Porsche 911UK Forum

Welcome to the @Porsche911UK website. Register a free account today to become a member! Sign up is quick and easy, then you can view, participate in topics and posts across the site that covers all things Porsche.

Already registered and looking to recovery your account, select 'login in' and then the 'forget your password' option.

GT3 Engine upgrdes - Manthey/Fearnsport - others?

Pip1968

Well-known member
Joined
26 Oct 2009
Messages
1,490
Just wondering what people's experience of engine upgrades were. I know NXI pushed the Fearnsport option rather than Manthey. I also know that there seem to be a few Porsche with the Manthey K400 upgrade (Is TerrB a subscriber to 991UK as I know he went the Manthey route) . What is the difference between the two - bhp figures and modus operandi (costings?). I have completed part of the cooling modification and will likely install a short shift at some point although I am not sure if this is part of the 'upgrades'.

Do all the GT3 RS have short shift sticks? I shall have to investigate the best option as I have seen it much discussed on the plastic bushes failing and which ones were considered the best option. It is a DiY for tinkerers is it not? Hopefully I will take the opportunity to get the centre console colour coded at the same time.

Neither (or any other tuners) option has any engine internal changes do they?

I realsie that there are two options for Manthey and do not really want to spend more than 20,000 (if I do go ahead) as then I may as well get a 997.

Anyway any opinions most welcome.

Pip
 
Leave it alone pip. Drive it more and spend the money on fuel ;-)
 
Firstly a 997 isn't any quicker than a 996 mk 2 on track IMO.
The K400 upgrade is a bolt on conversion, exhaust filter etc
K440 is a capacity increase to 3.9, so after market internals, Porsche only make a 3.8 piston.

Fearnsport can do the same for you and is the route I took on my 997 conversion.
As for cost it will come down to what condition your original engine is in, what parts you use etc. For an example an oil pump is £1000, con rods from Porsche £3600+, but your budget is realistic, and attached is a Manthey price list. Personally I'd go and speak to Matt at Fearnsport as your budget better fits his pricing with a lot of new parts fitted.

Power wise a straight 3.8 using Porsche piston rods appear to make about 445bhp and 350torque depending on exhaust system. Nicks 3.9 made about 460 Bhp and 355 torque, if you add upgraded cams you can make an extra 20 Bhp.

Good luck with your adventure :thumb:

http://www.manthey-motors.de/nextshopcms/cmspdf.asp?id=386

Here's a vid of me and Nick playing at Silverstone the other week. 996.2 440bhp 350 torque on slicks 997.1 475bhp 350 torque on cup 2s. And before you comment I know I should have saved the spin at the end and I did everything wrong, I'll put it down to being tired and last run of the day :grin:

 
This is complex question & the answer is basically summed up as "how much do you want to change to ensure reliability?".

I've driven the M400 / M410 conversion & you really have to wring its neck to get the best from it. I favour displacement as it gives you more to play with rather than trying to get even more out of an already highly tuned engine.

I went 3.9 Capricorn originally which was a bit of a 'mare for various reasons, all to do with Capricorn. That engine did me well but a dodgy map on the Syvecs meant I had a ring failure on a piston after 42,000 miles. When it was rebuilt last year, I went Porsche motorsport on the 3.8 piston & liner kit which necessitated the little ends being bored out to take the larger bushes required for the 23mm gudgeon pins; no biggie but you need to find a machine shop that is capable of working with titanium.

As I'd already replaced all the internals bar the crank & cams when the 3.9 was done, no additional work was required beyond replacing the exhaust guides; I also had the secondary air ports on the heads welded up while the heads were in the machine shop. The rebuild cost considerably less than the first one as a result of being able to re-use all the parts I replaced the first time around; for example, just replacing the valves, springs & cam buckets is ~ £3K.

How much or little is needed can really only be determined once the engine is stripped. It's then a matter of a judgement call by the builder vs. the willingness of the customer to fund new parts. My view is that trying to re-use old parts that the builder says should be replaced is a false economy that will result in a premature failure down the line.

Bearing in mind that one of the main benefits of increasing displacement is the torque increase, I'm happy with what mine is putting out now: 427BHP / 351ft/lbs. I have over 300ft/lbs of torque from 3.2K to 7.3K which makes the car effortless on the road & quick enough on track too.

This engine makes more peak torque than the RS 4.0 or the 991RS does :D
 

Attachments

  • dyno_761.jpg
    dyno_761.jpg
    112.3 KB · Views: 7,105
Pip1968 said:
Do all the GT3 RS have short shift sticks? I shall have to investigate the best option as I have seen it much discussed on the plastic bushes failing and which ones were considered the best option. It is a DiY for tinkerers is it not?
Pip

I just killed my 997.2 GT3 shifter at the 'ring after 5 years (Cup cables probably place it under additional loads). It had plastic bushes & the rear one simply broke all its 8 teeth off which allowed it to fall out of the back. This resulted in being unable to select any gear after Schwedenkreuz & having to coast round in neutral at 120mph, an experience I don't wish to repeat!

Replaced with the 997.2 RS shifter which has metal bushes. The shift action is perfect for me as I'm not a fan of short shifts (although it is pretty short, it's very positive). It's a DIY job & takes about 45 minutes.

I have a Numeric shifter & cables for sale which is adjustable if you are interested?
 
Might be a better option to sell and buy an already built car ?

There's a 996.1 for sale at border reivers that's had a 3.8 conversion by ansgar at PSi
 
mikem7709 said:
Might be a better option to sell and buy an already built car ?

There's a 996.1 for sale at border reivers that's had a 3.8 conversion by ansgar at PSi

Never heard of them before, but they seem to have some nice motors for sale. The SC they have looks a little odd without a whale-tail...
 
Roro said:
mikem7709 said:
Might be a better option to sell and buy an already built car ?

There's a 996.1 for sale at border reivers that's had a 3.8 conversion by ansgar at PSi

Never heard of them before, but they seem to have some nice motors for sale. The SC they have looks a little odd without a whale-tail...

The 3.8 996 was for sale at JZM when I bought mine, I believe it belonged to a guy called Nick who posted on here ? It doesn't seem to have done much if any mileage in the last 3 yrs.
 
NXI20 said:
Pip1968 said:
Do all the GT3 RS have short shift sticks? I shall have to investigate the best option as I have seen it much discussed on the plastic bushes failing and which ones were considered the best option. It is a DiY for tinkerers is it not?
Pip

I just killed my 997.2 GT3 shifter at the 'ring after 5 years (Cup cables probably place it under additional loads). It had plastic bushes & the rear one simply broke all its 8 teeth off which allowed it to fall out of the back. This resulted in being unable to select any gear after Schwedenkreuz & having to coast round in neutral at 120mph, an experience I don't wish to repeat!

Replaced with the 997.2 RS shifter which has metal bushes. The shift action is perfect for me as I'm not a fan of short shifts (although it is pretty short, it's very positive). It's a DIY job & takes about 45 minutes.

I have a Numeric shifter & cables for sale which is adjustable if you are interested?

So as I am no expert on these matters, apart from the metal bushes on the 997.2 RS. does it have a shorter shift than an OEM 996 GT3?
Again ignorance on my part but a numeric shifter what is that? It is not one of these LED arrangements that you see on Cup cars is it? If not what is its purpose ???

So Perhaps I should try a short shift (still no recommendations on who from) and a 997.2 RS.

Pip
 
Pip1968 said:
So as I am no expert on these matters, apart from the metal bushes on the 997.2 RS. does it have a shorter shift than an OEM 996 GT3?

Slightly, yes.

Again ignorance on my part but a numeric shifter what is that? It is not one of these LED arrangements that you see on Cup cars is it? If not what is its purpose ???

Read all about it:

http://numericracing.com/store/#!/Competition-Shifter/p/45359458
 
Thanks NXI20, I had a search last night after posting. I looked at Google pictures and then information and found the old 911 post from 2014

http://www.911uk.com/viewtopic.php?t=91028

So you have opted for Cup cables which from that post seem to be noisier than the Numeric ones but have what advantage over the Cup ones Nick? Is it just that you are OEM through and through - Brighton Rock?

Where would I be if I just installed a short shift or the 997.2 RS like you without Numeric or Cup cables???

Pip
Ps if I went for a re bore who is recommended as I assume you are saying Capricorn are not on the tick list.
 
Pip1968 said:
Thanks NXI20, I had a search last night after posting. I looked at Google pictures and then information and found the old 911 post from 2014

http://www.911uk.com/viewtopic.php?t=91028

So you have opted for Cup cables which from that post seem to be noisier than the Numeric ones but have what advantage over the Cup ones Nick? Is it just that you are OEM through and through - Brighton Rock?

I've had Cup cables since 2010. I'm not in a position to know definitively what the differences between them & the Numeric cables are. I bought a car with the Numeric stuff fitted & wanted to return it to standard, hence the Numeric stuff is going begging.

Where would I be if I just installed a short shift or the 997.2 RS like you without Numeric or Cup cables???

You'd have a slightly shorter shift than standard. It won't help with the cable slop which can only be solved by eliminating the plastic bushes on the standard cables.

Ps if I went for a re bore who is recommended as I assume you are saying Capricorn are not on the tick list.

You don't rebore a Mezger, you press the liners out of the water jackets. This makes it easy to change bore sizes. Your options are limited if you want to go with proven kits; you should be looking for Mahle forged pistons & either OEM Porche liners or the Capricon equivalents. Realistically, this comes down to the 3.8 Porsche OEM stuff unless you want to go off the reservation & try something from BBI in the US.
 

New Threads

Forum statistics

Threads
124,235
Messages
1,438,501
Members
48,619
Latest member
smiggles772
Back
Top