A very easy mod that increases power throughout the RPM range. The dyno has shown gains of 5 horsepower, and the throttle response is improved as well.

Tools required:

10mm socket with extension
small screwdriver or clamp removal tool


Time required:

30 minutes

For comparison purposes, the stock throttle body is 57 mm and the new internal bore of the throttle body is 61 mm. The body is bored and the butterfly is replaced.

1. Remove the intake tube from the clean side of the filter. If you haven't already replaced the factory clamp, just put the small screwdriver into the raised area and twist - it will pop open.



2. Now remove the intake snorkle by unclamping the side closest to the radiator. It will then wiggle out.



3. Unclamp the intake rubber hose from the throttle body.





4. Remove the wiring harness from the throttle body. You will need to push in the tab, then pull it from the throttle body side.



5. Remove the four 10mm bolts that attach the throttle body.



6. Once you have the throttle body lifted out a bit, it will give you more room to get at the clamp for the fuel line. Use a clamp removal tool or a pair of small pliers to slide the clamp down the fuel line.





7. Take the stock throttle body out.



Here is the area we are working in with the throttle body removed. Note the black bracket on one side of the throttle body mounting location. The new throttle body will go between the mounting surface and the bracket.



8. Wiggle the new throttle body into place.



9. Replace the line and clamp.

10. Start the 10mm mounting bolts once you have the throttle body in place. You can attach the wiring harness as well - it just plugs back on.





11. Replace the intake hose onto the throttle body.



12. Replace the snorkle with the forward clamp. Make sure the airbox side is in place, along with the small tab that locates the tube to the right of the airbox.



13. Replace the clean filter side of the intake hose.



Turn the key to the farthest position before start and let it sit for 10 seconds. Start the car and check for any intake leaks.

That's it! Now enjoy the improved throttle response and increased performance of your new throttle body.

Feel free to contact me with any questions.

Thanks to ficcion for the pictures!

Randy
randy@webbmotorsports.com
720-841-1002

 

Any idea yet on how much this will affect gas mileage?

 

Not yet - I just put it in. I'll keep an eye on it. Even with all of the other mods I've done, and with the leadfoot I have, I've been averaging 24-26 mpg.

 

I've never gotten a good understanding of what the throttle body is. I've heard it used quite a bit, but I'm new to tuning. Can someone fill me in?

 

Another great how-to...

 

>>I've never gotten a good understanding of what the throttle body is. I've heard it used quite a bit, but I'm new to tuning. Can someone fill me in?

Grinder,

On the old cars we used to have a carb, which regulated the air/fuel mixture, and then passed it on into the combustion chamber through the butterfly(s) and intake valves.

Now, the ECU determines the mixture, and the throttle body passes the mixture into the intake plenum. The throttle body butterfly opens and closes based on what the E-gas tells it to do from your inputs on the gas pedal.

That's a pretty simple answer, but I hope it helps. Let me know if you need any further explanation.

Randy

 

That's what i thought it was, but now i'm confused. If it only does what it's told, why do you see the HP increases?

 

Because it can do what it's told faster.

If the flow was limited by the throttle body, opening it up cleans up that restriction.

 

Hi,

I may have missed this - where can I find the larger throttle body (for sale)?

Thanks,
RW

 

Yes, Cost and where to find it?

Thanks Randy for yet another great how to.
I am probably going to make a nice color manual as soon as my photo printer comes in.

Things to do when it arrives...

 

You just couldn't wait until Monday huh? I totally understand.

Thanks for another great how-to Randy.

 

I'm guessing here - but I am assuming the Throttle Body is from MINI-Madness - they have it listed on their site but no price....is this correct Randy?

 

As I understand it, the throttle body (at least that Madness may be offering) is from M7. Randy?

R

 

Yes, it is the M7 throttle body. I don't have pricing info yet. I think it will be very reasonable - under $400, but don't quote me on that.

Dave,

I couldn't wait - I'm trying to do the dyno on Saturday, so I wanted all of the components in place. I still may use your car if it's OK in some of the dyno work next week or so. I need to be able to use a car without the pulley to see the gains of individual components.

Let me know if there are any other questions.

Randy

 

More great how to's from Randy! I just wish it was STX legal.

_________________
2001 & 2002 SCCA, STS, Pro Solo National Champion

 

Oh how I long for an S. All the cool things people are doing to them.

 

Jerry,

A lot of the cool things could also be done to your Cooper.

The throttle body, the header, an intake, a Magnaflow, a ported head...

 

Since this opens up breathing, I'm assuming that the gains are at the top end?

TIA,

Jeff

 

Actually Jeff, the numbers are better across the RPM range. They get better from the mid-range on (they diverge from stock curves at a sharper rate).

Randy

 

Is this new unit more than just the butterfly opening? I assume it is otherwise it would be more cost effective to send your old one in to be board out, then replace the valve and throttle shaft with the larger unit.

Now in the carburator world when you increase airflow to a certain point you must re-jet otherwise you may get hot spots or overheating. Will the computer correct for this? Measuring the newly introduced amount of air to be pressurized.

And... Man! you are making it tough for the desire to stay in stock class!!!
_________________

</p>
<a href="http://www.syntheticwarehouse.com">The Synthetic Warehouse</a>

 

Just to get the butterfly out you have to take apart the thing and its a very complex swiss watch design. Seriously you dont want to do this on your own.

If you mess it up its more than 400 bucks, not to mention the down time.

 

Seems pretty interesting but I have a few questions. Fuel in fuel injected engines is typically delivered by fuel injectors, not a throttle body. Are you sure thats a fuel line?


--
Cheese

 

Did a little research, the line at the throttle body is a vapor line. I think its the vent from the gas tank.

 

macncheese,

You are absolutely correct. I didn't mean to lead you astray with the use of the term - "fuel line". I just meant that it's a part of the fuel system. I should have said vent line.

Thanks for the keen eye!

Randy

 

>>>>I've never gotten a good understanding of what the throttle body is. I've heard it used quite a bit, but I'm new to tuning. Can someone fill me in?
>>
>>Grinder,
>>
>>On the old cars we used to have a carb, which regulated the air/fuel mixture, and then passed it on into the combustion chamber through the butterfly(s) and intake valves.
>>
>>Now, the ECU determines the mixture, and the throttle body passes the mixture into the intake plenum. The throttle body butterfly opens and closes based on what the E-gas tells it to do from your inputs on the gas pedal.
>>
>>That's a pretty simple answer, but I hope it helps. Let me know if you need any further explanation.
>>
>>Randy


Lets clear things up a bit further then The gas pedal is actually the "air pedal" in modern cars. All the throttle body does is control the amount of air entering the engine. There is no mixture at the throttle body, just a lot air (and apparently some gas tank fumes).