Larger displacement vs more boost
08-08-2015, 07:11 PM
#1
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Larger displacement vs more boost
I'm planning a rebuild this winter and stuck on whether to go with a 2.4L stroker or not. The ultimate question is, is it better to have a smaller displacement motor and more boost, or a larger displacement and less effective boost?
Setup will be my Novi 1200 spinning to its max potential @ 22 psi 1150 CFM. Application is a road race setup.
With a stroker setup, the overall effective boost will be reduced and may even yield less HP. But I'm thinking the overall torque curve may be higher? Not sure. I don't really care about peak HP and need something that will perform reliably for a road race setup.
A stroker will have higher piston speeds which is bad, but less overall boost which is easier on the block.
A non-stroked setup will have higher boost (which the sleeves will handle fine) and less piston speed. Maybe be more reliable?
Looking for comments/thoughts from the community on which config is more ideal. Thanks!
Setup will be my Novi 1200 spinning to its max potential @ 22 psi 1150 CFM. Application is a road race setup.
With a stroker setup, the overall effective boost will be reduced and may even yield less HP. But I'm thinking the overall torque curve may be higher? Not sure. I don't really care about peak HP and need something that will perform reliably for a road race setup.
A stroker will have higher piston speeds which is bad, but less overall boost which is easier on the block.
A non-stroked setup will have higher boost (which the sleeves will handle fine) and less piston speed. Maybe be more reliable?
Looking for comments/thoughts from the community on which config is more ideal. Thanks!
08-08-2015, 07:29 PM
#2
I'm planning a rebuild this winter and stuck on whether to go with a 2.4L stroker or not. The ultimate question is, is it better to have a smaller displacement motor and more boost, or a larger displacement and less effective boost?
Setup will be my Novi 1200 spinning to its max potential @ 22 psi 1150 CFM. Application is a road race setup.
With a stroker setup, the overall effective boost will be reduced and may even yield less HP. But I'm thinking the overall torque curve may be higher? Not sure. I don't really care about peak HP and need something that will perform reliably for a road race setup.
A stroker will have higher piston speeds which is bad, but less overall boost which is easier on the block.
A non-stroked setup will have higher boost (which the sleeves will handle fine) and less piston speed. Maybe be more reliable?
Looking for comments/thoughts from the community on which config is more ideal. Thanks!
Setup will be my Novi 1200 spinning to its max potential @ 22 psi 1150 CFM. Application is a road race setup.
With a stroker setup, the overall effective boost will be reduced and may even yield less HP. But I'm thinking the overall torque curve may be higher? Not sure. I don't really care about peak HP and need something that will perform reliably for a road race setup.
A stroker will have higher piston speeds which is bad, but less overall boost which is easier on the block.
A non-stroked setup will have higher boost (which the sleeves will handle fine) and less piston speed. Maybe be more reliable?
Looking for comments/thoughts from the community on which config is more ideal. Thanks!
08-08-2015, 07:37 PM
#3
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From personal experience I've always been a fan of higher revs whenever possible. To me, it seems like a higher redline will always out perform a larger stroke/lower redline setup. And more boost is always an option.
08-09-2015, 12:15 PM
#4
The NV1200 blower has a cap of 8350rpms with a 3.2" pulley =52,000 rpms. That yielded approx 17psi for me on a 9.6:1 sleeved block over bored to 89mm/F23 square. So any rpm beyond that you are shorting the life of the blower bearings(upgrade?) wile increasing IAT. So with that, as far as an efficiency standpoint, I would run the blower up to its max safe effective speed as I just laid out and that will determine your rpm range ie 8350rpm, and build a motor that is most effect in that rpm range. I think a 2.4 stroker can be made effective up to that point, but there will be higher stresses on the con rods due to the elevated piston speeds. I think for a road course application the stock F22 with the proper cooling ie oil, coolant and IAT will be more reliable and still yield you a nice 450whp.
The other option would be to move size to a smaller 3", drop the rpm band to approx 8100rpm and have a more reliable 2.4 stroker motor, which should yield similar peak hp (possibly a little more) but with a broader trq curve through that shortened rpm range. Playing with gear ratios may be prudent in order to dial in the best overall speed range for the track you will be running. If there is one particular track you see yourself running, that may be worth considering.
The blower speed is what ultimately determines your limitation, so use that to build everything else around to be the most effective in power and reliability.
The other option would be to move size to a smaller 3", drop the rpm band to approx 8100rpm and have a more reliable 2.4 stroker motor, which should yield similar peak hp (possibly a little more) but with a broader trq curve through that shortened rpm range. Playing with gear ratios may be prudent in order to dial in the best overall speed range for the track you will be running. If there is one particular track you see yourself running, that may be worth considering.
The blower speed is what ultimately determines your limitation, so use that to build everything else around to be the most effective in power and reliability.
08-09-2015, 03:48 PM
#5
Registered User
Thread Starter
Thanks for the input guys. The non-stroked setup does appear to be the better choice for my application. Other than piston speeds, the side loading at BDC is another factor to consider which I can't quantify.
Regarding the pulley config, at 7200 RPM is when I hit max blower RPM and spin it up to 61000 at 8500 RPM. I'd rather get boost a little earlier, knowing that I spend more time <7200 and usually redline at ~8000 on the track (to keep things safe).
My last task is to narrow down my choices on a machine shop!
Regarding the pulley config, at 7200 RPM is when I hit max blower RPM and spin it up to 61000 at 8500 RPM. I'd rather get boost a little earlier, knowing that I spend more time <7200 and usually redline at ~8000 on the track (to keep things safe).
My last task is to narrow down my choices on a machine shop!
08-10-2015, 01:15 PM
#6
In a road race application I would see it beneficial to get revs as high as possible. You already have the benefit of the torquey linear powerband of the SC so have a motor that capitalizes on that and you can rev out to stay in the high powerband. Now if you had a turbo setup I would say go stroker to increase the midrange torque but you dont need that. High comp, high rev, novi 1200 on race gas, 20psi, mid/high 400hp range will make the perfect track car. good luck!
08-10-2015, 01:39 PM
#7
Community Organizer
The NV1200 blower has a cap of 8350rpms with a 3.2" pulley =52,000 rpms. That yielded approx 17psi for me on a 9.6:1 sleeved block over bored to 89mm/F23 square. So any rpm beyond that you are shorting the life of the blower bearings(upgrade?) wile increasing IAT. So with that, as far as an efficiency standpoint, I would run the blower up to its max safe effective speed as I just laid out and that will determine your rpm range ie 8350rpm, and build a motor that is most effect in that rpm range. I think a 2.4 stroker can be made effective up to that point, but there will be higher stresses on the con rods due to the elevated piston speeds. I think for a road course application the stock F22 with the proper cooling ie oil, coolant and IAT will be more reliable and still yield you a nice 450whp.
The other option would be to move size to a smaller 3", drop the rpm band to approx 8100rpm and have a more reliable 2.4 stroker motor, which should yield similar peak hp (possibly a little more) but with a broader trq curve through that shortened rpm range. Playing with gear ratios may be prudent in order to dial in the best overall speed range for the track you will be running. If there is one particular track you see yourself running, that may be worth considering.
The blower speed is what ultimately determines your limitation, so use that to build everything else around to be the most effective in power and reliability.
The other option would be to move size to a smaller 3", drop the rpm band to approx 8100rpm and have a more reliable 2.4 stroker motor, which should yield similar peak hp (possibly a little more) but with a broader trq curve through that shortened rpm range. Playing with gear ratios may be prudent in order to dial in the best overall speed range for the track you will be running. If there is one particular track you see yourself running, that may be worth considering.
The blower speed is what ultimately determines your limitation, so use that to build everything else around to be the most effective in power and reliability.
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08-10-2015, 02:25 PM
#8
Originally Posted by s2000Junky' timestamp='1439151317' post='23709182
The NV1200 blower has a cap of 8350rpms with a 3.2" pulley =52,000 rpms. That yielded approx 17psi for me on a 9.6:1 sleeved block over bored to 89mm/F23 square. So any rpm beyond that you are shorting the life of the blower bearings(upgrade?) wile increasing IAT. So with that, as far as an efficiency standpoint, I would run the blower up to its max safe effective speed as I just laid out and that will determine your rpm range ie 8350rpm, and build a motor that is most effect in that rpm range. I think a 2.4 stroker can be made effective up to that point, but there will be higher stresses on the con rods due to the elevated piston speeds. I think for a road course application the stock F22 with the proper cooling ie oil, coolant and IAT will be more reliable and still yield you a nice 450whp.
The other option would be to move size to a smaller 3", drop the rpm band to approx 8100rpm and have a more reliable 2.4 stroker motor, which should yield similar peak hp (possibly a little more) but with a broader trq curve through that shortened rpm range. Playing with gear ratios may be prudent in order to dial in the best overall speed range for the track you will be running. If there is one particular track you see yourself running, that may be worth considering.
The blower speed is what ultimately determines your limitation, so use that to build everything else around to be the most effective in power and reliability.
The other option would be to move size to a smaller 3", drop the rpm band to approx 8100rpm and have a more reliable 2.4 stroker motor, which should yield similar peak hp (possibly a little more) but with a broader trq curve through that shortened rpm range. Playing with gear ratios may be prudent in order to dial in the best overall speed range for the track you will be running. If there is one particular track you see yourself running, that may be worth considering.
The blower speed is what ultimately determines your limitation, so use that to build everything else around to be the most effective in power and reliability.
08-10-2015, 03:25 PM
#10
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