Hey guys,

I'm almost done proving my theories in making a 54MM throttle body. I should have the prototype ready for this weekend.

If infact my research is correct, people should be able to do this for about $60.00,
and about 2 hours of labor.

I've talked to SLP who was making 52MM throttle bodies recently, about how they go
about doing it. I then researched a little
deeper on how to do it myself.

I'll be keeping this list posted with my progress, as well I'll have detailed instructions with pictures available online upon completion, and on my website.

Wish me luck.

-- Joe

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1989 Formula 350 4-bolt mains, Forged .030 TRW pistons, SLP 51010 Roller Cam, Comp-cams roller lifters, Summit 1.5 roller rockers, World Products Sportsman II
2.02/1.60 heads, Edelbrock TPI Intake, Cloyes Double Roller, timing chain, Mellings oil pump: 13.5 @ 100.23 MPH

Since close of track : Ported SLP runners, Ported Plenum, AFPR, Autometer 100lbs gauge, A/F ratio gauge.

http://www.joesperformance.com

-- Joe

 

Keep it up. This winter I am thinking of doing this. We have a honing machine at work and a metal lathe, so I was going to do it on slow days. Let me know what it intales.

Jeremy

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92 Z conv
5-spd B&M shifter
home-made ram air, air foil, headers, no cat, TB bypass, kevlar pads, slotted rotors, BMR panhard, alston SFC, 3.42's, Edelbrock STB, 350 in the works

 

If you make this work and write it up i'm sure plenty of people would like to see it again. WAY back in the day there was a tech article *somewhere* out there that had the process for boring TBs out. Went stp by step, including instructions to stop at certain IDs to fill in newly exposed crevices/passages w/ epoxy, etc. Also included templates/guides for making the new throttle plates.
If you can document it pretty well i'm sure it's something we'd like to have in the tech articles.

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Ed Maher - Moderator @ The TPI & Carb Boards
92 Z28 Convertible - Quasar blue / Tan top
305 TPI A4 2.73 - 14.7 @ 93.6
Stock except ported plenum and dual cats
-=ICON Motorsports=-

- Definitely prototypes, high powered mutants of some kind. Too weird to live, too cool to die

 

Hey,

I ripped out some 2.8 plates today. They are not quite as big as I first thought, because of how I was measurin ghte hole with the micrometer, but they are a LOT bigger than the stock TPI plates. So it will be more than worhtwhile.

On a side note, I may also try making up some plates.

I'll be boring this unit this weekend, (prolly friday) and will keep you posted on my progress.

-- Joe

 

Barry Gant in GA has Holley dominator butterflies for $10 a pair(last time I bought some)
The minor diameter is what you bore to (along the throttle shaft axis).
Making a proper elipse for the butterflies is a PITA, IMO, for the bux the Holley's are a good buy.

There is a slight magnesium content to what looks like an AL casting so go real slow or the tool will gall, and ruin the finish. Disasembly and reassembly in 2 hours is cutting it real close.

Large butterflies can be real misleading, they expose the engine to such more air at lower throttle openings, that the engine feels better, but you can lose WOT performance unless you really have enough engine to need them.

An interesting fact is 20% throttle opening is 70% of possible air flow.

Use extreme care in restaking the butterfly screws one falling out is disaster.

Also, the TV cable and adjustment may be a bit different, since the throttel opening to MPH may vary from stock.

 

Hi,

Whats barry Grants #??

-- Joe

 

Hello,

Ive been figuring out some CFM flow numbers
(based on other peoples flow bench testing
of various throttle body bores) and I figured, using 2.8/3.1 liter GM throttle
plates, you can expect:

Without an airfoil: 815-820 CFM
With an airfoil: 850-860 CFM

These are of course, "Guestimates".

-- Joe

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1989 Formula 350 4-bolt mains, Forged .030 TRW pistons, SLP 51010 Roller Cam, Comp-cams roller lifters, Summit 1.5 roller rockers, World Products Sportsman II
2.02/1.60 heads, Edelbrock TPI Intake, Cloyes Double Roller, timing chain, Mellings oil pump: 13.5 @ 100.23 MPH

Since close of track : Ported SLP runners, Ported Plenum, AFPR, Autometer 100lbs gauge, A/F ratio gauge.

http://www.joesperformance.com

-- Joe

 

Do you have an update for us???

Jeremy

------------------
92 Z conv
5-spd B&M shifter
home-made ram air, air foil, headers, no cat, TB bypass, kevlar pads, slotted rotors, BMR panhard, alston SFC, 3.42's, Edelbrock STB, 350 in the works

 

Hi,

Sorry. I'm using some 2.8L throttle body plates right now. The TB is at my buddies machine shop, I should have it back in a day or so.

I'll keep you guys updated when I re-assemble it, and also will have final bore specs from the machine shop.

I might try this for a few months, and also make a bigger version with some alum. plates. I can have the machinest make me perfectly round circles of same gauge, to any size I want and match-bore the holes.

The mounting holes can be made with a drill press fairly easily. They can be round or slotted, so they don't have to be perfect.
Because of how tight the bore is with the plates, you can't misalign them when tightenening, they will literally fall into
place.

-- Joe

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1989 Formula 350 4-bolt mains, Forged .030 TRW pistons, SLP 51010 Roller Cam, Comp-cams roller lifters,
Summit 1.5 roller rockers, World Products Sportsman II 2.02/1.60 heads, Edelbrock TPI Intake,
Cloyes Double Roller, timing chain, Mellings oil pump: 13.5 @ 100.23 MPH

Since close of track : Ported SLP runners, Ported Plenum, AFPR, Autometer 100lbs gauge, A/F ratio gauge.

http://www.joesperformance.com