70mm throttle body for 103

[duxthe1]

Had another project this week. I built a 70mm throttle body for my 103. Stock the throttle body is 64mm. I machined out a stock throttle body and fitted a 72mm od steel sleeve. I turned the steel sleeve to an id of 70mm and then fitted a modified throttle blade from a 70mm electronic actuator, from an 400E. (I think) The 70mm blade was 2.5mm thick and had to be machined to 2.0mm to get into the existing shaft. The shaft had to have the slot widened a little on both sides. The outer pivot bearing had to be moved outboard by a few mm. This prevents the installation of the c-clip but the assembly is solid without it. I've posted a few pics of it in the galleries. (Maye a mod will link it for me)

[Roncallo]

For if I convert my M120 to non electronic aftermarket ECU. I purchased 2 high performance 70mm throttle bodies for a 5.0 Mustang. Does anyone know what an M104 uses.

[John5788]

was the extra 6mm diameter worth the troubles? what's preventing you from making a TB bigger than 70mm? just the inside blade?

[JayRash]

Originally Posted by John5788

was the extra 6mm diameter worth the troubles? what's preventing you from making a TB bigger than 70mm? just the inside blade?

Am not sure to what extent the larger TB will yield power but am sure the mid range and top end will be better, and the sweet thing abt the CIS injection is that it will automatically readjust for the extra air flow.

[duxthe1]

Was it worth it, I don't know yet as I'm still prepping my cylinder head and I'm planning to install the T/B when I swap heads. On a stock engine it may not be worth it in terms of power gains, but my engine will be somewhat modded by the time I am done and I expect decent gains in my mid and high end power.

6MM doesn't sound like a lot but keep in mind that is just shy of a 10% increase in diameter. I chose 70mm b/c I had a spare 70mm blade. The blade is quite difficult to fabricate due to the bevel on the sealing edge so having a spare pretty much sealed the deal. As it stands with a 70mm blade there is barely any surface left on the mounting flange to seal it to the intake so I think 70mm is the practical limit for an OE based T/B.

[duxthe1]

Well I finally got the head and t/b put on. As expected, it has a noticable effect on mid-range and top end power. By about 3000 RPM it is pulling better than stock and at 3500 the exhaust note crisps up noticably and it pulls well to the upshift.

In addition to the t/b I also had done some port work to the cyl. head as well as a bit of unshrouding in the chambers. I also advanced the cam 3 degrees when I put it back together. It turns out that with a new timing chain and the cam advanced the car has much better off idle torque. Pulling off in second gear is easy now where it really struggled before.

[JayRash]

Originally Posted by duxthe1

Well I finally got the head and t/b put on. As expected, it has a noticable effect on mid-range and top end power. By about 3000 RPM it is pulling better than stock and at 3500 the exhaust note crisps up noticably and it pulls well to the upshift.

In addition to the t/b I also had done some port work to the cyl. head as well as a bit of unshrouding in the chambers. I also advanced the cam 3 degrees when I put it back together. It turns out that with a new timing chain and the cam advanced the car has much better off idle torque. Pulling off in second gear is easy now where it really struggled before.

as expected you should see better upper range power, had u left the cam as stock you would have sen better results at top end, but you would have seen lower low end.

advancing the cam 3deg would shift power down the revs by abt 500 rpms.

i think

[duxthe1]

I advanced the cam b/c the wagon had always been sluggish from a dead stop. Since it is a 4-matic I wasn't overly concerned with the power falling off in the higher RPMs. Fortunately with the head and t/b mods there is still more power at the redline than before. I replaced the timing chain with the head off as I'm pretty sure it was original. The old chain had a few degrees stretch and I'd estimate that the cam is now 6-9 degrees from where it was running with the old chain. The difference is night and day. I can just tip into the throttle a bit and it will pull off in second gear no problem. Now, kicking it down to first is fun instead of necessary. Still, it's no drag car and I do not have pretentions that it will be.

So far I have not been running with any changes to the fuel trim. I really wanted to get a feel for the new mods before using the lambda controller to fatten up the mixture. Running rich from a cold start this morning she really wanted to rip so I get the feeling that it has a bit more than I've yet seen.

The larger T/B has made a definate improvement in the mid range. Between 3k and 4k RPM I notice much better response pulling in 3rd gear. Before, you filed a request to pass and eventually it would comply (or kick down to 2nd and scream without really accelerating much). Now when you give it throttle the response is more immediate, not life changing but better none the less.

I'm still planning 2 more mods to complement those already done. First I'm going to mod my airbox to have a second snorkel going into the brake booster area to pull cool air from the windshield. I just don't see that stock intake snorkel keeping up with my new found airflow. Second I'm going to have a custom exhaust built to help get the spent gasses out the back. The wagon's stock exhaust is large, heavy, clumsy, and it's ability to flow decent is highly suspect. My plan is to "Y" the two exhaust manifolds into one pretty early and dump into a decent sized catalyst. From the cat I plan a small resonator and then muffler with the final dump in front of the rear tire. Maybe then I can leave be and just enjoy driving it.

[duxthe1]

Have as bit of info to update this old thread. The wagon has long since been turbocharged and currently has an OE 64mm t/b on it. Fast forward... I recently picked up a '91 300CE that needs a lot of love. Injectors and fuel distributor seal needed attention so I figured I'd pull the aif flow meter off as well and swap in the 70mm t/b while I was at it. I was pretty disappointed to find that the stock t/b on the 104.980 is in fact already 70mm. I noted a bit of postulating as to whether there was an OE t/b at 70mm, and can now confirm it.