Jeff,
While at the you-pull yard, I spotted a Shelby Daytona Turbo. Turbo
still intact. I'm sure you could find a small displacement car near you
as well. They shouldn't want too much for the turbo. Make your own
manifolds, linkage, oil supply/return, etc. And in the event the turbo
needs rebuilding, average cost runs between $250-$350.
You won't find a better way to improve the torque curve on your engine!
Glen, give Jeff some pointers.
WFO Herb
Keep the sticky side down.
Jeff Boatright wrote:
> Spridgeteers,
>
> Let's all take a deep breath. This is supposed to be fun!
>
> OK, back to the original question. How does one increase torque
> output on a BMC A series engine? In my case, the engine is a 1275
> with 40 overbore and a Kent 266 cam. However, I hope that what we
> discuss could be applicable to all spridget motors.
>
> One response was that intake gas velocity must be kept high. How does
> one do this? Vizard, in his inimitable way, shows the use of long
> (15+ inch) ram pipes with detailed discussion, but then mentions that
> none of this will really work with twin SUs. I don't understand why.
> But, is the only answer to switch to a single carb setup? As close
> readers of his book probably know, he spends most of his effort in
> increasing flow to increase ultimate power. Does anyone know of other
> sources of opinion backed by real data or anecdotal experience?
>
> Also, according to Vizard's charts, it is not necessarily always true
> that a modification that increases power at the high end results in
> loss of torque at the low end. Several of his charts show that torque
> often increases with flow. What does seem to occur frequently,
> though, is that that the power increase is proportionately larger
> than the torque increase. However, his data are all a little suspect
> for purposes of this discussion in that his goal is nearly always to
> increase power and let torque take care of itself; he doesn't
> systematically study torque. Of course, some would argue that he
> doesn't systematically study anything.
>
> Another response was to go with nitrous or increase capacity. The
> nitrous idea would be fun but maybe hard on the engine. It may be
> hard on the wallet. It does sound fun, though. Increasing capacity is
> something for engine rebuild time. I have upped mine a bit (to a
> calculated 1312 cc, I think, though the recent thread on cylinder
> volume has me second guessing). One downside, in addition to cost and
> time off the road, is that as the size increases, the engine does not
> idle quite as smoothly - it's the one advantage I've ever heard
> discussed about the 948 vs 1275.
>
> A final response was to go with supercharging. Now _that_ is
> expensive. But, it sure seems like the way to go for increase torque
> and power, particularly as complete, new systems can now be bought
> off the shelf (from MM and from the group in Australia). I'd have to
> win the lottery, though, to go this route.
>
> Anyway, there it is. I guess I'm looking for sub-$300 DIY torque
> solutions. But mainly, I'm simply ignorant to the extreme on this
> topic and would love to hear your thoughts on it.
>
> Thanks,
>
> Jeff
>
> _____________________________________________________________
> Jeffrey H. Boatright, PhD
> Assistant Professor, Emory Eye Center, Atlanta, GA, USA
> Senior Editor, Molecular Vision, http://www.molvis.org/molvis
> mailto:jboatri@emory.edu
|