58mm throttle body

[FLSY2730]

Has anyone had any idleing problems with these, anybody on here have one or a 52-54mm, how do you like it? any problems? When i had a 58mm on my iroc383 i had some idleing issues, it would go up and down when you were at a stop. Since i already bought one from arizona speed and marine i guess i am going to use it, i just dont know how good they are when it comes to idleing?

 

[2cold]

I've had issuses with the BBK ones making a whistling noise at idle on Mustangs.

 

[Pittman]

IF the stop is not adjusted properly it causes the IAC to go nuts and your idle will fluctuate. The IAC is trying to compensate. Seen this a few times on other cars. I havent put one on my sy yet.

 

[Falco]

I've never done this, but AFAIR you should port matching the upper intake with the 58mm. It's said to match fine with the 52mm. However I can't recall it exactly, but you have to fabricate something on the throttle arm, because it won't fit our application directly. Maybe replace it with the stock arm!? I don't remember. Do a search, or ask JWaller, he has done this.

HTH,

 

[jwaller]

I installed the bbk 52mm on my truck and it idles awesome. I did have to fab the stock linkage onto the bbk unit and I had to make my own adaptor to hold the tps bc the one I recieved was for a later model.

but as long as your truck doesnt have any preexisting condtions the TB itself will not hange the idle. you must adjust the sto screw so that the IAC counts are ~ 30-40.

the 52 matches perfectly. the intake must be milled out to accept the 58.

 

[Eluding]

FYI, on my naturally-aspirated 94 Firebird LT1 the 58mm BBK upped the rear-wheel HP from 365 (with the stock 48mm) to 377 with the 58mm. I'm not sure what the gains would be on a forced-induction engine.

 

[TheObiJuan]

I remember a thread like this about 8 months ago.
they had said going to a 58 was pointless because of the outlets on the (most) intercooler (Wether A2A or stock) are smaller than 58mm.
there would be more to gain from getting larger outlets on the IC's.

Forgive me, but I have to do this.
Lets look at what is most restrictive. The stock throttle body plates are 48mm in diameter each. Conversion from mm to inches: 25.4mm = 1 inch.
48/25.4 = 1.89in
Area = pie x (d/2)^2
= 2.805 square inches per plate
x 2 plates = 5.61 square inches total

Inlet to IC is aproximately 2in diameter.
Area = pie x (2/2)^2
= 3.14 square inches

So the cross setional area that air flows through the stock throttle body (neglecting the thickness of the plate and shaft) is 5.61in^2.
Whereas the cross sectional area for the inlet of the IC is only 3.14in^2
Consider that along with the fact that the throttlebody is a lot smoother passage than the rough and abrupt IC inlet and it kinda puts things into perspective. If you want to get more airflow, look at the IC inlet first.


_________________
Joe Lutz
Steel lernin hoaw to speal

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<font size=-1>[ This Message was edited by: joemama on 2002-01-11 00:18 ]</font>