anyone have a pic of what they did on the front of their plenum? :cheers:

 

Unless you're going huge cubes or forced induction I'd use that 58mm as a sweet paper weight in the office. :)

 

I took few photos when I did porting to mine 85 L98, installing HOLLEY NOS Avenger LT1 style 58mm.

(how do I post pictures here?)
ftp://ftp.shaw.ca/85_L98/pics/intake_tract/P5160004.JPG


[Modified by smar, 1:03 AM 6/10/2003]

 

this best shows what I did when I did mine

 

I did few calcs, 52mm is bit too small and 58mm is too big. So I installed 58mm. The 58mm compliments my low restriction intake and free flowing exhaust well. In future I am planning to go 383, 58mm will shine even more.
Other benefit is that larger bore T/B will reduce velocities and as a result of that parasite venturi impact on 2nd & 4th runner tube will be reduced.
Drivability is not a problem, yes the car is more responsive at the beginning of the gas pedal travel but still well streetable.

Happy tweaking

 

No porting tips, but you might want to take a look at Jim Mason's tip on improving idle characteristics with non-OEM bodies: http://www.hashmarks.com/techtips/throttle_body_mod.htm

:cheers: Brad

 

Proper gaskets and a dremal should work great..

 

Why not a 54 then? :)

 

have you ever noticed that in all the years everyones been swapping to 52mm and 58mm and mono blade 1300 cfm throttle bodies , they have said things like
I did not gain a great deal of hp
I lost some throttle responce
It sounds differant but I don,t seem to go faster
I only gained a tenth of a second plus a couple thousands in the 1/4 mile

Ive yet to find anyone that lost hp,once the engine was properly set up and adjusted with the larger throttle bodies a throttle body is not like the venturies on a carb that control the fuel/air mix, the computer and sensors and injectors do that on an EFI system, the throttle body is only a air volume control valve, your engine can only use (X) amount of air at any given point, as long as the throttle body is allowing that much OR MORE to pass UNRESTRICTED, its going to work reasonably well. the individual ports combined on even a 454 size sbc spinning 6500rpm (WAY OVER ADVISEABLE PISTON SPEED) only can use about 850-950cfm (do the math) that can be fed from dual 56mm throttle bores, since a 58mm is the closest size thats what most guys with large engines use,a 383 like mine with a custom stealth ram only needs about 775-825cfm. a 52mm is just a little to small and a 58mm is overly large BUT, TOO LARGE! WON,T HURT PERFORMANCE NEARLY AS BAD AS TO RESTRICTIVE MIGHT! ONLY TOO RESTRICTIVE/SMALL hurts!
yes you might lose a small amount of throttle responce, but an overly large throttle body won,t hurt high rpm hp if mounted on an engine with an intake with the correct port runner size/length, compression and cam timing. don,t forget that a great deal of how effective an intake system is is controlled by the rpm range where the exhaust system on that same engine scavages the cylinders efficiently. if you don,t have full lenght tuned headers and a free flow exhaust , adding a larger throttle body is likely a waste of effort. if you cant get rid of whats in the cylinder now you can,t refill it effectively anyway. keep in mind an engine is A SYSTEM, ALL PARTS MUST BE DESIGNED TO WORK EFFECTIVELY AT THE SAME RPM,AND DISPLACEMENT





[Modified by grumpyvette, 8:22 PM 6/7/2003]

 

alot of good points, thank you everyone for your input :cheers:

i would rather have too much air than not enough so i will go with the 58mm, also a pro-charger looks like it may be in my immediate future, so why buy twice :steering:

 

48, 52, 58 and brutal "uniblade" are the only option without getting into custom machinning.

 

Right on, you won't be dissapointed. If you have difficulty to fit the plastic ducting over your new 58mm let me know I might have sollution to it.

 

One more thing! check this out.
http://www.eecis.udel.edu/~davis/z28/buildup/

 

it won't be a problem, i hand built my own carbon fiber duct :cheers:

 

Here's my pics from porting the plenum for the 58mm:

http://www.sitesbytim.com/Pictures/C...fold/index.htm

 

Any pics? I am thinking of getting into the Composites world (College class next semester I am hopefully going to take). And looking for pictures of neat stuff.
Matt

 

sorry Matt, no pics, I've been putting it off for a while and will have some soon, I also have a carbon fiber roof panel and cold air intake set-up, all made by yours truly :cheers: