58mm tb?

[86seeS]

what cars came with a 58mm tb?

[Juggy]

98-02? hi po 3.8L minivans

town and country....expresso...

[86seeS]

thanks for the info!!!

[turbovanman²]

Very rare. FYI, Unless your planning on serious mods, they are not needed.

[86seeS]

i have a compleat tII on a stand for a spare but i really want a drag car so it may end up as a drag motor its compleatly stock as of now but not for long

[GLHNSLHT2]

IMO unless you're running a big plenum on a heavily ported 2 piece they're not needed. Even then I don't know how much my 58 gains me over a 52.

[puppet]

IMO unless you're running a big plenum on a heavily ported 2 piece they're not needed. Even then I don't know how much my 58 gains me over a 52.
Not to start an argument here but believe it or not a smaller plenum likes a bigger TB and vice versa. To understand this you have to consider what a plenums function is. As a reservoir for the runners, a bigger plenum will "locally" maintain the needed capacity of air for the engines cfm requirement and isn't affected as greatly by the turbulence a smaller TB will induce on the flow. Small enough to keep the dead air layer to a minimum within the plenum. Big TB ... empties into big space equals a potential for stagnant air layer/pockets.

A smaller plenum, on the other hand, benefits from a larger TB by allowing the runners to draw from the IC piping just forward of it ... supplementing the plenums volume. By nature of the larger TB size, turbulence is also reduced in the plenum, which for a smaller plenum becomes a plus.

Overall sizing is going to depend on an engines particular cfm requirement which isn't a cut/dried formula. So, I'm not implying that everyone should slap on a 58mm TB. That will depend on the package an individual has to work with. Plenum size can be worked around to a degree. A big plenum isn't absolutely necessary ... within reason. Runner distribution and profile are, for me, what matters most. Then make sure the cfm requirement of the engine is met by the TB size.

[86seeS]

very nicely put:nod:

[turbovanman²]

Not to start an argument here but believe it or not a smaller plenum likes a bigger TB and vice versa. To understand this you have to consider what a plenums function is. As a reservoir for the runners, a bigger plenum will "locally" maintain the needed capacity of air for the engines cfm requirement and isn't affected as greatly by the turbulence a smaller TB will induce on the flow. Small enough to keep the dead air layer to a minimum within the plenum. Big TB ... empties into big space equals a potential for stagnant air layer/pockets.

A smaller plenum, on the other hand, benefits from a larger TB by allowing the runners to draw from the IC piping just forward of it ... supplementing the plenums volume. By nature of the larger TB size, turbulence is also reduced in the plenum, which for a smaller plenum becomes a plus.

Overall sizing is going to depend on an engines particular cfm requirement which isn't a cut/dried formula. So, I'm not implying that everyone should slap on a 58mm TB. That will depend on the package an individual has to work with. Plenum size can be worked around to a degree. A big plenum isn't absolutely necessary ... within reason. Runner distribution and profile are, for me, what matters most. Then make sure the cfm requirement of the engine is met by the TB size.


True but its nice to have testers in the field. Gasketmaster, the 11 sec van, tried a 52 mm back to back and picked up nothing. Not to say thats a blanket statement but the rest of our system is a huge cork. I tried a 58 vs my 52 back to back and noticed nothing on my old 8 valve setup. Of course results will vary but our engines need alot more work before a 58 becomes needed.
Terry will be doing a 52-58 test on his van when he gets it finished, :thumb:

[puppet]

I think the dyno might show more evidence for a TB swap as to power under the curve. Terry's set-up may in fact do better with a 52mm vs the 58mm. Depends on the plenums structure. With the wrong sized (larger) TB you could make a larger plenum (of so-so design) perform just like a smaller one ... because of the dead air layers left undisturbed.

But you're right Simon. There are other areas that should be addressed first.

[turbovanman²]

I think the dyno might show more evidence for a TB swap as to power under the curve. Terry's set-up may in fact do better with a 52mm vs the 58mm. Depends on the plenums structure. With the wrong sized (larger) TB you could make a larger plenum (of so-so design) perform just like a smaller one ... because of the dead air layers left undisturbed.

But you're right Simon. There are other areas that should be addressed first.

I did pick up 5whp on the top end, back to back on the dyno from a 46-52mm years ago on my mild 8 valve setup. 5 hp is really nothing so I don't know if I'd call that a gain, lol.

[Juggy]

you guys gotta remember the gains are very minimal if any because the 58mm necks down to 54mm


2mm bigger then the 52mm

so unless they have opened them up to a true 58mm, then the claims mean nothing.