Ported 58mm T/B vs stock 58mm T/B testing.

[turbovanman²]

I've been running a ported one for around 2 years, so the other day, I decided to put a stock unit on for comparison, as its been reported that the bored out ones flow less on a flowbench.

Difference wise, its not as snappy free revving off idle, its definately softer off idle driving, its a tad laggier but boost wise, its seems to make more power, its hits harder and seems to pull harder at the same boost. Vacuum wise, I pull a 2 more inch's at idle and in cruise, pull 3-5" more.

As I drive more, I'll see if MPG change's as it seems to run a bit richer except at idle.

[Reaper1]

I'm interested to see where this goes!

[turbovanman²]

Surprised the crap out of me. Right off idle, I had this transition that was twitchy, if you revved it up and around 40km/h, its reduced by over 1/2, lol.

[CBMDennis]

How hard was it too port? Did you do it yourselft. What method did you use (tool wise).

Thanks in advance

Dennis

[turbovanman²]

How hard was it too port? Did you do it yourselft. What method did you use (tool wise).

Thanks in advance

Dennis

I had MPG Mike do it for me. I have a few spare honed out 58's if your looking.

[Aries_Turbo]

were the throttle cable cams the same on both?

[5DIGITS]

Surprised the crap out of me. Right off idle, I had this transition that was twitchy, if you revved it up and around 40km/h, its reduced by over 1/2, lol.

Simon,
The TB's have a built in method of reducing throttle sensitivity for better garage/parking lot "tip-in" control.
The first 3-5 degrees of throttle opening only allows air-flow past one side of the throttle blade.
You'll see that one side of the TB bore is different than the other - the single sided ramp is removed when the TB is bored.

[roachjuice]

I'm interested in what the outcome is.

[turbovanman²]

were the throttle cable cams the same on both?

Yep, I had to weld an auto cam onto the shaft as they never came on 3 speeds with tv cables so I have to swap it over.

Simon,
The TB's have a built in method of reducing throttle sensitivity for better garage/parking lot "tip-in" control.
The first 3-5 degrees of throttle opening only allows air-flow past one side of the throttle blade.
You'll see that one side of the TB bore is different than the other - the single sided ramp is removed when the TB is bored.

Thanks, figured that was the reason BUT doesn't make sense how on a flowbench flow suffers and the results I am getting when many other T/B's aren't ramped.

[4 l-bodies]

humm... maybe the factory did that for a reason huh? Now did you put a bead around lip to prevent hose from blowing off under boost? I remember Juggy cranked his t-bolt clamps so hard on his TB he started to oval his TB (lol)! whoops...

[BadFastGTC]

Simon, perhaps it would be advantageous to flow each throttle body on the manifold/head combination and take readings at various throttle angles and valve lifts to see how each one performs.

[turbovanman²]

humm... maybe the factory did that for a reason huh? Now did you put a bead around lip to prevent hose from blowing off under boost? I remember Juggy cranked his t-bolt clamps so hard on his TB he started to oval his TB (lol)! whoops...

It would make sense with everything stock but with everything now flowing more air than the factory dreamed off, kinda makes you go hmmmmmmmmm and again, other T/B's don't have ramps, etc.

Honestly Todd, I've never had an issue with hoses blowing off, even at 30+ psi and no bead. I run a piece of rubber hose to space it so my 2.5" hump hose fits, then a simple hose clamp holds it together.

Simon, perhaps it would be advantageous to flow each throttle body on the manifold/head combination and take readings at various throttle angles and valve lifts to see how each one performs.

That would be a great idea but at this time, can't be bothered, lol.

[Juggy]

been running one for years......
it will be approx the same benefit as if someone were to say go from a 46mm to 52mm TB......58 is 6mm bigger then 52mm...imagine that....

I have ported them by hand, and also on the CNC machine....

[turbovanman²]

been running one for years......
it will be approx the same benefit as if someone were to say go from a 46mm to 52mm TB......58 is 6mm bigger then 52mm...imagine that....

I have ported them by hand, and also on the CNC machine....

????????

Usually when people go to a 52mm, they don't do many mods. Alot of us has high flowing setup so THERE should be a difference. I think JT is running a 65mm T/B on his 2.4L Gaytona, , Lengel 70mm+ on his wild TIII.

[RoadWarrior222]

been running one for years......
it will be approx the same benefit as if someone were to say go from a 46mm to 52mm TB......58 is 6mm bigger then 52mm...imagine that....

One cannot simply compare the difference in diameter...

... the area gain is bigger, the larger you go. I were gonna post the math, but ascii math looks like arse, and it's simple high school stuff.

[sdac guy]

I had MPG Mike do it for me. I have a few spare honed out 58's if your looking.

Yeah, he did the flow comparison article in Up Front a while back. Even he was surprised that the stock 58 tb out flowed the one he ported.

Barry

[cordes]

One cannot simply compare the difference in diameter...

... the area gain is bigger, the larger you go. I were gonna post the math, but ascii math looks like arse, and it's simple high school stuff.

Use WolframAlpha

http://www.wolframalpha.com/input/?i...+46mm+diameter

http://www.wolframalpha.com/input/?i...+52mm+diameter

http://www.wolframalpha.com/input/?i...+58mm+diameter

ETA: That's a huge difference in area between the 46 and 58mm piece.

[ohiorob]

My best time was with a 52 changed to a 60 made no difference. maybe my intake is holding things back. don't know.

[turbovanman²]

I think a 52mm in my case would choke up my setup, I have a large plenum intake and high flowing head, but maybe I'll swap one back in when drag racing starts, get some runs in with the 58, try the unported vs ported, then put a 52mm in.

---------- Post added at 09:49 AM ---------- Previous post was at 09:47 AM ----------

Use WolframAlpha

http://www.wolframalpha.com/input/?i...+46mm+diameter

http://www.wolframalpha.com/input/?i...+52mm+diameter

http://www.wolframalpha.com/input/?i...+58mm+diameter

ETA: That's a huge difference in area between the 46 and 58mm piece.

That's awesome. Too bad you can't superimpose them.

[roachjuice]

im still running a 46mm i have some 52mm throttle bodies laying around. my manifold is ported to match a 52mm. i may give it a shot.