911T with 'S' pistons 'S' cams 46mm carbs and twin ignition

[TargaFlorio]

Hi guys,

How much power could you expect from stock 911T 2.0 with the following mods:

911T crank
911S Pistons
911S Cams
46mm carbs
Twin ignition
Dual pipe exhaust

Engine has chain tensioners upgrade, upgraded fuel pump etc.

Cheers,
n.

[jluetjen]

For this example, I'm assuming 2.0T heads since you didn't mention them.

So the operative factors are:
- 2.0S Pistons and Cam mean that basically the best that you can hope for is 2.0S performance.
- 2.0T heads have smaller ports then 2.0S heads (and in some cases smaller valves too). The end result is that this combination won't have quite as much at the top end (say 6500 RPM - 7500 RPM) as a 2.0S, but will be comparable to a little bit stronger from 4000 RPM up through 6500 RPM. THis is because the ports won't be able to flow the required amount of mixture at peak RPM. But it's not all bad since the smaller ports will improve the performance at low to mid-rev's. Porsche used engines similar to this in the late 60's as rally spec motors.

As far as the other stuff...
- 46 mm carbs: Overkill and way too much flow for what the ports can support. You'd do a lot better with 40 mm carbs. Even if this were a vintage race motor, the 46's would most likely be too big.
- Twin ignition: This will help the part throttle and low rev running quite a bit. Since the peak HP is constrainted more by airflow rather then by ignition, I doubt that it will do much for you there.
- Dual Pipe Exhaust: Noticeably more noice, but I doubt that you'll find much HP there.

That's my $0.02. If Henry Schmidt or Steve Weiner disagree with me -- my money is on them!

PS: Welcome Aboard!

[TargaFlorio]

Cheers John.

I forgot the mention the valves, the heads would carry the bigger 'S' valves.

And yes, the exhaust is for the aural delight.

Cheers,
n.

[kenikh]

So this just sounds like an S replica motor with twin plugs. Probably 175HP, but the 46mm carbs would nuke your drivability. 40mm would be much more appropriate. You might be able to get a little more power with headers, too.

[TargaFlorio]

Ok, that makes sense.

Thanks for all your answers.

Cheers,
n.