997 gt3 3.9 engine build

[mccrae]

Hi Guys

Just having my Gt3 engine rebuilt into a 3.9 at rpm anymore done this ? Would love to hear any results thanks John

[rrroro]

Would love to hear more detail about your build! Also what made you go for this conversion with them? Is it a repair or just want more power for instance? I’m aware of 3.6 -> 3.8 and 4.0 conversions using Porsche parts, but not 3.9. What internals / parts are you using?

[rrroro]

Ps which gen 997 GT3 do you have?

[Slippydiff]

Capricorn I’d imagine, in a Gen 1 3.6 motor.
It’s a cost effective upgrade that without any other mods should liberate 440hp and maybe a bit more. With cams & exhaust mods, closer to 470-480.
Their early 3.9 conversions were “problematic”, Manthey amongst others used them, but they seem to have sorted the various issues out.
There are other options, notably Mahle, but the last I heard, availability was an issue, and the costs eye watering, but if you want to keep things more OE and go 4.0, it would be Mahle 3.8 pistons with an OE 4.0 crank.

[TDT]

Please provide rolling commentary and updates on this project.
Sounds cool.

[mccrae]

Thanks guys will keep you updated,the reason for conversion was that the engine was completely worn and rebuilding was more cost effective than a new motor

[mccrae]

Around 70k but I used it for many years as a circuit training vehicle so it was well used

It’s Oakley one of anyone remembers it

[ChrisW.]

Slippydiff said:

Capricorn I’d imagine, in a Gen 1 3.6 motor.
It’s a cost effective upgrade that without any other mods should liberate 440hp and maybe a bit more. With cams & exhaust mods, closer to 470-480.
Their early 3.9 conversions were “problematic”, Manthey amongst others used them, but they seem to have sorted the various issues out.
There are other options, notably Mahle, but the last I heard, availability was an issue, and the costs eye watering, but if you want to keep things more OE and go 4.0, it would be Mahle 3.8 pistons with an OE 4.0 crank.

How far would you go chasing max power over temperament and longevity ?

The GT3 Cup engines are lifed ... the GT4 Clubsport engines are not ... and I know of GT4 Clubsports that have been raced over three seasons and when stripped were simply re-built with new bearings etc, all set for another three seasons ???

[Galahad]

Great project! Sharkwerks have built loads of 3.9 997 GT3s in the USA, along with some 4.1 Gen2 cars

https://www.sharkwerks.com/projects-mf_gt3-rs-r_g_...

They are meant to be a lot of fun!