What's the point in a front mount intercooler?
 

May sound life a daft question, but i'm new so please be nice.

Is this just a cosmetic mod, or does simply moving the intercooler actually make a difference?

Cheers

simple - its a lot more efficient than in the standard position at keeping the temperature of the turbocharged compressed (i/e heated) air at a safe level.

Its directly in the airstream and it does not suffer from the engine warming it up like a top mounted one.

And you can fit a bigger one.

The main benifit would be that you don't get the heat soak that you do from a top mount. Sit in traffic for 10mins and the TM will burn your hand due to hear soak from the turbo, mainfolds etc etc But as the front mount is in the bumber has nothing to heat it up.

You will also get a better cold air contact being at the front aswell as normally being a bigger intercooler you will be able to run a more safer level of boost and the colder that intercooler is the better the torque i think.

I was gonna go for a FM but got a nearly new STi 8 TM for £100 :cool:

Glad someone else asked what I was thinking.
Is there an issue with increased Turbo lag and possible damage?

on my car it made it laggier by about 100 RPM or s- its hardly noticeable. Damage is no problem, if you are worried just put a mesh guard over it.

The only downside IMHO is the fitting of the cheaper kits which requires a bit of metalwork, or the expense of the kits that dont.

All of them you have to chop the bumper apart from the odd one that sits behind the radiator thereby affecting the flow a little.

Then why the hell have Subaru been mounting them on top for all these years? Is the top mount purely aesthetic?

They are there as it is an easy manufacturing position compared to a FMIC. It is cheaper to make and assemble. The Nissan GTiR is the same.

For a road car @ 208 or 288 bhp the TMIC is generally fine. It is when we go outside the limits we find how compromised the design is.

Heat soak is evil.

I think the words that a FMIC adds to lagg is a nonsense in my experience with my Sti v3 using a 'laggy' TD05 20g on a 2 litre.

Graham

Hi Graham, I take your point but surely following the law of physics lag has to increase if you are increasing induction length by a couple of metres. Did you honestly not get any extra lag over the top mount? At what point does boost come in on your car?

Maz

I think Graham's point is that any small amount of lag it may add is not even close to outweighing the charge cooling benefits and temperature stability benefits. I doubt you'll find anyone on here who's fitted a front mount who would ever go back to a top mount.

The standard top mount only has ONE thing on its side -a very short boost circuit from compressor outlet to throttle body. However, it is not a perfect simple tube from one to the other - on its way it first hits a sharp right angle then is split pretty roughly into two, then each of these has to undergo another sharp upwards bend into the hot side of the intercooler, where it then is forced to make another right angle bend to flow down to the cold side, then if it's not coming straight down the middle into the throttle body, it has to be forced along the length of the end tank before doing another 90 degree bend into the throttle body.

When you think about it, I'd imagine the reason why people with front mounts on their Scoobs don't notice too much lag, is because it would be pretty difficult to devise a more convoluted and lag producing top mount design, even if you tried! Therefore, a front mount with a decent enough bore, smooth pipework and gentle bends may be able to perform almost as well as a factory top mount, even if it has added a couple of metres of plumbing. The laws of physics also tell us that every sharp bend that you introduce increases the lagginess just as if you'd added extra length or restricted the bore.

Hope this helps.

BTW I am not a front-mount fanatic. I run a standard v4 top mount and accept the performance limitations for the moment because I like my engine bay to look factory. But if there were a cheap, high quality, straight fit front mount, I'd do it like a shot. I just don't want to cut my bumper or wings and can't afford something like an APS kit which looks like it wouldn't be any hassle to fit.

Using that argument you could say why have Mitsi put front mounts on the Evo as standard?

one is a packaging reason - the horizontal cylinders leave a nice big hole to fill......with an intercooler.....neat!

As silent running says pipework is very short, but as 911 and myself also say (and we have both changed from a big TM to a FM) the lag comparrison is minimal.

The difference in charge temps (which i monitor) are big at my spec, but wont be such an issue at lower BHP. up to 350 ish BHP you will get a TMIC to cope no problem. After that just be done with it and put a front mount on.

Another point, the tmic gets uneven cooling,with the air hitting the back,so isn't using all it's potential(unless you fit a splitter)
The fmic gets as much air cooling as it can,with it's location.

Tim

Yes.
There are ways to drive around any lag on any turbo car that has real boost, you keep it fizzing above the spool speed.
I have 1.5 bar at 3400 and 1.6 at 3800 (iirc what Andy F said).This is with a big 20g which is not good on a 2 litre at low rpm. Let the engine drop below 3K and you will wait and wait for things to start going.
I agree with P1 that the difference is about 100 rpm.

The arguments by the above gentlemen I concurr with in favour for the FMIC, and we havn't yet touched on the tweeks we have made to make the installation a bit better...but that would be telling! :D

Good discussion, refreshing to be part of it on Snet of late.

Graham