JDM H22 LSD= better gas mileage than H23 tranny swap

[exratedaccord93]

Been doing some research about a tranny swap. I need to replace my clutch soon and my f22a6 (p2u5) tranny has a grind. I figured I might as well buy a tranny since I need to take it out anyways. People on Accordingly done have strongly suggested the h23 (M2S4) tranny because of it's shorter gears. I was told that H22 trannies have gears that are way too short. This is partially true.

In the data section of accordinglydone.com, I was able to look up the different gears for the h23 (m2s4), the JDM H22A (M2A4), the JDM H22a LSD (M2B4), and the USDM H22A1(M2F4). My main concern with swapping an h- series tranny on my f22 was the gas mileage. The shorter the gears, the lower the gas mileage. Upon using this calculator, I noticed that the USDM H22A1 tranny (M2F4) has a way shorter 5th gear than the h23 (m2s4)which means that highway driving would suck because you would be at very high rpms. In this case, the comparison of the usdm h22 tranny and the h23 tranny would lean toward the h23 tranny being a more practical swap. But looking at the 5th gear of the JDM H22 LSD, the h23 has a shorter 5th gear. The JDM LSD tranny has a better 5th gear for highway driving than the h23 does. They both have the same final drive. The real order of longest to shortest trannies (longest being better gas mileage but slower acceleration, Shorter being the opposite) would be:

1. F22a6 (p2u5)
2. JDM H22 LSD (m2b4)
3. JDM H22 regular (M2a4)
4. H23 (m2s4)
5. USDM H22A1 (m2f4)



In conclusion to my research, the jdm h22 lsd tranny (m2b4) or the regular Jdm tranny (it actually has a longer third gear than the lsd) would be more ideal than the h23 because of shorter 2nd and 3rd gears while still maintaining the longer 5th gear for highway driving.

Let me know what you guys think..... still researching the best tranny. BTW, I'm doing this because I'm eventually going to swap an h22. If I buy the tranny now, I can just buy a longblock when I'm ready.

[f22-dohc]

kickass

[timmy0tool]

this is a good find. i would personally go with the USDM H22A1 tranny. they have a long enough gear ratio for cruising while still having it short enough to accelerate quickly in given situations. how much better is the JDM LSD tranny compared to the H23? i'm sure they are pretty close, but i guess you are trying to save as much gas as you can. it really depends on your application. are you going for just gas mileage? for the acceleration? for the top-speed? you can really only have two out of the three.

edit: you edited your first post!

[cp[mike]]

good job taking the initiative to doing research, and the results are good to know, thanks!

[exratedaccord93]

[QUOTE=timmy0tool]this is a good find. i would personally go with the USDM H22A1 tranny. they have a long enough gear ratio for cruising while still having it short enough to accelerate quickly in given situations. how much better is the JDM LSD tranny compared to the H23? i'm sure they are pretty close, but i guess you are trying to save as much gas as you can. it really depends on your application. are you going for just gas mileage? for the acceleration? for the top-speed? you can really only have two out of the three.QUOTE]

With the h23 (ms24), you would be at around 3700 rpm at 80mph. The f22a6 (p2u5), I'm at 3200 rpms at 80mph. There is a difference of .127" in the gears. With the usdm h22a1, you would have a horrible cruising speed because there is a difference of .185" in fifth gear. The usdm h22 tranny would put you at around 4000-4100 rpms at 80 mph thus giving you WORSE gas mileage. The usdm h22a1 tranny is the worst tranny for our motors. The only advantage (acceleration wise) over the jdm LSD would be that 4th gear is shorter. Who needs a shorter 4th gear?

[NAiL05]

Isnt the gearing also in the Performance section of this forum? The only thing missing in that one is the tranny codes.

[timmy0tool]

you are correct. more here: http://www.cb7tuner.com/vbb/showthread.php?t=37839

USDM H22A1 PRELUDE VTEC 93-96 COUPE:
3.307 1
1.950 2
1.360 3
1.071 4
0.871 5
4.266 final

5th gear 195/60 R15
70mph = 3610 rpm
80mph = 4126 rpm


can you post the JDM H22A LSD ratios for comparison?

[koolkoreanked]

Cruising at 80 with my h23 tranny I turn just under 4k on the tach. With the usdm h22 tranny I turn right at 4k same as the jdm one. As far as acceleration... h23 tranny kicks ass. But I still haven't felt it with vtec so we will see. But compared to my f22 the h23 tranny has way shorter gears and pull in the low end even with the h22 engine behind it.

[hatchninja]

gangstar!

the accord tranny definitely needs some help. tranny, cam, compression, and tuning and you should have an impressively quick car.

[exratedaccord93]

JDM H22 LSD (M2b4)
1-3.307
2-1.950
3-1.360
4-1.034
5-.787
FD-4.266

USDM H22A1 (m2f4)
3.307 1
1.950 2
1.360 3
1.071 4
0.871 5
4.266 final

H23A1 (M2S4)
1-3.307
2-1.857
3-1.320
4-1.034
5-0.812
FD-4.266

F22a6 (p2u5)
1-3.307
2-1.809
3-1.185
4-.933
5-.685
FD-4.062

As you can see with the comparison of the gears, the M2b4 is the most practical. It has shorter 2nd and 3rd gears with a longer 5th gear than the M2s4. Keeping in mind that the larger the number, the shorter the gear, you can see for yourselves that the JDM H22 tranny is superior for acceleration while still providing a great cruising gear. Obviously not as good on gas as the p2u5 but with performance comes sacrifice.

[HondaFan81]

I always wondered why I have this M2B4 laying around ...good find bro , good thing I just "happened" to make the right choice for my application

[uslspct]

I'm in the same boat as you and I first concluded I would get a H23 tranny seeing as it would be easier to get and cheaper than a JDM H22's. But now I've said fuck it, I'll just get a F's tranny for cheap and later on splurge on the M2B4 for the reasons you already pointed out. But my decision is based on money right now. And if your gonna eventually put a H22 in that's even more reason not to waste money on an H23 tranny now.
There's also the option of the 97-01 USDM h22's tranny which has the 0.812 5th gear like the H23's. But that might be more money than the JDM's although you would be getting a newer tranny. But that don't mean much.
So go find a M2b4 or the one without an LSD. This is the best choice for now and your future plans.
Also, a side note, I've wondered why do the 2 JDM tranny's have all the same gears except 3rd? Is that just a typo someone goofed on or are those truely the right gear ratios?

[exratedaccord93]

^^^they do have different third gears for some reason. The non-LSD has a longer third gear. This is why I think the M2b4 is the best tranny for me. Now the only thing is finding one for cheap. I agree with uslspct that the h23 tranny is easier on the wallet but like he said, I'd be wasting my money on an h23 if I'm eventually going with an h22. I know that the h23 tranny would bolt up to the h22 but it still wouldn't be as quick as an m2b4.

[timmy0tool]

I always wondered why I have this M2B4 laying around ...good find bro , good thing I just "happened" to make the right choice for my application

ditto . i always think that 3rd gear is the "deciding" gear in a race. when the two cars hit 3rd at the same time, the outcome of the race is determined by the strength of the motor (and of course other factors) on 3rd gear.

this is a good thread. all threads should be as informative and concise as this one.

[cp[mike]]

any info on the euro R tranny?