2.7L Race Motor -> 2.5L Race Motor- need help with some info

[Vintage911Racer]

50 hours. They are full blown race motors.

I think you missed the point here.

The question asked was????

Arent the short stroke motors higher reving engines than long stroke?
I have heard that the long stroke motors peak in power at or around the 7000 RPM mark, so no need to shift at a higher RPM. I mean sure they could go higher but is there more power up there? I dont think so. ( I could be worng ). The short strokes however can produce power all the way up to 8000 and still be reliable all day long.

How long do you think a race motor should last?

[Plavan]

Mark-
The real question is also what cams they are using. Who has the long stroke? Is your Dad's a long stroke? I really want to know what Modisete (sp?) has in his car now. He was pulling my 2.7 on the straights.

With the 2.5 longstroke I guess it makes sence to go with 911 S cams to keeps the power on below 7500RPM's and avoid the vibration they talk about from 7500 to 8500 rpm in Starkey's book. John pointed that out to me.
I really do not plan ever going over 7500 RPM for that matter. I like engines to last awhile and save the $$$$$$.

[Vintage911Racer]

My dads motor is a 2.4 short stroke. Terry's Motor is a 2.4 Long stoke. and Modisette claims to have a 2.2, I am not sure of the stroke. But it is fast.

can you believe I have 3 years on my motor right now?

Frank is building me a motor after willow. YEAH.....

[BK911]

One major engine design consideration is mean piston speed. Mean piston speed is proportional to RPM and stroke. So for a constant mean piston speed, as you reduce the stroke you can increase the RPM. Generally, the faster you can spin an engine the more power it will produce. Of course there are other factors to consider.

And personally, I wouldn’t build anything over ~150hp on a 70T case. Definitely not a race motor. I’ve seen the beefier 72+ 3R cases crack with ~220hp.

[Plavan]

BK911,
I was worried a little about that case too. I found a nice 1966 911 alum case. Do you think this would be a good candidate instead of the 70 mag case. I know the alum is much stronger but will it handle all the machining?
Thanks,
Chad

[BK911]

Most of the 2.5 race engines I've seen are built on the early aluminum cases. I've also seen some on the 7R cases. I know people who've spent $1500 on a aluminum case and ~$1000 on the machine work required. Definitely not chump change!