Transmission Power Limits (HP)

[Nicholas R]

I've been searching because I remember it being posted but I cannot seem to find it; does anyone recall the limits of the DeLorean transmissions as far as horsepower, in both the automatic and manual? Both safe operating limits and potential failure points? Thanks.

[Rich W]

Hi Nicholas,

DeLorean Transmissions using a stock or modified PRV setup:

No specific values are etched in stone, since there are many other factors
that come into play, including various conditions of 30 year old transmissions
and how hard you "get on the throttle", can cause various failure conditions.

I have seen several transmission input shaft failures, with both stock and
turbo engines, but most were likely caused due to less than ideal alignment
between engine and trans. (missing alignment pins) or pilot bearing issues.

However, in general, "safe" conditions usually can exist up through 200hp.
The Legend Twin Turbo project had a goal of being able to operate up to
250hp reliably (with factory warranty), but even Legend had difficulties.

Do Not Forget about Maximum Torque Output, along with the HP figures.
It is usually the high torque conditions that will cause parts to fail, not the
actual HP output. Of course, heavy abuse will cause the most failures.

DeLorean Transmissions using Engine Swap setups:

Although you can acheive over 300hp with a heavily modified PRV setup,
most of the engines that are currently acheiving over 300hp with a DeLorean
transmission are engine swaps (including RUN DMC 3.8L Turbo at DMC CA).

My Buick Grand National 3.8L V6 Turbo powered DeLorean is running a stock
DeLorean transmission and even without the new ignition system parts and
new (larger) injectors, I was clocking over 250 ft/lbs of torque on the dyno.

Shift carefully and accurately, and then "get on" the throttle.

I hope this helps a little.

Later,
Rich W.

[content22207]

People throw HP numbers around without knowing what they represent. HP doesn't even exist in the real world (there is no such thing as a HP gauge). It is a somewhat arbitrary calculation made from other measurements that do exist.

An engine with 1,140 ft lb of torque, spinning 600 RPM, produces the same 130 HP number as a stock PRV -- how do you think a DeLorean input shaft would stand up to it?

Bill Robertson
#5939

[DARCOM]

how much torque can a auto & manual delorean transmission take.

[Rich W]

Since Bill has been recently on a kick mentioning the OP (Original Poster's)
information when posting his responses, may I remind Bill that the OP asked
about HP power limits when using a DeLorean transmission.

So, unless Bill decides to fabricate an adapter plate or custom bell-housing
to mate the DeLorean transmission to some engine with over 1,100 ft/lbs
of torque, I do not think the OP will find much value in Bill's reply.

My best guess is this setup would be most useful if you have the need to
tow the BTTF III Train with your DeLorean, instead of having the train push
the DeLorean. Sorry, I got a little "off track" toward the end of my post.

Later,
Rich W.

[Nicholas R]

Thank you for the help.

What are the primary failure points? Is it fracturing the input shaft? Stripping gear teeth? Damage to the trans-axle? I have heard that Toby sells a higher load bearing input shaft.

[Rich W]

DARCOM and Nicholas,

The stock automatic and manual transmissions can "handle" about the same
amount of HP, with 200hp in the "safe range" and 250hp nearing its "limits".
Again, a lot of this will depend upon the condition of the transmissions and
how abruptly the power is applied...gradual power to "get on" the throttle.

Automatic transmissions can (and should) be "beefed up" with a reinforced
flex plate and heavy duty torque convertor, like the RUN DMC at DMC CA.

Manual transmission can be "beefed up" with an improved input shaft, but
that will only move the first point of failure to another part...gear teeth?
Fifth gear is probably the most fragile of the gears in the DeLorean manual
transmission, but you can run the risk of "messing up" synchros as well.

As for making sure you get the extra HP to the stock manual transmission,
the stock DeLorean clutch can probably only handle up to 200hp - 250hp,
so you will need a clutch upgrade to make sure the power is transferred.

Later,
Rich W.

[dmc6960]

I believe Martin Gutkowski has said in the past, the stock auto trans can handle up to 200ft/lbs torque. Stock manual tranny can handle 240-250ft/lbs torque. With an input shaft upgrade the next failure point is moved up to about 300ft/lbs with fifth gear. Assuming your using controlled forced induction to get that high of a torque rating, you could setup ECU logic to limit boost in 5th gear so you can go higher than 300ft/lbs in other gears. Or you could just take it easy when in 5th if that's too hard to do.

Notice all these ratings are in torque, not HP. Bill does have a point there, it's the torque that will generally kill a trans, not raw HP.

[vwdmc16]

...there is no such thing as a HP gauge...



there happens to be one on the Buggati Veyron, even if its not 100% accurate it still technically has a hp gauge.

http://www.lotustalk.com/forums/attachments/f100/69882d1199041059-ran-against-veyron-ford-gt-racecar-others-upcoming-12hrs-sebring-race-05-veyron-power-gauge-det.jpg

[content22207]

About 130 HP is typical for a Motorcyle engine -- anyone want to put one in their DeLorean? HP numbers are the same, so performance should be the same, right?

Bill Robertson
#5939

[David T]

Properly modified the 5-speed can handle a lot of power. It is used in a Lotus set-up with way more than 130 HP. As for the automatic, IMHO, 130 is near it's limit. If you looked at how C1 clutch pack is made, spotwelded sheet metal, you would wonder how it handles even 130 HP! If it wasn't for the torque converter to soften out the peak torque loads it wouldn't last a minute!
David Teitelbaum

[DCUK Martin]

Lotus UN1 = Renault UN1

There is no difference.

Lotus V8's do break their transmissions and Lotus fit GTO single piece input shafts and gearsets to solve the problem.

The most powerful Renault to use the UN1 was the A610 with 260ft-lb though this engine was definitely de-tuned. In the Venturi 300 it pushes over 300 ft-lbs and it is in this region that Kevin Jones of GTO says the transmission is likely to break. 5th is indeed the weakest point but you have to be in it to break it. The input shaft and/or coupler is the next weakest point.

Technically it is actually power that kills transmissions, not torque. You can cheerfully put a static loading of over 500 ft-lbs through the DeLorean 5th gear and it'll be fine. Think about it: every time the shaft rotates 180 degrees, the force pushing the gears apart reverses and its this cyclic loading on the shaft that causes fatigue and failure. The faster the speed, the quicker the cyclic loading.

So what breaks transmissions is a function of shaft speed and torque, otherwise known as.... power.

I'd like to add that having owned both an A610 and a Venturi 300.... that's more than enough power for a DeLorean!

[David T]

To be complete about this you must also acknowledge that the power must go through the final drive in addition to the transmission (you cannot use one without the other). I have seen teeth ripped off the ring gear in a Lotus final drive and that was IN A LOTUS not a Delorean. The input shaft is a weak point but there are others and if you fix the "weakest link" be prepared to discover the *new* weakest link. As I have said in the past, the entire drivetrain was designed as a package. If you uprate or upgrade one thing be prepared to upgrade the ENTIRE package.
David Teitelbaum

[Nicholas R]

Lotus V8's do break their transmissions and Lotus fit GTO single piece input shafts and gearsets to solve the problem...

...The input shaft and/or coupler is the next weakest point.


I have heard that Toby makes the "bulletproof" coupler:
http://www.delorean-parts.com/Merchant2/merchant.mvc?Screen=PROD&Store_Code=DPNW&Product_Code=K1016DP&Category_Code=

Where can one find a stronger input shaft? Also is there any way to strengthen 5th gear?

[Nicholas R]

So what about the clutch? With the right mods the engine can handle 300hp but how much can a DeLorean clutch handle?

[David T]

The clutch is not the weak point so there is not a lot of experience with blowing out clutches. The first thing you will notice is that they will wear out a lot faster when you pass more power through them. Especially if you are "dumping" the clutch as in a drag race start. A standing stop, high engine RPM's and not slipping the clutch into first. Do it a few times you you will quickly find all of those "weak links".
David Teitelbaum

[DCUK Martin]

To be complete about this you must also acknowledge that the power must go through the final drive in addition to the transmission (you cannot use one without the other). I have seen teeth ripped off the ring gear in a Lotus final drive and that was IN A LOTUS not a Delorean.

Lotus uses the 3.88:1 final drive as opposed to the 3.44:1 in the DeLorean which is stronger (according to Kevin@GTO). Having said that, you still shouldn't manage to strip teeth off the ring gear unless you're doing something irresponsible...


The clutch is not the weak point so there is not a lot of experience with blowing out clutches. The first thing you will notice is that they will wear out a lot faster when you pass more power through them.


The standard NA clutch will slip in a 2.5 turbo engine at full boost. The clutch for that (which doesn't cost much more than a standard unit) will slip when bolted up to a 3 litre turbo PRV. The A610 clutch, which is made in small quanitites by Matra in France specifically for Alpine has distinct differences to its pressure plate against the standard configuration. The pivot pin on the clutch fork is also uprated for the extra force required. That clutch costs in excess of £500 (roughly $750) and is strong enough to break the transmission.

I don't know what the V8 Esprits use for a clutch, but the 4-banger turbos use the Renault 2.5 turbo clutch (at 3 times the price).


I have heard that Toby makes the "bulletproof" coupler:

Where can one find a stronger input shaft? Also is there any way to strengthen 5th gear?

The strengthened coupler only fixes one problem and certainly doesn't protect 5th. The only way to cover all the basis is with a single piece shaft & gearset from GTO Engineering. You can find it on my website on the performance page.