Porsche 993 twin turbo

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Re: Porsche 993 twin turbo

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Fusion Works wrote: Tue Aug 09, 2022 10:20 am Contact Brian @ http://rarelyl8.com/home.html

He can build you some headers that will work properly with your engine with proper primary sizes, made out of 321 stainless. They won't crack.
Thank you for the tip. These are super complicated headers because they have heat shields and heat exchangers integrated to them. The heat shields are there to protect the air cooled cylinder heads from heat and the heat exchangers are there for the cabin heating system. The exhaust gas flow tuning part is super simple, in contrast.

https://www.ladismantler.com/porsche-91 ... ctory-oem/

The seller is asking $4k for used factory exhaust manifolds, so there…
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Re: Porsche 993 twin turbo

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He does some headers with an integrated heat exchanger for the heaters. Remember he is used to building for 930 turbos. Similar air cooled engine construction and complications.

Better yet weld water jackets on the heads and fix that silly problem the way Porsche did on the 962. :D
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Re: Porsche 993 twin turbo

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My guess is this project will never get off the ground.
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Re: Porsche 993 twin turbo

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rp930 wrote: Wed Aug 10, 2022 8:54 am My guess is this project will never get off the ground.
On the one hand, you’re probably right.

On the other hand, the car I just bought for this project arrived today from Hamburg, Germany:
D9C6DD70-5F7C-4F7A-B50D-7FDB1BD60D46.jpeg
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Re: Porsche 993 twin turbo

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ptuomov wrote: Wed Aug 10, 2022 10:06 am
rp930 wrote: Wed Aug 10, 2022 8:54 am My guess is this project will never get off the ground.
On the one hand, you’re probably right.

On the other hand, the car I just bought for this project arrived today from Hamburg, Germany:

D9C6DD70-5F7C-4F7A-B50D-7FDB1BD60D46.jpeg
Nice! They are great cars as is. I have driven plenty of stock and modified ones. The stocks ones always perform and are very quick, the modified ones I’ve driven are stupid fast and pretty much useless. Reliable HP is the goal. No matter what you do to it there will always be something more modern (water cooled) that’s faster. Ok I’m off my soapbox now.
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Re: Porsche 993 twin turbo

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rp930 wrote: Wed Aug 10, 2022 10:13 am No matter what you do to it there will always be something more modern (water cooled) that’s faster. Ok I’m off my soapbox now.
Mid 8's @ 169mph for a water cooled Porsche is pretty quick

https://www.motor1.com/news/415236/pors ... drag-race/


I have a 996 GT2, along with a 930. Other than the nostalgic look/history and attention, the water cooled car is better in every respect.
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Re: Porsche 993 twin turbo

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My sixteen year old daughter has a learners permit and a 1020hp Tesla that does 0-60mph in under 1.9s. So it’s obvious that my quixotic quest is about something else than absolute performance for minimum cost.
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Re: Porsche 993 twin turbo

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rp930 wrote: Wed Aug 10, 2022 10:13 amNice! They are great cars as is. I have driven plenty of stock and modified ones. The stocks ones always perform and are very quick, the modified ones I’ve driven are stupid fast and pretty much useless. Reliable HP is the goal. No matter what you do to it there will always be something more modern (water cooled) that’s faster. Ok I’m off my soapbox now.
I've driven one for about 850km now, and I'd have to say that compared to the other cars I drive regularly (2018 AMG E63S Wagon, 2021 Tesla Model S Plaid, and 1987 Porsche 928 S4 twin-turbo in particular), the 993 Turbo feels light and... slow. To people driving other old 911 models, it must be the opposite!

There's no eyeball flattening acceleration by any means, it's very gradual acceleration even when going thru the gears at higher rpms. It does get up to a fast speed pretty quickly, but I haven't yet gotten the feeling "what the hell just happened" with the speed far in the triple digits mph -- that doesn't seem to happen without specific intent.

I feel that one is sitting pretty far in the front and pretty low, which makes the speed seem higher than it actually is (the opposite extreme case is Tesla). I think the overall cabin loudness also contributes to that feeling. This specific car had all the wear items in the suspension replaced five years ago (a EUR 25k receipt...) so I'm not surprised that it rides pretty well. The car certainly goes exactly where I intend it to go on the road, steering assist level is to my liking.

One thing that feels surprisingly good is stopping distance. The brake pedal is very stiff with little assist, but when you do push it hard the car really stops. This must be the fact that as a rear-engined car there's still some weight/downforce on the rear wheels when braking. I don't know.

Writing about it now, it's becoming clear how little I understand how cars actually work and how poorly I can articulate driving impressions and relate them to technical facts.

I think the car could handle a lot more power, by the way. That's just a feeling.
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Re: Porsche 993 twin turbo

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ptuomov wrote: Sun Aug 14, 2022 2:53 am
rp930 wrote: Wed Aug 10, 2022 10:13 amNice! They are great cars as is. I have driven plenty of stock and modified ones. The stocks ones always perform and are very quick, the modified ones I’ve driven are stupid fast and pretty much useless. Reliable HP is the goal. No matter what you do to it there will always be something more modern (water cooled) that’s faster. Ok I’m off my soapbox now.
I've driven one for about 850km now, and I'd have to say that compared to the other cars I drive regularly (2018 AMG E63S Wagon, 2021 Tesla Model S Plaid, and 1987 Porsche 928 S4 twin-turbo in particular), the 993 Turbo feels light and... slow. To people driving other old 911 models, it must be the opposite!

There's no eyeball flattening acceleration by any means, it's very gradual acceleration even when going thru the gears at higher rpms. It does get up to a fast speed pretty quickly, but I haven't yet gotten the feeling "what the hell just happened" with the speed far in the triple digits mph -- that doesn't seem to happen without specific intent.

I feel that one is sitting pretty far in the front and pretty low, which makes the speed seem higher than it actually is (the opposite extreme case is Tesla). I think the overall cabin loudness also contributes to that feeling. This specific car had all the wear items in the suspension replaced five years ago (a EUR 25k receipt...) so I'm not surprised that it rides pretty well. The car certainly goes exactly where I intend it to go on the road, steering assist level is to my liking.

One thing that feels surprisingly good is stopping distance. The brake pedal is very stiff with little assist, but when you do push it hard the car really stops. This must be the fact that as a rear-engined car there's still some weight/downforce on the rear wheels when braking. I don't know.

Writing about it now, it's becoming clear how little I understand how cars actually work and how poorly I can articulate driving impressions and relate them to technical facts.

I think the car could handle a lot more power, by the way. That's just a feeling.
I’m not surprised it feels slow in comparison to the cars listed. It seems like all you are interested in is straight line acceleration. The 993 Turbo was a well balanced machine capable of smooth acceleration out of a corner without upsetting the balance. Once you overpower it that will no longer be the case. Have fun.

I also predict the viscous coupling will be the first point of failure. It was never designed for high horsepower. There is a reason the the high horsepower cars (GT2) were rear wheel drive.
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Re: Porsche 993 twin turbo

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rp930 wrote: Sun Aug 14, 2022 9:07 am I’m not surprised it feels slow in comparison to the cars listed. It seems like all you are interested in is straight line acceleration. The 993 Turbo was a well balanced machine capable of smooth acceleration out of a corner without upsetting the balance. Once you overpower it that will no longer be the case. Have fun.

I also predict the viscous coupling will be the first point of failure. It was never designed for high horsepower. There is a reason the the high horsepower cars (GT2) were rear wheel drive.
"Have fun." I think I am going to have a lot of fun with this 26 year old machine, as it's always more fun to drive a slow car fast than a fast car slow!

My 16 year old daughter and I took turns with the car and she gave the casual review: "It's very cool. It's not that fast, but it sure makes noise! Kind of the opposite of my car. I like it."

It's not just straight line acceleration. This car is half a minute slower around Nurburgring than anything that me or my daughter drive as daily drivers.

It stops well, that's for sure. It turns ok, too, although not as well as the 997 S cabrio and 991 GTS cabrio that I've owned and also driven a lot.

How much more power and toque can this car in your opinion put to ground without becoming utterly uncontrollable out of a corner?
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Re: Porsche 993 twin turbo

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ptuomov wrote: Sun Aug 14, 2022 2:49 pm
rp930 wrote: Sun Aug 14, 2022 9:07 am I’m not surprised it feels slow in comparison to the cars listed. It seems like all you are interested in is straight line acceleration. The 993 Turbo was a well balanced machine capable of smooth acceleration out of a corner without upsetting the balance. Once you overpower it that will no longer be the case. Have fun.

I also predict the viscous coupling will be the first point of failure. It was never designed for high horsepower. There is a reason the the high horsepower cars (GT2) were rear wheel drive.
"Have fun." I think I am going to have a lot of fun with this 26 year old machine, as it's always more fun to drive a slow car fast than a fast car slow!

My 16 year old daughter and I took turns with the car and she gave the casual review: "It's very cool. It's not that fast, but it sure makes noise! Kind of the opposite of my car. I like it."

It's not just straight line acceleration. This car is half a minute slower around Nurburgring than anything that me or my daughter drive as daily drivers.

It stops well, that's for sure. It turns ok, too, although not as well as the 997 S cabrio and 991 GTS cabrio that I've owned and also driven a lot.

How much more power and toque can this car in your opinion put to ground without becoming utterly uncontrollable out of a corner?
It’s not how much power, it’s power delivery. High HP turbo motors can get very peaky with narrow big power bands. Just like old muscle cars older Porsches have nostalgic value but the newer the better for power and handling.The Turbo S’s were 450 and quick so that’s a good guideline. At some point you have to enjoy it for what it is.
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Re: Porsche 993 twin turbo

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Is there a way to regear the transaxle and front diff (assuming an AWD car). Porsche has a hard on for some LONG gears. Notice what they did with the New Cayman GT4 RS. They got it right.
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Re: Porsche 993 twin turbo

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Be carefull with hot rodding the 993 turbo 4wd. The 1st gear pinion is cut on the input shaft and will deform under high load, customers doing burnouts with stock motors have done this. Also some fast guys road racing the stock 993TT with sticky tires. Trans gets noisy or stuck in gear. Main shaft alloy is not as hard as gear alloy, pinion is small.
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Re: Porsche 993 twin turbo

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What kind of driving is the most damaging to the 993 turbo driveline and how to conserve while still having fun?

My thinking is that in terms of engine modifications, drivelines like lower torque and higher rpms and power coming in gradually with load. Do you agree?
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Re: Porsche 993 twin turbo

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Here's a question about turbo lag.

When I read posts about turbo lag, I never know exactly is the accepted forum definition of turbo lag.

None of the _street_ turbo cars that I've worked have any appreciable turbo lag to speak of in the following sense: When you're driving hard and shifting near the redline, the engine is simply on after the shift and there's no lag. All of them have a turbo lag in the sense of starting with a high gear cruise and flooring the car at low rpms without downshifting.

But well tuned naturally aspirated engines also bog down if one floors the gas pedal at high-gear low-rpm highway cruise. In my experience, carbureted and mechanical throttle cammed engines can really lose the plot, electronic throttle ones often save the driver by effectively ignoring the driver's right foot until rpms are up. FBW throttles simply don't open fully and dual throttle ITBs (like Suzuki) have the computer not fully open the second set of throttle valves.

Downshifting the transmission on this 993tt to the correct gear for maximum acceleration with the car already moving will result in an engine speed higher than 4300 rpm. Based on my driving this car in its stock form, the power is on instantly at that 4300 rpm and I can't perceive any lag. Maybe my senses aren't that finely tuned.

Furthermore, if one is willing to downshift, then the way to combat turbo lag is to install a larger compressor wheel and increase the engine redline. This allows one to productively downshift to a higher initial rpm. This on the face of it is the opposite of the usual turbo lag advice.

So what is the best definition of a lag? Do people not downshift their cars when they get into it on a highway? Am I missing something?
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