Turbo Mike's Motor Thread

TROLL · **Posted:** Wed Mar 12, 2008 11:54 am

cool, thanks for the explanation... looking forward to seeing your results since it is different than anything i've seen before in subie world

NSFW · **Joined:** Wed Nov 22, 2006 10:23 pm **Posts:** 397

TROLL wrote:

looking forward to seeing your results since it is different than anything i've seen before in subie world

Same here. It's great to see something outside-the-box like this.

ralli · **Posted:** Sat Mar 15, 2008 9:31 pm

Turbo_Mike wrote:

Ken's got it. No matter how much technology exists, at 9.0:1 CR, 20-22 psi with a good flowing turbo is really pushing the limits of whats "safe" on pump gas. Sure you can run that much or more boost with less ignition timing or more fuel, but thats not going to make power. So instead, I'm utilizing a different technology. Twin scroll, high rpm, high flow, high boost diesel turbo. Yeah its gonna be a little laggy off boost, and its not going to make much NA power, but its a worthwhile trade off (I hope) to be able to run very high boost on pump gas. And Ken is also right, I'm de-stroking a 2.5L, so by doing this, the usable operating range of RPMs will be greatly increased, so even with a late spool, there should still be a lot of area under the curve. The whole build with the de-stroke and low compression isn't something thats really proven out yet in the subaru world, so in addition to the theory, its also going to be a good experiment of whether or not this type of modification responds well on a EJ motor....

ride5000 wrote:

TROLL wrote:

what is your reason for going with such low compression? isnt the car gonna be a total dud out of boost?
i dont know, i was taught that low compression/high boost is and old philosophy based on old technology and doesn't apply nearly as well to today's engine setups.
when i was going to do a built 2.5L i was going to aim for 9:1 on pump gas with moderate boost... and make good power on and off boost. nick at je strongly recommended this as did some others.
curious to your reasoning for going the other direction...

seems to me like he wants to run a lot of boost, and doesn't really care about torque under the boost threshold.

so you run a low static compression and put a high pr turbo on. for example, a diesel turbo.

the age of the technology has little to do with it. engines make power from fuel and air, and if you put more of those in, and light it off properly, you'll get more of it out. that hasn't changed in 100 years.

from the looks of his specs he might be destroking a 2.5 block, which will do well to net a long rod/stroke ratio, reduce CR, and still preserve quench.

That really sounds like a really neat setup. I'm really interested to see how it works out. Can't wait to hear more!

272s for cams... am I wrong in thinking that is a REALLY long duration on suby's? I've neer really looked into cams on a suby either so I have no idea. Just curious. Good luck man, keep up updated!!

Freon · **Posted:** Sun Mar 16, 2008 1:54 pm

Depends on what "272" means. At 0.050" lift? At 0.020" lift?

Turbo_Mike · **Posted:** Mon Mar 17, 2008 8:45 am

Stock EJ205 Cams:
256°/256° total duration
205°/205° duration at .050
.365"/.361" lift in inches
9.27/9.17 lift in mm

BC 272 cams:
272°/272° total duration
220°/220° duration at 0.050
.400"/.400" lift in inches
10.16/10.16 lift in mm

blkscooby · **Posted:** Sat Mar 22, 2008 11:58 pm

MIke, very interesting setup. Can't wait to see the results.

BTW, look at your post count :twisted:

Turbo_Mike · **Posted:** Wed Mar 26, 2008 3:15 pm

Well I got sick of waiting for cams (which are still a few weeks away I guess), so I bought an early 04 STi drivetrain and stuck that in the car for now.

It was surprisingly easy to convert over. I'm still using my WRX ECU and intake manifold/injectors to simplify things, since I dont have a gas pedal sensor and all that crap. The red intake is way prettier but oh well. The WRX intake bolts right on to the STi engine, and I already have modded stock injectors and TGV deletes on it.

I had already done the 07 STi rear diff with 04 STi axle/brake conversion in the rear. The 07 STi diff accepts a stock WRX driveshaft. The 04 diff/driveshaft has a bigger flange in the back so I just swapped out the diff to the 04, and I'm using the 04 STi driveshaft. So now its all 04 STi in the rear end of things.

The front was a breeze. My stock crossmember fit, and my stock axles worked. I guess early 04 STi and bugeye axles are interchangable.

I had checked part numbers at the local auto parts store on front axles, starter, and alternator. They all listed that they were different parts. And they all were a direct fit from my stock stuff.

Coils, coolant temp, crank position plug right in. Knock sensor needs to be changed to the WRX one to fit the harness. The STi heads dont have a front style cam position sensor like the 2.0 does, but all I had to do was remove the rubber plug and stick my sensor in the hole and it works. Theres also not a bolt hole to bolt the sensor in. I didnt feel like taking the AVCS solenoid or the cam pulley off to do it right, so it got a zip tie for now.

The WRX pitch stop fits, clutch slave works, and speedo sensor plugs right in. I had to change the harness on the tranny to my old harness for reverse and neutral switches, but again, they plugged right in. Since I dont have a DCCD controller, thats left unplugged for now.

The shifter is pretty much impossible to install onto the tranny after its in the car, so I left the whole shifter mechanism on the tranny when I put it into the car. The shifter support bushing fits, the shifter rubber floot boot works with the wrx bracket and screws, so all I did was change the center console front section to a STi piece, which also fit nicely in my stock console.

Took about 7 hours to do the whole thing. Guess I'll try my luck at a whole STi setup.

Turbo_Mike · **Posted:** Sun Apr 06, 2008 10:50 pm

Since the cams "should" be in next week, I figured I'd put together a test mule and try out the whole setup with crappy parts vs hurting good parts. I just took apart an 07 sti engine which had 2 good pistons and I had 2 good pistons left from my sti shortblock, so I had 4 to play with. And I have a bunch of heads laying around so I was gonna give it a go... but I used my sti connecting rods in another 2.0 that I built. So I tried putting the sti pistons on a set of 2.0 wrx rods and its a no go. Theres a reason sti rods are "shaved" on the top. Its a clearance issue. I double checked my eagle rods that I got and they work with both 2.0 and 2.5, so its all good. Also my motor is an ABAB bore size, and I had 3 B pistons and only one A. Guess I'll just wait and to it "right" once with all new stuff.......

I changed my order to 100mm for my new pistons so I can have them matched to the cylinders 100%.

One week review on the sti engine/tranny... its pretty damn good. The car is peppy and fast enough for now. The gear ratios are ridiculous. Theres just no sane reason why they are like that. I shift and shift and shift, im in 5th, look down at the speedo.... 35 lol And it screams on the highway. I just took a 120 mile trip and used more than a half tank. Thats not so good.. I gotta work on the CL/OL timing. Its going into OL at a little under 0 psi on the highway in 6th and running in the mid 13s AFR up hills. Thats my issue. I know its not gonna hurt the motor so its not that big of a deal. Havent really had much play time with it, busy working on everyone elses cars....

But really, every single gear is way too short for anything. You have to shift in corners all the time, use 5th around town, use 5th in the quarter, and even though its 6 gears, 6th is actually more gear reduction than 5th in a regular 5 speed (more rpm on the highway with a 6 speed than a 5 speed) The only benefit is its fun as hell to drive. Because I love shifting all the time, and it gives me something new to be entertained in my car. And the DCCD center diff is awesome. I know so many people that have never used manual mode or touched the center diff. I love it, and it actually will go full RWD :lol:

NSFW · **Joined:** Wed Nov 22, 2006 10:23 pm **Posts:** 397

Does your car have different diff ratios than the cars the 6MT was intended for?
I'm pretty sure 6th gear in the 6MT Legacy is a lower ratio (less RPM on the freeway) than 5th in the 5MT Legacy.

Turbo_Mike · **Posted:** Mon Apr 07, 2008 9:10 am

NSFW wrote:

Does your car have different diff ratios than the cars the 6MT was intended for?
I'm pretty sure 6th gear in the 6MT Legacy is a lower ratio (less RPM on the freeway) than 5th in the 5MT Legacy.

2003 WRX 5MT
1st- 3.454:1
2nd-1.947:1
3rd- 1.366:1
4th- 0.972:1
5th- 0.738:1
Final Drive = 3.90

2004 STi 6MT
1st- 3.636
2nd- 2.375
3rd- 1.761
4th- 1.346
5th- 0.971
6th- 0.756
Final Drive = 3.90

4th and 5th in the 6 speed are almost the same as 3rd and 4th in the 5 speed. And 5th in the 5 speed is more overdrive than 6th in the 6 speed.....

Legacys have different ratios than the imprezas, with the main thing being that the LGT gets a 4.11 final drive with a 5 speed. Which means higher rpm in all gears than impreza 5 speeds. The 6 speed LGT-B got a 3.45 final drive AND a taller 6th than the 5MT 5th, so you are correct about the legacys.

Turbo_Mike · **Posted:** Wed Jun 25, 2008 10:59 pm

Time to bring this one back from the dead...

Heads got decked and pressure tested a couple weeks ago, and I stopped in today as they were being ported and polished... grabbed some pics.

Block is back as well, 100mm, pistons matched, gonna paint it and start building probably this weekend....

I've been so happy with the sti motor, I havent been in a rush to do this one.... but now its time to get a real motor back in the car...

Turbo_Mike · **Posted:** Sat Jul 19, 2008 5:47 pm

well, its done and its in... got about 300 miles on it... I'll submit my review in a few days..
using the VF34 for break-in, the motor laughs at the VF34.. 6 psi @ 1900 lol

for now, pics:

crank, rods, and pistons balanced to zero grams..

ACL coated race bearings

block assembly

Pistons in, note the 2mm negative deck height..

Heads, BC 272 cams

"modified" water pump housing, 08 sti 11mm oil pump (shimmed too, crazy oil pressure)

Assembled shortblock

Pulling the STi motor/trans

New motor ready to go in

Drop it in with the tranny on it

Nice stock exhaust back on it lol

Temporary VTA PCV for break-in

Time to go...

GeneralTJI · **Posted:** Sat Jul 19, 2008 6:09 pm

Great build... very interesting route you have gone, I like it

How is off boost power with that real low compression setup?? looks like it's building boost very early so along with that I'm assuming it's got enough of off boost power as well...

Awesome! keep us updated!

RomRaider

Turbo Mike's Motor Thread

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