diy 85 mm throttle body mod

[lowbean]

Do not attempt this on your own. I searched the forums and net, very highly mechanically inclined with access to great tools and cnc equipment was used on the project. I now have a beautiful truck that idles rough and upon deceleration must be thrown in neutral to avoid no throttle response whatsoever. The throttle response is great, but will not hold an idle well. I would highly discourage any "brother in hemi" of attempting this mod yourself. I do close tolerance machining (.003-.005) and screwed it up, I thought for sure I had it nailed too.

 

[White Beauty]

Not good!! Any pics of what you did do?

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[Power247]

That stinks!! Its amazing what a fraction of a mm can do. At least you have good options for getting a high quality replacement.

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[Casper]

Trick is to remain at 80mm under low loads and only have increasing diameter as you approach WOT. That way all parameters are normal at idle, low load and on deceleration. Opening up the entire TB to 85mm will lean you out at idle and throughly confuse your computer.

 

[lowbean]

The computer is definitely confused, I am debating leaving it parked until thursday (when the new one comes in). Maybe if I installed a throttle body spacer it would help, hahaha

 

[Casper]

Most of the commercially produced ported TBs use 5-angle CNC Porting

Notice that you start at stock 80mm then progress to 83mm and only near WOT do you hit 85mm.

 

[lowbean]

I started at 82 and tapered it to 85 and apparently started the 85 too soon, the idle is between 800-1200 up and down now. I would never try this again and I hope someone like myself sees this thread. If you can program a 5 axis and know throttle body nomenclature that's one thing, it's best to just leave something like this do a company that's done the R&D and specializes in it.

 

[Etroze86]

Great info, always a believer of learning from mine or others mistakes.

 

[fastNugly]

hey lowbean, very nice!

 

[lowbean]

The last saga in the chapter is me driving a Kia till friday, I thought the new one would arrive tomorrow. I swear I heard my Hemi laugh at me this morning, haha. When I put the new one in I'll definitely shoot an update.

 

[audio1der]

For clarity, you DIY ported your stock TB to 85mm, and half-shafted it?

 

[lowbean]

That is correct audio, the new one came in today "from Moe's" and things are back on track now. Felt like a kid waiting on the new one to arrive. Now onto the next challenge...

 

[Hemi450hp]

Glad you are up and running again.