Hi all, hope everyone is doing well. I was curious if anyone has any experience with or any opinion on whether there is any advantage to increasing the diameter of our throttle body even though we have a NA engine? From everything I gather, ours is 74 mm. I see lots of options for the E55 TB, usually bored to 82mm and I was curious if they are interchangeable (even if I have to swap out the electronic part from my existing tb to the E55 one) as there does not seem to be anything available for us. Cant seem to run this topic down on any of our boards, but looking at the crossfire boards there seems to be some indication they are interchangeable. All thoughts and opinion are welcome, thank you for looking.

Steve

I looked into doing this on my W208 CLK55 but couldn't figure out a way to modify the manifold to have a larger bore.

Good point, still a bottleneck so no real benefit. Thank you for the insight.

i'm getting intake manifold modified to work on a slightly bigger TB (77-78mm). will let you guys know how it works out, hopefully in the next cpl of weeks.

Hey bro., did you port your TB..?,,

our TB is (74mm), just bore it out to get (77mm>>78.4mm),

and ported a shaft as well,

i've done that year ago with (George) MaxBore,,

it's really great mods., better and fast response, but don't have any Dyno numbers till yet..

-;-ZAYED-;-

Also, a 5.4 engine needs roughly 550cfm at max. A 74mm throttle body can handle well over 700cfm. Just look at all the dyno videos from mustangs and other cars with bigger throttle bodies, didn’t add much power.

Also a Porsche Panamera throttle body is 76 or 78mm but it should also work. You need to bore our your intake manifold also, because it’s also 74mm. That means taking it apart and and resealing it and cleaning all those metal shaving out. I would EGR delete the car also, and get rid of the metal pipe in the path of the air flow. Getting a different intake system will add power also.

yep got it bored by george, hopefully can test it out soon. as mentioned, plan is to bore out the manifold as well to match the TB. it will of course need to be opened up which i'm keeping my fingers crossed on. i know its not the easiest thing to put back on.

regarding the optimal size for TB, based on my "calcs" which i need to go back and check, its was around 78mm. for stock car, the 74mm is fine, but become restriction after 400hp.

You trying to make 400whp? NA?

no that was crank but my goal is 375 to the wheels. lets see if i can there...

The most I’ve made so far is 356whp. Getting custom headers made this summer and cams order next week. I was running it on E70 with a flex fuel kit, but it didn’t make anymore power. So in need to figure that out. My old car made 20whp on e60.

Just had for me to believe that 2/4mm bigger throttle body will add any power. Acufab has a cfm flow carts of stock throttle bodies and 75mm can flow 700 to 900 cfm.

I will look around the shop and see if I can find a 74 throttle body and send it to maxbore. I have to spare intake manifolds. My car currently has a brand new manifold. It’s a pain to grind down that magnesium alloy that it’s made out of.

it might not work out, but when i researched this extensively last year i was convinced we needed to open those up a little more. felt like 78mm is sweet spot. regarding 375whp, i'm ready to be disappointed but hopefully i get close enough to be satisfied. not doing any more mods to engine, this will be it. lol for now, i was eyeing renntech s/c on ebay recently

I would install a stock 113k blower. Way better than renntech or kleemann setup.


I am trying for 400whp NA, then swap a 113k motor closer to the end of the year

lets see, if i get better around track and can handle extra power i will do that. right now i'm trying to balance out the car.

benefit of renntech for me is that i can keep my engine. its getting completely rebuilt with 11cr pistons (from slk55) and p&p heads. it would be terrible to just throw that away. if i was not focused on rebuilding another car, i would have liked to just buy it and decide on it later.

I really don’t feel like there is enough cooking in that renntech blower. For 5000$ send us your car we can install a 113k blower on it, and a legit cooling system.

haha we might do that, lets see how this track season goes and might be able to discuss next year

I am sure 209 113s have 11.0 compression. Also still not sure about any of them having 11.0 compression. Every slk55 I’ve seen a dyno sheet from stock makes the same 295 to 305whp as my 2000 model e55, my 2002, and our 170,000 mile clk55 with factory plugs that made 301whp.

In the Mercedes brochure is says a 209 clk55 has 11.0 compression

the pistons are diff, slight for higher cr. its not a big deal either way, that only makes up <10hp. btw the slk55 are rated same as w210 e55. the w203 & 209 made a little more, i think 15more? main diff is exhaust

I think Mercedes lied about all of it. Cause they all dyno 300whp avg

i'll try to post pics, but pistons are different - visually at least. i didn't take measurements to confirm CR difference.

what’s causing my mafs to fail circuit A. short , on number 3 in less than 2 years i am only using bosch 2003 clk 55 209

????????????????????????????