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Oversized throttle bodies


Chewievette

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I've been designing an individual throttle body intake for my car and I need to know what the effect of having large TBs would be. The car came with a single 52mm TB, what would be the effect of running six 48mm TBs? I just dont want to go to all the trouble of making this intake and have it kill performance. Thanks.

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I too would be interested in this information. What about twin throttle bodies, or triple throttle bodies?

Would you need/want one AFM or more (i.e) if you had two separate intakes.

Has anyone done/seen anything like this?

 

I would be doing it on a NA motor.

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I've been conteplating this ITB system as well. My question to you is that if you're going to run an MAF, then wouldn't it be easier to simply fabricate a manifold and plenum without the ITBs, and have a large single thottle body behind the MAF on the plenum? If you're running an MAF in addition to the ITBs, wouldn't that be unnecessary complexity being you've got to fabricate a manifold and plenum anyway (I'm new to the EFI stuff)?

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Well, let's see what Corky Bell has to say:

Typicaly, a street manifold will enploy just one throttle plate or one mutiple plate progressive throttle body, attached to a plenum that feed all cylinders. The one-plate-per-cylinder style will exhibit lower flow loss and is thus suitable for maximum power. With just one plate total (or a progressive throttle), a considerably crisper intake manifold vacuum signal is generated. This grately increases the accuaracy with wich low-speed fuel and ignition can be calibrated and is thus better suited to a street driven automobile. Synchronizing the flow, cylinder to cylinder, through multiple throttle plates is another matter altogether.
FYI, Corky is quite THE reference regarding turbocharging.

 

Hope it helped.

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Well, let's see what Corky Bell has to say:

Quote:

Typicaly, a street manifold will enploy just one throttle plate or one mutiple plate progressive throttle body, attached to a plenum that feed all cylinders. The one-plate-per-cylinder style will exhibit lower flow loss and is thus suitable for maximum power. With just one plate total (or a progressive throttle), a considerably crisper intake manifold vacuum signal is generated. This grately increases the accuaracy with wich low-speed fuel and ignition can be calibrated and is thus better suited to a street driven automobile. Synchronizing the flow, cylinder to cylinder, through multiple throttle plates is another matter altogether.

 

 

How would one (and pointers to any literature is appreciated) tie the throttle position sensors (electrically combine the differing resistance mapping) on staged throttle bodies if one was only using ignition and throttle position for managing a multiple TB setup?. Has this been done before?

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How would one (and pointers to any literature is appreciated) tie the throttle position sensors (electrically combine the differing resistance mapping) on staged throttle bodies if one was only using ignition and throttle position for managing a multiple TB setup?. Has this been done before?

 

just like nissan did it on the dual-throttle plate intake T/B used on JDM Fairlady Z's...

 

Throttle rotation is throttle rotation, using a rotary position sensor anywhere the linkage is solidly linked will work. I have a Kinsler adapter that remote mounts up under the dash on the firewall. Nowhere near the throttles, but if you linkage has no play, what's the difference?

 

I have seen people put drill rod in the stock SU throttle piece on the balance tube to actuate their TPS.

 

The throttle position is relative. If you are going total Alpha-N (TPS and RPM based fueling only) that is all you need. If you have a MAP sensor in there, or a MAF, then TPS is relative, you don't need to know where each throttle is, the MAP will tell you that, you just need to get a relative position in relationship to idle and WOT. It will scale anywhere in between, and compensate based on MAP or MAF feedback.

 

BTW, the Megasquirt Extra Code will take a MAF feedback loop in place of a MAP signal. It's compatible.

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