I did a mod for the Vitesse that worked out pretty well and gave great
power. I was running a shorter than full length pipe and ran it into a
welded up cannister about 12" long and 6" wide and 4" thick. The exhaust
after exiting the pipe into this chamber thinks it is outside in the free
air and I got the same power as if the full length pipe was not there. This
method was quite fruitful and as I think about it now I know I used it
several times.Yes, you can fool the exhaust.
----- Original Message -----
From: "Jack W. Drews" <vinttr4@geneseo.net>
To: <WEmery7451@aol.com>
Cc: <kaskas@earthlink.net>; <RJunkermei@aol.com>; <fot@autox.team.net>
Sent: Tuesday, December 11, 2001 2:09 PM
Subject: Re: exhaust size
> WEmery7451@aol.com wrote:
>
> >In a message dated 12/10/01 9:28:28 PM Pacific Standard Time,
> >kaskas@earthlink.net writes:
> >
> ><< In my long dyno testing of this engine I found that a single pipe was
> >better
> > than a dual combination. >>
> >
> >Kas's little black book says to use 2 1/2" OD tubing. I have known of
people
> >who used larger than 2 1/2" diameter tubing. Is it to be assumed that
the
> >larger OD tubing hurts rather than helps?
> >
> >I might be using 2" tubing. If so, another attempted upgrade. This is
the
> >four cylinder engine.
> >
> >
> Two anecdotal experiences, from which you can draw your own conclusions:
>
> 1. I ran my engine on an engine dyno for a day. We did several runs
> with different length pipes but all with 2-1/2" diameter. Kas's results
> were that best hp was with a 45" pipe and he exited it just ahead of the
> right rear tire.On my engine we got the following results, ranked lowest
> to highest hp (yours may be different):
>
> 112" of 2-1/2" pipe (to back of car) -- baseline -- lowest
> 57" -- 3 hp more than base
> 42" - 4 hp more than no pipe
> 57" , same carb settings, -- 5 hp more than no pipe
> 57", carbs leaned by 4 flats -- 6 hp more than no pipe
>
> Why these lengths? Well, first of all I wanted to see what the 42"
> results would be. However, I didn't want to route it out the side and
> put up with tearing off my exhaust pipe because it was the lowest part
> of the chassis. This might not be as big a problem as I envisioned.
>
> I then determined that if I made it 57" long, it would end behind the X
> member but in front of the fuel cell. I tried this at the track, putting
> a downturn on the end to deflect the hot gasses downward. The first time
> I drove through the paddock on a dirt road, I was totally engulfed in a
> cloud of dust and dirt.
>
> Then I reasoned that since I didn't want my pretty car getting all
> dirtied up all the time, I'd sacrifice hp by running it out the back,
> but hopefully minimize the loss by increasing to a 3" pipe from the 57"
> point to the rear of the car. It works fine, probably giving up a few
> hp. Handicapping myself since I'm asuch a good driver. Ahem. However --
>
> 2. A couple of months ago a chassis dyno became available to me. I put
> my car on it and did several runs. On one of the runs, all the settings
> were identical to the previous run, but suddenly we had 3 more hp at the
> rear wheels. Why? After puzzling over this for awhile, we discovered
> that the flex pipe connecting the collector to the exhaust pipe had
> split and was leaking badly -- giving us 3 more hp.I guess I would
> conclude that running the pipe all the way to the rear of the car does
> indeed rob a few hp, even though the diameter is larger, but I must
> admit that with my sorry driving ability I'd be hard pressed to tell the
> difference of three hp, but at least my car stays clean..
>
> Now if I could get significantly more flow through the head, I might
> make an exhaust change so I can beat a Porsche somewhere.
>
>
> As they say, "Go figure".
>
> --
>
> uncle jack - red, white, and New Blue
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