The difference between the JP Mod and JP Stock is simply that... Modified and Stock. The Modified JP B5 has alot of work done to the sleeve and crankshaft with porting and polishing to smooth out the powerband and increase run times. Efficient fuel delivery helps the engine run very well and greatly increases performance.
Check out
www.jpracing.com and you will see some pictures of JP Modified sleeves.
The JP B5 Stock engine is pretty much a Novarossi P5. The P5 is the base engine that alot of these companies use to modify and definitely produce great results. Max Power also uses the P5 as their base engine but they have done a bit more work than the JP line of engines (I have both and have compared).
I do not have any experiences with the B8T so I can't really say that those temps work with that engine as well. I do have a Novarossi 421B in my truggy and that is very similar - 8 port and Novarossi. So far its running around the 240-260 range as well but only has about 1.5 gallons through it and has not fully come in on its own yet so consistent temps and run time are still a little sketchy
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