Data from drag strip

Sat May 5 12:59:46 GMT 2001

On my 383 Minirammed motor my map drops as well.  I am
still using a totally gutted maf sensor.
My map starts out about 98 then falls t oabout 90 at
6500.  I removed the ducting and the map only fell to
about 96.I then reinstalled the ducting wiht the maf
and the map fell to 90 again.
So I believe the dicting and maf and then even
throttle body do need toge upgraded.  Now a 58 mm TB I
belive will handle upto a 406 to about 6500 but say
you build a 422 that spins to 7000 a 1300 may be in
order.
Dennis
--- timsiford at hushmail.com wrote:
> Eureka.  I never thought of that.  I witness the
> same phenomena concerning 
> my 1990 MiniRammed IROC.  I take her up to 6500 and
> always see the MAP drop 
> from 100 to about 96.  I perceived this to be an
> intake restriction upstream 
> of the TB.  I tested this theory a little bit at the
> track by running no 
> air filters.  My track times were exactly the same
> and the Diacom readings 
> were the same.  I have always known that my exhaust
> is very very weak (SLP 
> 1-5/8" headers through a 2-1/4" Y-Pipe and then back
> through the 3" Flowmaster 
> catback).  My setup is definitely unbalanced and I
> have been aware of this 
> for some time now.  I should be running at least
> 1-3/4" headers into a 2-
> 1/2" Y pipe.  Cool deal.  I never linked in my head
> that the drop in MAP 
> may be due to my crappy exhaust.
> 
> Tim
> 
> At Tue, 01 May 2001 02:32:07 -0400, Bob Valentine
> <bob at tecmark.com> wrote:
> 
> >
> >Another scenario could be a restricted exhaust
> would be interesting 
> >to put
> >some sort of pressure tap in the exhaust and see if
> it corrosponds with 
> >the
> >map drop.  I'd wittnessed the same MAP drop issue
> before I had a BBC
> >throttle body on the 403 Olds, but that was prob.
> an extreme case.  
> > 
> >
> >I see IAT temps all over the place, my IAT is in
> the air cleaner on 
> >top of
> >the TB.   Gets warm during idle, easily cools off
> 10-30 degrees during
> >cruise.    Humidity is a factor also, more humid =>
> more temp drop. 
> >  
> >
> >-> Bob Valentine
> >-> bob at tecmark.com
> >
> >At 10:41 PM 4/30/2001 -0700, you wrote:
> >>
> >>Good evening gents,
> >>
> >>I was @ the track the other day & was checking out
> the data tonight 
> >&
> >>thought I would run a few things by Y'all.
> >>
> >>we had a small discussion about Intake Air Temp a
> while back & I had 
> >noticed
> >>that by the time I was @ the end of the 1/4 that
> the IAT was about 
> >3 degrees
> >>cooler (I have a super ram, cold air intake & a
> 383).  this I thought 
> >was
> >>pretty cool & had not noticed it before.  This
> time I went I was running
> >>slicks & I just noticed that even during the burn
> out (I was not doing 
> >a
> >>burn out with the radials, no sense, they went up
> in smoke any way),
> > that
> >>the temp came down about 3/4 of a degree. I was
> doing about 45 to 55 
> >second
> >>burn outs.  I had thought that it was flying down
> the track that was
> >>actually cooling the intake tract, thus reducing
> IAT's.  But it appears 
> >that
> >>just pulling air in does it.  just an observation
> is all.
> >>
> >>Second is that I noticed that the MAP was actually
> dropping as the 
> >motor
> >>came up to about 5200 rpm.  I take it to about
> 5700 to 6000 for the 
> >shift
> >>point & from 5200 to 5700 you can watch the MAP
> drop.  I could not 
> >figure
> >>out what was "wrong".  makes me think, one of two
> things.  first is 
> >that the
> >>383 has enough volume @ that RPM to start to draw
> a slight vacuum on 
> >the
> >>plenum (although I don't think so, that is why
> Lingenfelter made it 
> >so darn
> >>big) OR, that there might be a restriction
> upstream of the TB, that 
> >is
> >>allowing the motor to draw a vacuum on the plenum.
>  I think that the 
> >later
> >>is probably the case, cause of the Cold air tubes
> that I have.  I think 
> >that
> >>the next time to the track I am going to take my
> clothes dryer duct 
> >& some
> >>duct tape & do a couple of runs to experiment. 
> Also we had a discussion
> >>about IAT's & taking cold air from the engine bay
> (K&N right on TB 
> >vs. cold
> >>air package).  I forgot my TB K&N so I was not
> able to do that test.
> >>
> >>thoughts?
> >>
> >>Bob Wooten
> >>r71chevy at earthlink.net
> >>www.r71camaro.homestead.com
> >>
>
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=====
Dennis Zacek
http://geocities.com/bowtie8

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