F24 Rev Limit
08-19-2014, 12:17 PM
#1
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F24 Rev Limit
Finally tuning my built 10:1 compression ILP F24 stroker. It will have a SOS S/C with 3.6 pulley. What rev limit should I use? Head is built with all ferrea valve train.
08-19-2014, 01:29 PM
#2
I wouldn't go past 8500. The head can probably take more, but the longer stroke will become a problem. You can easily rev the K24 crank to 9000+, but it's just a question of how long you want the motor to last.
With the OEM cam (assuming) and bigger displacement, the motor will probably be choking too much above 8000 anyway. Have a look at the torque cure once on the dyno, and you'll know right away.
With the OEM cam (assuming) and bigger displacement, the motor will probably be choking too much above 8000 anyway. Have a look at the torque cure once on the dyno, and you'll know right away.
08-19-2014, 08:14 PM
#5
What did your engine builder tell you it could handle? They built your motor and should know the exact specifications. I assume you told them what your goal was with the sc?
You invested a lot in a built motor, yet I can tell you that you are barely pushing any pressure through it, why? If it were me id want to get all the potatoes out of that blower and make your engine build efforts worthwhile. A 3.6" pulley is a moderate option for a bone stock Fxx engine.
The stock f22 revs happily to 9k with a sc attached to it. 8500rpm is about where the hp peaks however. On an f24 you will be roughly 500rpm down from that, so about 8k rpm, but that doesn't mean it won't handle more if you want a broader powerband.
The thing with your centrifugal sc vs say a turbo or roots charger is you won't get to reach its efficiency range/ benefit unless its being spun. Two ways it gets spun is by the pulley size and the engine rpm. Since your lowering the engine rpm, you will need to compensate by running a smaller pulley to spin the blower faster earlier in the rpm.
The ideal way to go about dialing in your charger to the power curve of your stroked motor, is to mate the pulley that maxes the blowers internal speed to the engines max out put capability/rev limit set forth. So off the top of my head that means you will want a 3" to 3.2" pulley and set your rev limit to roughly 8k-8400rpm. This will get you the most bang for your buck, the most trq down lower from the boost and stroked motor, wile gaining the most pressure and hp the motor can produce up top. Spinning the blower half assed with a 3.6" will keep you out of your efficiency range with the blower and the engines capability.
You need to compensate with more output if you are to lower your rev limit and therfore increase your shifting frequency, or you won't be accelerating much faster then the guy with 50 less hp but 1000 rpm more through each gear. Unless you plan on running a lower numerical gear set in the rear end like a 3.90 or 3.73? You have a motor and blower capable of over 300trq and 450whp, yet you are running a gear set that only hits 56mph at redline 8200rpm in second gear (even less if you drop revs to 8k) but potentially adding double the whp and trq.
You invested a lot in a built motor, yet I can tell you that you are barely pushing any pressure through it, why? If it were me id want to get all the potatoes out of that blower and make your engine build efforts worthwhile. A 3.6" pulley is a moderate option for a bone stock Fxx engine.
The stock f22 revs happily to 9k with a sc attached to it. 8500rpm is about where the hp peaks however. On an f24 you will be roughly 500rpm down from that, so about 8k rpm, but that doesn't mean it won't handle more if you want a broader powerband.
The thing with your centrifugal sc vs say a turbo or roots charger is you won't get to reach its efficiency range/ benefit unless its being spun. Two ways it gets spun is by the pulley size and the engine rpm. Since your lowering the engine rpm, you will need to compensate by running a smaller pulley to spin the blower faster earlier in the rpm.
The ideal way to go about dialing in your charger to the power curve of your stroked motor, is to mate the pulley that maxes the blowers internal speed to the engines max out put capability/rev limit set forth. So off the top of my head that means you will want a 3" to 3.2" pulley and set your rev limit to roughly 8k-8400rpm. This will get you the most bang for your buck, the most trq down lower from the boost and stroked motor, wile gaining the most pressure and hp the motor can produce up top. Spinning the blower half assed with a 3.6" will keep you out of your efficiency range with the blower and the engines capability.
You need to compensate with more output if you are to lower your rev limit and therfore increase your shifting frequency, or you won't be accelerating much faster then the guy with 50 less hp but 1000 rpm more through each gear. Unless you plan on running a lower numerical gear set in the rear end like a 3.90 or 3.73? You have a motor and blower capable of over 300trq and 450whp, yet you are running a gear set that only hits 56mph at redline 8200rpm in second gear (even less if you drop revs to 8k) but potentially adding double the whp and trq.
08-19-2014, 11:50 PM
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08-20-2014, 02:20 PM
#10
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Junky.
I appreciate your thoughts. I previously had a 3.2 pulley on my f22 and I couldn't go a whole race session without it slipping. I should have mentioned this is a track day car and reliability is what I'm after, with a little more grunt for the straights. I was pretty happy with my f22 and 3.8 pulley making 380 hp. I figured this with the 3.6 would be plenty of fun for the track, but since I spend a lot of time in the upper rpm range on track, I wanted to see what most people with a stroker were spinning to reliably.
I have an OS Giken clutch diff with 4.10 gears in it. I will be running 275/40 nittos on all 4 corners.
I appreciate your thoughts. I previously had a 3.2 pulley on my f22 and I couldn't go a whole race session without it slipping. I should have mentioned this is a track day car and reliability is what I'm after, with a little more grunt for the straights. I was pretty happy with my f22 and 3.8 pulley making 380 hp. I figured this with the 3.6 would be plenty of fun for the track, but since I spend a lot of time in the upper rpm range on track, I wanted to see what most people with a stroker were spinning to reliably.
I have an OS Giken clutch diff with 4.10 gears in it. I will be running 275/40 nittos on all 4 corners.