[Tommcat]

i tried porting the throttle bodies on the 998. they arent real smooth as they taper down from the inlet to the outlet so i blended out the sharp steps and opened up both ends by 1mm.
on the flow bench, they went from 145 cfm at 15" to 157 cfm. that is per throttle body.
i'll be putting a set on the dyno soon for a direct comparison but i am pretty confident that it will add a small amount of power.

 

[joe_f7]

Effects on the tune?

 

[ONTTURBO]

Nice work.

 

[Tommcat]

Effects on the tune?

Unknown as of right now, once i do a direct comparison on the dyno and look at AF, ill know more.
I will say though, that i doubt very much that the increase in airflow will be significant enough on its own to require any tune changes.

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[joe_f7]

So it looks like it's all smoothed out and widened after the butterfly so it doesn't leak air past at idle like a bad bore job on a set of carbs like back in the day.

 

[Tommcat]

So it looks like it's all smoothed out and widened after the butterfly so it doesn't leak air past at idle like a bad bore job on a set of carbs like back in the day.

yep. i polished the area where the blades contact a tiny bit, but dont really remove material there, for that exact reason.
i'd like to do an actual over bore and use bigger throttle plates at some point, but this is a start.

 

[joe_f7]

Any updates?

 

[Tommcat]

Any updates?

No. I just got my summer test dummy in yesterday. Im going to get baselines done on tunes next week and then start trying parts.
I have the throttle bodies, several exhausts, external intake, our own adjustable billet wastegate actuator.
From there we'll be porting the head and finally it will get one of our cam kits.
Id also like to do a spark plug comparison, and test multiple engine oils.
All data will be shared on our Facebook page as i get it, and here when i get the chance.

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[joe_f7]

Well I don't have FB, but I'll be in touch and watching

 

[MBR44]

keep up the good work. You will be a hero if you can get an intake to divert air evenly to all cylinders.

 

[Tommcat]

keep up the good work. You will be a hero if you can get an intake to divert air evenly to all cylinders.

working on that. i did one prototype that did do a better job on distribution, but it made less power. so clearly that was not what i wanted, but it was data so thats a start.
i am thinking about eliminating the factory throttle bodies completely and doing a large plenum and one single throttle body.

 

[cfm]

Single throttle bodies can be touchy. Sometimes too much of an on/off switch when they get big enough. However, sometimes making the linkage real slow helps.

for trail manners, I'd work more on the intake manifold design and then switch throttle bodies if the intake manifold determine you need to do this.

Now, I have to admit I've never looked into this. Do you have an external and internal pic of the factory set-up? Thanks,

 

[Tommcat]

Single throttle bodies can be touchy. Sometimes too much of an on/off switch when they get big enough. However, sometimes making the linkage real slow helps.

for trail manners, I'd work more on the intake manifold design and then switch throttle bodies if the intake manifold determine you need to do this.

Now, I have to admit I've never looked into this. Do you have an external and internal pic of the factory set-up? Thanks,

Straight into the center cylinder, directly from the charge tube. No internal baffles or diverters

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[XCR1250]

I used to make oversize butterfly's for bored carbs many years ago, someone could probably make same for those newer setups.

 

[Tommcat]

I used to make oversize butterfly's for bored carbs many years ago, someone could probably make same for those newer setups.

If these show me something on the dyno in the next few weeks, I'll look into doing a true over bore with bigger plates.

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[ONTTURBO]

working on that. i did one prototype that did do a better job on distribution, but it made less power. so clearly that was not what i wanted, but it was data so thats a start.
i am thinking about eliminating the factory throttle bodies completely and doing a large plenum and one single throttle body.

What did your proto type intake look like Tom ?

 

[Tommcat]

What did your proto type intake look like Tom ?

Tapered box style with side inlet.

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[cfm]

In the middle Can you come in from the top and blow down straight to the floor? or from the floor directed straight to the top ? Blowing against a wall straight on disperses air well.

 

[Tommcat]

In the middle Can you come in from the top and blow down straight to the floor? or from the floor directed straight to the top ? Blowing against a wall straight on disperses air well.

I dont think direction of flow was an issue, i think it was likely a miscalculation of plenum volume, and/or runner length.
A lot of math goes into those and I dont pretend to be an engineer, so that was a semi educated guess on my part and i likely guessed wrong.

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[cfm]

I have PipeMax that can do NA quite well, real well actually, but not turbo. Not my version anyway.

IMHO, since you have IR stack injection, the plenum/airbox in front of the individual throttle bodies can be made larger than you would think. It's not like throttle body/bodies feeding a plenum then runners.