Chris Delling wrote:
>
> Looking for some subjective opinions here.
Cool! I'm your man. Forget what the Mastadons say...
> My question regards bang for the buck. Given an engine with an
> 8.0 to 1 compression ratio, vs. the same engine with a 9.0 to 1 ratio, what
> % of increase would be expected. I am laying out my plans (and budget) for
> my winter project, namely extracting more from a stock 77 B mill (sans
> emissions, add Weber DGV). Trying to weigh the relative gain to be had by
> swapping to higher comp. pistons vs. stock (without any other mods, for
> comparison sake).
Lemme see. From 8.0 to 9.0 is 12.5% increase. If your gonna do that with
new pistons and a hone, and if you do your homework on piston rings, you
can get 10% more compression from less blowby. So with 20% more
compression, yes, you'll see a difference. Now, unless you like mixing
cat placenta with your gas, you might oughta consider a road-cam or 3/4
cam to go with them pistons. The greater overlap will _decrease_
compression under light loads and low rpms so the motor is less likely
to ping.
Then, as Thomas and I both subscribe, there is nothing the matter with a
well tuned Weber DGV. If your LBC has the stock early LCB manifold and
decent breathing, then what you should find is a car that will REV!
Yep, you gotta have high compression to REV and you'll find all your new
power about 1,500 rpm higher than you find it now. With only a mild cam
in may even idle and you won't have to rape the clutch at every light.
O'course, more revs needs a stout bottom end and a valve train that
doesn't go asthmatic at redline.
Hopefully you cashed in your mutual funds last Wednesday and your ready
to make this more tangible investment. I've obviously laid the ground
work for a full rebuild.
So, ah, how do you drive your car anyway? Don't get me wrong. The TR6 I
have is only 7.5 to 1 -- not much more pumping pressure than practiced
flatulence. Higher compression would definately help the car as its
passing ability on the highway is limited -- and that is where you'll
probably love your new peices parts.
--
Bob Allen, Kansas City, '69CGT, '75TR6, '61Elva(?)
"POSITIVE THINKING: Self-improvement through self-deception."
|