Quentin

well, since this is the first post that i am making, let me give you a little background. My best friend and myself are in the process of starting up a performance shop, and we have recently started on our first car. it is a sc400.

Today, we installed a true dual 2.5 inch exhaust from the cats back. the cats were cut so that we did not have to use an enlarger pipe to fit the 2.5 inch system. it consists of borla mufflers and borla intercooled tips. the system turned out beautiful. And the exhaust note is beautiful. very subdued at idle(barely noticeable), but the exhaust screams at WOT. pics and wav files will soon be up on our webpage. I will be sure to post a link to the aforementioned exhaust page sometime in the next few days.

We also did a dyno run with the car in stock form. mind you, this isnt very easy with the toyota auto tranny. the stock numbers from the dyno were: 179.9 hp and 200.1 ft/lbs of torque. this is prior to doing a tuneup. we will be going back to the dyno shortly to get the numbers to the wheels after the exhaust.

ill make sure to keep you guys posted.

cheers,

machinegt

what year is that sc400?

Quentin

the lexus is a 92 model year....

sorry bout that....

the_ez_rhino

uhhhhh..... the sc400 is 260 rwhorsepower stock.... I dont see how that works.....

matt7184

The 92 SC400 comes with 250HP at the CRANK. 180 RWHP seems kinda low to me, did it need a tuneup?

Quentin

the car did need a tune up pretty bad. the plugs were pretty scored(sp?). The next dyno run should be in a couple of days, and it will be with new plugs, wires, and other tuneup items and cleaning.

260 hp would be at the flywheel. with an higher mileage car needing a tuneup, 180 isnt that bad considering the auto eats up a bunch of the power. we should be well over 200 hp on the next dyno run. with only the exhaust.

cheers,

the_ez_rhino

i dont get all this cracnk / flyshaft / wheels ****..... ahhhh well

Toan Nguyen

Alot of people quote hp at the flywheel because it's a higher value and represents the true power of the engine. When the power gets transmitted to the rear wheels, alot of power is lost through drivetrain and other factors.

From memory here are generic loss figures :

RWD - 30-40% power loss through drivetrain
FWD - 20-30%
4WD - 40-50%

So if you are making 300hp at the wheels in a RWD car then assume you modify that figure by 1.3 to get the flywheel power of the engine. Engine power is more useful as drivetrain can always be upgraded to become less lossy, but then you start chewing gearboxes etc.

Toan.

MadMaxSC400

there's something wrong with that thing.. I saw a 4.0L GS put down 235hp to the dyno before they started tuning the ECU they were installing. Simple math tells me that with my 1/4 miles I'm making a lil more than that and mine's only a year older. Hell, STOCK they put more than that to the tires. That thing needs work.

Slick Lex Coupe

The 4.0L GS engine puts out 300hp at the crank and the 4.0L 92 SC400 engine puts out 250hp at the crank so the numbers do sound somewhat sensible considering he said the car needed plugs and wires. I've heard the drivetrain loss for an automatic car is about 20%. 250hp minus 20% equals 200rwhp. So I'd say he's on. And the GS that put down 235rwhp is more than a 20% loss. 300hp minus 20% equals 240rwhp. Also take into consideration that the GS has a more efficient 5 speed auto as opposed to the SCs 4 speed.

scoii

Plugs are scored? Maybe. Could be the right rear wheel had about 10 pounds of air in it that day. Car actually runs pretty good. Will be interesting to see those plugs.

The Ikon

Automatics lose 17 - 20% at the wheels due to the automatic transmission...

Manuals lose 15 - 18%...

The rwhp should be around 200hp using the 20% deduction formula. As "Slick Lex Coupe" stated... However, it will vary slightly from car to car depending on "conditioning" of that vehicle.

Quentin also make sure the oil is fresh and it is 5 weight oil. I've read in "Sport Compact car" the differences an oil changed made in a dyno. Plus get the rotors and caps change too. Keep us posted on your progress and what is your web site?

On the SC with traction control and the ECT on the transmission should these be "on" or "off"? Does it make a difference?

The Ikon

scoii

http://www.mechtech-ms.com/html/turbo.html
an interesting article that suggests this dyno run was not so bad afterall.

Sexlexo69

Hey man you said 179 hp and 200 torque? IT seems like you lost 100 horses. Where they at?