Porsche G50. Is a turbo box necessary?

I've read and researched much about Porsche G50 transaxles. Its my understanding the only difference between a 5 speed non turbo and a 5 speed turbo box is the size of the ring and pinion and the strength of the case. Generally speaking though the price of a turbo box is twice that of the non turbo. Ultima cars does not recommend using an expensive turbo box and in fact said they use a stock G50/03 for their record breaking 0-100-0 runs. I read a thread about how stout 930 4 speed turbo boxes are. Non turbo 5 speed Porsche G50's, How hard they can be run?
 

Russ Noble

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Intriguing Bill, that's the first time I've ever heard that the G50/5x has a beefed up case. Do you have any specific details?

How hard can the G50/0x be run? Probably quite hard, but for how long? It comes down to how sticky your rear rubber is, and how much torque that rubber allows you to put through the trans. Not to mention your driving style and whether you treat the thing with some mechanical sympathy or are just some ham fisted un coordinated twit!

A G50/0x may be good for setting a record breaking 0-100-0 time, but if you drive it like that all the time how would it's longevity fare? Since you are asking the question 'how hard can it be run?' maybe you really are a candidate for the beefier trans. Only you know the treatment you are going to give it. Only you can decide which trans you need to run.

It comes down to peace of mind, if you are going to give it an unmerciful thrashing, do you want to be living in fear that your not inexpensive /0x is about to lunch itself? Not to mention the inconvenience when it does...How expensive is it likely to be when/if it does destroy itself? Would it not be better to put a little more cash up front and be less likely to have these issues in the longer term?

But for 'normal' (what is that???!!) everyday driving I'm sure a /0x would be an excellent choice. Probably also a reasonable choice if you run it hard, but how hard and how often? Who knows.....If you are continually hard on it, that oft repeated phrase may apply here......'You can either pay now, or you WILL pay later!'
 
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Ron Earp

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Just a side note that I found out this week - it appears the 930 boxes are extremely competent and can handle a lot of power. However, two independent Porsche transaxle shops were consulted with respect to longevity on the 930 box and the 13 hr VIR enduro we intend to run.

Both indicated the box would not survive without an oil cooler setup. Therefore the Lola is being fitted with a oil cooler/pump assembly which RCR is handling for me. The G50s are the same with respect to cooling if you wish to run it for long periods of time. I was told Porsche factory teams learned this back in the day, the hard way.
 
For those reasons mentioned by Ron, and on the advice of Erik Johnson, I am installing a pump and cooler with my 930LSD.
 
Intriguing Bill, that's the first time I've ever heard that the G50/5x has a beefed up case. Do you have any specific details?

How hard can the G50/0x be run? Probably quite hard, but for how long? It comes down to how sticky your rear rubber is, and how much torque that rubber allows you to put through the trans. Not to mention your driving style and whether you treat the thing with some mechanical sympathy or are just some ham fisted un coordinated twit!

A G50/0x may be good for setting a record breaking 0-100-0 time, but if you drive it like that all the time how would it's longevity fare? Since you are asking the question 'how hard can it be run?' maybe you really are a candidate for the beefier trans. Only you know the treatment you are going to give it. Only you can decide which trans you need to run.

It comes down to peace of mind, if you are going to give it an unmerciful thrashing, do you want to be living in fear that your not inexpensive /0x is about to lunch itself? Not to mention the inconvenience when it does...How expensive is it likely to be when/if it does destroy itself? Would it not be better to put a little more cash up front and be less likely to have these issues in the longer term?

But for 'normal' (what is that???!!) everyday driving I'm sure a /0x would be an excellent choice. Probably also a reasonable choice if you run it hard, but how hard and how often? Who knows.....If you are continually hard on it, that oft repeated phrase may apply here......'You can either pay now, or you WILL pay later!'
I agree Russ. Pay now or pay later. I think i might be wrong about the stronger case. Went back and read some emails from an expert and they said the only difference was the bigger ring and pinion. Theres a g5052 for sale on ebay from los angeles porsche dismantlers right now. hmmmmmmm its tempting. Already been burned once by a wrecking yard though.
 
As I am on my G50.50 Turbo, plus a billet side plate and here's why (I believe these were posted before):
Ouch! Ive heard about strengthening the side plate. What do you estimate your power to be around? Could you tell me more about driving conditions, car weight and tire size and type when it broke? The porsche transaxle expert ive talked to recommend billet shift forks and steel synchros as well. Oil coolers also seem to be the way to go. Thanks for your input!
 
Bill,

Fortunately, those pictures are not from my G50 but only serve as an example of what might happen. I believe that tranny was "handling" 600+ HP. Yes, an oil cooler is a great idea. A few running Porsche transaxles have cryo-treated the gear-sets. But I'll defer to the Porsche experts on what's necessary or not.
 
Bill,

I found the thread on another forum. Looking back it seems the car had a supercharged LS7 so the HP/TQ was way up there!
 

Russ Noble

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Doc,

Was that a /0x trans or a /5x?

Either way the guy was an idiot not running a billet sideplate with the sort of torque he must have had. IMHO that is the cheapest, most effective mod you can do. A total no brainer!

It would be interesting to know more details and what he has done to rectify the situation and how it is holding up now. And how long he had run it before he destroyed it. Also whether he had rebuilt the trans or was just running a second hand one 'as purchased'. More than likely running it 'as was' since he hadn't even bothered about the side plate.Can you post the link to that site please.

Interesting that when Porsche went from the 930 to the G50/5x they went to a smaller ring and pinion but bigger gears (greater shaft distance) but the weak point is the sideplate. I wonder what the failure mode of either of these trans is when fitted with sideplate and cooler?

I am still waiting for someone to come up with photos, or even anecdotes, of a 930 failure. So far nothing...... http://www.gt40s.com/forum/gt40-tech-powertrain-transaxles/19746-930-failure.html
 
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Caption on pic is 'Toms 935', not a good look, eh Russ. But without knowing the state of the trans-mileage-treatment etc its a bit tough to make a judgment call.
 

Russ Noble

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Lifetime Supporter
With regard to the G50. Apparently it was an /01 on its first outing after being rebuilt with dog gears. At least they should still be alright. I'm amazed that an apparently experienced shop would let that go out the door without a beefed up sideplate. There again who knows, they may not have been informed of the application....

With regard to the 930. I have reposted Pete T's offering on the 930 thread. http://www.gt40s.com/forum/gt40-tech-powertrain-transaxles/19746-930-failure.html
 
Ron,
Ref the cooler on the trans. We had a Mendeola in our off road racer. We used synthetic lube but it would come out smelling burnt after just 1 race. We would have bearing trouble on the rear shaft. We plumbed a cooler and the lube was beautiful after that. I dont remember the temp drop we saw on the trans just from a small cooler but it was huge. When is your race and is there going to be internet coverage?

Jim N
 

Russ Noble

GT40s Supporter
Lifetime Supporter
Is it just me or did those gears in the 930 failure pics look very blue? As in too much heat?? I think that was 3rd gear that went.
Yeah my bad. That is 3rd.

Initially I thought the blue was heat but when I looked closer it looked like remnants of blue oil. Swepco 201 maybe?
 
Ouch! Ive heard about strengthening the side plate. What do you estimate your power to be around? Could you tell me more about driving conditions, car weight and tire size and type when it broke? The porsche transaxle expert ive talked to recommend billet shift forks and steel synchros as well. Oil coolers also seem to be the way to go. Thanks for your input!
Hi

It is hard to tell from the picture but it looks like the broken sideplate was a "small side plate".

Porsche has manufactured two different OEM sideplates.

The weaker one is about 13mm high (thick). One can see on the picture that it is thicker in the center and than runs down and gets thinner.

The stronger sideplate is about 21 mm thick and has a stronger webing. They where used on the G50/5x but also on some others ( my G50/05 has had one as well).

According to two gearbox specialist they are as good as billet ones and maintain the OEM look.

Attached a pic of the stronger side plate. It is clearly to see that it doesn´t gets thinner from the center towards the outer circumfence ( compared to the broken one above)

I´m also preparred my gearbox for running an oil cooler. Álso i´m using a ATB differential instead of a LSD ( which is much harsher in the locking up phase).
Finally a spend also some money on good oil (SWEPCO 210).

We will see if it holds up my 520 HP 331 and the wide rears ( 345)

TOM
 
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Well opinions very on this but I would not recommend exceeding about 550HP for the G50.0x series.

You can do a bit more with the turbo, and I like the reliability of the turbo far more.

I would certainly like the opportunity to discuss your options if you would be open to that.

Let me know if I can help.

Erik Johnson
GBox Sales Manager
(303) 440-8899 work
(303) 895-4828 cell
 
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