fantastic read!

 

Thanks for the write up, one of the better ones I have read. Would you mind letting me hear the wastegate and also checking out your car? I plan on FI this year and will also be daily driving it so would like to see a completed car.

 

sounds like they did open dumps on your car.

nice write up though, have fun, and keep the shiny side up!

 

Thanks, I just try to convey my layman perspective, with regards to these setups. I paid decent $$$ for SC, and more even to troubleshoot it, then again for TT, so might as well share some things I learned, in case people see similar symptoms.

In retrospect, if I was close to Stillen facility, I'm sure they would have fixed the problem with pulleys (which caused the alternator belt to slip and wear), but they were unwilling to pay for shipping the car to CA, then fixing it, then shipping back. I was unwilling to continue aspiring for 300-340whp, and decided to save up for the proper mod like turbo.

I'm going to write a small (subjective) post here about Stillen's overall design, with regards to how I see it. I'm no expert, so take with grain of salt or two .

Oh, and yes, the last dyno was Dyna Pak. SGP has that in-house, so we just went with it.

 

As you well know . But we came very close to fixing it, pitty it was their pulley assembly that was out of whack on my car.

I still believe that Stillen, if you get lucky and it runs right, is a nice setup for non-hot climates and for daily driving. Daily-driven Stillen Z feels as fast as a turbo on the butt-dyno. Its when you get on highway, or enter higher speeds/rpms that it loses out to TT (for similar boost levels, of course).

Chances are, if you're a nice driver (like me ) you won't be speeding much on regular roads, and most of your driving experience would be short spurts of acceleration between light, or on highway before you hit 100 or so. In most of those, Stillen would be quite ok against more powerful setups, since you're likely not stretching the RPM into turbo territory too much.

This is also partially true with drivers not accustomed to turbo (turbo novices, like myself) going against a Stillen SC novice. They can punch it all the way, while I have to watch for slipping tires and losing grip if I go overboard, so I'd be more cautious, whereas they can go all out from 2nd and up (assuming dry pavement). Of course, that changes after some experience.

 

That rings a bell! Two short pipes, pointing downwards towards the road. Its hella loud in cabin @ WOT, probably due to echo from pavement below. It also scares traffic next to me, and in front of me, so everyone just gets out of my way now. Makes for a smoother commute .

 

Here are some pictures of that small intercooler core that Stillen uses.

First pictures here are the core of the intercooler portion that goes underneath the blower. As you can see (I included a quarter for size comparisons) it is small and thin. The red rectangle in one of the pictures is the area of the intercooler core piece that is exposed to air passing from blower to engine (my best guess). As you can deem, of the whole core piece only about 50% is used actively, the rest is storage for your circulating coolant. The rest of the core piece still benefits in terms of holding more cooling liquid, but the exposed section is the one that actually contacts the compressed air for a very short fraction of time, hence it being thin and small does not help too much in hot weather.

The side picture shows just how thin this thing is.

 

Furthermore, the small core piece of the intercooler is held inside an enclosure. How much of the space in that enclosure is used? Pictures are worth 1000 words...

 

the stillen intercooler is an air to water intercooler vs. the air to air intercooler found on most all street turbo applications. air to water is alot more effiecient than air to air, but may be the reason you felt a difference when the temps got hotter. if the water radiator (for the stillen intercooler) didn't have good air flow, then heat soak would make it not operate correctly.

 

So, overall, it looks as though most of the stuff that the Eaton blower sits on is just empty space, rather than a one-piece sandwiched intercooler core, like I've seen in aftermarket on other Eaton-ed cars. As such, it is not very efficient IMHO, and most of it is just lifting the Eaton blower up, making for the whole assembly to sit high enough to warrant that bulging hood modification.

Also, this design could be the reason why Stillen had to settle for M62 blower (as opposed to bigger M90 blower) -- lack of space and possible heat soak. Poor little M62 (rated for engines between 2.0L and 4.0L) works hard to provide boost to our VQ35. Exceeding 8psi of boost makes the blower spin over its recommended RPM in most aggressive driving scenarios. If this was M90, It would be much better mated to our displacement IMHO.

The front piece looks a bit better. Yes, it is thin, but it is big and hold liquid coolant (rather than air), so it does not need to be as thick as the air-to-air intercoolers.

Here are few pics of the front piece...

 

Indeed. Still, such a small section of the intercooler, providing all the cooling needs seems like a waste of space to me. Instead of putting it in an enclosure, I would have made the whole thing one piece, with radiator fins running all the way through. I'd guess it would not be of any larger surface area, but (from cross-section) it would provide 2-3 times the thickness of current radiator fins, when it comes to cooling the passing air.

 

if you had to intercool a roots type blower, how would you do it?


thats my point. it is about as good as it gets. if you took it a step further, you make an ice tank with dry ice to help cool the water. intercooling a roots style blower is done with air to water intercoolers.

 

Here is a piece of the Pontiac Grand Prix (OEM M90 Eaton mated to 3.8L V6, but no intercooler stock) aftermarket intercooler kit. It is all one piece, utilizing all the space available between blower and engine, to cool the passing air.

 

the cross section area is only half or less the stillen.... ?

 

I'm not arguing that at all. I'm arguing the design of Stillen's intercooler. Per picture above, if Stillen designed their intercooler as one piece, and utilized same space they utilize now between blower and engine, Stillen's intercooler radiator piece would be ~1.5 times as thick as the one shown for pontiac. As you can see in my previous pictures, there are a decent number of quarters between the blower and engine, most of them not radiator fins, but rather just empty space.

 

The radiator piece is as thick as stillen's, but the whole sandwiched component is thinner than stillen's. And even if its thinner, consider the design... This design concept uses all available space for the radiator. Also, it fits the opening on the Eaton blower, so it is -- volume-wise -- as small as possible, making the coolant flow faster through it for same gpm coolant pump.

I'm mostly addressing the volumetric efficiency and the design concept. Pontiac intercooler uses 100% of space between blower and engine for cooling the passing air. Stillen's setup uses, at my best guess, about 50% or less.

 

point taken, believe me, i'm not taking favorites at all, but many things to look at. i have seen beautiful air to water intercoolers on blown motors, and for the hp and boost level the stillen is at (with stock compression) that intercooler they use should be enough to cool the amount of increase in temp the air will see.
let me look up some equations. hahaha

 

i understand your point, but, the intake charge will have to go through the outer fins also on the stillen. granted, not the most effiecient, but how would you do it?

 

Overall, I'm pretty sure Stillen guys know they could have designed it better, but at higher cost. At some point, they probably had to consider cost of the whole kit. They had to stay competitive.

For our current boost pressures (6-8psi), I think their design is ok, even if not ideal.

However, I'd like to see them come up with a stronger kit, at higher cost, with better intercooler design, with M90 blower, perhaps a water (or dry ice) spray system on the intercooler front piece, low comp pistons, etc., etc... and running 10-14psi of boost. It would be an interesting setup.

EDIT: Oh, and with an in-dash LED, letting me know when my intercooler coolant pump failed . Its very sneaky how their coolant pump will fail (due to a blown fuse, for example) but you'll have no idea, unless you check under the hood.

 

Wow bascelik, the other day I was just looking through Stillen's catalog and thinking about a Stage II SC. You're write up really solidified going turbo for F/I or nothing else.