----- Original Message -----
From: "James J." <m1garand@speakeasy.net>
Date: Sunday, June 5, 2005 8:39 pm
Subject: Porting
> I'm lucky to have an excellent machinist, who is a retired engine
> builder for a Busch series team, and now runs the engine lab for
> University of Maryland in the upstairs of his shop. He has wet
> and dry
> flow benches, ultrasonic gear and precision cam profiling gear,
>...
Sounds less like luck and more like having your own mechanical angel!
>...
> 1) Mirror polishing the intake reduces turbulence, but allows for
> fuel
> puddling (even with EFI, but not so critical with direct shot
> heads,
> like the LS1 and LS6)
I have to admit, I don't have access to the people, equipment, and knowledge
base that
some of you have; I just read what I can and play with what I've got...
That said, it is my understanding that surface finish (mirror polished or not)
also has
an effect on boundary layer turbulence, with the short of it that a polished
surface
can actually increase tubulence (and therefore decrease flow), particularly
when the
gas flow is changing direction, like on the "far side" of an intake port.
> 2) Having a little step-up along the bottom of the port between
> the
> intake manifold and head also creates a little shear turbulence
> which
> helps keep fuel in suspension
Okay, perhaps what I've been reading is out of date. My understanding for such
steps
(on both intake and exhaust sides) is to create an "anti-reversion ditch", to
encourage flow
in one direction but not the other -- necessary when the cam timing includes
lots of
overlap.
>...
>
> My next step with him is deciding the optimal ram length for the
> Rover
> EFI pseudo-individual runners in a sports-car application (stock
> Rover
> length is for low-end SUV torque)
That's an experiment I'd love to hear about. I have ex Range Rover systems
that will end up on both the 'B V8 and TR8.
-Keith Wheeler
Team Sanctuary
///
/// mgb-v8@autox.team.net mailing list
/// Send admin requests to majordomo@autox.team.net
/// Send list postings to mgb-v8@autox.team.net
/// Edit your replies! If they include this trailer, they will NOT be sent.
///
|