[dstewart]

Yet another day at the dyno and the truth behind Throttle Bodies.

I have to leave for work in a few min so just a quick note. Yesterday was very interesting. We played with several configurations (including two long, and two short stacks) and the best setup for my bike was, SP1 T-bodies long stack on the front short stack on the rear. We lost nothing at the top, let me repeat, we lost nothing at the top compared to the SP2 T-bodies. We did gain almost 15 HP from 7k to 9k, and a slightly lesser amount elsewhere.

The original intent was to eliminate a problem I was having when the bike was running under 180 deg above 8.5k over 90% throttle. Even with proper A/F ratio my specific configuration just could not burn the fuel at WOT at high RPM unless the engine temp was close to 200 deg. This has been a problem for me since day one with this build. We came up with the theory, the lack of ventruri vacuum at WOT with the larger T-bodies led to a combination that did not adequately atomize the A/F for a complete burn. Once the head temp was sufficient this problem lessened. Thats also why if we leaned the A/F ratio out to 14.5:1 or grater the problem whet away but so did some power.

It appears the smaller SP1 T-bodies are more then sufficient for 145 to 150HP. In my case we gained nothing but tuning problems with the SP2 parts and lost significant upper mid range. I wont have time for a few days but I will get some dyno charts up in the next week or so. My engine is far from stock so your results may vary, but rest assured the SP1 T-bodies are good for more then 145HP.

Thanks to Andy Palmer of West Coast GP Cycles, Josh Kaufman and Lou Alvarez for their continued help.