Which Throttle Body to Get????

[Redleg13]

Randy takes a stock throttle body and bores it out to 61mm from the standard 58mm. MiniMadness takes theirs out to 63mm. Prices are very close... what to do???

[goin440]

I remember reading from somewhere that one TB was too big. I can't place the numbers nor manufacturer so I don't know if it was a 63mm or a 68mm (the 3 vs. 8 thing), or +. I recall the reading mentioning testing several bores and found the upper limit of optimal bore size, but was early in the testing too.

Looking at your existing mods, I see no reason to doubt the larger with the price similarities.

[TonyB]

Since I don't recall a 68, I believe it is the 63, and I've heard the same. Bigger is not always better Seriously though, there were reported driveablility issues with the 63, at idle I believe. The 61 appears to be the one to get, at least now...

I was looking to make this purchase by the end of the summer to give these a bit more time to pan-out. I do wish we could keep the stock though, especially here in CA in case there are smog ramifications...

[jdw5155]

I know Randy did a ton of testing with different suppliers on this part and did find that some were not effective for one reason or another. I may be joining you soon on the 61mm unit as well.

Regards,
Jim

[Mugami]

there have been other treads talking about the overbored TB's. Most of the discussion has to do with the thinking used for Carbs. IOW bigger bore mean more top end and less bottom and vise versa. Randy who i believe has only the pulley, intake, cat back exhaust and ecu up dates. Perfers the 61mm. Which he states gives the better all around performance. Now the Mini of Sterling which has more inline with the mods JDW5155 has.. The heads and headers replaced as well perfers the 63mm TB. Also keep in mind they do race this mini on the track where TOP end is key.

In say that Matching a TB to the engine needs is whats needed. The more mods you make the more air is needed to make it work properly. I cant remember off hand what the formula use by Hot Rodders to say what kind of Carb to use. But since it has to do with Flow rates more than just size (carbs are done in Cubic Feet per Minute than dia. size) You may use that formula after finding out what the CFM of the TB are. This may help with the dicision may not but is something to keep in mind.

[Andy@Ross-Tech.com]

I'd buy one that isn't held together with tape, as this one obviously is:

[Redleg13]

ok, I give up... maybe my eyesight is really getting bad, but I don't see the tape?! Let's be a little more direct: I know they say a picture is worth a thousand words, but in this case I'll settle for something less cryptic...

[Grinder]

The tape is silver... Look upper left of that first pic.

[QQQ]

So this mod would cost me around US$ 500, what does it give me in terms of performance? Can't imagine it would give me much more than 5 whp. Increase in power over the entire rev range, middle, top end? Anyone? Dyno's?

Cheers

[TonyB]

depending on what you have... up to 7 across the band, so i hear.

[QQQ]

Thanks Tony,

Anyone with pulley and ECU who has the TB fitted? Worth the $$$ or rather spent the cash on a new header?

Thanks

[jlm]

So far I have tooled up and bored out one throttle body to 61mm and have been running it on my rig for about two or three months. A few enthusiast may remember seeing it at Helix last time I was there, but no significant power gains were shown (my car has a history of punky dyno results).
They are tricky to disassemble and put back together correctly. I also made a few jigs to assist machining. The things are a pia, so i'm not interested in any one-offs. A couple of distributors have indicated they are going to send me 10 pcs, which is my minimum to do a machining run, but so far, nada (I've been ready for over two months). It seems forking over $1,700 for the initial ten stockers is too dear, even though at least that many can be sold right away, and the cores would keep the ball rolling.

The stock bore is 57mm; going to 61mm is no problem. 63 is about the max people have suggested. There is no appreciable machining difference between the two. I use a mechanical clamp on the band when re-assembling.

Interest has peaked lately, so I may be getting a load of units to modify.

[obehave]

Quote:

Originally posted by QQQ
Thanks Tony,

Anyone with pulley and ECU who has the TB fitted? Worth the $$$ or rather spent the cash on a new header?

Thanks

My 2¢. Do the header.

[QQQ]

Quote:

Originally posted by obehave
My 2¢. Do the header.

Thought so obe, cheers

[SMG]

i'm waiting for my 61mm.....hehe