Question: What's the driveline loss with a manual tranny?

[SergntMac]

This topic came up in another thread here just a while ago, when someone posted links to a dyno site where two Cobras were compared side by side. One was apparently bone stock, and the other modified, with produced remarkable differences in the comparasion. Good, but...

I'm aware of our driveline loss with an automatic tranny, but I noted that the dyno operator factored in a driveline loss of 16 percent for both manual six speed Cobras. This 16 percent tax seems excessive to me, rather stiff for a manual tranny car...Anyone?

[FiveO]

I believe its about 20% with our cars.

Stock they make 302 hp to the crank.

With a 20% loss that would put 240 to the wheels...or about that.

If I recall most of the stock Marauders that have been dynoed were putting about 240 or just over to the wheels.

Can anyone confirm or deny?

[TripleTransAm]

Seems high, that manual tranny loss.

I recall some half-dozen years ago, some of the F-body guys in Toronto had a group dyno session and the operator had some sort of technique in which to determine the actual parasitic losses in the drivetrain. I don't recall the method, but I think it involved some sort of coast-down measurement.

This resulted in an actual 'hp' and 'tq' value of losses, which you would then add to the measured value at the rear wheels to obtain the supposed crank hp/tq values. Only at this stage could you work backwards and obtain a percentage value.

I think using a fixed percentage only works when keeping within a certain window of power production, but I cannot prove or disprove this theory. I'm finding it hard to believe that if a MM motor was upgraded massively to produce 1000 hp at the crankshaft output, that one would see upwards of 200hp lost along the drivetrain. But I'm open to be corrected, as usual...

About the specific dyno run mentioned above: how does one arbitarily come up with a value like 16%??? Why not 15%? Or 17%? Seems to me there has to be a way of getting this info, along the lines of what I mentioned above.

[BillyGman]

I was under the impression that even if you have a manual trnsmission, you're still going to lose pretty close to the same amount of HP through the drivetrain as you would w/an automatic transmission. Atleast that's what I've been told by the Dyno operators. I think you have to figure that it's going to take a certain amount of HP just to turn the rear end differential along w/the axles. granted, that by itself wouldn't take 20% of the HP your engine has, but it has to be facord in. But perhaps this is simply heresay.

[rayjay]

Based on Ford Focus dynos done on a stock Focus, the loss was approx 16% give or take 1% with a MTX. The MTX Focus tranny was the same as the SVT Contour's except for the final gear ratio of 4.06 . Sounds like they used a known average on the Cobras. The ATX Focus had a significantly higher HP/TQ loss. As with the MM, the cure was a chip.

[TripleTransAm]

I honestly have never heard about an auto tranny sucking up the same amount of power as a manual drivetrain, from ANY of the operators I've ever spoken to, nor from any of the dyno sessions I've followed over the years (and there have been many).

The nature of an automatic transmission is such that there are more places where you can lose power due to friction and such. The manual tranny is much more simple in nature... one gear on the input shaft driving a gear on the half shaft, and then one gear on that half-shaft driving a gear on the output shaft. Simplified, but the basic idea of a manual tranny. An auto tranny, in turn, has many paths to delivering that power to the rear. Just the fact that some gear carriers or drums have to be 'seized' by bands or clutches allows for some possibility of slippage which results in lost power, even after the tranny is 'in gear'. And all these objects have to ride on bushings or bearings, all resulting in increased contact (ie. friction) surfaces. I suppose if these things were riding on needle or teflon bearings that it might not be as bad, but with the '03 MM we have to deal with a tranny that happens to soak up a lot of available push, by its design.

And we haven't even begun to look at the torque converter yet!

[SergntMac]

I was under the impression that even if you have a manual trnsmission, you're still going to lose pretty close to the same amount of HP through the drivetrain as you would w/an automatic transmission. Atleast that's what I've been told by the Dyno operators. I think you have to figure that it's going to take a certain amount of HP just to turn the rear end differential along w/the axles. granted, that by itself wouldn't take 20% of the HP your engine has, but it has to be facord in. But perhaps this is simply heresay.
I disagree that it's hearsay, Billy, because it's really flat out bull*****! Sorry, my friend, your sources are smoking you.

I'm not trying to poke you in the nose here, Billy, but good Lord, what you suggest goes against the grain of my last 40 years of everything I've ever learned about cars, and I apologize that I cannot be more polite in saying so. It's not your fault you have been mislead.

I'm the first to say I don't know much about cars, and my learning windows are wide open here too. However, to suggest that manual and automatic drivetrains share similar power losses simply as a matter of how they function can only be the result of too many years of placating the disillusioned FWD crowd who don't care what RW numbers mean to begin with.

Based on my own experience with the '03 and '04 Cobra, both in driving them and watching them perform at the track, it's an easier sell to say that Ford fudged the advertised stock 390 HP rating, publishing the RW number, and not brake (flywheel) horse power. I've seen too many "400 plus" stock Cobras running mid 12s off the showroom floor to accept the "16 percent" rule.

[BillyGman]

I was merely speculating MAC daddy. Not arguing. This is an open forum, no? Most of my hi-perf experience is w/manual transmissions. The Marauder is the first hi-perf car I've owned w/an auto transmission, so this is new ground for me. Shoot me why don't ya? If I didn't know better, I'd think you have a Cobra yourself and are taking all of this personal. EZ big guy....it's only cars we're talking about here, not your family or anything.


....and besides all of that, this entire thread is heresay anyway unless any one of us can come up w/dyno figures of two cars of the same model and engines that have a manual and an auto transmission respectively, which are otherwise identical right down to the stock tune.

[martyo]

This is an open forum, no?

Well Billy, that's a good question. Let's think about it for a moment, shall we? There are those among us that feel that their opinion are more correct than someone else's opinion. I bet you agree with that, eh?


....and besides all of that, this entire thread is heresay anyway unless any one of us can come up w/dyno figures of two cars of the same model and engines that have a manual and an auto transmission respectively, which are otherwise identical right down to the stock tune.

Yep Billy, you hit it right on the nose here. In fact, most of the content on this site is populated with opinion and this place is really justa gigantic cocktail party donchaknow? We all come in here, mingle and share our opinions. Correct, eh? Every now and again someone siddles up next to ya and shares an opinion that he insists is the gospel, but in the end it is just opinion. Now, my experience has been that some of the folks in attendance at this big ol' cocktail party of ours don't take kindly to the fact that their opinions are just that, opinions.

Just my 2 cents. Your results may vary.

[TripleTransAm]

....and besides all of that, this entire thread is heresay anyway unless any one of us can come up w/dyno figures of two cars of the same model and engines that have a manual and an auto transmission respectively, which are otherwise identical right down to the stock tune.


Well, I don't have the exact curves with me, but I did personally witness two bone stock LT1s dyno back to back. Bear with me that there were a *few* differences: one car was a 1996 Camaro SS automatic, the other a 1997 Formula WS6 6-speed. Both were run in the respective 1:1 gear ratio, and both wear 17 inch tire/rim combos of the same width. The auto has a 3.23:1 rear end, while the 6-speed uses a 3.42:1 ratio, so that's one other difference to consider. Another thing to consider is that the SS was an early SS with the optional SLP exhaust (2 outlets on the left side) that had not yet received the "cone of silence" noise limiter that came on later cars so equipped. The rating was something like 310-320 hp with this exhaust. The WS6 on the other hand, had the factory exhaust and was rated at 305 hp.

The WS6 put down a solid 20-30 hp on the dyno versus the SS.

Performance-wise, it's a different story. The excellent-shifting GM tranny allowed the SS to easily rip off 13.7s when he was running his best, and the WS6 had to put some serious effort behind rowing that 6-speed to arrive at the same results. But that's the story the dyno told that morning in the Fall of 1999.

[BillyGman]

Thankyou Marty. I'd like to think that because of some people being like this :cheesed: that others here don't have to be like this :hide:

[martyo]

Thankyou Marty. I'd like to think that because of some people being like this :cheesed: that others here don't have to be like this :hide:

Yes Billy I would agree. But once again, that is just my two cents and your results may vary.

[BillyGman]

Steve, although that might not be conclusive because of the minor differences in the two cars as well as the contibuting minor factory HP ratings, that is an interesting comparisant. Thanks for that info bud.:banana2:

[TAF]

gigantic cocktail party...
huh...huh...huh, huh....he said cocktail party...huh,huh, huh...huh, huh

[looking97233]

something else to consider: manual and auto cars are tuned different from the factory. So even getting an exact match of cars except tranny will not yeld comparative results.

[TooManyFords]

I disagree that it's hearsay, Billy, because it's really flat out bull*****! Sorry, my friend, your sources are smoking you.

I'm not trying to poke you in the nose here, Billy, but good Lord, what you suggest goes against the grain of my last 40 years of everything I've ever learned about cars, and I apologize that I cannot be more polite in saying so. It's not your fault you have been mislead.

I'm the first to say I don't know much about cars, and my learning windows are wide open here too. However, to suggest that manual and automatic drivetrains share similar power losses simply as a matter of how they function can only be the result of too many years of placating the disillusioned FWD crowd who don't care what RW numbers mean to begin with.

Based on my own experience with the '03 and '04 Cobra, both in driving them and watching them perform at the track, it's an easier sell to say that Ford fudged the advertised stock 390 HP rating, publishing the RW number, and not brake (flywheel) horse power. I've seen too many "400 plus" stock Cobras running mid 12s off the showroom floor to accept the "16 percent" rule.

I think you've been huffin' too much of that ghost paint Mac! The parasitic loss between our tranny and a manual is about even, provided the torque converter is locked. When it is not locked, the parasitic loss is about 5-7% greater.

Notice I said "about".... Obviously this only occurs when the car is in cruise mode and the demands are reasonable on the drivetrain. I suspect everyone could argue, (successfully) just about any point between 0% and 20% as long as they provide the setting for the test.

Long story short, the automatic we have is far superior to the ones of old. It will never reach 0% loss, but neither will an manual. It's just that the gap is closing fast.

John

[Brutus]

Has anyone compared dyno runs for a Mach 1. Its available with both a stick and an auto.

[MikesMerc]

There is definitely a greater power power loss with an automatic trans vs a manual trans....period. That's fact. How much more loss with the auto varies from trans to trans. The biggest culprit is the TC.

No one needs "scientific" proof here on these forums to make that claim. There is decades of automotive experience which proves this point and ranks the question of "is there a difference in power loss between an auto and manual trans" into the Basic Auto Knowledge 101 class.

All that said, the difference is typically in the 5 to 10% range (additional power loss) with an auto trans. This has been proven time and again with the 5-oh and 4.6 mustang crowd, F body guys, and just about every other performance platform with both tranny variations offered.

None of this is opinion btw:)

[SergntMac]

"MacDaddy" ROTFLMAO! Thanks, Billy, I need a good laugh.

I opened this thread to get an answer for a genuine question. I was sincere, and I want to thank those of you who treated the topic accordingly. Since then, I've discussed this with professionals, and I accept their answers as fact. I got a long dry look from one of them, as if to say "you're kidding, right?" But as long as I bought the beer, I could pick their brain. I am paraphrasing them now;

"You'll never get two identical cars for a test. You can dyno your car, and then dyno your engine separately, but that would show the loss on your car alone. Typically, today's manual driveline loss is in the low single digits, and autos somewhere in the mid to upper teens. An across the board 20-25 percent is an extreme, and dated theory." They said a lot more, this will do.

IMHO, this coinsides with the general opinion set forth here "that things are getting better." Indeed, they are, auto trannys are getting more efficient, along with other driveline components. I can accept an auto tranny loosing 15-20 percent, but I cannot accept likewise loss from a manual driveline. It goes against everything I've ever known.

Thanks again, to those who helped. I learned a lot more that I expected.

[Amsoil_Dealer]

I have heard 15% for manual trannys as well from dyno jet operators. I have never dynoed an automatic car so i don't know what they say about that.

Driveline loss comes from natural losses associated with meshing gears. It is a simple law of physics. It stands to reason that an Automatic will have more drive line loss but it is not as dramatic as one might think. 2-3% is my guess. Maybe someone like Lidio can shed some light.

At the end of the day it really does not matter. More often than not an automatic with the same gears and engine will beat a stick in the quarter mile simply due to more efficient gear changes. No man can shift as efficiently as an automatic can so any losses inherient to the tranny are overcome by more efficitent shifting.

Don

[jgc61sr2002]

At the end of the day it really does not matter. More often than not an automatic with the same gears and engine will beat a stick in the quarter mile simply due to more efficient gear changes. No man can shift as efficiently as an automatic can so any losses inherient to the tranny are overcome by more efficitent shifting.

Don[/QUOTE]


I tend to agree. :up:

[SergntMac]

I tend to agree. :up:
Oh...I agree too, no question on that...Just not my topic.

Anyone have any doubts about an auto tranny beating a stick in drag racing?

[BillyGman]

Oh...I agree too, no question on that...Just not my topic.

Anyone have any doubts about an auto tranny beating a stick in drag racing?Nope. But it's my understanding that manual transmissions are gonna hold-up to the torque a lot longer. It seems like all the real heavy duty high HP drag cars w/automatic transmissions need to have those transmissions rebuilt every year or so, while I haven't heard that being the case with manual transmissions.

So I take it that just like w/a number of other choices, the automatic vs. manual choice involves trade-offs. You just can't have it all. Pluses and minuses w/either choice.

[MitchB]

Driveline loss is not a constant, nor a common given percentage of crankshaft output... anymore than is differential loss. The numbers you hear are all approximations, at best. And they're a near approximation at best and only work within certain parameters. An 800 RWHP car does not loose 120 HP to trans parasitic loss! The trans does not consume 60 HP more compared to a 400 RWHP car. That's an enormous amount of power to loose. Driveline loss is much more linear than you might suppose. I dunno, maybe the largest power consumer on the dyno is confusing everyone. And what do you thing I am refering to?

Mitch

[GordonB]

SergntMac,
From my experiences with my other performance car, the usual parasitic loss is 15% for manual and 20% for auto. This has been borne out numerous times among our club members (CCA). This is the diff. when dynoed.
However, at the drag strip, it is quite a different story with Automatic trannys usually besting a similarly equipped manual.
GordonB

[Warpath]

Keep in mind that power is lost through heat production. So, an engine producing 1000 hp may have more driveline loss than a 500 hp engine with identical drivelines. More heat will be produced with more power. I don't think it is quite linear. I don't think the 1000 hp engine will produce 75 hp more heat than a 500 hp engine. That's my opinion though. I've read some other opinions that state driveline loss is constant regardless of hp input which with I disagree.

Anyway, back when the 1999 Cobras came out, they did not make the hp advertized. Ford published a test procedure which stated to use 15% driveline loss. The 99s have the t45 5 speed manual and IRS. There is some additional loss through the half shafts not experienced in solid axles. I don't know how much. But it would be small.

I think the 03-04 Cobras are underrated in response to the fiasco created by the 1999 Cobras. I've seen bone stock 03-04 dynos coming in at around 350-360 rwhp which works out to be ~410-420 bhp using 15% loss.

[cyclone03]

IAt the end of the day it really does not matter. More often than not an automatic with the same gears and engine will beat a stick in the quarter mile simply due to more efficient gear changes. No man can shift as efficiently as an automatic can so any losses inherient to the tranny are overcome by more efficitent shifting.

Don
Well I was going to disagree with this statement useing the record stats from NHRA.Com but guess what, Stock and Super Stock class for class the top ET's come with autos,SS/AA is Quicker than SS/A,AS/A quicker than A/S etc...

Darn autos!

I don't think it's the gear change though,I think its the converter.
A race stick box will shift at WOT no problem,does lose less HP but that converter off the line kills em everytime.It's all in the 60ft time!

[SergntMac]

Don't worry about hijacking this thread. I got my answers, carry on.

I dunno, maybe the largest power consumer on the dyno is confusing everyone. And what do you thing I am refering to? Mitch
My "guess" would be tires and tie-downs. The tie-downs have always bothered me, but there's no way around them. A while back, Zack, Mike and I goofed around with tire pressure on a DynoJet 245HS and caused a 10 RWHP gain by inflating the rear tires to their maximum rating, 45 PSI, but no change in RWTQ.

I've mentioned this 411 before, and it's why I refer to a dyno as a test tool of some value, but not the end all it's made out to be. It's true value is showing where your power comes on so you can improve your tune. The sums, peaks, and RW numbers tend to be more a p*ssing contest than anything else. You can have all the high numbers you can glean from a dyno, but that doesn't make the car quick.

BTW...I appreciate the posts about auto vs. manual in drag racing, and I mostly agree. You get more control over your launch with a manual, but it's rare that a manual can be shifted as tightly as an auto, without spending a lot of money on real high end fancy pro stuff.

Anyone remember the "clutch-flight" transmission? Are they still around? Been years since I've heard anyone mention them.

[cyclone03]

Don't worry about hijacking this thread. I got my answers, carry on.
Anyone remember the "clutch-flight" transmission? Are they still around? Been years since I've heard anyone mention them.

How about the Crower-Glide,oh man now we're "dating ourselves".
BTW the clutch-flight and crower-glide morfed into the Lynco planetary trans a stable of Pro Stock for many years.
Now they're going back to "gear" boxes.

[MitchB]

My "guess" would be tires and tie-downs. The tie-downs have always bothered me, but there's no way around them. A while back, Zack, Mike and I goofed around with tire pressure on a DynoJet 245HS and caused a 10 RWHP gain by inflating the rear tires to their maximum rating, 45 PSI, but no change in RWTQ.

I've mentioned this 411 before, and it's why I refer to a dyno as a test tool of some value, but not the end all it's made out to be. It's true value is showing where your power comes on so you can improve your tune. The sums, peaks, and RW numbers tend to be more a p*ssing contest than anything else. You can have all the high numbers you can glean from a dyno, but that doesn't make the car quick.

The largest driveline power consumtion comes from the rear wheels/tires. There is at least one individual I know of who has both an engine and chassis dyno and this has been confirmed. Now when you use an apparatus like a dynojet 248 that measures how fast you can accelerate a drum of known mass, you have no way of factoring this in. Accelerating the wheels/tires accounts for most of the driveline loss you see and is larger than the trans/diff by several magnitudes. Trans/diff power consumption is very nearly linear and flat. If you use an eddy current dyno that allows you to hold RPM with throttle, the picture would be significantly different. The dynojet in it's most currently used form is very misleading because it does allow you to load the engine in a steady-state condition and, more importantly, it does not impose the kind of loads you will encounter in actual driving conditions. Shops have been catching on to this, but it has not been so fast. Many people had their cars tuned on a dyno, only to encounter tuning related failures in actual driving. Live and learn...

Mitch