Does anyone one know why I should not be able to bore out my throttle body on my lathe, remove the butterfly from the shaft and turn and fit a bigger butterfly that sits at the correct angle.
I have the tools but I have wondered if I am missing something, I don't think so but ....?
I am not using the car for the next four months so why not.
How hard can it be?
The butterfly sits at a slight angle, the bore grows in size, so the butterfly grows in diameter a proportionate amount.

 

Sounds simple to me.

I say go for it!

 

I'm with Tighed ! Go for it ! How large are you looking to bore it out ???

 

180, you can buy a 74mm TB to install on the NA. Bulldogger sent his out and had it bored to 77mm(?) and a new butterfly installed. He has a SRT though. I have been thinking the same thing as you, but making the butterfly is a PITA. I am going to port match the manis this winter, so I may think about it again....

Here is the link to the company that bulldogger used...$175 isnt a bad price for this....

Maxbore.com throttle body boring service

 

I was thinking of boring it out as much as I dared and then taper the bottom diameter out to 74 mm. Maybe the best I can do is 70 mm and then the taper.
I am not sure of the shape of the throttle plate, is round or slightly oval? I have had these things in my hand out of cars and bikes but cannot remember. No matter, if its oval I will put it on an angle and turn it. I would make the plate a bit thinner and round the edges as per Woody Waldig's mod. Taking the screws out that hold the plate to shaft may be a small problem if they are staked to prevent them from falling out.
The increase in area would be minimal at 70 mm, about 6%, compared to 16% at 74 mm. The major benefit would be elimination of some of the turbulence.
The simplest variation of this mod would be to just add the chamfer to the existing bore, a 3 mm chamfer rather than a 2 mm chamfer and round of the throttle plate edges.

 

The butterfly is round and is easily removed. The screws are not staked, blue loctite is good stuff. If you made it thinner you will have to make a spacer to hold it so it dosent falp around in the bigger hole.

 

Sorry to sidetrack this for a minute, but I gotta ask:

MikeR: what all is involved in port matching your manis? Are you paying to have it done? Do they need the whole motor, or can you just send the manis and the upper intake/supercharger/intercooler? What does it cost? Would they port match a set of phenolic spacers to go with them? How about some custom gaskets?

TIA,
Tom

 

Just an FYI, it's not an easy process to take these throttle bodies apart. They are meant to go together once and then not be serviced. I've got the first one I tore apart in a box in pieces because I discovered upon disassembly that the gear is an injection molded plastic part that is molded around the shaft and you don't want to mess that up.

 

I counted on removing the throttle plate and pulling the shaft out. That looks feasible in all the pictures I have seen, maybe not though.

 

There is drilling involved to remove it properly.

 

Maxbore does it all the time, he did mine and the car runs like a dream no issues at all.

 

Tom, you can do it yourself. I am talking about pulling the intake plenums and the SC and then matching those to the gasket/phenolic spacers I am using to get rid of all the over hangs at the plenums and the feed throughs on the SC and the intake at the head. A little judicious grinding and polishing should do the trick. There are a couple of folks here that wrote it up and had pics. MD SRT6, 240M3SRT and BrianBrave??? I have 6mm phenolics from C3P and NW gaskets on both sides of the phenolics.

https://www.crossfireforum.org/forum...t-2-heads.html

https://www.crossfireforum.org/forum...-airboxes.html

https://www.crossfireforum.org/forum...r-srt-6-a.html

 

Rudy, I pulled my TB off, took out the butterfly and started to take the electroncis off and said....... hmmmmm..... $175 is starting to look pretty good for a guaranteed working unit back.... so I rounded the leading edge of the butterfly and put it all back together....thanks for reminding me.

 

Precisely. This isn't something for just anyone to do is the point I'm making. You need special tools that most don't have to do this correctly. It's easy to tear stuff apart but tearing it apart in a manner that lets you put it back together is altogether different, hence my box of throttlebody parts.

 

If you can explain what has to be drilled for me I would appreciate it. I have the drills and a pedestal drilling machine, the lathe etc. I was a tool maker once upon a time and pretty good at machining.
You are starting to put me off of this project, but better now than when its in pieces on the bench and me cursing like a drunken sailor.

 

If you have the tools to do it, by all means go for it. The hardest part will be carefully drilling out the little metal cover on the side opposite the motor housing and then carefully pressing out the shaft and pressing it back in. You need to be especially careful of the little brushes for the TPS sensor. They are on the gearset connected to the butterfly shaft. If you have any questions, PM me your number and I'll give you a call and explain everything.

 

If you have all the right tools it's extremely simple.

 

180 ... you can use mine as a demo if you want ... just be gentle. I was planning on going bigger than stock in the spring anyways.

 

WEEKEND AGAIN, YIPPIE !

Gasket matching made a better feel to the car and has to assist the response. My write ups describe it and Id do it again.'

When I opened the throttle body electronics, I saw a great potential to screw up the traces and brushes of the resistive sensors. be cool with that area, its sensitive.

The throttle body mods will assist some but youll need a free flowing intake system to see it. THe needswings CAI has 30 inches of water column restriction at wot. THats lots and lots less than the stock intake. The newer dual was designed to reduce that restriction that amounts to a ONE PSIG PRESSURE DROP. THATS 7% OF THE ATMOSPHERIC PRESSURE . BIG gain there, and my starting point before you do much to the throttle body.

The real restriction is the computer control of the throttle body opening. Iam working that and the fuel control system that Iam debugging can handle the operation. When the throttle opens like your foot tells itWITHOUT delay the car is an animal; during transitions like on and off the gas. Full to the floor is the same just you get there like now. Think this thru, led tail lights are like on now, thats whats available if the computer is not a PITA holding you back.

If you have any concert for a dual intake of low restriction, just take off the intake elbow of your CAI to the TB and drive a block or two without it, thats all it will take to convince you about the restriction your living with. Cai is a great gain but there is much more available and you can experience it for free in 2 minutes, assuming you dont draw too much attention and get a ticket feeling this out.

WEEKEND AGAIN, YIPPIE !
W DY

 

Thanks Mike!!