the topic by anyone who knows what they are talking about says that a larger intercooler will not noticeably increase lag.

I always thought that like... shorter piping = less lag.. and thought it was the same for intercoolers... Was worried that going from 520x200x65 to 600x280x80 would increase the lag cause its quite a bit bigger.

there has been several threads about this with very knowledgeable people chiming in. intercooler size does not matter, if i remember correctly once you start up the car it pressurizes the whole system. a intercooler twice the size takes like .000004 more seconds or something very small, you will not notice anything.
i have the thread bookmarked on my other computer..so one i get on there i'll post it on here. i think it was from the g20 forums.

I'd go for the smallest intercooler that still provides adequate cooling. I know there are formulas that you can use to figure that out but I'm no engineer lol. The easiest way to see if your existing intercooler is up to the task is probably a temperature probe.

there has been several threads about this with very knowledgeable people chiming in. intercooler size does not matter, if i remember correctly once you start up the car it pressurizes the whole system. a intercooler twice the size takes like .000004 more seconds or something very small, you will not notice anything.
i have the thread bookmarked on my other computer..so one i get on there i'll post it on here. i think it was from the g20 forums.


Thank you, will be a interesting read. Ill search on G20 and see if i can find it. If everything seems correct ill just use my new kit.. since it cost me near to nothing :rofl:

Ive got a BFIC with just a T25 running off of 2.25" pipes to 3" ports on the IC. There is no lag. With the GT28, probably will be about the same. Here is what it looks like.
http://i2.photobucket.com/albums/y25/cnknguyen/0801091140.jpg
http://i2.photobucket.com/albums/y25/cnknguyen/0802090200.jpg

An intercooler that's too big will increase lag and pressure drop. I found the website I was looking for that explains why, look about 3/4 of the way down:

http://www.are.com.au/techtalk/intecoolersMR.htm

The extra lag is noticeable. Why else would I trade my air/air for an air/water unit with shorter piping?

Is it severe? no. But it depends if .2-.5 seconds is severe to you or not.

here's why. A larger intercooler may only take .2 seconds more to fill up, but that air still needs to hit the throttle body. Then it needs to go to the exhaust where the turbo will spool even more. There is a noticeable difference, it just may not be as extreme as you would expect.

I always thought it goes by a percentage, but I'm dumb. So my IC is this % bigger, I would feel it at this RPM instead of this one... a % from Idle.. or something like that... I'll shut up now

boost onset will likely stay exactly the same. But boost response will be different. Much different.

I was thinking about it some more and you can't just consider the extra time it takes to fill up the intercooler. When you are out of boost, the intercooler is simply a restriction. If a larger intercooler is a larger restriction then obviously you make less power out of boost which of course hurts boost response.

Does anyone have a back to back dyno comparing a larger intercooler to a smaller one with no other changes? I would like to compare the power before boost onset.

I am going to test fit the new intercooler tomorrow with the T25 and see if i notice any difference.

The intercooler you have on right now is a perfect size.