46mm vs 48mm throttles

[masa]

Incase you want to buy new ones i might have one set of housings.

Just bare housings for use groupA head.

Btw these are still available at bmw ms, also+ throttle plates+ shafts+poti.

Matti

[junkyard_sal]

+1 on price and part number for the various 46mm TBs.

I would love to see the dynos for these parts. I agree with Jimmy, that I don't think you need to the 48mm+ TBs or monster money to build strong and fun 2.3L S14 motors.

I just built an M3T spec motor for less than 10k including my purchase of a core motor, Schrick cams (Roughly $1K), and the MS cam timing gears ($500+ by themselves). I am running the stock 46mm TBs. After break-in I will pull some dyno runs.

[mrsha007]

Great thread. Can someone move it to the Our Best Topics sub-forum?

[evommm]

Yes this GREAT!!!! lots info and i hope people post thier results it will help future builds
M

[Az in Oz]

I am very interested in this thread. You would have to think that all things being equal the 48mm units have roughly a 9% increase in volume flow capability and so would make more power, but that's only a small part of the overall process. I have access to both for my build but will be using 46mm but I might see if a dyno run can be done once tuned, with the 48mm units.

[inastrangeland]

I just noticed that I forgot to update this thread with the results of the 46 vs. 49 TBs.

Here is the link, post 38

http://www.s14.net/forums/showthread...ght=2.5&page=3

On another note, as it turns out, the motor was slowly tearing itself apart due to a poorly machined head. Even with the head and cam issues casued by it, the motor still made more power above 7K rpm. I think if the motor had been in the same condition as it was when tuned for the 46s, it would have made the same or more power under the curve.

I now have a local shop doing all my machine work and am building 2 more 2.5 motors. Just rebuilt a stock 2.3 and am testing the miller MAF setup. Will have more info as the builds progress.

[proctor750]

Man I'm glad I found this thread. I was contemplating bumping up from the stock 46's but definitely not anymore. I assume there is a bit more comparative data a decade on?

The homoligation theory makes total sense - The larger tb's are useless on the street car but gave an excuse to use them on the race car. Wonder what a bone stock late evo would do with the 46's retrofitted..

[JS154]

I can confirm that 46mm street TBS with stock (not oversized) valves with a proper combination of cams, compression, fuel, map, head port and header choice can make greater than 300BHP on a 2.3LS14.

[jimmy p.]

I can confirm that 46mm street TBS with stock (not oversized) valves with a proper combination of cams, compression, fuel, map, head port and header choice can make greater than 300BHP on a 2.3LS14.

Which confirms what I had theorized in the beginning of the thread what seems like forever ago (well it was what 9 years ago), the larger TBs were a homologation for the next evolutions of the larger, more powerful 2.5 litre DTM engines that were 360HP and above.
The original 2.3 litre Gruppe A iterations made 300+ HP on 46mm TBs.