Bonneville America Forums Forums Technical Forums Performance Mods Airbox, Airbox Mods or Pods?

Hi all,

I posted this on RAT yesterday on the subject of airboxes, airbox mods and removal and as it's more relevant to you guys I thought I'd better post it here.

I know many America and Speedmaster owners are waiting patiently for the EFI tunes and it's been a long time since we said about releasing them, but they are nearly done and it won't be long at all. But I thought you may be interested in what we have learnt about airbox mods and airbox removal with pods by way of a dyno graph.



As a reference, tune 9 is as it says, tune 6 is with a Breathe, DNA filter and full airbox mods which involved cutting out the internal baffle and cutting the bottom out of the air filter with a corresponding hole in the bottom of the airbox as this is common among owners and tune 3 is basic airbox mods with just the Breathe and DNA filter installed.

As you can see, with pods you start to gain bhp from 5,500rpm and will start to feel it at around 6,500rpm, but you do lose torque in the low to mid range. This configuration does give the most top end power as expected.

Full airbox mods were surprising as I was expecting to make decent gains in the mid range compared to just the Breathe and filter, but it was the same as with pods, mid range torque was lost below 5,000rpm. Small gains and loses are made from above 5,000rpm to the rev limiter compared to the basic airbox mods.

Installing the Breathe and DNA filter with no mods to the airbox gave the best low to mid range torque up to 5,000rpm and then as with full airbox mods gave small gains and loses to the red line. This configuration gave the best low to mid range benefits.

Always good to see objective performance data. For comparison purposes, please keep in mind that the above dyno runs show DIN correction, which will automatically produce higher numbers than SAE correction. My advice to those of us in the North America is to focus on the relative & not get too hung up on the absolute numbers.

Absolutely agree, that's why I didn't state power figures in the text. The main point being the differences in the torque curves between these popular induction mods, this doesn't change whether SAE or DIN.

This dyno is for the short silencers, but it's very much the same for long silencers and TORS.

From my perspective the improvements are spectacular. Well done!

i'd like to see these focused around the cdi mods.

PieMan, if you could indelge my ignorance and show me the light, I would appreciate it.

What is DNA, DIN, Megas, so forth?

MW, I'm sure others can chime in.
DNA is a brand of air filter, similar to UNI or K&N.
DIN, like SAE is a unit of measure, kinda like Foot pounds vs Newton meters.
Megas, well I don't know but think it might be megaphone exhaust.
Anybody else want to throw real information out there or even just a WAG?

MattyMo is correct with his descriptions. Also megas are 17" reverse cone megaphone silencers we used for these dyno runs and the Breathe is a high flow airbox intake cover we developed and sell to help improve overall torque and power produced from the engine.

Great. So when are your tunes available (I already have the #3 setup - DNA & Breathe) and how much?

Can you also please post the A/F chart for the #3 dyno?

Mike - pm sent

Here you go Richard, this is what you can expect.

Looks good. Pm sent about timing.

This morning I carried out the final dyno run for the pods with TORS tune, so here's a dyno for the guys with TORS fitted. This is with no airbox mods, just a Breathe and DNA performance air filter vs. airbox removal and DNA performance pod filters.

Hi Mike, I forgot to ask. Was the Staintunes dyno run with or without the removeable restrictors?

Hi Richard, the Staintunes had the restrictors removed.

So the whole tune thing, Is this something that can be done with the factory chip or do I have to go out and buy a power commander or other such device? This is the first mod I am looking at doing along with some pipes maybe the bc cocktail shakers or bubs?

The "tune" PieMan/Mike is talking about is written to your motorcycles ECU. No additional hardware is added to the motorcycle. This let's the ECU send tune corrected (for any performance mods) signals to the fuel injectors, ignition timing and such. Not having the base tune signals manipulated by an aftermarket device (PowerCommander) you have to buy and then pay to have installed.
You communicate with the ECU using the OBDII port under your seat via an application called TuneECU and a particular USB to OBDII cable(~$20). The TuneECU program runs on PC and not Mac. It's a shareware type program, download for free and contribute to the creator if you like. The program is really useful for general maintenance and diagnosis and also allows "tuning". NOT something most of use should do, but it also allows you to load a map modified by someone much smarter than me! I paid a distant tuner for a custom tune using TuneECU after mods. Triumph factory tunes (base & aftermarket exhaust) are really all that's out there for most configurations.
Mike is such a tuner and should have some tunes out soon (looks like soon maybe?) for the America/Speedmaster line much like he already has for the Bonneville/Thruxton line. Check out his site for some good information.
If I have misstated anything somebody please correct me. Jay, I hope that helps.

edit: maybe it goes without saying or maybe not, this applies to the EFI models as the carbed ones actually require changing out parts like jets & needles

Maybe the tune will be put out before christmas, that way i'll know what to get.

Does anyone know if these runs are completely different than the British Customs complete airbox replacement system? They offer (2) K & N filters (or UNI's) and a mounting plate, so, all things that are supposed to be mounted near the airbox have a place to mount, once the stock items are removed. Also, is it assumed that the larger bellmouth is installed?

Dave (new to forum!)

Dave, the runs plotted using the DNA pod filters would apply to most any "air box removed, pod filters installed" set up. The ARK, NARK, Freak or a DIY version would be much the same. The difference between the DNA, UNI or K&N brand filters may be measurably different but the difference would be very small. You would not likely be able to "detect/feel" a difference in filter brand, but if you were racing and looking for every .25 or 0.5 HP gain then go with the best you can get.
And yes, I think Pieman is using his Breathe bellmouth and DNA filter if the air box is still installed.

Hi All,

at long last our America and Speedmaster EFI tunes are now available HERE.