Throttle body flow rates

[itsafatboy]

was wondering if anyone has done flow rates on the different throttle bodies, and the older ones so i have the old billet HPI 53mm with 1,8 intake runners, would like to know what it flows , i think i remember it flowed more than the SE 58 but just can't remember.  i have had it since 02 or 03 it was one of their originals.

so i have the 53mm with the 6.2 injectors on a 116.9" bike i emailed HPI since they told me that was the one i needed at time well now they tell me they would sell me the 58mm on the new bodies they have he said i have a oldy but goody so not sure if mine just flows better or not, and if id really gain anything by going bigger ,

i would rather just have mine modified to 55 but HPI don't do have that service any longer.     

[Coff 06]

Can't comment on flow. I have a HPI. 55/58 that's a few years old.
Jimmy told me the 55mm with the 58mm manifold helps with the flow.
Mine also has 1.8 runners        Coff 06

[Ohio HD]

I guess I would start by trying to understand if your TB is a bottleneck or not. Who ever tuned it would be the best person to ask that.

Also the SE58mm TB moves some decent air. Below is the dyno sheet for the 117" that No Cents built, making 136 horsepower and 127 torque. That motor ran great, I know because I put about 40k miles on it. I've also seen 124" motors make decent power with the SE58mm.

A larger TB may add some torque and HP in the curve, but I doubt it would raise the HP or torque totals unless the TB you have is restrictive.

[itsafatboy]

i really dont think its a bottle neck i just have seen how times have changed and seems bigger is better on throttle bodies but maybe im seeing it wrong ,  im staying with the 53 i have dont think bang for buck would be worth it

[Deye76]

If you can find it, Mike Roland did some excellent testing on TB size, here on HTT. Been awhile though.

[Coff 06]

Is it a one piece? Or could you change out just the intake manifold?
Maybe a later model might increase your flow rate a little.
      Coff 06

[wfolarry]

What do your heads flow? If you have big flowing heads then a bigger throttle body would help. If they're early heads you're probably at their limit.
I don't remember exactly what that combo would flow but for reference a 51 with a 1.710 would flow 275. That was my go to for 95" motors.
Back then bigger TB's just made for a bigger top end. Drivability was terrible. I'd talk to a tuner about your setup & see what he says.

[kd]

When I bought one of the HPI 62/64 w/ 1.8 runners test throttle bodies for my 120, I was questioning Jimmy about the split (larger) plenum behind the throttle plate.  He told me they experienced a smoother  low rpm tune that was easier to achieve because it softened the overlap pulse interference that is common to the short "manifold" distance in the big twin.  It also improved the low RPM manners in the higher lift cams with compression.  We had a bit of a conversation here back then and input from the tuner community seemed to agree it would help. 

[itsafatboy]

Is it a one piece? Or could you change out just the intake manifold?
Maybe a later model might increase your flow rate a little.
      Coff 06

its a two piece , the runner is fine its a 1.8 to heads so it is what it is , i could just go bigger body i suppose but i sure like the billet one i have they were pretty bad ass back in 02 , i would rather just bore mine to 55 or 58 but they dont offer that any longer

[itsafatboy]

What do your heads flow? If you have big flowing heads then a bigger throttle body would help. If they're early heads you're probably at their limit.
I don't remember exactly what that combo would flow but for reference a 51 with a 1.710 would flow 275. That was my go to for 95" motors.
Back then bigger TB's just made for a bigger top end. Drivability was terrible. I'd talk to a tuner about your setup & see what he says.

ok the heads i have are the Zippers big billet heads for 4" and 4 1/8 in bore, they have the D shaped exhaust and raised intake , the sheet i see they had for these said flow 300 at about .500 lift then pretty straite from there for other lifts , the exhaust flowed 200 at .500 lift increasing to like 215 through lifts , not sure how good that is , we did shave a bit off the head to get compression and use a .030 gasket,

 

[wfolarry]

Then the 55 or a 58 would work.
I like the 55/58 TB with the 1.8 port.

[Bagger]

Below is the dyno sheet for the 117" that No Cents built, making 136 horsepower and 127 torque. That motor ran great, I know because I put about 40k miles on it.

What was the engine build of the 117"?

[Ohio HD]

What was the engine build of the 117"?

The info is from No Cents

4.375" stroke x 4.125" bore
Fueling Reaper 594 cams
wfolarry CVO 110" heads
Compression 11.3:1
SE 58mm T/B with 5.3 injectors
D&D Boarzilla exhaust

I put the motor in my bike and bought a Boarzilla so everything matched. He let me have the TTS MAP as we both had 2008 touring bikes.

[itsafatboy]

Here is my dyno when i had BC gerolomy heads and TW8g, and propipe, with the same 53mm throttle body ,
so now have tw9BG cam, zippers heads , and boarzilla