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Old 11-13-2001, 12:55 AM   #1
bsquare
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Default Torque vs transmission life

Rather than look at the EJ20 vs EJ22T vs EJ25 debate from the perspective of maximum power output, I wonder at building an engine designed to give high peak horsepower, but torque levels the transmission can survive (perhaps mildly upgraded with STi RA parts, but no dogbox). I suspect the massive difference in torque peaks and curves is why the WRX drag racers have stock transmissions surviving multiple launches.

What about building a motor specifically intended to have "usable" low-end that maintains streeability while avoiding that tranny snapping torque for which the EJ25 is, unfortuantely known? By usable low-end/streetability, I mean specifically that the motor keeps torque levels at least comparable to a decent NA EJ25 (say, 180ft/lbs at 3000rpm, off the top of my head, with peak torque not exceeding 250ft/lbs), but with a power peak of perhaps 400hp at 7000rpm. Note, I am not talking about any specific displacement or motor configuration at this point, just the target performance.

Does anyone think this would help the weak transmission situation?


Ben
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Old 11-13-2001, 01:38 AM   #2
Eric SS
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Honestly I don;t think it would help to much. Dan (DannyAtWork) has destroyed his gearbox when his 2.5RS was NA. They are just inherently weak for some stupid reason. Like you said, the 2.0 (And hopefully the EJ22T ) don't make as much torque down low so you won;t see as many broken gearboxes. I wish there were a better way to do everything but I guess you have to choose either transmission life or low end torque in our cars.

My EJ22T has a very noticable torque loss down low (below 2,200rpm's) I used ot be able to go up decent grade hills in 5th gear at aroun 2,000rpm's but not any more! Gotta shift into 4th and use the boost. It's a trade off but what are ya' gonna do...

Eric
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Old 11-13-2001, 02:15 AM   #3
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Read this.... food for thought.....

http://www.i-club.com/forums/showthr...hreadid=113069

Maybe torque IS the problem, but not in the way we thought before.
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Old 11-13-2001, 02:31 AM   #4
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well i think the problem is the amount of torque...the EJ25 makes a CONSIDERABLE amout of torque w/o any form of FI. Now take the added torque of a T3 turbo and apply that to the already astronomical amount available @ 3500 RPM....now on top of that add the shock of an ACT clutch and i think that is where you are seeing your driveline failures occur. Now bear in mind that the current 5 speed was designed 17 years ago for a 75 HP car. NOw when everything is spinning you are VERY unlikely to see a broken trans...past 2nd unless you are making some HUGE HP. Hopefully there will be a rememdy for this problem that is NOT a dog box and NOT a close ratio system.

Jeremy
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Old 11-13-2001, 03:22 AM   #5
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So, you agree that the EJ25 torque is a major concern and that perhaps tuning for less torque and more top end could reduce the problem?


Ben
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Old 11-13-2001, 03:26 AM   #6
Eric SS
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Definetly.
That's why Subaru put the exact same transmission in the new WRX as the 2.5RS. Even though it has 227hp and 217ft/lb (I think) torque, it won;t break trannies like the 2.5 will. Well, not as easily anyway.

But I guess it's all what you are looking ot do. If you want it more for a daily driver and occational street warrior where you won;t be shock loading it (i..e. highway racing), then low end torque might be the thing for you.

Eric
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Old 11-13-2001, 03:28 AM   #7
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If you aren't shock loading it, you can have a lot of torque, actually. That's the problem, if you have a lot of torque, you must drive with care.


Ben
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Old 11-13-2001, 03:30 AM   #8
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Exactly what I was trying to say. I meant to say "low end torque", not 'low in torque' let me change that...

Eric
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Old 11-13-2001, 04:54 AM   #9
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I'm not so sure that our transmissions can handle the RPM's at which the low torque/high horsepower figures come in.

Now as we all know, horsepower = (torque * RPM) / 5252. Theoretically, if you want to make a max 250 ftlbs. of torque and 400 hp, you're looking at running that peak hp at just over 8400 RPM.

Now, shifting down to 2nd at 60mph is tough, but can be done (note: with clutch DISengaged). Theoretically within the trans you are simulating to the synchros that you're shifting down to the 2nd while the input shaft should be going about 7500rpm. Now you're talking 8400rpm, which is around 68-69mph. Now I haven't tried this one, but I imagine it to be a rather interesting time trying to get that puppy to engage.

All of this, and you have to take into consideration other factors, like loads on the internals... I seem to remember something about rod length vs. RPM vs. stroke. The speed that the rods travel at certain RPM's are supposed to be so phenominal that it would just disintegrate a normal bottom end.

I'm curious now... does the EJ20 have the same bore size as the EJ22T or is the EJ22T larger, like the EJ25? Because I believe if the bore is larger, there is the possibility that the stroke is shorter and that the rod speed is much lessened by that. If not, then theoretically destroking an EJ25 might be the answer to rod speed problems.

After you've solved the rod speed problems, though, you will have to deal with the heads. I'm sure that even the uprated valve springs that we have available wouldn't be enough for high boost, very high RPM applications.

After all that, the only other things I can think of are :

Will the oil/water pumps be able to handle such high RPM's?
What type of ignition coil can handle this? Most likely not stock...
Will you need to install a gargantuan tach. with a bright-ass shift light by the driver's side a-pillar?

And finally... is it all worth only 400hp?
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Old 11-13-2001, 06:04 AM   #10
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B-square....i 1000% agree that half of the tuning problems with the EJ25T's is the AMOUNT of torque they DO have on tap and such a low speed(engine speed that is)....now if youa re not shock loading it i beleive you could have a reliable daily driver. Conversly i think you could also run a low boost/high boost style system that prevented you from making more then 1-2 PSI thru first and second gear thereby SIGNIFICANTLY lessing the chances of you multipliying the torque to the point where you have entered the danger zone. I personally would love to have a clutch i could ride a little, this clutch sucks so much i am still tring to pinpoint the friction point. I feel guilty every time i just pop the clutch rather then sliding it into gear. Gimme a clutch that i can TELL where the hell the friction point is and i will be allright, just takes a lot more CARE to drive the car.

8- I believe that the WRX stroke is about 1/2" shorter then that of the 2.5 also i believe the bore is the same as the EJ22T...they just run longer rods in the EJ22 to get the extra 200 cc of displacement. I am not sure exactly what the bore and stroke of each motor is, we should investigate...also need to find out if an EJ22 crank will fit a Phase 2 EJ25 block

We'll all be around for a LONG LONG time.

Jeremy
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Old 11-13-2001, 08:30 AM   #11
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Default

To the best of my knowledge:

Type: Bore x Stroke
EJ18: 3.46"x2.95"
EJ20: 3.62"x2.95"
EJ22: 3.81"x2.95"
EJ25: 3.92"x3.11"

Also:
SVX: 3.81"x2.95"
3.0L H6: 3.51"x3.15"

-WaC
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Old 11-13-2001, 08:31 AM   #12
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ASAIK,

EJ20 = 75mm stroke 92mm bore
EJ22= 75mm stroke 96.7mm bore
EJ25= 79mm stroke 100 mm bore.

Think these are right ??

EJ 20/22 have the same rod length, and are slightly shorter than the EJ25 rods. 130.4mm/131.5mm IIRC.

Happy.
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Old 11-13-2001, 11:48 AM   #13
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Jeremy,
I was/am considering the APEX'i AVC-R for the exact reason you mentioned. It has the ability to adjust boost by gear, and on different maps. So you could have a street map that's say 1-2psi in 1st and 2nd, then bumps to full for the remaining, or even stays at 1-2 in 5th gear. Then another map that's full boost all the time.

As far as the tranny goes, I think it's the torque, weak tranny, and an overly agressive clutch. What was Dan using when he blew his gearbox, NA? I think it was the ACT.
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Old 11-13-2001, 11:59 AM   #14
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if you dont know how to shift properly and smoothly the ACT will kill your tranny...if you do it properly you're fine. The combination of lots of torque down low, and speed shifting or dumping the clutch on an RST will destroy your tranny....But if your smooth, dont mash the gas until your in gear and moving, i THINK you'll be ok...god I hope so.
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Old 11-13-2001, 02:04 PM   #15
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Default

right but see my problem is my mom still needs to borrow my car occasionally(downfall of living at home) so i need something that has more room for USER error. Driving a Scooby is ALOT different from her POS saturn that needs a clutch. I am hoping centerforce will offer a clutch soon and we'll see what happens, otherwise it's clutchmasters for me.

Jeremy

oh yeah thanks for the sizes guys
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Old 11-13-2001, 03:07 PM   #16
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Yes bsquare, you're correct. That would be very nice way to solve broken trannies. Shiv did this. Although this example isn't so good considering he broke a half dog tranny, but it was third gear, so i guess the example is still a good one. Also Adam Bloom was running an sti RA tranny when he ran his 12.6 on the ej25, it went fine. Now the car belongs to a guy that has the same tranny with a 400hp ej20 that runs 11.88 so i think it is all in the way you drive it. I believe that with the sti ra tranny and some care you should be fine. If you lower the boost at lower rpm's thats even better. Also theres no need to run 1-2psi in first and second, then theres really no fun in the turbo because you don't get the sick acceleration the car is capable of. I say taper boost at lower(launching rpms, whatever you see fit) and then progressively back to full boost in every gear. Talk to shiv about this, he'll help you alot. But i think this is a very good plan.
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Old 11-13-2001, 04:27 PM   #17
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shiv did some adjustments, but nothing as aggressive as I am talking about. As we covered in this thread, here are the relevant numbers for the EJ motors:

(multiply stroke and r/s ratio to get rod length in millimeters)

Engine Bore Stroke R/S Ratio
EJ20 92.0 75.0 1.74
EJ20-str 92.5 79.0 1.67 (stroked EJ20 w/ EJ25 crank, r/s is a guess)
EJ22 96.9 75.0 1.74
EJ25 99.5 79.0 1.67

Then Conduit suggested an EJ25 destroke to 2.33L to get the 1.74 r/s ratio and I took it further suggesting the use of 8.5:1 CR forged pistons, which should give 8:1 CR after the destroke. However, I wonder if it wouldn't be simpler, if seeking the limited torque, high RPM power above, to just use an EJ22T, get forged internals, put on some STI heads (instant 22B!), and then tune. I don't see why such a combination couldn't survive repeated trips to 8500rpm.


Ben
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Old 11-13-2001, 08:55 PM   #18
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i always read that people ahve problems with there trannys... i mean i ALWAYS read it... makes me not wanna fix up my car sell it and buy a prelude.. again but i still cant afford a lude and the insurence...
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Old 11-14-2001, 12:58 PM   #19
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hmmm, so when you guys talked about doing it properly on the clutch, you mean to shift at low rpm (meaning press the clutch, waitng 'til rpm drops low, then shift and released clutch smoothly) or just do it slowly/smoothly regardless of rpm (like you can shift and release clutch at 4k or higher rpm going from 2nd to 3rd).

I had a feeling that tapping the accelerator too hard during clutch engagement isn't healthy to your tranny no? Well on top of that a rough engage...

-Benson (Another MY98 Owner)
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Old 11-16-2001, 03:43 AM   #20
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I certainly think you have a good idea here, in terms of moving the torque peak higher to save the tranny.

I started with a legacy turbo compressor, and it was like being supercharged. Gobs of low end torque and 5 psi from below 2,000 rpm up to about 5,000 rpm when it ran out of steam. I fried the clutch in 3 days and installed an ACT clutch and then blew second gear within 3 months.

Shortly after that I went to a VF23 compressor and it now doesn't build 5 psi until about 2,700 rpm and 10 psi by 3,000 rpm. It screams all the way to redline, and definitely feels softer at lower rpm now. I have been running for 10 months without a problem.

I also take special care to not bang it into gear as I upshift, which took a little time to learn with the ACT clutch and stock friction disk. However, at hign levels of boost at the drag strip, and 5,500 rpm launches, it still grabbed really hard going into second gear when aiming for fast times. I feared I would blow it again but it held up.

Larry
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Old 11-16-2001, 07:29 PM   #21
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Default

Quote:
Originally posted by HndaTch627
right but see my problem is my mom still needs to borrow my car occasionally(downfall of living at home) so i need something that has more room for USER error. Driving a Scooby is ALOT different from her POS saturn that needs a clutch. I am hoping centerforce will offer a clutch soon and we'll see what happens, otherwise it's clutchmasters for me.

Jeremy

oh yeah thanks for the sizes guys
Larry (imprezars.com) sells and uses an exedy clutch (I believe)...


Speaking of rough clutches...when my stocker clutch goes I am getting another stocker...until my wrx swap atleast...just so I can abuse my tranny (on accident) and not blow any gears...

-justin
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Old 11-16-2001, 07:41 PM   #22
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Word on the street is that Centerforce is soon to release clutches for the WRX (and hopefully the RS). Clutchmasters definitely has a clutch for the RS and it has much nicer engagement than the current ACT clutch. Maybe ACT can make a Subaru clutch that doesn't chatter and grab, but I'd rather have either of the previous 2 options before risking it.


Ben
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Old 11-16-2001, 10:05 PM   #23
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Default Tranny options!

A rebuilt autotranny is always an option too. Had mine rebuilt for about $1200 and it never broke again, even after repeated turbo/nitrous runs. Even the nitrous engagement from a dead stop didn't break the tranny (wear the clutches). Everything is fine to this day.

Although I have a 2.2ltr, there had to be some torque to get the wagon up and moving to almost 84mph in the 1/8th. Just stating that there are other options out there.
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Old 11-16-2001, 10:10 PM   #24
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How much boost are you running? Also, your use of a 2.2L seems to give credence to my believe that using a smaller motor and pushing the power band up will improve transmission life.


Ben
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Old 11-16-2001, 10:34 PM   #25
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Default Boost

Quote:
Originally posted by bsquare
How much boost are you running? Also, your use of a 2.2L seems to give credence to my believe that using a smaller motor and pushing the power band up will improve transmission life.
Ben
I WAS running 5lbs of boost with a 60 or 70 shot of nitrous. Turbokit was sold back in May.
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