Upper plenum project 75mm Maxima TB
 

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So boring, a throttle body that doesn't require any tuning and a location that requires zero other changes.

Nice work, looks a LOT better than what others have done...now finish it and sell it to me lol.

Is a 75mm throttle body even worth the effort?

Roughly 20% more airflow potential over the stock 70mm and some other details that are beneficial.

What other details? I've got a spare upper here that I'm looking into modifying to match the ported lower plenum and runners.

The shop I'm working with may want to offer this as a service if the dyno results are positive so I don't want to share their theory. It's nothing someone with a sharp eye that has held both throttle bodies can't figure out from the picture. 2 of the details are no ecu tuning and it can drop in place without changing any other intake parts.

Very interested in your results. When do you expect to be able to get before and after dynos?

Look for an update late Monday as far as progress. As it stands testing will be on 2 03's both 6mt. One has the built motor from my old car and the other bone stock. Stock vehicle will be stock versus the modded upper plenum with the objective to outperform a spacer. Built motor currently has a Kinetix Velocity manifold and I have already posted a test of it compared to an APS tall boy. The main goal of this plenum is to not have the rapid drop off of power experienced after about 6200-6400 rpm. Testing will be on a Mustang dyno as that's what is locally accessible.

Patiently waiting , not really, just waiting for your results

Sounds good, in for progress!

Quick side note: I checked out your other thread about comparing the Kinetix velocity to the APS tallboy. When I looked at your pictures, is the blue upper plenum the APS? Thanks.

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Progress today, everything ready for welding. O ring flange and then just shots down a 3.25 and 3.5" pipe over the stock tb opening. prototype using 3.25 elbow, the outer plenum supports deleted for flow and volume.

The 3.25 doesn't really look much bigger than stock, how does it compare to the maxima tb?

It's about 25% larger and about 3mm larger than the max tb exit. Fixes the worst choke point, well dyno testing will prove or disprove that for certain.

Cool, I had a feeling it was bigger than the TB but in the pic the difference does not look like much. The angle of the pipe should end up being better than stock by the looks of it as well.
Would it even be possible to use the 3.5" pipe with the maxima TB, or would you need to use a smaller adapter flange?
I hope it works good, I would like to see more experimental stuff like this for the DE. I'm tired of people saying that you cant make 300whp with this engine, it would be roughly 100hp per liter with is very attainable with modern technology.

Are you planning on running this upper plenum with a spacer as well?

Once/if this is developed, I'd be interested in testing this out with before/after dynos if you would like another independent 3rd party tester.

The way a spacer works and the way this works are 2 different things, although the result may appear similar. I'll be conducting testing and if it works it's for sale, if not I took a bullet for everybody else.

nice job on this! cant wait to see results. hopefully there will be more substantial gains with this.

Any idea on the price point on this, also could the maxima tb be ported to a bigger size to allow a bigger size that is still plug and play?

The tuning headaches to solve the drivability issues won't be worth boring it. The fact that people have hit 300rwhp with the stock tb the almost 20% larger 75mm should move the ceiling high enough. Take a look at 996 GT3 dynos, they came with 74-75mm throttle bodies.

Ok, I was thinking about this the wrong way I guess, I thought the problems that people had with going bigger was due the electronic control aspect of it, not because of the size.