Summore if I put block 2.0 Ltr into a B16A, which FD is more suitable??
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Just wondering B16B from a type-R using which FD??
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Which is better? 4.4lsd or 4.785lsd?
- Thread starter Wanggot
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B16B OEM is 4.4FD. DC2R had 2 spec. one is 4.4FD and the latest will be 4.785 (forgot which year started with 4.785. 98 if not mistaken)
- Apr 18, 2006
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Actually with the B20B options, there are many options to maximise the speed from the first gear, one is with 4.2FD, but you'd need good torque at high rpm to use it.
Or simply swap 1st (or including 2nd) gear to maximise the usability of the torque of the B20B. There are two choices, which is usually 2.5(or something around that range) or 3.070 from mFactory. The advantage of 3.070 is that it works for B16A/B as well, while a 2.5 is a little to high for 1.6L torque. (the above assuming retaining 4.4 FD)
I can't say it's the perfect setting, but it's better than the stock 3.2 1st with 4.4FD on a B20B. My test on a quad B20B, first gear only last for 2 secs or less, before hitting peak speed at 60kmh@8K rpm.
Do note that 1.6L can use 2.5 1st gear ratio, but only with a 4.7/4.9/5.0 FD. if 4.4 first gear takes damn long to hit 70-80kmh with 8-9K rev limit (around there) LOL.
The reason 5.0 FD has limited use is because most honda transmission gears, aftermarket wise, has nothing lower than 0.747 for 5th, limiting the use of 5.0FD for street use/cruising.
Oh yeah.. anyone got the straight cut mFactory gear on their car?
I'd like to hear the whine it makes... how loud it would be at 8-9K :P
Or simply swap 1st (or including 2nd) gear to maximise the usability of the torque of the B20B. There are two choices, which is usually 2.5(or something around that range) or 3.070 from mFactory. The advantage of 3.070 is that it works for B16A/B as well, while a 2.5 is a little to high for 1.6L torque. (the above assuming retaining 4.4 FD)
I can't say it's the perfect setting, but it's better than the stock 3.2 1st with 4.4FD on a B20B. My test on a quad B20B, first gear only last for 2 secs or less, before hitting peak speed at 60kmh@8K rpm.
Do note that 1.6L can use 2.5 1st gear ratio, but only with a 4.7/4.9/5.0 FD. if 4.4 first gear takes damn long to hit 70-80kmh with 8-9K rev limit (around there) LOL.
The reason 5.0 FD has limited use is because most honda transmission gears, aftermarket wise, has nothing lower than 0.747 for 5th, limiting the use of 5.0FD for street use/cruising.
Oh yeah.. anyone got the straight cut mFactory gear on their car?
I'd like to hear the whine it makes... how loud it would be at 8-9K :P
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- Apr 18, 2006
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depends on RPM and torque the B20B makes.
If you make a lot of torque at lower end, and at 7K rpm and up torque already dropping, then 4.2 FD is a better choice.
If you have a lightened crank assembly, and your torque at the higher end is retained past 7-8K, with a rev limit of 9K or more, then 4.6.
But 4.6 will have higher FC than 4.2 on the stock EG gearbox, because you will be running about 4.5K rpm while cruising at 100kmh in 5th gear.
with 4.2, 5th gear will result in about slightly less than 3K rpm while cruising at 100kmh, so a better choice for a daily driver. you won't win drag battles with specifically built B20B engines with non-streetable ratios, but you'd still have a decently fast daily driver.
FD is not the final equation of the gearbox vs. speed. You'd also have to factor in tire sizes.
Running 195/55R15 tires and running 195/50R15 tires is also a way to play with your final drive. Although the same width, the tire circumference is not same, so using a smaller tire like the 195/50 is almost like using a bigger (4.4+) FD.
That is why, although you may hear various FD choices, you'd have to look at your tire sizes first, because that is the final equation of translating engine speed to vehicle speed.
- Apr 18, 2006
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here's a gear chart of two tire sizes running the same ratios, but with different FD.
as you can see from the speed at 8000 rpm, the speeds are almost similar. Tire expansion is a factor, but let's assume they are similar models with similar expansion rates, just with different sizes. but in truth, different tire sizes offer different expansion rates, so even gear calculators can't be 100% accurate to real life (of course, they don't mention this)
In short, if you were using 195/50R15 before with stock Y21 and 4.4 FD, simply by swapping tire sizes to 195/55R15 you can actually gain the effect of near +/-0.1FD ratio, depending on which tire you started out with.
notice the speeds at 8K RPM being very close, even with tire swap, because it is offset by a different FD.
in fact, if you wanted to get a feel of what 4.2 FD feels like, you can run 215/50R16 and achieve near 4.266FD ratio, as the chart below shows. That is, if you can get enough fender clearance to fit 215/50R16, he he.
Another factor in play is tire rotation resistance. more surface contact and more softer compound will make the car feel heavier or not, depending on if your engine has enough torque to offset that resistance. A 195/55R15 semi slick is way more heavy to rotate that a similar street compound 195/55R15 tire. Same with 205/50R15, which is wider. Don't forget the weight as well, though the bulk of the weight is usually the sidewalls and tread material, so this may vary, and sizes can't be an accurate measurement.
The reasons FDs are available in a multitude of sizes is because not all tire sizes can fit in the car.
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- Apr 18, 2006
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don't have to look at all the numbers.
The only pertinent numbers are the speed vs. RPM
With 4.4+ FD, top speed per gear is reduced, but get more acceleration
With less than 4.4 FD, top speed per gear is increased, but with less acceleration.
The point of the earlier post is to state that minor FD changes can be done by tire size changes.
like for example, if you are using 195/55R15, then to get a similar effect of using 195/55R15 + 4.5+FD, you can use 195/50R15 instead.
The main idea FD manipulates top speed per gear. Additionally by doing this, it also keep the the revs in a certain RPM range.
Like most small cc high rpm engines, best torque is always around the 7-9K range, because the small cc cannot generate torque at low rpms. But torque is always less than a comparable big cc engine like B20, so the additional RPM capability is best compensated with a bigger than 4.4 FD for purposes of torque multiplication.
That is probably why for most B20B owners swapping from B16 feels the 1st and 2nd (occasionally even the third) gear being too short, but not so with the 3rd, 4th, or 5th, while the B16A owners feel that the 3rd, 4th and 5th gears being too long. It's all in the amount of torque generated on each engine, and where.
The only pertinent numbers are the speed vs. RPM
With 4.4+ FD, top speed per gear is reduced, but get more acceleration
With less than 4.4 FD, top speed per gear is increased, but with less acceleration.
The point of the earlier post is to state that minor FD changes can be done by tire size changes.
like for example, if you are using 195/55R15, then to get a similar effect of using 195/55R15 + 4.5+FD, you can use 195/50R15 instead.
The main idea FD manipulates top speed per gear. Additionally by doing this, it also keep the the revs in a certain RPM range.
Like most small cc high rpm engines, best torque is always around the 7-9K range, because the small cc cannot generate torque at low rpms. But torque is always less than a comparable big cc engine like B20, so the additional RPM capability is best compensated with a bigger than 4.4 FD for purposes of torque multiplication.
That is probably why for most B20B owners swapping from B16 feels the 1st and 2nd (occasionally even the third) gear being too short, but not so with the 3rd, 4th, or 5th, while the B16A owners feel that the 3rd, 4th and 5th gears being too long. It's all in the amount of torque generated on each engine, and where.
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- Apr 18, 2006
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yaka 4.2 bro dc_vtec.. heheheim using 4.2. cannot joining discussion..
on hiway looks like 4.9 ja..
bwhahahaha just a figure of speech, shiro. i m trying to understand or at least i think i do. but pls dun test me
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