Re: RE: MP 4bbl throttle body ?

From: Mark Kuzia (flyboy01@mediaone.net)
Date: Sun Jul 29 2001 - 00:43:02 EDT


I want to agree with you on T-body size. I have been trying to tell people
that for years, you only loose part-throttle response with too big a TB. I
frequently drive WOT, I don't care, but for a V-6 that never sees WOT, you
might want to keep the response. The whole point of having the right CFM
with a carb is velocity and atomization. You should never restrict a TB, you
will loose horsepower.

Mark Kuzia
flyboy01@mediaone.net
http://people.mw.mediaone.net/flyboy01/home.html
1995 Dakota 13.79 @ 102.45 mph
~360ci, 5-spd, 8 3/4 rear / 3.90-SG
1994 Dakota 15.36 @ 91.56 mph
~318ci, 5-spd, 3.90 LS (bone stock, no mods)

----- Original Message -----
From: <chris@slowcar.net>
To: <dakota-truck@buffnet.net>
Sent: Saturday, July 28, 2001 11:36 PM
Subject: Re: DML: RE: MP 4bbl throttle body ?

> | I'm sure the 4bbl TB would flow far to much air out of the box for my
engine
> | size/mods, but I was thinking that I could get a restrictor plate to cut
down
> | the CFM to whatever worked best.
>
>
> I still haven't bought the argument that you can over TB an engine
> like you can over carb one. The downsides to a to big tb would be
> mainly loss of throttle granularity (e.g. a 1% change with a 4bbl is like
> a 5% change with a stock 2 barrel, so you loose some of the "precision").
> It's not like a carb'd engine where vacuum over the ortifice meter's
fuel -
> that's done independently.
> As for the velocity argument - the airs going into a plenum - once it
hit's
> that, boom, it slows down anyway. If it were a velocity stack setup it
might
> be difference.
> I don't think the TB will help much either (at least on a stock
displacement
> engine) - pumping losses really aren't an issue (which is what the TB
helps) with
> the CFM that would be turning.
> I think a restrictor plate would be more trouble than it's worth
honestly. If
> you want the 4bbl just do it - you probably won't pick up any power, but
it
> shouldn't hurt anything. I would definitley consider the progressive
linkage
> that Brend mentioned earlier!
>
> | Any chance you could post a picture of the mod you did to the 4bbl TB to
> | adapt the TV cable?
> | Also, what engine setup are you running (ie. year, cubes, mods, obd 1 or
2)
> | In addition, what valve sizes do you recommend?
>
> I will try and get a picture of it and post it - I really just drilled
a small hole,
> tapped it, ran some threaded rod in it, and fixed the TV cable connection
> over it. But will try and get some pics.
> Old engine was a 318 with heads+Cam, M1. OBDII, but has a haltech DFI
> piggyback computer that handles fuel and spark. New engine is a solid
> roller 408.
> Valve size I would stick with a 1.625 exhaust, no reason really to go
bigger.
> On the intake I would like a bit more valve, but honestly anything bigger
than
> a 2.00 valve and I don't think you can do a good valve job. My head
porter
> tried first with a 2.02 and with a 5angle valve job hit water (not good).
Honestly
> with a good valve and valve job you aren't giving up a whole lot with the
smaller
> valve, and on a smaller cube motor it's definitley the way to go anyway
(try
> and keep velocity up).
>
>
> Chris Bennight
>
>



This archive was generated by hypermail 2b29 : Fri Jun 20 2003 - 12:02:14 EDT