If EFR budget...
#43
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Looking at the gear ratio's, the RX7 transmission matted up to a 4.3 rear end wouldn't be a bad option at all. Now if you had a Miata that came with the 6 speed 3.909 rear end it would be pretty steep gearing!
If you are making 500 HP I don't see the RX7 transmission gearing with 4.3 rear end being an issue.
Keith
If you are making 500 HP I don't see the RX7 transmission gearing with 4.3 rear end being an issue.
Keith
#44
Looking at the gear ratio's, the RX7 transmission matted up to a 4.3 rear end wouldn't be a bad option at all. Now if you had a Miata that came with the 6 speed 3.909 rear end it would be pretty steep gearing!
If you are making 500 HP I don't see the RX7 transmission gearing with 4.3 rear end being an issue.
Keith
If you are making 500 HP I don't see the RX7 transmission gearing with 4.3 rear end being an issue.
Keith
#46
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Stock 6 speed with 3.636 rear end at 7000 RPM (best combo for 6 speed)
1st 34.7
2nd 57.6
3rd 79.4
4th 103.9
5th 130.6
6th 155.0 and 80 mph = 3600 RPM
RX7 TII with 4.3 at 7000 RPM
1st 34.8
2nd 60.1
3rd 87.0
4th 121.1
5th 168.4 and 80 mph = 3300 RPM
RX7 TII with 4.1 at 7000 RPM
1st 36.5
2nd 63.0
3rd 91.3
4th 127.0
5th 176.6 80 mph = 3200
If you put the 3.636 gears in there with the RX7 transmission you are going way tall. If car was making enough power you would top out at 200 mph!
#53
On the street? Nothing. But when every tenth of a second matters on track, the drop from 2nd->3rd->4th is too wide. Compare the TII 2nd-3rd-4th-5th to the 6-peed's 3rd-4th-5th-6th, the 6-speed has much closer ratios.
If you can find a circuit racing gear set for it like this Our Website
But at that point it's probably cheaper to get one of the custom gear sets that will fit into a Miata transmission (5 or 6 speed) so I don't know how promising that is as an option.
If you can find a circuit racing gear set for it like this Our Website
But at that point it's probably cheaper to get one of the custom gear sets that will fit into a Miata transmission (5 or 6 speed) so I don't know how promising that is as an option.
#56
Thrust math beggs to differ. If you have 400ftlbs, perfectly flat from 4000rpms to redline you're going to accelerate at the same rate from 4000rpms to redline. If you change gearing to keep you at higher rpms, then you're going to have better mechanical advantage on the ground and more thrust because of the gear ratios not the fact that you're at higher rpms.
#59
4.8 seems excessive. If i were to do it with a BP, i'd go with a 4.3 or a 4.1 with the knowledge that you should be making enough power to shred 6spds on the regular.
MFactory® Competition Products - Gear Calculator
But this.... this is my jam right here.
MFactory® Competition Products - Gear Calculator
But this.... this is my jam right here.
#60
TQ and good gearing wins races. The thing is, that is almost the same thing as saying HP wins races.
The V10 F1 cars made fairly pathetic TQ next to say a Viper. But since they revved to like 17K, they could use gearing that would have a Viper topping out at 40 MPH. IIRC the rumor was that they would run 9s pretty easily, with only 300WTQ AFAIK
tl;dr The key is to have good TQ multiplication at all times. Having relatively wide gearing splits is not automatically a bad thing if you have the TQ band to match, and you get good multiplication from an aggressive rear gear. That TQ band has to be flat and extend to high RPMs. You can then stay in TQ, run decent TQ multiplications (aka not having to get into lower multiplication/high gears early on), and not have to shift so often either.
The V10 F1 cars made fairly pathetic TQ next to say a Viper. But since they revved to like 17K, they could use gearing that would have a Viper topping out at 40 MPH. IIRC the rumor was that they would run 9s pretty easily, with only 300WTQ AFAIK
tl;dr The key is to have good TQ multiplication at all times. Having relatively wide gearing splits is not automatically a bad thing if you have the TQ band to match, and you get good multiplication from an aggressive rear gear. That TQ band has to be flat and extend to high RPMs. You can then stay in TQ, run decent TQ multiplications (aka not having to get into lower multiplication/high gears early on), and not have to shift so often either.
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