Hi Guys

I have both the GRS and GP intercoolers, but am undecided about which is 'best' for my MCS, many hours of reading searched topics on here and I'm no closer to finding out a definitive answer.

I fitted the GP intercooler about 6 months back and found the improvement noticeable, more than I expected from an upgrade intercooler with just a couple of extra rows welded on! Then, a few weeks back I had the chance to pick up a bargain priced new GRS unit (so did). Comparitively it is somewhat larger than the GP unit, but only something like 10% internal (3 additional rows over stock to the GP's 2, and GRS claims 35% increase over stock).

Anyhow, fitted it, but was a little surprised it did not give me the same noticeable on the butt-dyno improvement over the GP as the GP had over stock. GRS looks beefier and the hood deflector section is an improvement over the GP's - the foam narrows the air path to the size of the intercooler face inside the scoop. It also fits snugly and looks well made. The cores are very neat CNC'd affairs, BUT the transition from end tank to core is not as efficient as the stock or GP cooler. If you were to look into the cores of a stock intercooler there is a neat funnel into and out of each core, so air should pass smoothly through without pooling anywhere. By comparison the GRS cores sit approx .5mm into the end tanks off a flat surface, and do not funnel. I would have thought this is a bad flow design by comparison, and since I'm sure I have read here that the GRS drops a bit of pressure by comparison to stock, perhaps this is why. Being as 'best' is a combination of factors (cooling/pressure drop/flow characteristic) if the GRS is only offering slightly better cooling, but dropping air pressure, which is the most important factor? I think the GP cooler is lighter which probably gives it better recovery rate.

So, due to a lack of any hard comparison I wish to test them to see which performs better for me. I do not have any guages, and was wondering if an OBDII item like Scanguage2 will give me suitable info for a comparison? I believe you can read manifold pressure and inlet temps with it, but could someone please advise if these sensors are suitably located to provide any useful figures (MAP I believe yes, not sure where inlet temp measuring goes on though, I am hoping post intercooler).

Any advice or comment welcome

Alex

 

If I had to choose between the two, I would go with the GP intercooler.

Based on a couple points you have already mentioned,
the way the stock/GP units are manufactured on the inside allows for very good air flow, with very little pressure drop.
They are also very "light" and do recover quickly.

 

That is my train of thought. A well designed diverter and it could be more effective (eg Alta air diverter/sprayer). Shame, as I like the aesthetics of the GRS.

Any views on my testing plan?

Cheers

 

Testing ICs is not an easy task, especially without the proper equipment.
You mentioned a ScanGaugeII earlier, if you have one, you can do a MAP and IAT test of both ICs.
Just make sure that ambient temp, coolant temp are as close to same for both tests. Basically, be quick when swapping the ICs.
Be consistent, same drive gear, WOT, RPM, etc

A properly designed scoop will also make a pretty big difference in IC performance.

 

Thanks again for the reply. Whereabouts are the intake air temps measured? Post intercooler I take it, so in the intake manifold?

 

Actually, I'd like to run this test with my m7 DFIC and the stock IC with my SCG II.

But it can't be valid for one or the other, since the cooling air intakes are routed differently.

For example, the sealing foam on top of the DFIC wouldn't exactly be optimum for the oem IC.

Any ideas?

 

We tested ours stock IC compared to the GRS at the drag strip and it showed a good mph gain from the 1/8 to the 1/4, seeing as you live in Atlanta I know there's a very nice 1/4 mile strip their.


1/8mph 80.80 1/4mph 99.51 gained 18.71

1/8mph 91.49 1/4mph 102.28 gained 20.79

 

True enough.

But to remove the foam sealing for the m7 DFIC and apply the totally different foam sealing for the oem IC would be more than I'd want to do.

I've been thinking of comparing them on a dyno with the bonnet up for both.

 

That would be a pain in the a$$, there really is no way to test the two without moving the foam aound.
I don't think that would be a very efficient test, as the bonnet scoop plays a pretty big role in the effectiveness of the IC, stock or aftermarket.

What you could do Jim, is to participate in a dyno day, there certainly will be someone there with the stock IC setup. See if they are willing to let you swap their hood onto your car after you install the stock IC. It's only a few bolts.

 

Interesting!

The DFIC really works at dropping IATs, which is a good thing.

I just wonder about the effect of its pressure drop.

 

I'm no expert, but from reading your post you have sold me on the GP...Now, where to get one!

 

you want absolute pressure (not boost) divided by absolute temp. That's density. So with OBD logging, you can drive the same road the same way, and compare the data. That's what TonyB and I did a while back with the GRS and a scoop.

But what's best is use case dependant. One that's best in a 1/4 mile may not be best for road racing or street use. And it depends on what else you have on your car.....

Not as simple as it seems...

Matt

 

Someone call me?!

And same ambient temps for these runs... I remember watching my home-based weather station, and when it finally displayed the right temp, with key in-hand, it was time for some canyon fun. Good memories... and I learned a lot!

 

I just finished the install of the GP intercooler on my 05 MCS this morning. The butt-dyno definitely tells some improvement, but I won't have a chance to get it on a dyno for a tune for a month or so. When I had it on the Dyno in January it was pulling 164whp, with a 15% pulley, and Webb HDI. I've since added the Alta Sportone exhaust and now the GP Intercooler, so next is to have Mynes Performance here in Mesa, AZ do a tune, and see where they can get me.

Since the GP IC does restrict access to the spark plugs, I went ahead and did new plugs and wires while i was at it. That and swapping in the GP Intercooler barely took an hour. I love the fact that it maintains a pretty much stock look and I can always go back to stock real easily if needed.

Now to decide whether to paint that new "Works" labeled IC cover... hehe.

 

I'm sure you'll love the GP IC, cause I do.