LT1, Crossfire, etc.., Intake runner lengths and other rambling

[Gwyn Reedy]

I'm curious about the Crossfire setup also.

My interest is in mid-range torque and driveability. I have an Impala with
LT1 (or is it LT-1?) and it runs strong, is very smooth, and will pull over
20 mpg. Also have a number of 60's and 70's vehicles with small and big
block Chevy V8 engines and carburetion. They start hard, stumble when you
lug them, and get awful gas mileage (but they run fine at WOT). I don't want
roller cams, 8500 RPM, etc., and none of them will ever earn a time slip.
Just want to make them as enjoyable to drive as the electronic engines.

I'm really curious about the runner lengths on the Crossfire as well as the
TPI. Hope someone will be able to come up with that information. And we need
to compare apples to apples - are you measuring from the intake valve or
from the port on the manifold?

Tunnel Ram manifolds for carbs (usually sticking through the hood) are a way
to have a ram intake with carbs. (Of course there was the cross ram 2 x 4bbl
on small block and on Chrysler 426 Hemi, and do you remember the Dodge 383
back in 1960 that had the carbs outboard of the valve covers to get longer
intake ram passages?) I wonder if anyone ever put a 4 bbl on a right angle
adapter mounted in place of the throttle body on a TPI. (If you needed to
run a carburetor because of racing rules or something.) You'd get the RAM
effect without such a large hole in the hood...

Gwyn Reedy
Brandon, Florida
mailto:mgr at mgrcorp.com

-----Original Message-----
From: owner-diy_efi at efi332.eng.ohio-state.edu
[mailto:owner-diy_efi at efi332.eng.ohio-state.edu]On Behalf Of
ECMnut at aol.com
Sent: Thursday, December 10, 1998 11:49 PM
To: diy_efi at efi332.eng.ohio-state.edu
Subject: LT1, Crossfire, etc.., Intake runner lengths



>   I have been under the impression that long intake runners are for
>  low-end torque, and short runners are for high RPMs.  What type of
project
>  are you considering?  Maybe then we could get some folks to analysie it
in
>  greater detail.

Yep, I was of the same understanding, just looking for RPM ranges.
 I bumped into an old racer buddy the other day and stopped
by his garage.  He's got a '68 Camaro drag car, 355 chev, .
.700 lift roller cam, 850 holley carb,  13:1 comp, powerglide trans...
  He says there is no way a GM ECM system will replace his
Holley & dual point dissy and still  turn 9.90s...

I told him to build a low comp shortblock and
put some turbos on it with a milder cam, and the EFI will knock
his socks off..   Their are 3.8 liter Buicks that weigh 1,000
pounds more than his car, that earn quicker timeslips.
He likes loud cars and hates my turbo talk..
Gets upset when I call him a caveman..
He is still considering a naturally aspirated EFI setup..
His roller cam doesn't pull much vac at idle which has me a
little hesitant to try a MAP system.  Another concern is that
his engine regularly sees 8500 RPM.  I don't think that the
GM ECM can do that.  Not sure though..
Thanks,
Mike V