Rickard 993 Turbo

What camsshafts options is there, i have heard that the gt2 cams are a nice uppgrade

Kevin

Rickard, if you are going to install camshafts you should address your rods..

However, to answer your question, you need to pick the profile of camshafts that your tuner, tunes the ECU for and too.

Rickard 993 Turbo

This is not the rute im going for, i will build my engien by my self and decide whats forts to go for

Then i only want to have my car tuned, this is only becouse i can't tune th emotronic bye my self onthervise i would do it

Kevin

If you install camshafts without installing rod bolts you will have a high risk of a rod failure.. It's not 100%, but it is highly likely.

Rickard 993 Turbo

Why should there be that, a Gt 450hp factory engien has diffrent camshaft but same rod bolts as i have understod it

Kevin

The 450 engine just has a ECU tune, K24's and additional oil cooler, camshafts are the same as a normal 993TT fitted with K16's.. Which are very similar to 911 SC grinds that many 930 owners have installed.

Rickard 993 Turbo

Yes i know, but the Gt2 should have other camshafts better suited for 500-520hp, they also have kkk24, and they should have the same rod bolts, so thats why im asking if changing to gt2 camshaft on a 450(k24) eqiped cars would be a nice setup, including a custom ecu tune

Kevin

You have a 10 year old car.. The rod bolts fail, they stretch, the bearings ovals, this causes tremendous heat to build up, oil is flashed off the metal to metal contact. The rod breaks and exits the case..

Rickard 993 Turbo

Okey

So stay at 408hp is the advise then....doesn't sound like a nice car to modyfie then..

Kevin

You can run the car up to 500HP and limit the torque to 650-680Nm... Here is a visual example of a minor rod failure, a major failure would be the rod punching through..

Geoffrey

To answer your question on camshafts. For a custom application, I would flow test the heads, determine the rev range that I wanted the engine to perform in and have a custom camshaft ground. With that said, I've experimented with a number of different "off the shelf" camshafts and believe that the GT2 Evo is an excellent choice for a street built engine. It isn't overly large and keeps the powerband below 7000rpm which will not add as much stress to the rod bolts as a larger cam with higher RPM range will. It is the tensile stress on the rods/rod bolts that cause them to break, not the additional compressive loads from higher cylinder pressure. You will of course need to source the proper ECU tuning and I might suggest Todd at Protomotive for that.

I would have to ask the cause of the rod bolt failure in the above pictures. There are a number of reasons a rod bolt can fail with human error being high on the list. An overrev (from a missed downshift) will often cause the rod bolt to stretch, weaken, and eventually break. I would agree that 550hp is approaching the limits of the stock rod/rod bolt and I would approach with caution.

Peter S 993tt

Out of curiosity - do you have to worry about this if you keep it stock?

Geoffrey

As mentioned above, outside of human error, the rods/rod bolts are fine for stock application.

Rickard 993 Turbo

Geoffrey

Thanks, this is exactly the info i was searching for....I also understand that best would be to flow everything, but im not building a race engien, i just want a fast street engien, and i would like to have a tested route that i proven...

I thought like this

Stock kkk24
free flowing exhoust
No cats
Maybe gt2 cams
Custom tuned ecu

ebaker

You could probably get more power easier and cheaper using stock cams with hybrid turbos.