Port your 6.1 intake for a 90MM throttle body

[jink25]

So you bought a new 85 or 90mm throttle body, now what?

Well here is the story from start to finish of what I did to make sure I was taking advantage of the newfound airflow that the throttle body could provide.

You will need a drill or preferably a die grinder, and some larger size sanding wheels. I purchased the sanding wheels and extra sandpaper at ace hardware.

Also, you most likely will need to take your intake somewhere that has a mill to remove the lip on the surface where the throttle body mounts. This is the only part of the job that requires special tools.

Try to get the largest size sanding wheel that will fit easily into the neck of the intake. The wheel I purchased had a rubber drum which makes it easier to sand with, as well as helping to avoid digging into the intake with an edge of the sandpaper.

I started porting using 50 grit sandpaper, then finished up with 120 on the sanding drum. I decided to finish using regular sandpaper at 200 grit with my hand for a final finish. The smoother you can make the surface the better.




Here is the base point where my intake started. The o-ring is removed and the opening is nowhere near 90mm. I also suggest removing the bottom plate on the intake prior to doing any grinding. This will help in the cleaning phase later on as well. The gasket is reusable, so don't worry about taking off the bottom plate.




This picture shows the intake part way through the grinding process. As can be seen I didn't use any special tools, only an ancient drill and the sanding drum. (Special thanks to my brother for stealing my good drill and not returning it.) If you have a variable speed drill I suggest using it, or even better is an air die grinder.

Also note, I stuffed a rag into the intake to try to keep some of the metal debris from going too far into the intake. Some debris will get in there no matter what, and will have to be blown out once you are done grinding.



This picture shows the grinding process part of the way through. As you can tell there is quite a bit of material that needs to be taken out. When grinding just be patient and keep moving the sanding drum to avoid digging into one area. The key is to keep the opening as concentric as possible.




At this point the intake was very close to 90MM where I could stop grinding with the 50 grit sanding drum, and switch over to the 120 grit drum.

Note the lip on the face of the intake where the throttle body mounts. This will need to be removed in order to seat the gasket for the throttle body.

A mill is the best choice for getting a nice flat surface for the gasket to mount on. You will need to find a machine shop or someone with a mill to do this work for you. To mill the lip down you just need to square the intake with the mill and make sure it is clamped down good.

It is best to take several slow passes with the mill making sure not to remove too much material in one pass. This will help to keep the surface flat without deflecting the cutting bit.

The total cost for this project including having someone mill the surface flat should be under $100, maybe only $15 if you have free access to a mill and need to purchase the sanding drum. This is much cheaper than having a shop do the entire thing for you.






Here is the final product. As you can see the entire surface has been milled flat, and the throttle body mounts flush to it.

[BHINDA8]

Do you have pics of it finished before installing throttle body?

I am thinking of doing this.
Thanks for the info.

[BDA1855]

Nice Work!

You could of taken the 120 wheels to the casting inperfections in the intake also for some increased airflow as well...

[jink25]

Do you have pics of it finished before installing throttle body?

I am thinking of doing this.
Thanks for the info.

I didnt take a picture after milling, but I will have the throttle body off soon anyways and will post a picture.

[jink25]

Nice Work!

You could of taken the 120 wheels to the casting inperfections in the intake also for some increased airflow as well...

There was a little work I could have done inside the intake, but I didnt want to have to re-do the internal heat coating. This intake was originally a Ported FRI one, I just opened it up for the 90MM TB. The runners on this are extremely smooth, FRI did a really nice job on it.

[Bailman]

Hey, Jeff. Have you gotten to the track with your beast yet?

[Hemi31]

I have done 4 of these now.I use a local machine shop to machine the flange and do the port work myself.

[jink25]

Hey, Jeff. Have you gotten to the track with your beast yet?

I have not made it to the track yet since we have not nailed down the issues my motor is having. It could be my cam, computer, torque management......the list goes on. So far it has only made 427 rwhp...hmmm missing 100 hp somewhere????

[jink25]

I have done 4 of these now.I use a local machine shop to machine the flange and do the port work myself.

Modern Muscle milled the intake flange for me, at the time I didnt have a cutting bit large enough on my mill which I do now...oh well too late.

Milling takes about 20-30 minutes taking your time to do it right.

[Hemi31]

Milling takes about 20-30 minutes taking your time to do it right.

Yep.....takes longer to square the intake than to mill it.

[jink25]

Found this in my cell phone...

[Chef Tom]

That look's great. I think I can do that myself. HAPPY NEW EVERYBODY!