Evogone
08-08-2012, 09:39
Interesting result on the rollers today in the Rallycar.
Origional build mapping showed 228bhp 182lb/ft with 2" diam exhaust, Peak about 7k, went on 3 different occasion and was withing 1/2bhp..
Full 2.5" exhaust fitted and full top end rebuild (everything the same inc. timing) the map needed a few tweeks as a result of the exhaust. Its now eliminated some of the bumps in the torque curve but in essance the exhaust just moved the torque curve 500rpm higher but after 6k held the torque curve longer before dropping off. Now the power is still climing after 7.5k where previously is was dropping off. Results where 243bhp @ 7800rpm torque 180ft/lb. We even backed the timing back a little and were conserative due to using pump fuel.
:grin:
Cliokongen had a very similar effect on his ITB engine which is similar spec (slightly lower cr and milder cams) with the exhaust. He also modified his manifold to have the mating down pipe of 2.5" dia to match the exhaust. This is the next step for me the back to the rollers but conclusion is if you have a high spec build then 2.5" exhaust is a must...
Before everyone says figures are rubbish, these are all on the same rollers so the step change is the important aspect rather than the absolute figures BUT these rollers are hub rollers and read very consistantly and are very accurate based on lots of feedback. Although did have one scare when the fuel pressure dropped on one run but was due to the exhaust boiling the fuel up due to not air getting to it.!! covered the exhaust and was fine after that.
Car goes very well, at the last event a guy came across whos was running a Millington engined Mk2 freshly built by Melvin Evans and said F@*% thought i would catch you up on the straight but couldnt, was well impress with the car.
Hopefully cars all OK for the next round of the championship for the Promenade stages 7/8th September on New Brighton sea front, great event with night time super special stages on the Friday.
Origional build mapping showed 228bhp 182lb/ft with 2" diam exhaust, Peak about 7k, went on 3 different occasion and was withing 1/2bhp..
Full 2.5" exhaust fitted and full top end rebuild (everything the same inc. timing) the map needed a few tweeks as a result of the exhaust. Its now eliminated some of the bumps in the torque curve but in essance the exhaust just moved the torque curve 500rpm higher but after 6k held the torque curve longer before dropping off. Now the power is still climing after 7.5k where previously is was dropping off. Results where 243bhp @ 7800rpm torque 180ft/lb. We even backed the timing back a little and were conserative due to using pump fuel.
:grin:
Cliokongen had a very similar effect on his ITB engine which is similar spec (slightly lower cr and milder cams) with the exhaust. He also modified his manifold to have the mating down pipe of 2.5" dia to match the exhaust. This is the next step for me the back to the rollers but conclusion is if you have a high spec build then 2.5" exhaust is a must...
Before everyone says figures are rubbish, these are all on the same rollers so the step change is the important aspect rather than the absolute figures BUT these rollers are hub rollers and read very consistantly and are very accurate based on lots of feedback. Although did have one scare when the fuel pressure dropped on one run but was due to the exhaust boiling the fuel up due to not air getting to it.!! covered the exhaust and was fine after that.
Car goes very well, at the last event a guy came across whos was running a Millington engined Mk2 freshly built by Melvin Evans and said F@*% thought i would catch you up on the straight but couldnt, was well impress with the car.
Hopefully cars all OK for the next round of the championship for the Promenade stages 7/8th September on New Brighton sea front, great event with night time super special stages on the Friday.