What intercooler for GTI?

[iigx]

Just booked my Polo in for an May day for the Intercooler. Once thats in then I can look at the tune. Perth weather is too brutal.

[gavs]

Intercoolers are pretty basic things - i wouldnt think about them in too much depth.

Pretty much anything will be an upgrade to the teeny tiny stock unit.

Theres no way id spend $1000+ dollars on one though.

Hmmm, yes it is in theory but in execution, not so much.

On a balls-out tuned car then the difference between aftermarket on a dyno shootout etc probably won't make that much of a difference however on an un-tuned car, it could make a massive difference in drivability and even the cooling performance of the intercooler.

I know a few ex subaru fan-boys and toyota 1jz/2jz fans and so many times I saw or heard "I bought this massive intoercooler off ebay for $300 and then got the pipes, so good, i only had to use the jigsaw once to make it fit! But now, the car is slower! is it because of the weight? i checked my boost and i don't have a boost leak...."

While seemingly simple, CFD analysis shows how complex little things like this are. Like an exhaust manifold. There is a good explaination on APR's usa website I think it is that explains how on the stage 4 Golf R motor, the amount of CFD they did to make sure that each exhaust pulse hit the turbine at exactly the right moment to ensure the turbo is always spooling at the exact maximum efficiency is phenominal.

[Lucas_R]

I agree in part with what you are saying Gavs - and the problem with some of these intercoolers is that they are simply too big (or way too big in some cases) for the engine/turbo that its fitted to.

On my old 200sx, i fitted a intercooler from an XR6 turbo which uses a Garrett core. It was about 2 times (approx) larger than the stock intercooler (which was sidemounted in the bottom passenger side of the bumper) and had the same size inlets and outlets as the stock intercooler. I bought my own alloy piping kit and silicone joiners and clamps and fitted it over a weekend. The intercooler cost me $50 and i spent about $300 all up on the piping kit and silicone joiners etc.

That intercooler filled the gap in the front bar almost perfectly and didnt require ANY trimming or cutting of any bumpers / crash bars etc. I ran that for nearly 3 years without a problem. No difference that i could feel in turbo lag either because the core wasnt oversized for the car and i only added about 30 - 40cm worth of additional piping.

When you see a Toyota Starlet or Daihatsu Charade with an intercooler that goes from headlight to headlight and bonnet to road then not only does it look ridiculous, but its total and utter overkill.

As you mentioned, this happens with alot of WRX guys, they remove the stock top mount and fit a front mount and then complain of the lag. The reason for the lag is partly due to an oversized intercooler in most cases, but moreso due to the fact that they have just added about 3m of piping which didn't exist before which equates to a large intercooler in itself in terms of air volume. This actually happened to a friend of mine with a Liberty B4, we intalled a front mount together but he hated it, so it was removed and sold and bought an upgraded top mount.

The good thing about the intercoolers for the Polo GTI is that your not really adding any additional piping (perhaps a small amount only to mate up with the stock piping), so its only really the core size that needs to be taken into account. The intercooler i linked to in a previous post was just an example of what i would be looking into if i had a Polo GTI. Because the stock intercooler is so tiny, you would want to likely double the stock coolers volume to make a worthwhile upgrade.

[BLN355]

The other thing thats being over looked is the 6r Polo's inherent average at best standard cooling system. The HP cooler while being a bit pricey takes into account the standard cooling system and is made with less obstruction to the radiator not impeding the cooling any more than stock which is the deal breaker (for me atleast). All the other cores seem to not have taking that major point into consideration.

[Lucas_R]

The other thing thats being over looked is the 6r Polo's inherent average at best standard cooling system. The HP cooler while being a bit pricey takes into account the standard cooling system and is made with less obstruction to the radiator not impeding the cooling any more than stock which is the deal breaker (for me atleast). All the other cores seem to not have taking that major point into consideration.

Whats wrong with the stock cooling system? Im sure it's up to the task of a tuned up street driven car with the odd track day thrown in. If the car is destined for heavy track use then i could understand an upgraded thicker radiator with more capacity. And how does the HP cooler have less obstruction to the radiator than any other brand of intercooler?

Another option:

etuners : Technique Archive

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[yokom46]

I would like to have one of all of the APR things.

[Guy_H]

Intercoolers are pretty basic things - i wouldnt think about them in too much depth.

Pretty much anything will be an upgrade to the teeny tiny stock unit.

Theres no way id spend $1000+ dollars on one though.

Unfortunately thats wrong, wrong, wrong - you get what you pay for.

On a Polo the intercooler sits in front of the other components - creating a pressure drop here will limit airflow to these compnents and running the risk of cooking an engine & Air conditioning that will struggle to function with the increased temperatures.

Poor core & end tank design will give you an intercooler that's WORSE than stock - as was the case with Forge's intercooler for the Polo 9N - it was worse than factory, and the turbo struggled to make the specified boost. The turbo struggles - creates more heat, increased the intake temperatures. Flush your money down the toilet!

Your intake air (depending on what boost your tune is requesting) spends HUNDREDTHS of a second in the core, so it must be efficient to extract heat.

I have not analysed any other aftermarket intercoolers for 6R Polo's, but I certainly know how ours works!

[VWindahouse]

If you speak to the uk guys, HP are "stupid" with their stepped core design but it's no surprise that's what they say when APR UK are developing their own intercooler. As I pointed out to them, the proof is in the dyno graphs and real world performance in Australian conditions. A few of the local 9n Polo Gti owners have swapped out their forge intercoolers for Seat Sport ones instead, speaks volumes to me. The twintercooler option seems interesting to me because I logged temps with the factory cooler and they were horrendous after a repeatable 30km, 100kph run. On an 18 degree day I saw temps up around the 40's. Forge then take that air, send it around a corner into another cooler (which blocks off more radiator space) with no evidence in relation to pressure drop/vs flow etc.

Gavs and Guy are right. Not all intercoolers are the same.

I know it's not the new Polo but here is dyno proof from mine. Red line is Forge, Blue line is Seat Sport absolutely no other changes.

[gavs]

Thanks mate, proof is in the pudding right there.

Lucas mate you too are dead right. Getting an intercooler like you did or even the Seat Sport ones which are so much cheaper than a lot of the aftermarket solutions out there can be a great win, like the S3 cooler for 118TSI Golf owners. Unfortunatey for us though, there just isn't that level o swap ability with our Polos, I wish there was because it would make modding so much easier! VAG have made the Polo GTI in this platform the performance benchmark rather than the Seat product this time so the best bolt on upgrades for this model platform unfortunately are already on the car.

Like Guy said, we are talking about a product that needs to drop that charged air down in temperature as quickly and as much as possible without hindering other systems, as well as doing it without hampering the performance of the engine, all in a car that is carrying an engine that was initially designed for much bigger vehicles with less power output. I think it's actually a very complex piece of static componentry.

[yokom46]

The more I read the more I need.
gimmeh