3.8 engine upgrade. Anyone in this forum done this?

tyinsky · 1 Jan 2018

Sutton said:
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 said:
Right now Im getting looks right 1st and removing unnecessary weight from engine, aircon, seats etc Im sure it will make it feel faster :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

AVI_8 said:
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 said:
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.

Nik · 1 Jan 2018

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-for...ownside-of-doing-a-4-0-air-cooled-engine.html

Cameltoe &amp; Heel · 2 Jan 2018

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

ChrisT70 · 2 Jan 2018

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.

Sutton · 2 Jan 2018

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.

tyinsky · 2 Jan 2018

All good points. :thumbs:

Once in for a full rebuild, moving up to 3.8 is not a big difference in cost (unless the old, worn parts are being left in place).

Not worried about resale. I bought the car for me to enjoy - otherwise I'd most likely be sealing it or doing a top end. Intending to keep long term. Agree most buyers usually dislike non standard Porsches however I would of paid more for one that had had a decent rebuild were it 3.6 or 3.8.

If I do it the car won't be an RS replica. Just a RWD widebody with a little more torque.

nickjonesn4 · 2 Jan 2018

tyinsky said:
All good points. :thumbs:

Once in for a full rebuild, moving up to 3.8 is not a big difference in cost (unless the old, worn parts are being left in place).

Not worried about resale. I bought the car for me to enjoy - otherwise I'd most likely be sealing it or doing a top end. Intending to keep long term. Agree most buyers usually dislike non standard Porsches however I would of paid more for one that had had a decent rebuild were it 3.6 or 3.8.

If I do it the car won't be an RS replica. Just a RWD widebody with a little more torque.

Mine will also stay as a standard looking widebody!

Hi there. Having originally been set on 3.8 conversion, had a long chat with Richard Chamberlain at CTR about this and he recommended not to bother with the 3.8 unless going to a full £20k++ rebuild. His advice was to get the leak down test done and that a top end rebuild with ARP studs as a precautionary measure would most likely do the trick due to the strength of the 993 engine ie very few need a full rebuild. Mine is getting done in January with ported heads, slightly more aggressive cam and custom exhaust. Aiming for 330-345bhp and a whack more torque. Will be posting up results and progress reports in the new year so hopefully can be of some help in you making your decision.

nickjonesn4 · 2 Jan 2018

nickjonesn4 said:
tyinsky said:

All good points. :thumbs:

Once in for a full rebuild, moving up to 3.8 is not a big difference in cost (unless the old, worn parts are being left in place).

Not worried about resale. I bought the car for me to enjoy - otherwise I'd most likely be sealing it or doing a top end. Intending to keep long term. Agree most buyers usually dislike non standard Porsches however I would of paid more for one that had had a decent rebuild were it 3.6 or 3.8.

If I do it the car won't be an RS replica. Just a RWD widebody with a little more torque.

Mine will also stay as a standard looking widebody!

Click to expand...

Hi there. Having originally been set on 3.8 conversion, had a long chat with Richard Chamberlain at CTR about this and he recommended not to bother with the 3.8 unless going to a full £20k++ rebuild. His advice was to get the leak down test done and that a top end rebuild with ARP studs as a precautionary measure would most likely do the trick due to the strength of the 993 engine ie very few need a full rebuild. Mine is getting done in January with ported heads, slightly more aggressive cam and custom exhaust. Aiming for 330-345bhp and a whack more torque. Will be posting up results and progress reports in the new year so hopefully can be of some help in you making your decision.

Meant to add that like you I will be keeping mine looking like a standard widebody.

tyinsky · 3 Jan 2018

Sounds like some interesting mods Nick. :thumbs:

I'm determined not to change the drivability of the car and trick cams make me nervous. All depends on what you/me/the next person want from the build and I'm probably the odd one here in that I'm not looking for a big leap in power. I'm after a smooth, easy to drive engine that has a little more oomph when overtaking rather than keeping the car in the high revs and getting a much faster car.

Realise there is an urban myth that the 993 engine is bulletproof. Right or wrong, I can't see that my car will not show any signs of wear in both halves of the engine after +150k. It's a mechanical object and 20-years old. Makes sense to me to go all the way if the engine is coming out.

bazhart · 3 Jan 2018

I don't know if this helps understand the dynamics better - but although my comments about our 3.7 and 3.9 conversions relate to M96/7 engines - the issues I explained about torque and increased capacity limits are true for all engines.

Last week one of our cars conducted a back to back test between an older 996 3.4 tiptronic converted to 3.7 and a 996 C4S 3.6 (that would normally leave the 996 3.4 well behind).

The outcome was that they performed equally - neither being quicker than the other - and this is a typical way of understanding the differences - in that - a 3.7 capacity running on the same original components will increase torque (which is what drives acceleration) and top end bhp (by virtue of the increased capacity) but usually not quite as much at the top end as it would if it had been designed for that capacity in the first place.

Hence the extra 100cc that the 3.7 had compared to the 3.6 was insignificant as it really just made up for the slight lack of breathing at the top end and the torque made up for the lack of variable valve lift etc.

Similarly we have found in the past that a 996/7 3.6 increased to 3.9 results in a car with performance almost identical to the original std 3.8 version - the extra 100cc's compensating for the other slightly under specified parts of the original cmaller capacity design.

As we specialise in liquid cooled cars we cannot offer direct comparisons with the 993 conversions but I see no reason why the results would not be similar - more torque and acceleration, sharper pick-up but not neccessarily much greater maximum speed.

Baz

nickjonesn4 · 3 Jan 2018

tyinsky said:
Sounds like some interesting mods Nick. :thumbs:

I'm determined not to change the drivability of the car and trick cams make me nervous. All depends on what you/me/the next person want from the build and I'm probably the odd one here in that I'm not looking for a big leap in power. I'm after a smooth, easy to drive engine that has a little more oomph when overtaking rather than keeping the car in the high revs and getting a much faster car.

Realise there is an urban myth that the 993 engine is bulletproof. Right or wrong, I can't see that my car will not show any signs of wear in both halves of the engine after +150k. It's a mechanical object and 20-years old. Makes sense to me to go all the way if the engine is coming out.

Yep. If under testing my engine needs a full rebuild I would do the capacity increase but at 80k I would be unlucky. Will be very interesting to see your results and details of the build so please keep us informed.

My brief to Richard was not dissimilar to yours. I won't be going lightweight flywheel and the car won't be tracked it turned into an RS clone. Also no new EMS etc etc Anyway. Look forward to comparing notes!

tyinsky · 3 Jan 2018

bazhart said:
I don't know if this helps understand the dynamics better - but although my comments about our 3.7 and 3.9 conversions relate to M96/7 engines - the issues I explained about torque and increased capacity limits are true for all engines.

Last week one of our cars conducted a back to back test between an older 996 3.4 tiptronic converted to 3.7 and a 996 C4S 3.6 (that would normally leave the 996 3.4 well behind).

The outcome was that they performed equally - neither being quicker than the other - and this is a typical way of understanding the differences - in that - a 3.7 capacity running on the same original components will increase torque (which is what drives acceleration) and top end bhp (by virtue of the increased capacity) but usually not quite as much at the top end as it would if it had been designed for that capacity in the first place.

Hence the extra 100cc that the 3.7 had compared to the 3.6 was insignificant as it really just made up for the slight lack of breathing at the top end and the torque made up for the lack of variable valve lift etc.

Similarly we have found in the past that a 996/7 3.6 increased to 3.9 results in a car with performance almost identical to the original std 3.8 version - the extra 100cc's compensating for the other slightly under specified parts of the original cmaller capacity design.

As we specialise in liquid cooled cars we cannot offer direct comparisons with the 993 conversions but I see no reason why the results would not be similar - more torque and acceleration, sharper pick-up but not neccessarily much greater maximum speed.

Baz

Nice insight. Thanks Baz :thumbs:

tyinsky · 3 Jan 2018

nickjonesn4 said:
Yep. If under testing my engine needs a full rebuild I would do the capacity increase but at 80k I would be unlucky. Will be very interesting to see your results and details of the build so please keep us informed.

My odometer reading is almost double your car :thumb:

If I follow through we should have some interesting posts between us in a month or two

Rallyeman · 3 Jan 2018

Jackel did the 3.8 conversion in his yellow RS tribute, currently for sale in JZM I think

nickjonesn4 · 3 Jan 2018

tyinsky said:
nickjonesn4 said:

Yep. If under testing my engine needs a full rebuild I would do the capacity increase but at 80k I would be unlucky. Will be very interesting to see your results and details of the build so please keep us informed.

Click to expand...

My odometer reading is almost double your car :thumb:

If I follow through we should have some interesting posts between us in a month or two

Nice one. Look forward to it :thumb:

3.8 engine upgrade. Anyone in this forum done this?

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