Max power/torque for autos

[Henrik]

I am wondering what the community feels is the maximum HP and torque a D with automatic transmission could reliably handle. For the sake of consistency, let me have engine dyno numbers (as opposed to at the rear wheels).

[Tomcio]

Henrik,

From what I know and what I have seen I can say that 130HP is pretty much the maximum what the automatic transmission can handle. You might get away with slightly more power if you operate the throttle smoothly.
Really, if you need more power you need to learn to drive a stick. They can handle more power, are more reliable and most importantly MORE FUN! ;)

[Henrik]

Henrik,

From what I know and what I have seen I can say that 130HP is pretty much the maximum what the automatic transmission can handle. You might get away with slightly more power if you operate the throttle smoothly.
Really, if you need more power you need to learn to drive a stick. They can handle more power, are more reliable and most importantly MORE FUN! ;)

Thanks. 130 HP at the flywheel is the stock rating. So, in other words, you are saying that it can't handle ANY additional hp/torque? Are you sure about that? How does DMCH justify the Stage II and III upgrades? While riding with Stephen Wynne in a Stage III car a couple of years ago, I distinctly remember him saying that he recommends the auto tranny for Stage III.

[jamesrguk]

Max 130bhp?

I have a dyno test that says otherwise, I understand that 200bhp at the flywheel is about the limit for the stock auto.

Most dmc autos fail/have problems due to electrical gremlins such as the govenor/shift computer not because people have put too much power through them.

Yes stick shift is better suited to greater power and I would say a more sporty feel than an auto.

The auto is a pretty good peice of kit sadly people often focus on the weekest link which is the computer gov which was just a poorly made (of its time) electric circuit which is easily updated with modern components to make a reliable unit.

J

[Tomcio]

Some time ago I bought a DeLorean with an automatic transmission and a Buick engine that had something around 180HP. The transmission could not handle this power and it wasn't because of the governor. When I opened the casing parts fell out. It was a total mess inside. I don't know how exactly it happened as I have only seen the aftermath but this engine was clearly more than the transmission could handle.
Are you sure that Houston uses stock automatics for their Stage II and III upgrades? I believe I've heard something about some upgrades to the internal components to allow for more power. I might be wrong though...
In my opinion the automatic transmission in stock configuration can handle stock engine. Anything more and the transmission might not be up to it. That is my opinion.

[Delorean Industries]

Some time ago I bought a DeLorean with an automatic transmission and a Buick engine that had something around 180HP. The transmission could not handle this power and it wasn't because of the governor. When I opened the casing parts fell out. It was a total mess inside. I don't know how exactly it happened as I have only seen the aftermath but this engine was clearly more than the transmission could handle.
Are you sure that Houston uses stock automatics for their Stage II and III upgrades? I believe I've heard something about some upgrades to the internal components to allow for more power. I might be wrong though...
In my opinion the automatic transmission in stock configuration can handle stock engine. Anything more and the transmission might not be up to it. That is my opinion.

They do not upgrade the trans or stock internals on boosted applications.

[Chris Burns]

I have seen several engine swaps done with Delorean automatic transmissions (including a Chevy V6 and a Mazda Rotary). I would not put anything other than stock through the 3 speed auto. Now the 5 speed... That's where you have some flexibility!!:Headspin:

[Josh]

Torque breaks things, not HP

[Farrar]

Where is that video of the engineer saying that the auto trans could handle a supercharged PRV V6? Anyone else remember that?

[Michael]

DMCH has confirmed the stage III supercharged packages are safe to run on an auto trans car.

[Nicholas R]

DMCH has confirmed the stage III supercharged packages are safe to run on an auto trans car.

Yea but they've also said that the stage III car produces 157hp at the wheels on a manual transmission car. I mean... yea it's an increase, but it's not necessarily pulling the front wheels off the ground. The person that mated the ford V8 to the auto definitely tested its capabilities more than the stage III. However, from what I read that car never really ran right.

[Shep]

For what it's worth, my D has 60% higher HP than stock, so roughly 208 HP, and it's an automatic. I've revved that thing to maximum RPM's and maximum throttle on occasion and the transmission more than handles it. While it should be noted that the transmission is freshly rebuilt, any transmission that's damaged is going to have issues anyways, regardless of whether it's auto or stick, and those issues will be exacerbated when you throw more HP at it. And yes, everything after the engine is 100% stock. I'm fairly certain it could handle even more HP without having any issues with the transmission, but I'll play it safe and stop short of quantifying that with numbers.

[Nicholas R]

For what it's worth, my D has 60% higher HP than stock, so roughly 208 HP, and it's an automatic. I've revved that thing to maximum RPM's and maximum throttle on occasion and the transmission more than handles it. While it should be noted that the transmission is freshly rebuilt, any transmission that's damaged is going to have issues anyways, regardless of whether it's auto or stick, and those issues will be exacerbated when you throw more HP at it. And yes, everything after the engine is 100% stock. I'm fairly certain it could handle even more HP without having any issues with the transmission, but I'll play it safe and stop short of quantifying that with numbers.

Wow, I haven't read your blog but what have you done to it to produce that kind of power? Is that 208 measured at the crank or at the wheels?

[Shep]

Wow, I haven't read your blog but what have you done to it to produce that kind of power? Is that 208 measured at the crank or at the wheels?SPEC I cat-delete exhaust, performance camshafts, and quite a bit of fine-tuning at DPI. I'm basing those numbers off of a wheel dyno, but going by percentages rather than actual numbers. Josh gave me his "corrected" figures of 70 HP stock and 112 HP with my setup, which adjusted to the OEM specification of 130 HP stock equates to 208 HP.

[Nicholas R]

SPEC I cat-delete exhaust, performance camshafts, and quite a bit of fine-tuning at DPI. I'm basing those numbers off of a wheel dyno, but going by percentages rather than actual numbers. Josh gave me his "corrected" figures of 70 HP stock and 112 HP with my setup, which adjusted to the OEM specification of 130 HP stock equates to 208 HP.

I'm a little confused. You measured 112hp and are assuming its really 208hp? I'm not trying to be a jerk or anything, I'm just not sure how that works out. Can you elaborate? If you're loosing 96hp between the flexplate and the wheels something would be wrong. 48% loss is a pretty big deal and that energy has to go somewhere. For reference, my bone stock auto measured 90hp at the wheels, then 99hp once I put the UK exhaust on. I can post the graphs if interested.

[Michael]

Yeah, I'm not following the math on that either.

[Shep]

I'm a little confused. You measured 112hp and are assuming its really 208hp? I'm not trying to be a jerk or anything, I'm just not sure how that works out. Can you elaborate? If you're loosing 96hp between the flexplate and the wheels something would be wrong. 48% loss is a pretty big deal and that energy has to go somewhere. For reference, my bone stock auto measured 90hp at the wheels, then 99hp once I put the UK exhaust on. I can post the graphs if interested.You're missing the stock measurement of 70 HP. This was back when Josh figured all the HP numbers we've been using were "inflated" and posted more realistic (i.e. lower) numbers. He made a thread on it here (http://dmctalk.org/showthread.php?5491-DPI-Engine-Performance-Stats-DYNO-Results-by-the-numbers), providing more scientifically-accurate numbers than what the industry typically uses. His "more accurate" numbers measured the stock drivetrain at 70 HP at the wheels. The factory spec is 130 HP at the engine, so the wheel HP that Josh measured is ~53.846% of the factory-provided engine HP. That same dyno with the deflated numbers measured my D at 112 HP at the wheels. Adjusting by the same percentage, we get 208 HP. This is where the number comes from.

[Ron]

Mathematically, it assumes 70/122 == 103/X, so:
.625 = 130/X
.625 * X = 130
X = 130 / .625
X = 480

Totally off subject- This reminds me of a test bonus question I didn't have time to answer. It went something like this:
"How long does it take for a pump capable of pumping 5 gallons per minute at level to empty a 20ft long inverted semi-hemispherical tank with a diameter of 3ft with a lift of 20ft (lift formula is bla bla...)". I answered, "0 minutes, since the tank is inverted, it would empty instantaneously!" When he returned the test, he stood towering over me and asked, "Ron, what is the definition of a tank?" I replied, " An encloooooosed container used to hold liquids or gases??" He he laid it on my desk and walked on, straight faced. I flipped to the question and saw, "Yeah right +5"....full credit for the question, which gave me 100, exempting me from the final, a godsend for a guy on overload in his senior year in a semester system.
:yesss:

[Nicholas R]

You're missing the stock measurement of 70 HP. This was back when Josh figured all the HP numbers we've been using were "inflated" and posted more realistic (i.e. lower) numbers. He made a thread on it here (http://dmctalk.org/showthread.php?5491-DPI-Engine-Performance-Stats-DYNO-Results-by-the-numbers), providing more scientifically-accurate numbers than what the industry typically uses. His "more accurate" numbers measured the stock drivetrain at 70 HP at the wheels. The factory spec is 130 HP at the engine, so the wheel HP that Josh measured is ~53.846% of the factory-provided engine HP. That same dyno with the deflated numbers measured my D at 112 HP at the wheels. Adjusting by the same percentage, we get 208 HP. This is where the number comes from.

I suppose you can do the math however you like but but that seems like a pretty excessive amount of extrapolation to me.

"If you torture the data it will confess to anything." - Ronald Coase

In your case, the more you lower the stock number, the more your projected number is going to increase. The fact that you had 70 with a worn engine and now have 112 with a rebuilt engine, doesn't really mean the relationship between actual and spec stays the same. When you were reading 70hp at the wheels, I guarantee you weren't making 130 at the crank.

You really think you're only getting 53% of the power from the engine to the wheels? Not trying to burst your bubble, but in all honesty, if you measured 112hp at the wheels, you should really hope that you are not creating 208hp at the crank, because if you are, you have a very major problem. That's an engineering nightmare. You cannot just loose 48% power. The energy has to go somewhere. Where do you think it's going? Can't just chalk it up to "transmission losses".

[NightFlyer]

You're missing the stock measurement of 70 HP. This was back when Josh figured all the HP numbers we've been using were "inflated" and posted more realistic (i.e. lower) numbers. He made a thread on it here (http://dmctalk.org/showthread.php?5491-DPI-Engine-Performance-Stats-DYNO-Results-by-the-numbers), providing more scientifically-accurate numbers than what the industry typically uses. His "more accurate" numbers measured the stock drivetrain at 70 HP at the wheels. The factory spec is 130 HP at the engine, so the wheel HP that Josh measured is ~53.846% of the factory-provided engine HP. That same dyno with the deflated numbers measured my D at 112 HP at the wheels. Adjusting by the same percentage, we get 208 HP. This is where the number comes from.

I thought that one of the points of Josh's post was to do away with the crazy-high / "inflated" drive-train loss assumption, and instead use the more realistic assumption of a 15% drive-train loss for the automatic.


With this being an automatic we will allow for a 15% drive train loss...

So, if your car measured 112 whp, then that would put the bhp at roughly 132.

[Shep]

Good points everyone, I stand corrected. Please disregard. I'll shut up now :)

[Nicholas R]

I always feel like people over estimate torque converter losses. Yea at low rpm they're completely ineffective but as the rpms increase, so does the efficiency. Most reach 85%, 90%, even 95% efficiency at the top of the power band. It's all about the rotating speed. At full throttle, automatics do a very good job transferring power.

Also I don't want to come off as a jerk or make you feel bad, I just try to make sure all the information works out.

[jamesrguk]

These are the results from my recent dyno run, auto trans decent exhaust, no cat and the Volvo fuelling, no other work done.

We dyno'd many deloreans throughout the day and believe the dyno was pretty accurate.

Sorry the pics are upside down I don't seem to be able to flip them on my ipad

James

[Nicholas R]

These are the results from my recent dyno run, auto trans decent exhaust, no cat and the Volvo fuelling, no other work done.

We dyno'd many deloreans throughout the day and believe the dyno was pretty accurate.

Sorry the pics are upside down I don't seem to be able to flip them on my ipad

James

I'm confused, are you the 145hp or the 113hp? I'm guessing the 113 because the torque curve on the 145 is way too clean for an automatic.

I cannot remember the details but isn't there a difference in the European output spec? Isn't it something like 20 mor hp than the US spec? Either way nice job :thumbup:. I maxed at 99hp with my auto.

[jamesrguk]

I'm confused, are you the 145hp or the 113hp? I'm guessing the 113 because the torque curve on the 145 is way too clean for an automatic.

I cannot remember the details but isn't there a difference in the European output spec? Isn't it something like 20 mor hp than the US spec? Either way nice job :thumbup:. I maxed at 99hp with my auto.

They're both my car, but I think the 145bhp is calculated at the flywheel, but the accurate figure is 113hp which was measured at the wheels.

Effectively my car, although not from the factory, has the 'euro spec' engine which essentially amounts to no cat and slightly different non lambda fuelling, but looks 100% stock.

J

[SEO Motorsports]

Hmmmm.....sound like the limit needs to be pushed and tested to me...

[DeLorean03]

Hmmmm.....sound like the limit needs to be pushed and tested to me...

What a coincidence. I was just thinking the same thing (: ...

[Nicholas R]

By all means you two, have at it! Who's going to be the first to take their auto to the limit?

[Farrar]

Torque, torque, torque! :D

[SEO Motorsports]

By all means you two, have at it! Who's going to be the first to take their auto to the limit?

Already in the works.

[Nicholas R]

Glad to hear it :thumbup: