I want to have my LT4 TB bored out to 52MM. Anyone know where I can get it done?

Anyone used or know about these folks?
http://xtremefi.com/Q&A.html

there is no real benefit. The stock TB can handle 900+ CFM... why add more? You don't need it.

I am really more interested in the mod they do that puts ball bearings on the butterfly shaft.

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I have a Hotcam and a pair of EM longtubes that I will install soon. Will the stock 48 mm still be good?

Where did you get your flow numbers?

Anyone else have a view on this? When does the MAF become the limiting factor?

Droptop, I've got the hotcam and a set of Hooker longtube headers on my LT4. Based on everything I've read over the years on LS1TECH.COM, CF, CAMAROZ28.COM, etcetc there is no benefit from doing either the larger maf or throttle body at this level of power. Its only when you get to much larger numbers that it becomes cost effective. My next mod is going to be an electric water pump. Just my $.02

Yeah I know. I have searched extensively on this subject and it seems to be divided on whether the 52 will help or hinder. I also see widely varying numbers on the CFM rate of the stock 48mm. I have a 52mm Performance Products on it now. I may put the stock TB back on.

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And I have gotten into epic battles trying to explain "conductance" to those same meat heads.

Your Restriction is the Smallest CFM point throughout the entire system. So asking about the Flow restrictions of the MAF is a good question.

Bogus seems to have the Tech specs on the 48mm being 900cfm"

Those are the things you need. Once you open up one orifice then you can concentrate on the next restriction and so on and so on.

I am pretty sure the 900 CFM number is high, I only found one number for the MAF which was around 700 CFM. I didn't detect any difference when I put on the 52MM. I did it mainly in anticipation of the cam and headers mods. Plus it is a polished pretty piece. The thing I didn't like is that I couldn't use the Grandsport top plate as it doesn't fit the 52.

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I have alot more than that baby cam and longtubes and im still using a stock throttle body that has been polished out to 49mm, and the MAF housing is stock, but also polished out.
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Yes i have a view on it, and it is dont waste your money on sh*t. Ive run mine in SD mode with the MAF removed and with it in place, and no difference was seen. Itll flow way more than youre ever going to need with such a tame cam in it.

You feel a boost with the bigger throttle body, but its all in your head. There is no more power there at all. Effectively what youve done is made it so pushing the pedal down 1/4 allows the same amount of flow as 1/3 with the 48mm, so youre not having to push your foot as far to feel abit of part throttle power.

You want power? Meet the engine half way and put your foot down.

At WOT, the air flow has a bigger area to fill with a 52mm TB as appossed to a stock 48mm, so it theoretically flows at a slower pace, and that means theoretically less oxygen will enter the combustion chamber in a given time, due to slower flow. This means less torque. Less torque means less horse power. Less horse power means you may as well have taken that money you wasted on a TB way bigger than you needed and spent it on beer, cause youd get alot more out of pissing it up against the wall.

If a 502 RamJet can make 500bhp with a 48mm TB, i cant see any good reason why youd ever need anything bigger.

If you dont want to believe it, you can very easily see for yourself, get some sort of a scanning device that can display the MAP reading, flog that guts out of it at WOT through a couple gears, when you see it reach something close to the atmospheric pressure (around 98-103 KPa depending on where you are), youre flowing well within limits. At WOT, i still see numbers up around and over 100 KPa even at 6,000rpm.

I like the piss on the wall part.


Can I write my name with the piss? gawd what a crack up

Case,

I agree with you. The 48 is probably all you need. I did seem to lose some torque when I installed the 52. I have a G Tech. I think I will measure 0-60 with both.

The polished 52 sure is pretty though.

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You have got the right idea, but I don't think you have got it totally correct.

Best way is to log MAP at WOT from a very low RPM all the way up to redline....what you want to look at is not so much the value of MAP, but does MAP drop even a little bit at WOT from just off idle to redline...(MAP at WOT near idle should be pretty close to the current barometric pressure)

Think about it this way, the barometer reading is always around say 30, but there is a significant performance drop if the barometer is 29.5 vs 30.0

MAP is the same way....even a little a drop will result in significant power loss...

BTW I like my 58mm throttle body..works for me

Yep, thats about what i meant in a nutshell, you just worded it abit better than i did

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Sorry to jump in a little late but I can vouch for xtremefi, I bought a 52mm throtlebody from him and the machine work is very nicely done and it was about (I think) $225 without a core.

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Thanks! That's what I needed. $169.99 unpolished w/o core. $249.99 Polished w/o core. On ebay.

If you just want the rebuild with the ball bearings, it is $79.99.