The story is not about performance/horse power. It is about the mindset that created an inaccurate assessment of performance.

Actually. Porsche experimented with short and long stroke 2.5 liter engines and the results were as follows.

70-71 2.5l short stroke 87.5 x 66 250hp @ 7800 188 f/lb@ 6200
70-71 2.5l long stroke 86.7 X 70.4 270 hp @ 8000 191.6 f/lb @ 6200

Of course in the development of the long stroke engine they discovered the inherent problem with the 70.4 crank at high RPM. The crank would develop a high RPM harmonic that would spit the flywheel off. The cure for that issue was a redesigned crank used in the later 2.8 and 3.0 RSR engines.

According to the above specifications , the short stroke was a 2.38 liter engine and the long stroke was 2.49 liters , so not really
a simular comparison .

Carrera 3.0 engine rebuild
 

No, there were long and short stroke 2.5’s. 2.3’s all SS.

Thanks guys for all the replies.

I went for the Cat Cams as this camgrinder is very local to me and I read on this forum of someone from Denmark who had the same cam in his 2.7 with ITBS and he had 270hp at the crank. If I can get to similar number i would be very happy!

I'm also using the valve springs from CAT Cams which are made by PAC springs in the USA.

Just ordered a lot of tools from Stomski Racing and my case, crank and heads are at the machine shop to have them checked and rebuild, balance the crankshaft with pulley and flywheel.

Lovely tools by Stomski have arrived today. Not bad one week after ordering in the USA to Europe.

http://forums.pelicanparts.com/uploa...1741905916.jpg

yep, I use them and love them.

The piston pin C clip tool from Stomski is a very good thing!!

My reground cams for Cat Cams arrived together with their springs. Now waiting for the machine shop.

http://forums.pelicanparts.com/uploa...1742919394.jpg

Some more parts.

Supertec head stud kit
http://forums.pelicanparts.com/uploa...1746362297.jpg

ECUMaster Black ecu and sensors
http://forums.pelicanparts.com/uploa...1746362297.jpg

Nice pieces & parts. Thx for keeping this thread going. This will be fun to watch. Best of luck. Patrick

You will love the Stomski bits and they will take the likelihood of an error on your part down to near-zero. Excellent investment!

I use this dynamic compression ratio calculator, I hope it’s of use to you,

https://uempistons.com/p-27-compression-ratio-calculator

What ITB's are you using?

Glad to see another Emu Black ecu join the group. Amazing value.

Thanks!


Still deciding between Jenvey ITB or a local dutch company KMS.

https://kms.vankronenburg.nl/products/throttle-body-kits/porsche/throttle-body-kit-porsche-911-optional-airhorns-45mm

Thanks Mike. The value of the EMU black does seem to be excellent!

In the meantime I have received my DP motorsport amber fanshroud. Also had some parts Cerakoted.

My 3.1 supertec piston/cylinderset will arrive this week :cool:
http://forums.pelicanparts.com/uploa...1749296966.jpg

And the 3.1 pistons and cylinders received. Now waiting for the engine shop to have my heads, crank, case ready.
http://forums.pelicanparts.com/uploa...1749716175.jpg

So picked up all the parts from the machinist. Crank was balanced and checked, heads rebuild, case cleaned and inspected, rods checked and new ARP bolts, all new bearings.

I also balanced the the connecting rods to within 0.1 gram. Had a friend 3d print a jig to balance the rods. Worked great!

http://forums.pelicanparts.com/uploa...1754010095.jpg


http://forums.pelicanparts.com/uploa...1754010110.jpg


I'm now looking into all the sprockets for the timing chains. Does anyone know if the Sebro sprockets are any good? Or am I better of using the old sprockets with new chains?

Looking good. Which version crank pulley and trigger wheel is that?

When it comes to sprockets, I tend to re use them if they are not showing obvious signs of wear. You can go crazy and repace EVERYTHING but if the chains were aligned previously and nothing solid went through the engine, then they should be good to reuse.
If I come across one which shows signs of wear from the chains rubbing or if it suffered a tensioner failure, then they are all likely being replaced.

Crank pulley is from Adapt Motorsport.

Thanks Mike I will have a good look at my sprockets than. Unfortunately I misplaced my chains so I don't know which one was left and which one right side. If the sprockets look to be in good condition some new chains would be ok?