stereophile33

The intake manifold has some corrosion and needing to pull it off and fix. While in there, are there other things I should consider doing?

I assume the larger TB's that are sold are just repurposed OEM units. Does anyone know what those are from?

HLG600

I believe they are from the "550" cars, which use the 5.5L M273 V8.

stereophile33

Thanks!

stereophile33

So I assume someone has used the M113K throttle adapters in the M156? I cannot seem to find much when I search.

But my assumption is they work.

HLG600

The M113K is a different platform with no overlap.

You need a M156-specific adapter plate and tuning to account for the larger throttle bodies. Velocity stacks are also key.

Here's a complete kit for reference: https://www.vrpspeed.com/product/vrpm156tb/

Alternatively, if you're just doing preventive maintenance, RMT sells an upgraded plate that works with the stock throttle bodies: https://rebuildmastertech.com/merced...it-1561400801/

stereophile33

M113K uses the same 74mm TB as the M156....so in theory bolt pattern is the same, and the M113K TB adapters would work with the 550 TB's in the stock RMT plate.

Sounds like folks havent tried this before..

figuwx

Why do you want a bigger throttle body? All that does is lose authority over the torque of the motor... read, ever see those mustang and chargers go completely out of control? Usually because they have a to big a tb and when they shut the throttle, to late, the engine still gulping lots of air and happy fish tailing we go!

As long as the TB is not forcing the air to hit it's reynolds number, the TB should not be touched.

MB/Daimler ran a ton of compute resources on calculating the fluid dynamics of said TB on the engine. Bigger is not always better and that statement holds true for throttle bodies. See F1 and their tb size (usually in the 60/70mm range).

stereophile33

Thanks for the info.

As someone that 15 years ago was building 120hp/l NA motors and 518hp/l turbo motors for vintage euro cars I've got plenty of CFD and flowbench experience...

This is more experimentation to run on the flowbench and run some tests to see what happens.

But to satisfy the bench racers in the crowd. yes, I understand that velocity often matters more than total flow as laminar efficiency is of greater concern than just about anything else.

I also recognize that every system is a series of optimizations. CFO's and packaging and supply chains also have inputs on those optimization calculations. I'm just playing around with my daily to see what can be learned as I think the M156 is one of my favorite engines of all time.

HLG600

Would be nice to have more cross-compatibility, but unfortunately these are different throttle bodies that are mounted in a completely different way.

Could they work with modification? Perhaps. But I wouldn't assume they are plug 'n play.

M156-specific part number: 156-141-02-25

M113K-specific part number for the 03-06 SL55, which uses the 74mm TB: 113-141-06-25

M113K-specific part number for the 07-08 SL55, which uses an upgraded 80mm TB: 113-140-01-04

HLG600

Mustang / Charger drivers losing control is mostly tied to the combination of very-to-overly powerful RWD vehicles and a lack of skill / judgement.

While I tend to trust the factory more often than not, automatically assuming the factory got it right isn't realistic. Case in point, larger throttle bodies for the M156, which are a proven upgrade that have been on the market for many years now.