Weber Big Throat on N42 manifold

[Larry Mahanor]

Of all the mods I've seen for the throttle body on an L6 manifold, it's typically been using the 60mm unit from a 240SX. I've not seen mention of the Weber Big Throat, a 65mm unit that was a popular upgrade during the 280Z hay days. Does anyone know of a reason why this wouldn't work? The TPS shaft is a D type which mated to the original 3 contact stock TPS switch. I was wondering if a potentiometer type TPS might be impossible to find for it, which would be necessary to work with aftermarket ECUs. I found an old Big Throat in my attic and would like to use it. Stickshift

[BRAAP]

There is some debate on whether or not the big throats actually do increase the engine output, i.e. are they worth any time and expense to install, other than "WOW" factor when the hood is open. I pitch my tent in the camp that believes a larger then stock throttle body on the stock L-6 EFI intake manifolds offer no real performance gain over the stock TB, even on mildly modified L-28's!

 

As for the TPS, yes there are POT type TPS that will work. The Weber is designed to accept the stock switch style TPS and guys have converted their stock TB’s over to Potentiometer style TPS to use with aftermarket EMS’s.

 

Back to larger TB's and any real or perceived performance gains, these threads cover that topic;

http://forums.hybridz.org/showthread.php?t=147745

 

http://forums.hybridz.org/showthread.php?t=119894

 

The most influential restriction of the intake tract is the intake runner of the stock EFI manifold itself, after that has been addressed, the stock AFM is the next air flow restriction, then after that the TB could be considers a possible restriction after those other two issues have been dealt with. Here is a discussion on the different plenums and runners of the stock EFI intakes with measurements of the manifolds etc;

http://forums.hybridz.org/showthread.php?p=899487#post899487

Edited February 12, 2010 by BRAAP

[Daeron]

Larry, I don't know if you would remember me personally but my Dad, Uncle, and brothers and I used to play around with Equipe Rapide at the Fairgrounds in WPB, and at the Harness track and down at MetroZoo back in 99 thru the early 2000s.. Tim, Chris, Dennis Carey? (My name is Shawn by the way.)

 

I do not know if you ever knew our friend Peanut, but he was a local Datsun guy for many years and he had affixed one of these Weber TBs to his Turbo project car years and years ago. I know this because my old man has his setup sitting on a bench. I've also seen at least one or two other people using them, since they are a fairly common performance part to have kicking around gathering dust someplace. 60-75mm throttle inlet seems to be good for up to 300-400 horsepower without breaking a sweat, so using one of these would certainly remove the TB as a potential restriction point.

 

If you were using aftermarket EFI, you would have either a MAP sensor or possibly a MAF somewhere, and the AFM would be deleted. Six times 32mm ports on an N42 manifold works out to 4823 mm^2, (7.35 sq in) and a 65mm TB works out to 3316 mm^2 (5.144 sq in) 75mm is 4415 mm^2 (6.83 sq in)

 

Even though I presented the numbers in a way that makes it seem like the manifold is way more than even a 75mm could match, effectively no more than two ports would be breathing simultaneously anyhow. I just like doing the math when it comes to these things, because it enriches a thread.

[big-phil]

thats what I had on my stock intake

here are pics of a 240sx, and webber. I think the TB with the gasket is the 240sx?

[Larry Mahanor]

Thanks to all for the excellent info. Shawn, I remember you and your family very well. I ran into Tim at the Palm Beach School Board last year, working my day job and he gave me the sad news of Dennis passing on last year. My condolences to the whole family. Dennis is registered with the Internet Z Club (Carl Beck) as one of the original Z racers. I'm running the Z racer at the Sebring Vintage races next month, and if the car comes away healthy, the Walter Mitty Challenge at Road Atlanta, April 29 - May 2. This year The Mitty is going to have a Nissan theme with Pete Brock as a special guest. Nismo ran a picture of my car in their 2010 motorsports calendar for the July month. On the manifold, I'm inclined to have one fabricated. I know it will be more expensive, but I'm thinking the pay off would be great. I was on the site BandmZcar, and he fabricates some hard core parts, like a plate for making an intake manifold. Joe at ESSATECH in Ft. Lauderdale is a great fabricator of such things.

[Daeron]

Many thanks, Larry. I think the Mitty is going to be something of an Homage to old Uncle buck for us this year, since he had sold the BRE car about a year and a half ago and it should be appearing there restored. Me and Tim definitely plan on going, but I am not too certain what the scope of that venture is going to be. Tim was trying to run an event at Sebring this year (same week as the 12 hour) so I don't know who is going where, when.

 

Anyhow, catch you there!