ZDriver.com - Intercooler Writeup! (Long)

Well, I pulled an all-nighter, so I needed something to keep me awake now that it's morning. I decided to compile as much information as I could on the side mount intercooler options available for the 300ZX (that I know of), so here it is.

OVERALL SIZE
Stock is 6.5"H x 6.75"L x 2.25" D = 98.72ci
HKS is 10.2"H x 7.8"W x 2.5"D = 200ci
GReddy is 6"H x 8"W x 4.5"D = 216ci
Z1 is 7.25"H x 8"L x 4.5"D = 261ci
Apollo is 5.5”H x 16”L x 3”D = 264ci *
Stillen is 9.4"H x 8.4"L x 3.5"D = 276ci *
Arc is 8"H x 9"L x 4"D = 288ci *
Ash's "Massive" is 9.4”H x 8.0”W x 4.5”D = 338.4ci

* indicates a likely increase in pressure drop due to length. Intercoolers longer than 8” will generate slightly higher pressure drop.

CHARGE FACE (how much air it can flow) (square inches)
Stock – 14.625
Apollo – 16.5
HKS – 25.5
GReddy – 27
Arc - 32
Z1 – 32.625
Stillen – 32.9
Ash – 42.3

AMBIENT AIR FACE (frontal area) (square inches)
Stock – 43.875
GReddy – 48
Z1 – 58
Arc – 72
Ash – 75.2
Stillen – 78.96
HKS – 79.56
Apollo – 88

ANALYSIS
Using these three charts, there are several things we can take notice of when making a decision as to which intercooler to buy. For the best performance, it is important to have the largest possible intercooler with the least possible pressure drop.

Obviously, Ash's Massive Side Mounts win in overall size, but that's not the only thing that's important. While they are the biggest overall, they are 4th in ambient air face. This means that, in comparison to Stillen, HKS, and Apollo, they are going to directly face less air. Where this SMIC lacks in ambient air face, it makes up for in charge face. Due to its depth and height, the intercooler can flow lots of air.

Now, before you say "hey! Apollo has the largest ambient air face, I'll get that!" I'll point out why it's not always best to have the largest ambient air face. When your turbochargers start to compress the air in the system, the compression surges from the turbos to the engine. In order for it to get there quickly, there needs to be a fair amount of restriction. When the air enters the intercooler, it has to spread out over the entire volume of the intercooler. The less time it spends in this huge area, the better. By having a 16" long intercooler, the air takes much longer to compress. This means pressure drop, which means lag. Your turbo WILL spool up slower with an Apollo FMIC. The charge face of the Apollo FMIC is also less than 2" larger than stock! Hardly worth $1000 (ok... $995 through Z1motorsports.com).

Again, before you say "but Stillen and Arc are both larger than 8" too! They must be just as bad!" I'd like to point out that they're hardly above 8 inches. While Arc is an entire inch longer, Stillen is only four-tenths of an inch longer. This means that the Arc will have a little more pressure drop than the others, but it makes up for it in overall size. As does Stillen... the .4" is easily overlooked when you consider its ranking among the competitors in the other categories.

When you consider the rank of each intercooler in relation to the others in each category, you end up with this.

Stock - 8 8 8 - avg 8 =8th
GReddy - 6 5 7 - avg 6 =7th
HKS - 7 6 2 - avg 5 = 6th
Z1 - 5 3 6 - avg 4.6 =5th
Apollo - 4 7 1 - avg 4 = 4th
Arc - 2 4 5 - avg 3.6 = 3rd
Stillen - 3 2 3 - avg 2.6 = 2nd
Ash - 1 1 4 - avg 2 = 1st

Apollo ends up 4th overall when considering ONLY the dimensions, but the HUGE pressure drop one would experience with this intercooler cannot be overlooked.

If you haven't ruled this intercooler out yet, I'll go one step further and point out that it negates the natural design of the Z32 by crossing the airflow to the wrong side of the engine. As it was designed, the driver's side turbo feeds the passenger's side of the engine and vice-versa. Because the Apollo FMIC crosses the air from one side, across the front of the car to the other side, it causes the driver's side turbo to feed the driver's side of the engine (and the like on the passenger's side). While this may not be a big deal, it is important to note that the exhaust stroke of one side of the engine causes the turbo to pulse when there's an intake stroke on the other side, thus making the system more efficient. By negating this, the Apollo FMIC is causing the turbo to feed a side of the engine that isn't accepting air on an intake stroke. This will add to the lag, as well as having a negative effect on overall power output.

If you haven't ruled out this intercooler by now, God help you, because I'm not patient enough.

Moving on to the intercoolers that matter...

Now, before you rush onto AshSpecZ.com to order the Massive SMICs, there's something else to consider. This specific intercooler uses 2.5" inlets and outlets, which means you're going to need different fittings to use it on your 300ZX. Not to mention, you won't get the full effect out of this intercooler without a complete 2.5" intake piping system ($700 through AshSpecZ.com) and some 60mm throttle bodies. When you consider that the intercooler alone costs $1000, and air guides would cost another $125, you might want to reconsider. If you're building for 700+rwhp, go for it, but it's not necessary until you're making huge numbers on huge turbos.

You can consider the cost to be a downfall for Arc as well. At $2131 (SPLParts.com), they are BY FAR the most expensive SMIC option for the Z32. When you consider that they don't even rank best out of the comparisons I've provided, it doesn't make much sense.

For the cost, HKS and GReddy don't look that great either. Though HKS did great in ambient air face, due to its incredible height, it did horrible in charge face because it's only .5" thicker than stock. At $970 (UltimateZ.com), it's not too appetizing. As for GReddy, $920 (SPLParts.com) doesn't sound too bad, but this intercooler ranked just better than stock by my comparison (which is largely subjective - you might put more weight on certain things that I did). The GReddy SMIC's also retain the use of the stock intercooler ducts, which saves you money and will likely increase overall efficiency.

For the cost, the Z1 sidemounts are a decent deal. $848 (Z1Motorsports.com) gets you marginal ambient air face, good charge face, and middle-ground overall size. Mid-ground performance for the cheapest cost!

But for once, Stillen comes out as the winner (in my opinion) with a product that isn't a knockoff of someone else's. $950 (UltimateZ.com) gets you an intercooler that does well all-around - never lower than 3rd in a comparison. The downfall of this intercooler comes in its size. It is the largest that will fit without larger intercooler piping, but that comes with the downside that you may have to modify your turn signals to make them fit. There are also ducts available for these, at a cost of $186 (UltimateZ.com), which will allow them to be even more efficient. Considering its overall performance, competetive cost (on the grand scheme of things), and available ducting, it's easy to ignore the slightly increased pressure drop that may result from having such a long side mount intercooler.

Now, I've compared everything that I have equal information on, but finding information on these products is damn near impossible.

In fact, Ash is the only one who posted pressure drop and CFM info, and I happened to find a 3rd party test of Stillen, so here it is...

Ash’s “Massive” - 427 cfm @ 1psi pressure drop

[Considering I'm 99% sure that Ash's smaller SMIC option is the same as Z1's, I can also include this info.]

Z1/Ash (Sport) - 306 cfm @ 1psi pressure drop

Stillen - 332 cfm @ 1psi pressure drop

Again, Stillen performs very well.

I also have some 3rd party results concerning outlet temps of stock intercoolers vs. GReddy vs. Stillen.

ambient temp 70-72 degrees, 1 hour difference between intercooler swaps

Stock IC 0-120 mph
1. 175 F
2. 215 F
3. 235 F

Greddy SMIC 0-120 mph - stock air guides
1. 130 F
2. 140 F
3. 145 F

Stillen SMIC 0-120 mph - air guides used
1. 140 F
2. 145 F
3. 145 F

I believe that GReddy's did the best on the outlet temperature tests because the car used during these tests had a stock fascia. The gills in the stock fascia don't allow air to get very "high up" on the intercoolers surface, so a shorter intercooler with a deeper core will get the greatest airflow over its entire surface. So while the top of the Stillen is probably being heatsoaked from a lack of airflow (even with the airguide), the entire surface of the GReddy side mount is getting air.

Continued in 1st response... (what's this 10k character BS?! lol)