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tyinsky
Spa-Francorchamps


Joined: 29 Jun 2012
Posts: 332
Location: London, UK

1997 Porsche 993 Carrera 2S

PostPosted: Sat Dec 30, 2017 9:50 am    Post subject: 3.8 engine upgrade. Anyone in this forum done this? Reply with quote

Hoping a few who browse these pages have upped the capacity and can share their opinions/experience of increasing the capacity to 3.8 litres along the lines of the X51 engines.

I realise outright power figures can be achieved with other methods like remaps and exhausts - my car is around 290bhp with the help of Wayne Scofield. And I’m not particularly excited by fitting a lumpy aftermarket cam that could be a pig to drive in traffic.

Extra torque does interest me. Not yet had the car two years and it has already clocked up a lot of miles on road trips. North Coast 500 in Scotland, Wild Atlantic Way on Ireland’s West Coast, over the French Alpes to Nice and back along Route Napoleon. Surely this is the type of thing that will suit the 3.8?
 
  
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bazhart
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Joined: 20 May 2009
Posts: 838
Location: Bolton Lancashire


PostPosted: Sat Dec 30, 2017 10:00 am    Post subject: Reply with quote

All engines are designed to provide the torque curve the project identifies as right for the model and the market etc.

To simplify a comples subject - it is reasonable to say that it is the breathing ability of the enginein a particular rev band that is what is crucial and the bigger the inlet and exhaust components = the bigger the flow capacity and therefore the higher the revs that the peak torque is obtained.

Variable cam timing and lift, variable inlet pipe connections etc have enabled designers to design for power at high revs and then get back torque at lower revs creating a wider than tradditional power band = good acceleration.

Increasing the capacity merely means that the enigne is like on that a designer would create to produce peak power at slightly lower revs (because the breathing parameters are the same but the flow amount higher).

So there are 2 benefits - (1) = slightly lower torque band (good for acceleration) (2) slightly more top end power because although the peak mass air flow might well be the same it is pushing down on a bigger piston area (or longer stroke - or both) and so even the same peak mass air flow = more power.

The biggest diference is usually the feel of mid range torque and sharper pick up.

Baz
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Endoman
Österreich


Joined: 11 Apr 2011
Posts: 966
Location: Bolton U.K.


PostPosted: Sat Dec 30, 2017 1:19 pm    Post subject: Reply with quote

Nice to see Baz posting again.
Loads of posts on Rennlist, no doubt you have looked.
General concensus is poor bang for buck but worth considering if new P&Cs required.
When I used to race class capacity limit was 1650cc. So we all did it apart from those who fitted an MGB block in an MGA and ground the 1800 on the block to look like 1600 (not me). That's racing where every little bit helps. On the road it's only worth the bragging rights imho.
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wozy
Imola


Joined: 06 Feb 2013
Posts: 839
Location: Worcestershire


PostPosted: Sat Dec 30, 2017 1:50 pm    Post subject: Reply with quote

This is all a bit high tech for me, but put into laymans terms. The 3.8 conversion when I last looked was at 10K euros plus VAT but NLA. ......... even if it was available, the price put me right off. Very Happy
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Porsche Cars of Great Britain launched the 993 in the UK in early December 1993 registering 12 x UK cars on the 6th & 7th of that month; mine is one of them.

993 C2. MBM. C4 mounts, RSRs, RS Short shifter. RS steering wheel. FSDs & M033s
Previous 2.7S, 3.2, 964 and 968CS
 
  
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Pretzel
Hockenheim


Joined: 20 Apr 2014
Posts: 650
Location: Bedfordshire


PostPosted: Sat Dec 30, 2017 3:06 pm    Post subject: Reply with quote

Endoman wrote:
When I used to race class capacity limit was 1650cc. So we all did it apart from those who fitted an MGB block in an MGA and ground the 1800 on the block to look like 1600 (not me). That's racing where every little bit helps. On the road it's only worth the bragging rights imho.


Some of us kept to 1622cc allowing for re-boring when required.
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bazhart
Approved Trader


Joined: 20 May 2009
Posts: 838
Location: Bolton Lancashire


PostPosted: Sat Dec 30, 2017 3:14 pm    Post subject: Reply with quote

I agree that 3.8 to 3.9 is not so much of a difference to justify the cost - unless - that is - you already have scored bores and pistons and need new cylinders etc - when it becomes very little extra for a bit more mid range punch.

It is also more interesting for a 3.6 to 3.9 - especially if the engine needs rebuilding anyway.

It is not good practice to increase the capacity too much because the restrictions of the inlet and exhast system will limit peak bhp benefits and result in very sharp mid range take up.

Our conversions are therefore 3.4 to 3.7 and 3.6 or 3.8 to 3.9 which overall will give a good result.

We may experiment with larger increases later in 2018 but if so they would not be available until the end of that year and it is by no means certain that they would prove nicer to drive or faster than the present conversions yet would be more expensive requiring new crankshafts as well.

Baz
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RobIpswichUK
Kyalami


Joined: 27 Aug 2010
Posts: 1923
Location: Ipswich (at a guess!)

1994 Porsche 993 Carrera 2

PostPosted: Sat Dec 30, 2017 3:22 pm    Post subject: Reply with quote

What about a supercharger conversion. Definitely increases the grunt, and better value (bang per buck) than the increased capacity.

Been driven in a 964 with a supercharger and that was very rapid in comparison to my 993, and the instantaneous shove back in your seat was fun.

Not sure how it stacks up pricewise or reliability/longevity etc, but maybe worth considering.

Anyone any experience of the installation or ownership proposition?
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Rob
'94 C2 Iris Blue (+ White Stripes!)
Cup 2's, Big Ovals, FSD's/Eibach, OMP Strut Brace, 200 Cell Powerspeed Cats, 1.75" Hollamby Exhaust bypass, Carnewal FPB.
Mercedes SL (R230 lowered + wheels)
Range Rover Sport (L320 chipped)
Mercedes E Class (W211 chipped)
TT Roadster (standard - wife’s daily!)
 
  
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tyinsky
Spa-Francorchamps


Joined: 29 Jun 2012
Posts: 332
Location: London, UK

1997 Porsche 993 Carrera 2S

PostPosted: Sat Dec 30, 2017 4:18 pm    Post subject: Reply with quote

Thanks for all the replies. Baz, the technical explanation is very good thumbsup

Supercharging is for someone else searching for big power gains and who likes the whining noise. Occasionally I experience too much whining from the passenger seat.

I’ve so far drawn the line at 3.8 in order to use the MAHLE product, and I like that there was a 3.8 offered originally. It’s important to me the car remains enjoyable to drive. It’s not going to be a track day weapon.

Someone here must have done a 3.8 build to their car? Given they are 20-years old, top ends fairly common due to the exhaust valves, leaks can appear everywhere and so on - surely it makes sense to rebuild the whole engine and be done with it for many more years? Is there some sort of ‘Porsche Illuminati’ rule involving black balls and 25 bag valuations keeping people at 3.6?
 
  
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madge
Nürburgring


Joined: 29 Dec 2015
Posts: 458
Location: Hampshire


PostPosted: Sat Dec 30, 2017 5:12 pm    Post subject: Reply with quote

tyinsky wrote:
Supercharging is for someone else searching for big power gains and who likes the whining noise. Occasionally I experience too much whining from the passenger seat.


That reminds me of a Mini Cooper S with the supercharger that I had when they first came out. Of all the things I hated about that car (which was a lot), the whine of the supercharger was probably number one. Hopefully it's a very rare occurrence for anyone to spoil the glorious sound of a 993 engine with that horrible whining. what It would be as good a reason as any that I can think of for the illuminati to get busy with the tar and the feathers.
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Sutton
Spa-Francorchamps


Joined: 04 Mar 2009
Posts: 261
Location: Surrey


PostPosted: Sat Dec 30, 2017 6:31 pm    Post subject: Reply with quote

There are a few 3.8 kits out there. Consensus from over the Pond is to go for the Mahle RSR pistons and cylinders as these barrels are sturdier. They do require some work on the crank case to seat properly, but if you're going the 3.8 route, you might as well add that to work for reducing crank windage.

Seeing you launch your car off the line at the gymkhana , you're obviously happy living near the redline.
Very Happy
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tyinsky
Spa-Francorchamps


Joined: 29 Jun 2012
Posts: 332
Location: London, UK

1997 Porsche 993 Carrera 2S

PostPosted: Sat Dec 30, 2017 7:10 pm    Post subject: Reply with quote

Sutton wrote:
There are a few 3.8 kits out there. Consensus from over the Pond is to go for the Mahle RSR pistons and cylinders as these barrels are sturdier. They do require some work on the crank case to seat properly, but if you're going the 3.8 route, you might as well add that to work for reducing crank windage.

Seeing you launch your car off the line at the gymkhana , you're obviously happy living near the redline.
Very Happy


I can still smell the clutch and tyres! Bandit
 
  
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Sutton
Spa-Francorchamps


Joined: 04 Mar 2009
Posts: 261
Location: Surrey


PostPosted: Sat Dec 30, 2017 7:51 pm    Post subject: Reply with quote

We weren't standing that far away and could chew on the tyre smoke. You left two lovely black lines on the tarmac Thumb

If it's torque you're after, there's no substitute for capacity. It's just a question of ££ and whether you think it's a worthwhile trade off.

Are you talking to Redtek/ 9M/ Hartech etc?
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911livin
Trainee


Joined: 31 Oct 2017
Posts: 58



PostPosted: Sat Dec 30, 2017 9:09 pm    Post subject: Reply with quote

I have been thinking about going from 3.6 to 3.8.. as a long term plan as I wanted my 993 to be as close to RS spec I can get, looks and performance. Im more interested in mid range punch than top end speed. for me, blasting from 0 to 90mph feels GREAT.

right now Im getting looks right 1st and removing unnecessary weight from engine, aircon, seats etc Im sure it will make it feel faster Very Happy Hand
 
  
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AVI_8
Trainee


Joined: 19 Jan 2014
Posts: 83
Location: Prestwick


PostPosted: Sun Dec 31, 2017 11:22 am    Post subject: Reply with quote

I haven't owned but have driven a 964 3.8 conversion, to be honest I couldn't feel much difference, but if you're having to replace pistons and cylinders anyway then the only downside is the cost, 3.6 pistons and cylinders £3600
3.8's are £5400, that's a big price increase for what is closer to a 3.7 than a 3.8 3.8's are 3740cc or there abouts.

Bang for buck is not very good, but if money is no object.
 
  
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highway
Albert Park


Joined: 08 Nov 2007
Posts: 1708



PostPosted: Sun Dec 31, 2017 1:27 pm    Post subject: Reply with quote

Whilst I can see the attraction of staying OEM, this long redundant performance kit apparently yields little in terms of real world gain. It costs mental money as well. Even if you sourced the parts and got somewhere reputable to fit, it’s still not going to be perceived as a factory build, which may or may not matter. If you were hell bent on more aircooled performance without swapping to a 993 Turbo, then I think I’d be researching big name companies who are making their living upping the air cooled NA ante. It’s going to be big money though.

I remember a Rennlist thread where a company were working on a California compliant air cooled 400hp motor. Wonder what happened to that?
 
  
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tyinsky
Spa-Francorchamps


Joined: 29 Jun 2012
Posts: 332
Location: London, UK

1997 Porsche 993 Carrera 2S

PostPosted: Mon Jan 01, 2018 7:54 pm    Post subject: Reply with quote

Sutton wrote:
We weren't standing that far away and could chew on the tyre smoke. You left two lovely black lines on the tarmac Thumb

If it's torque you're after, there's no substitute for capacity. It's just a question of ££ and whether you think it's a worthwhile trade off.

Are you talking to Redtek/ 9M/ Hartech etc?


Have talked to 9E in Sussex and a lot to Tech9 in Liverpool. Both have had the car in their workshops.

911livin wrote:
Right now Im getting looks right 1st and removing unnecessary weight from engine, aircon, seats etc Im sure it will make it feel faster Very Happy Hand


Thought about doing this also but that's as far as it got. I couldn't believe the weight of the new aircon compressor that went in it! I like my comforts to much Smile

AVI_8 wrote:
I haven't owned but have driven a 964 3.8 conversion, to be honest I couldn't feel much difference, but if you're having to replace pistons and cylinders anyway then the only downside is the cost, 3.6 pistons and cylinders £3600
3.8's are £5400, that's a big price increase for what is closer to a 3.7 than a 3.8 3.8's are 3740cc or there abouts.

Bang for buck is not very good, but if money is no object.


Agree it is not good value. At 150k miles and plenty of oil leaking from different places it seems right to do a full rebuild rather than seal it up or do a half job with a top end. Once you get to that point it starts to become an odd decision not to go up to 3.8. Or perhaps I have already lost the plot?


highway wrote:
Whilst I can see the attraction of staying OEM, this long redundant performance kit apparently yields little in terms of real world gain. It costs mental money as well. Even if you sourced the parts and got somewhere reputable to fit, it’s still not going to be perceived as a factory build, which may or may not matter. If you were hell bent on more aircooled performance without swapping to a 993 Turbo, then I think I’d be researching big name companies who are making their living upping the air cooled NA ante. It’s going to be big money though.

I remember a Rennlist thread where a company were working on a California compliant air cooled 400hp motor. Wonder what happened to that?


I'm not really chasing power, just considering the rebuild given the car is 20 years old and has done a lot of miles. Very little addition in size between a 997 C2 and C2S engine but it does make a difference. I like the idea of adding a little bit of difference to the car, and hopefully some noticeable torque.

It would be wonderful to have one of those 4.0 Williams Cosworth engines that are going in the latest Singer but sadly the budget will never be that exciting.
 
  
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Nik
Imola


Joined: 03 Apr 2007
Posts: 816
Location: Surrey


PostPosted: Mon Jan 01, 2018 10:42 pm    Post subject: Reply with quote

Does anyone (other than Williams/cosworth) offer a 4.0 option for the 993?

ETA: looks like there has been an attempt:
https://www.engineswapdepot.com/?p=17747


But then this thread suggests 3.9 is the maximum logical size to aim for.
https://rennlist.com/forums/993-forum/685232-what-is-the-downside-of-doing-a-4-0-air-cooled-engine.html
 
  
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Cameltoe & Heel
Suzuka


Joined: 26 Jan 2009
Posts: 1065
Location: Preston - Lancs


PostPosted: Tue Jan 02, 2018 9:59 am    Post subject: Reply with quote

It hasn't been done that much here in the UK, I'd say unless you actually need new pistons/liners then don't bother as the investment isn't worth the power torque return.

Sounds like you just need a standard rebuild, perhaps blue printing your rebuild would yield a decent improvement perhaps inline with 3.8?, I think people like 9M will do that for you but again will cost.

Also a 3.8 conversion doesn't equal RS engine...

Trev
 
  
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ChrisT70
Barcelona


Joined: 26 Mar 2015
Posts: 1480
Location: The Sea


PostPosted: Tue Jan 02, 2018 10:39 am    Post subject: Reply with quote

its when you come to sell and you realise it limits your potential market a little. not everyone wants a tweaked engine, a lot will prefer a receipt for a fully rebuilt standard size engine build. if you do go 3.8 and have "thousands" of quids worth of invoices for it, and its fairly recent it might not be as much of an issue to some.
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Sutton
Spa-Francorchamps


Joined: 04 Mar 2009
Posts: 261
Location: Surrey


PostPosted: Tue Jan 02, 2018 1:03 pm    Post subject: Reply with quote

The graph is pinched from elsewhere, but is useful for comparative purposes. It's showing the difference in acceleration through each gear between a 3.6 and 3.8 engine, down largely to torque.

Whilst the delta as a number isn't significant, the delta as a percentage is. We can also see the effect over the rev range, rather than just focusing on delta between peak bhp and torque numbers which don't tell the whole story.

The person whose graph this belongs to had the full RS conversion, rather than the X51, so I suspect the X51 graph won't show as big a difference.

As many have pointed out, there's another question about whether the conversion is worth this.
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