So either ESP was too slow for you, or (more likely) you had a car that was prepared to a level in excess of what the Street Prepared rules would allow - which almost always means a boost controller.
Welcome to Street Modifed!
Street Modified is a happy place for DSMs, as almost every single thing that is commonly done to them by the drag race crowd is perfectly legal. Boost controller? Legal. Big-ass aftermarket turbo? Legal. Intercooler the size of Alberta and a Kombat Body Kit? Legal and legal. Fun stuff!
However, not everything legal is desirable. Autocross Is Not Drag Racing, Nor Is It Road Racing. The design of a world-class autocross car takes a little more homework.
Fortunately, that what makes for a good autocross car also makes for a kick-ass street car too, so you get to both have and eat your cake to a certain extent.
The first thing an aspiring Street Modder should do is go out and duplicate everything done to the ESP cars. (see the ESP Tech Page) The suspension, wheels, and most of the engine work is the same on an SM car as on an ESP car - in fact, an ESP Talon with a boost controller makes a decent SM car.
Once that's all done, it's time to turn your attention to the turbo system. All that was forbidden in ESP is now open season!
So you will be putting on a boost controller and turning up the boost. That means the same upgrades to fuel pumps etc. that the drag racers do. You also MUST have a boost gauge, and either an O2 sensor voltage monitor, and EGT gauge - or both. You can also toss out that stock O2 sensor housing, and either port it, or replace it with a replacement from forcedperformance.com.
The T25 is also coming off - time to get something that will hold boost up top. However, we still have to keep our mortal enemy, lag, minimised, so no 20G or Frank 5 for you! Instead, you have three choices:
- The Mitsubishi TDO5H-14b - the stock turbo from a 1G DSM. This isn't a bad choice, as they can be had for next to free from 1G owners moving up the ladder. They will hold well over 20 lbs to redline, and they spool fairly quickly. You will need a "16G install kit" to fit it, but it's a fairly painless install. The 14b, however, is the laggiest of the 3 options - you will notice the lag out of slow corners.
- The Garrett T28/Super 60 - this is a hybrid turbo that starts off life as a T25, but gets a T28 exhaust
turbine and a Super 60 compressor wheel. It bolts right into the T25 space, with no adaptor kit required,
but tends to cost a little more than the 14b 'cause you're buying this new.
The Super60 has a bit of a bad rep with the drag race crowd, 'cause it costs about the same as the 16G for less power output. What they're overlooking is that it spools WAY faster - faster than the 14b, and it flows more than the 14b too. More power, less lag... sounds like a winner!
- The Forced Performance "Big 28" - This may well be the ultimate autocross turbo, and may wind up being
the ultimate 2G drag upgrade turbo too. Still in the design stages, this turbo is also based on the T25
core, with a T28 turbine section. However, it has a 520 CFM @ 15psi compressor wheel that outflows
(and is more efficient at high boost levels too) than the mighty 16G! Faster spool and more power.
And as it turns out, the Big 28 absolutely kicks ass. It spools almost as fast as the T25 did, and pulls hard through the entire rev range, maintaining over 20 PSI all the way to the limiter. This is the turbo for an SM car.
Hey, we won a ProSolo Championship with this turbo - it works.
Once you start messing about with different turbos, you start needing to worry about fuel control. The stock ECU is actually pretty flexible, and it's hard to hurt anything (as it runs way rich and loves to pull timing - safe but slow) However, once the mass flows start getting up there, you'll need to consider stepping up to bigger injectors, and a big intercooler seems to put the ECU into "dump fuel" mode - not to mention the dreaded "fuel cut" the shows up when mass flows get REALLY large.
There's two ways to handle this - piggyback computers (like the Super AFC) or replace the ECU with a standalone EFI system.
We played with the piggyback stuff for a little while, and in terms of value for money it's not a bad option. The piggyback computers will give you enough control to bring things back into a reasonable mode of operation. What they don't do though is give you enough control to really optimise fuel and timing. They're band-aids, not real tuning tools.
So we bit the bullet, and went to a standalone system produced by ProEFI. The upside was a monsterous improvement in throttle response (we switched to speed/density from the stock mass-air) and big power gains. The downside is a very, very steep learning curve. You go from controlling nothing (stock ECU) to controlling EVERYTHING - which is more opportunity to screw things up. Having programmed idle speed control myself now, I have a level of respect bordering on awe of the guys that programmed the stock computer.
It's totally worth the effort, but make no mistake, it's a lot of hard work.
Note too that you absolutely must do the fuel pump rewire mod, or even the best fuel pump will run out of pressure.
The other big effort we've been making is getting the weight out of the car. SM now has minimum weights, and the minimum weight for a DSM AWD is 2600lbs. Now it is going to be very difficult to make that weight legally, but you have to make the effort and get as close as you can. We're down (Jan 2002) down to 2804 lbs dry.
BTW, if you're planning on doing race seats, the seat mounts on a DSM are asymmetrical in 3 axis. You've been warned!
Jan 2002: Once you start making big power, and especially if you do ProSolo, you will start having driveline reliability issues. Do yourself the favour, and replace the centre diff with either a Quaife or a KAAZ at first opportunity. If you have the money, you might as well replace the front diff too - we broke both in rapid succession last year, and it killed two events and cost us several thousand dollars in prize money. Replace them before you break them.
Having the front limited slip should offer some performance advantages too, but we haven't had opportunity to test that yet.
One final note: if you pull the rear seat (now legal in SM) be sure and put a chunk of carpet over the hole. Go fast with class!
For more information on our SM car setup, visit the Far North Racing team page at fanorthracing.com