2 replies to this topic

[babsbrown]

Hi guys

My 1098+40 is currently running a 3.1 FD.
It has a 12g295 head
9.4CR
Evo 001 cam.

I use it to cruise around as a toy really, but I've entered dome hill climbs.

I have a 3.64fd and I'm contemplating a change for some more low end grunt.

With the torque of the long stroke 1098 I'm wondering whether this Is going to be a worthwhile investment in time.

I will be fitting a lightened verto flywheel this week.

I will be driving to most events so It's also nice to cruise.

Thanks in advance, Babs

Edited by babsbrown, Yesterday, 06:03 PM.

[DeadSquare]

Although it won't be good for getting off the start line, stick to the 3:1, for pleasant cruising.

 

If you get bitten by the Hill Climb Bug, then start to think about improvements.

[whistler]

I have just done the reverse of what you're thinking. I've gone from a 3.44FD with S/C gears to 3.1FD with standard helical gears because I wanted a higher cruise speed.

The S/C 1st gear would have been too high for the 3.1FD hence reverting to a helical gearset. The 1098 is a long stroke torquey engine so to gain acceleration a lower FD is needed, as you are suggesting. Personally I wouldn't go lower than 3.76FD as you'll be running out of revs in gears. The 1098 crank, from what I've read and been told, is not really suitable for over 6000rpm so you will be limited by that. 

Back in the 60's I had a 997 cooper engine with a 4.1FD for rallying. It would scream up to 8000rpm but was no good for road cruising.

It's a compromise. Hill climbing would need a low diff, like the 4.1FD but you'd run out of revs.

I love my 1098 but know its limitations. Mine puts out 78bhp and about 80 ftlbs torque.

Hope my ramblings make sense. I expect other more experienced opinions will be along shortly.