Re: Turbochargers on Daks. Was: Re: RE:discrimination against low trucks?!!!

From: Robert France (robert@srpl.com)
Date: Wed Nov 24 1999 - 02:21:09 EST


>it up yourself, or take it to a shop? I'd like to do a twin turbo
>setup on my Dak, but I haven't been able to figure out how to make it
>a simple bolt-on yet.

heh heh heh (giggle giggle giggle) oh yeah, simple bolt on?!? :P

>intercoolers, etc! I'd really like to do twin turbos to reduce the
>lag, but that takes up twice the room. I probably aught to just do it
>right and have some headers made.

and costs twice as much for turbos too!

>make me a set of custom headers. :-( I do plan to get a MIG welder
>one of these days, but I'd still need a tubing bender. (Well, maybe
>I can get a shop to bend up the pipes.) My problem also is that
>I don't know a whole lot about the theory of designing headers, so
>they won't be much more than tubes to get the exhaust to run through
>the turbos... Maybe it doesn't matter quite so much on forced induction
>engines though. ?

DON'T BUY A CHEAP MIG WELDER!!! I did, I bought an Italian-Made 120V
"130Amp" plug-it-into-the-wall style MIG (Cebora?) and it is a piece of
junk. It has no real voltage regulation system to control arc strength. My
brother bought a Lincoln (or if you are a union man, get a Miller) 170Amp
220V unit, and it all of a sudden solved all of my "welding
inadequacies"...ie for once it wasn't me, it was the equipment!!! You can't
understand the difference until ...you get under your brother's girlfriends
car to fix her rusty tailpipe, and the crappy welder just won't work, but
the good welder is hard not to do a good job.

Make the header out of mild steel, then ceramic-coat it; I have helped do
this on a friends road-race car without any problems, so it should stand up
to street use which will NEVER get it as hot as the race track gets it in
30 min of full-throttle, full boost. (unless you run your truck at full
throttle, full boost for more than 30 minutes on the street!!!)

For a turbocharged engine header, you don't need to make the header primary
pipes any larger than the exhaust ports; the turbine nozzle usually has a
cross sectional area of less than 1 square inch. Making a turbo header
"big" for "ultimate flow" is unnecessary, but do make the output of the
turbo dump into the biggest pipe you can fit, and MAKE SURE THE HEADER
PRIMARY PIPES ARE EQUAL LENGTH!!! This makes a huge difference to reversion
wave rejection and turbine response time. Also, make the primary pipes as
long as possible; any reasoning that applies to a naturally aspirated
engine also applies to a turbocharged motor as well.

> Anyway, keep us updated on your progress! :-) Based on some earlier
>DML discussions, and particularly from the input of Shaun H., I'm leaning
>toward the Garret VNT units.

Stay away from that piece of crap! VNT technology went the way of the Dodo!
If you learn to drive a turbo motor, you don't need to rely on unreliable
and expensive tricks to do the work for you; keep the revs up medium high
to keep the turbine flow in the low-mid range of your turbo flow map and
match the header primary lengths on a relatively long primary header, and
there won't really be turbo lag, just traction lag!!!

RF



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