Dynamometer: Powertrain loss = how much???

[oldeskewltoy]

I strongly recommend reading this first - Drivetrain Power Loss - The 15% "Rule"- Modified Magazine



Now that the engine has been in for the better part of 1000 miles I decided to go to the dyno





Hmmmmm, seems disappointing with those numbers... but NOT disappointed with the torque "curve"... or should I say torque flat. The torque peaks @ 2700 now, instead of 4800. The torque is very linear and supplies 90% or more of the torque from 2000, to 5550 rpm.


Now for the numbers.... I am disappointed. David Huang who runs Forged Performance (tuner shop with the Mustang dyno) said that it has been his expereince that EVOs usually have a drivetrain loss between 28% and 31% ?? That seemed awful high to me until I did some research....

The whole drivetrain loss subject is VERY interesting. It appears different AWD drivetrains have different losses. The Subaru drivetrains tend to lose about 20%-25%, EVOs tend to lose 25%-30% All-Trac Celicas are often at, or close to 30%..........

BUT......... There is also arguments that MOST systems don't lose a set percentage, but they lose a set number (the Subaru guys say 60hp), and then as power increases, there is a small additional amount of power lost do to the additional power causing SOME additional loss but not a set percentage for the entire loss.

So what do I use to back calculate the All-Trac in the Corolla??? I couldn't tell you, because I find NOTHING related to the All-Trac Corolla drivetrain. Now the All-Trac drivetrain is similar to the Celica system - both use E series transaxles, the big difference is the Corolla uses a solid axle in the back, while the Celica uses an independent rear. So if I use 30% drivetrain loss, then my flywheel hp # would be @ 102hp, and torque would be a grunt-like 110#/ft

reminder of my 4AFE - 4AGZE bottom end netting in about a 1/2 point bump in static CR. Ported head extensive work on #1 exhaust port. Stock cams, newer type, but stock intake manifold, stock exhaust manifold (log), the Ireland header downpipe needs to be modified to fit the all-trac transaxle, so currently the exhaust side is bone stock

MY opinion: I'm in the BUT catagory of believers. I believe there is a set drivetrain loss, and then as power is added (with mods) the loss increases but at a small percentage rate then the initial loss. So what is the E series All-Trac drivetrain loss? Your guess is as good as mine


One VERY interesting note... Grunt's first pull was HORRIBLE... netting a paultry 58hp, and 60#/ft. I was feeling quite embarrassed... but they took a look @ how she was on the dyno** and noticed that the tires were quite deflected (under inflated by about 6-8#s) The brought the tire pressures up and the result is the reading above


Here is what I can tell you..... The final torque # is ABOVE the final hp # (72hp to 77.5#/ft). This is substantially different from the stock engine where there was more HP, then torque. Also the new engine is far stronger then the engine that came out... I can only guess @ what that engine would have planted


** - see next post for more details....

[oldeskewltoy]

Some perspective..........
http://www.toymods.org.au/forums/pre...esson-***.html

do a page search for 4a-fe, and 4afe. the three listings show 2wd versions. Those engines planted 61.4hp (45.8kw), 65.1hp (48.5kw), and last 69hp(51.5kw). That makes my 71 hp more ... and in 4wd, it looks pretty good.

While searching I did find a few other 4AFE dyno results, but the only one I found running mostly stock planted 77hp, and 80 #/ft, but again that is in 2wd and not using a Mustang dyno, but a dynojet




Here is a stock 7AFE... on a Mustang dyno, but again it is 2wd

but you did dyno in 4wd?

I'd be curious to see what it would dyno at in 2wd mode (for those that don't know the corolla alltracs have electronic selectable 4wd)...... because I believe the alltrac ae92/5's have 60/40 or 70/30 (I can't remember) with the latter number the figure to the rear.... so if you dyno'd at 71.7whp in 4wd mode..... how does the dyno calculate the variance in power between the front and rear?

Is that figure just the wheels with the highest power? A comination between the two (which would skew the figures down)? or....?

I know that it is possible to make the Celica all-trac drive in just fwd... or I believe I read that. The All-Trac system in Grunt doesn't allow just 2wd, it is full time awd, and you can lock up the center diff. The runs were done with the center diff unlocked, but the system was driving all of the drums, one in the rear, and the 2 in the front.

The Mustang dyno is such that you set the rear drive wheels on the top of the rear roller, and then ideally it is set to length to run the front tires in the "V" between the 2 front rollers. Grunt is shorter then their unit was set to, so the rear tires were on the rear roller, but the front tires were not fully in the "V", but were propped against the rearward of the two front rollers.

But getting back to your post... these pulls(4 total - the one with low tire pressures, and 3 others) were all done in 4wd, so comparing my numbers to any other 4AFE powered AE9x would pretty much require their pulls to be on a Mustang dyno, and in an AE95 to even know how well she actually did. OR to know the drag/power loss the E55/E57 all-trac gearbox is when fitted to an AE95


Btw.... all these numbers are @ the wheels... the only "flywheel" numbers are in the 1st post and those are loosely based on a 30% drivetrain loss. I had hoped to find a few dyno runs in this forum, but when I checked I found no other 4AFE, E55/E57 (all-Trac transaxle)equipped runs to compare them too. In fact I found no other All-Trac/AE95 dyno runs of any kind, in any forum