One of the goals at the outset of Project Evo, our longterm 2008 Mitsubishi Evo GSR, was to match or best the GT-R's power to weight ratio.
Well, we reached the limits of the stock turbo a while back. And since weight removal isn't an option for us, that leaves just one rather obvious alternative.
You see above one very serious piece of hardware to skew the ratio. Though there are a few bolt-on upgrade turbos available for the Evo X, we settled on the Garrett Evo X upgrade unit in GT3076R guise as it has some tricks up its sleeves the others lack.
Click the jump to geek out with me.
With any of the bigger turbo choices out there including this one, you'll be giving up some low-end response. That is a given, but we'd prefer to get as much cake as we can while still smashing the treat into our gaping maws.
Unlike the other turbo choices, the Garrett is a ball-bearing turbo. If you've ever had even a passing interest in turbos, you've heard about what balls can do for you--ball bearing turbos have less friction than a conventional journal bearing, which improves boost threshold and quickens transient response. More snap, in other words.
The less-sexy--and arguably more important--aspect of ball bearing turbos that you rarely hear about is that they have much higher load capacity than those with conventional bearing systems. It's simply more robust.
Many aftermarket turbos are simply bigger wheels slapped on the existing conventional bearing system. These units rely on whatever reserve bearing load capacity was there in the first place. If you're lucky, that margin doesn't get used up completely. If you're unlucky, you end up with smoking and grindy-sounding turbo bits.
Second, take a look at the Garrett's turbine housing. It's a purpose-designed, proprietary housing that has a larger internal cross-section than the stock Evo X turbine housing. We opted for the 0.94 a/r housing, the larger of the two available.
The point of a larger turbo is not simply to be able to run more boost. It's also to have less exhaust manifold backpressure at whatever boost you run. A larger turbine housing increases the turbine's flow capacity, which in turn reduces the exhaust manifold pressure.
Reducing exhaust manifold pressure directly improves the engine's volumetric efficiency, assuming you can alter the valve timing to take advantage of it. Which we can, using the Evo X's dual Mivec variable valve timing. Rather, Road Race Engineering can, as they will be the ones doing the tuning.
If you were to instead simply hog out a stock turbine housing to fit a larger turbine wheel, you wouldn't make the most of the larger wheel's flow potential. You'd still have a heavier wheel to spool up, though.
There's also a ported shroud (green arrow in pic) on the Garrett's compressor housing. The stock Evo X turbo has a non-ported shroud, mainly because the turbo is small enough to not need one.
Ported shroud? WTF? Here's more. Once you install a turbo with a higher-flowing compressor, surge becomes a potential concern. A wider compressor map helps combat surge. And a ported shroud does exactly that--it widens the map.
The big wild card to our big power plans is the octane we'll be using. Remember, Project Evo consumes 91-octane pump fuel. It's like bringing O'Doul's to a house party and expecting to score with the prom queen. You've got to have some crazy mad skills to pull it off.
We'll see whether we can scratch the surface of this bad boy's full green-Hulk potential, though, and so will you.
MSRP (GT3076R): $2440
Jason Kavanagh, Engineering Editor
breif says:
05:18 PM, 08/19/09
Sweet. Interested to see the dyno sheet and reactions.
srlracing says:
05:36 PM, 08/19/09
This should be good. A friend of mine did a similar build to a new STI that you guys are doing to the Evo. He went to the recommended "best" Subaru tuning shop and the result of his build is terrible. Narrow power band and turbo lag the likes not seen since the 80's but in that 500rpm range he has a pretty good amount of power. So hopefully your build is better matched. Today's engine magicians are magically able to get big power out of pump gas.
lowmilelude says:
05:36 PM, 08/19/09
$2400 is the kind of money that makes me go "And while we're at it, we might as well ratchet up the compression ratio, get a standalone FMS, and see how long the stock driveshaft and axles will last. Yee haw!"
roadburner says:
06:07 PM, 08/19/09
This project reminds me how moronic my last vehicle purchase choice was; I need a car like the GSR that is much more mod friendly.
Grrr...
church123 says:
06:29 PM, 08/19/09
Ouch, $2400 is getting up there for a turbo - I just paid $1100 for an FP-Red for my X. Not as much potential as the 30R, but easier on the wallet.
You guys really need to think about running meth injection to make the most of that turbo. It's got 500+ whp capacity and you'll be hard pressed to make that on pump gas (it can be done, just not easy).
You'll probably need to extend the rev limiter a little too since the spoolup on the 3076 will be quite a bit later, narrowing your powerband. I have a 3076 on my race car which is a 2.2 liter engine with more compression than the Evo and it still takes till almost 4k rpm to spool. Some pretty well developed X's on evolutionm forums are fully spooled somewhere around 4500 rpm with tubular manifolds, etc.
Look forward to seeing the results.
norsairius says:
07:25 PM, 08/19/09
this makes me think about what jeremy clarkson once said about turbos:
"A turbo: exhaust gasses go into the turbocharger and spin it, witchcraft happens and you go faster"
which is probably only what people less interested in the details of a turbo need to hear.
anyway, the posts for project evo and its mods have been kind of spread out, is there any chance we may get a general update of the list of modifications done to the car so far?
that aside, looks good! I'm excited to see how the turbo kit works out.
jondimellow says:
08:13 PM, 08/19/09
.... and get a list of prices spent on the car
how do your mods effect the long term life of the car?
kingkhalas says:
08:17 PM, 08/19/09
makes me want to buy the car when you guys are done with it.
07mx5 says:
08:31 PM, 08/19/09
i can't wait to see the finished product go against the GTR. What sorts of comparison tests are in store? I'm hoping in addition to standard track tests, real world livability opinions will be included.
dragonflight says:
08:34 PM, 08/19/09
Who services this vehicle? I can only imagine that the Mitsubishi dealer would run as soon as they had the hood popped...
kurtamaxxxguy says:
09:57 PM, 08/19/09
Sounds good.
Is the plan to eventually put Project Evo on the race track?
If so who will be the Edmunds race team?
It could be a great way to get additional publicity for your web site!
slickersdrip says:
10:58 PM, 08/19/09
Ouch. And I just spend a few hundred getting my O2 housing replaced on my SRT-4, which was extremely painful.
This is gonna add turbo lag, won't it? Generally I'll kill turbo cars with twice my power up until about 60+. Dyno queens FTL.
church123 says:
11:09 PM, 08/19/09
The lag won't be that bad slickersdrip - at least from a drag racing perspective - I might find it irritating in daily driving. Plus, with AWD, you just load it up on the launch limiter at 5k-6k rpm, build some boost and go. :)
joefrompa says:
08:03 AM, 08/20/09
I really don't care for this style build in a daily driver. Who the heck is going to drive around either:
A. Constantly launching at 4-5k
B. Keeping the RPMs constantly above 4k so you have usable boost (though your response still isn't fantastic either)
It's great to be able to run really low quarter mile times, and really fast 0-60, and all that. But do a 3rd gear pull from 50-75 or a 4th gear pull from 50-100. That's how I drive 99% of the time when I want maximum acceleration.
I do applaud you for the ball-bearing turbo though. Much more reliable design.
One day, I'd like to go with a twin-scroll unit in my 2008 legacy gt. ~300awhp, loads of torque, and pretty much full boost by 2500 rpms with pretty darn good acceleration at 1500 rpms. Plus quite reliable and not destroying the stock drivetrain.
canadaphant says:
08:05 AM, 08/20/09
Wheelmaps? Surge lines? Thrust loads? I'm in nerd heaven-this is what I do at work-on a wee bit bigger scale :-)
canadaphant says:
08:18 AM, 08/20/09
And on that note, I wonder if putting some prerotated inlet guide vanes (if you can't afford or control adjustable ones) would be more efficient than a ported shroud. A less graceful method would be using a controlled recycle loop-you'd never surge, but if you're using EC controls anyways, you can probably get away with just adjusting the IGVs to avoid surge-this is just a turbo, after all...
billybobbovine says:
08:39 AM, 08/20/09
you guys really need a water/meth kit as your next mod
spdracerut says:
08:54 AM, 08/20/09
Joefrompa, a friend and I have driven an Evo X with this same turbo. He has a 2.0L WRX wagon and he said the Evo had better response and spool than his wagon which is stock; more than double the horsepower doesn't hurt either. You start getting significant boost at 3k in the lower gears, and at 4k, you better be holding on tight!
One person with this turbo is hitting 20psi at 3600rpms in 4th gear, 27psi at 4000rpms. In 5th gear, he's getting 20psi by 3400rpms. The X is geared very short. I want to say that 80mph in 5th gear is 4k rpms! People are topping out 4th gear at 8k rpms on the dragstrip at ~118mph. In this case, 4k rpms is only about 60mph in 4th gear.
With regards to pre-rotated IGVs, I'm sure they work better in controlling surge, but I'm also sure they're more expensive :)
joefrompa says:
10:12 AM, 08/20/09
Spdracerut - Good info on the Evo X....
that being said, I hated my 2005 WRX Wagon 5-speed (actually a Saab 9-2x aero).
When I first got it, I pulled out into an intersection in 2nd gear at around 1500 rpms and tried to accelerate. I think I rolled backwards.
Once I learned to drive it, it became alot of fun. But that car definitely is not a role model for low rpm function, turbo lag, and transient response.
By comparison, my 2008 Subaru Legacy GT still sucks for stock power delivery, but it's acceptable :)
I consider turbo technology to be making huge strides in the BMW 335i and VW/Audi 2.0t....but then again, the flat torque curve takes away from the fun :)
hondapilot2004 says:
02:12 PM, 08/20/09
How much power did the car have before this turbo? Holy cr@p have fun with this guys
billybobbovine says:
02:33 PM, 08/20/09
the 2.0T in stock form has such a flat torque curve, while fun, its small K03 turbo runs out of steam by 5500 RPM. With a stg. 1 tune, you actually get boost faster, but it takes a little while to hit full boost. So it almost feels like lag, because when full boost hits its a tidal wave.
supergoji says:
05:24 AM, 08/24/09
GT3076R for 2200 bux? damn.
us 300zx guys get two GT3071R's for 3500 along with a few more goodies. and thats good for 900whp+.
wayno_san says:
05:52 AM, 09/ 1/09
How's the install going? Any updates?
skunkworks says:
11:17 PM, 09/ 8/09
Come on IL, I've been checking the site every day for an update. Give us a tease at least....