Originally Posted by PowerHouse

The first thing I see right away is the two cars. I remember the 8.5 and 9 when my buddy was sponsored by ofna and the 8.5 was a very heavy car. It took everything we had to get that car around the track in a timely fashion. The 9 was considerably lighter and responded better to less output engines so I would start there as the main difference. I am not saying it is the only difference but it is a major contributing factor. If you get bored and want to switch the engine in each car and run it to see how each car handles each engine, that would be ideal but I wouldn't sweat it.

I will break down the the engine first. The Toro Nero and Bonito share about 95% of their parts. The Bonito has the physical changes to the case which include the machining on the upper block to allow room for the lowered head, extra cross sutting holes for additional cooling as the head now covers more of the case and will have a higher heat retention, the back plate has the steel ring to slow conrod wear when it walks on the pin and brushes the case from time to time. The only timing difference which will have an effect is the transfers are 2* lower than the toro which means the transfers will open later and close sooner which should give the engine more low end torque but since the exhaust port timing was not altered, it also gives the engine more blowdown timing which will give it more peak rpm so the engine may have a more linear feel.

Another thing I noticed is the venturi size. You mentioned you have a 6.5 on the toro and an 8 on the bonito. Initial engine response is not only dictated by timing, compression ratio, pipe length and volume etc but also by how fast it can build a fuel signal. The smaller and more taper the inlet has, the quicker and stronger the fuel signal builds which will give the engine a quicker response and the larger and less tapered the inlet is, the slower and smoother it builds the vortex around the needle to draw in the mixture giving it a more linear PTO.

So all in all, you have 2 different cars with 2 similar engines but they have enough differences to give them different running characteristics and the two different vehicles and venturi inserts amplifies the differences. If you want to get a fair comparison, you should run both engines with both 6.5 and 8mm inserts in the same car to see the real differences between them. You don't have enough of a control subject to give yourself accurate results. There are probably some other subtle differences between them that will also vary the results but the ones I talked about would be the big ones.

Bottom line, if you like what each engine is doing for each car, that is all that should matter.