Has anyone dynoed their SVX?

[1994SubaruSVX]

I think I am going to dyno my SVX before I come to the Midwest Meet. If nothing else it will be documented proof of what aftermarket exhaust and filter can do. Plus I am personally want to see documented proof showing hp increases over stock. I will get the car dynoed this weekend and I will be sure to bring the paperwork to the meet. I wish I would have dynoed the car before all my mods. Oh well to late now. So has anyone dynoed their SVX?

Just came from AlteredAtmosphere (northern MD), they have an AWD Dynojet (one of only two in the country from what I understand)

Quick down & dirty for 21May2k1:

THE MODS (power producing only)
-K&N drop in filter
-Level10 stage 3 trans
-custom 3" custom cat-back w/single Flowmaster

THE PEAKS
-HP 149.8 @ 5600rpm
-TQ 157.2 @ 4400rpm

torque drops off DRASTICALLY after the peak and I was running lean at the lower end (ie closed loop) both of which are due to my overly large cat-back, which is there in preparation for the Lysholm 3300ax. I got really bad jaggies starting at 5600rpm on, indicating that my ignition is not up to snuff either.

Can't post the pic til' I get off my fat @$$ and get a scanner.

Unfortunately (if the Subaru specs are accurate) even with a Level10 you're looking at drivetrain losses of THIRTY-FIVE PERCENT!!! (31% for torque).

OUCH!

[1994SubaruSVX]

so i will be able to show hp and torque for a fwd svx with 2 and a quarter inch cat-back, dual in dual out high flow converter, and two magnaflow mufflers. i left the two stock cats to insure that my exhaust would not run lean. i will post the results.

Well with a turbo and rear wheel Drive (which is less drivetrain loss than FWD) I could have a SVX with 230HP @ the wheels hopefully a lot more than that

[1994SubaruSVX]

hp than a fwd? just curious? anyway i will have the results this week if my car is out of the shop otherwise it will be first couple of days this coming week. i will scan in the results so there will be no second guessing.

Here is my theory. I believe in most cars FWD robs less power than if they were RWD. But since the SVX's tranny is desgined to be a rear wheel drive tranny. they use a shaft that goes through the transmission from the back where power is than transfered up front where as in my car it goes directly to the rear diff. Also have AWD SVX owners ever noticed that the car barely has any more power when in FWD. where with my car it feels like you just lightend the vehicle 300LBS. It revs much faster than it dit when it was AWD

Take a look at your shop manuals. If you zone in on the transfer case section (between the main gearset and the propellershaft) you'll notice that the shaft coming from the gearset is connected by *gears* to the propeller shaft that runs to the front wheels. That same shaft is connected by only a *wet clutch* to the rear shaft.

The 4EAT is a *front* drive vehicle untill the wheel speed sensors pick up funny happenings and engage the clutch to the rear wheels (up to around 50% torque transfer).

(re: your FWD vs RWD comparison). Actually your typical FWD drivetrain sucks up LESS hp than a RWD unit. FWD trannys are typically very compact (read: small and light), compared to a RWD which has to turn a 3-5 foot long driveshaft, in addition to full length axleshafts, whereas your average FWD is tucked directly up under the engine and turns axleshafts directly.

Also, (re: barely the same power levels when the rears are disabled) What you're feeling is loss of *traction*, not power. Under a WOT acceleration, when the ECU detects wheel spin (and it will, as heavy as this car is), it engages the transfer clutch (fully on a WOT standing start in this case). Yank the FWD fuze and you get tire smoking wheel spin (kinda' dopey lookin' when it's just the fronts) because you've got only two contact patches clawing for traction vice four (and to make things worse, those two have had all the weight transferred off them during the launch). Although the tranny no longer has to rotate the mass of the rear drive assembly (more HP to the ground), the fronts still have to deal with the dead weight and frictional losses (and propel a 3580lb car all on their lonesome). The above is also the reason for the faster revving (less mass to rotate).

Sorry for the long disertation, just wanted to make sure no one told you wrong.

[eddycat2000]

Originally posted by KEVINL
But since the SVX's tranny is desgined to be a rear wheel drive tranny. they use a shaft that goes through the transmission from the back where power is than transfered up front where as in my car it goes directly to the rear diff.

Where in thee heck did you get that load of hooey from? Subaru's from day one were front wheel drive...and in 1975 they added the RWD components. It was just a matter of progression that brought us to the 4EAT trans.

[SVXMAN2001]

hey svxtypeR, what is this I see about 150 hp? I thought the svx was 230hp! Please tell me this is a typo

chris
92 claret svx
90 grey subaru legacy-355,000 miles

[Red SVX 92]

That's 150 WHEEL horsepower (WHP), my guess (I emphasize guess). The regular rating is BHP (I forgot what the B stood for), which is higher than the WHP (There's power loss through various components, drivetrain, etc.) For an all wheel drive car, I personally think that's about right. I know that a stock Subaru Impreza was dynoed at 96 hp by some magazine, don't remember which. Also, AWD vehicles have lower dyno'd numbers at the wheels, that's why the difference between BHP and WHP for FWD and RWD cars isn't as severe as AWD vehicles. I think someone said that it was because of more contact patches on the dyno (4 tires in contact instead of 2).

Just wondering, SVXTypeR, how much did the dyno testing cost?!?! When UPRD's dyno was still open for business in LA, the fees were something like $500/hr+! Seems that it was a nice status symbol to have an AWD dyno, but few people ever actually used it.

The HP/TQ figures I gave are at the WHEELS. The figure Subaru (and every other car manufacturer) gives is HP/TQ at the CRANK (often times without even the flywheel attached!). (to SVXMAN2001) The above was what my comment about drivetrain losses was referring to.

This was my first dyno session for the car so I wanted to establish a baseline but I didn't get around to it til' I already had some minor mods going (I'd like to grab somebody in the local DC/Metro area with a *totally stock* car to get a *real* baseline). I only took (needed) two runs so it was pretty cheap, 140-ish bucks if I can remember correctly. A regular session ended up being no more than $200/hr, no where near the outlandish $500/hr fee UPRD (now inexplicably known as Under Pressure Racing and Distribution) was charging.

The only reason they (UPRD) got away with stupid prices was because at the time they got it (a couple of years ago) they *actually did* have the *only* AWD chassis dyno in the country! I don't remember who built the unit but UPRD quit using it because they kept having problems. Not sure on specifics of why, but I *do* know that the readings were extremely low due to excessive frictional losses (two rollers per wheel instead of one like on the more popular Dynojet), and some sort of mechanical issues.

Red- the Scooby Impreza was dynoe'd at UPRD by Sport Compact Car about a year-and-a-half ago (I have about FIVE YEARS worth of back issues for that rag, If you *really* need the article, I could look it up...). Also the HP drain between FWD/RWD/AWD is due to the amount of ROTATING MASS attached to the motor. Picture the below, this is what the motor has to spin...
_______
FWD- typically tiny (econobox-sized) gearsets, small differential, short axleshafts (with cv joints), hub/rotor/wheel/tire assembly X 2.

RWD- larger (average to large sized) gearsets, 3-5 foot long propeller (drive) shaft, (typically) larger differential, full-length axleshafts (with or w/o cv joints), hub/rotor/wheel/tire assembly X 2

SVX AWD (Ls-L)- average sized gearset, transfer case (center differential if you will). TWO 3 foot long driveshafts (one with a CV joint), front AND rear differentials (for a total of THREE diffs), FOUR axleshafts w/ cv joints (making a total of NINE CV JOINTS!!), hub/rotor/wheel/tire assembly X 4 !! (the fact that it's an automatic just adds insult to injury).
________

You see from the above (and my dyno readings) that the SVX uses up in excess of 80hp JUST TO SPIN THE DRIVETRAIN!!!! I'm pretty sure i'm not alone when I say "That reeeeely SUCKS!!) (But, I love AWD none-the-less)

BTW- The "B" in BHP stands for brake. (ie. HP under brake or load, the Dynojet roller weigh something like 1500lbs a piece!!)

[1994SubaruSVX]

my car is fwd and weighs only 3485lbs. i just recently weighed it at the memphis motorsports park. the 3485 was with me in it. my car is quick and at highway speeds it really shows up. ask aredub. anyway i will have the documented data to show the difference in hp at the wheel between fwd and awd soon enough.