They are probably figuring an increase in HP due to a few basic power mods. Muffler, intake, etc. You won't find many that are 100% stock. Either way, if it's a guesstimated number based on the factory-rated flywheel HP it's a pretty useless number.

Dave

 

thanks.

 

You probably pulled ahead your friend's USDM RX-7 at high speed because you have a shorter 5th gear ratio. Shorter gearing gives your engine more mechanical advantage over the wheels, at the expense of top speed. Assuming everything else in both cars is equal (power, weight, aero drag...) the car with shorter gearing will reach top speed first, but the car with taller gearing would be able to acheive a higher top speed eventually (assuming they both have enough power to pull to redline in 5th gear).

From what I've heard, the only difference between the JDM and USDM transmissions is the 5th gear ratio. Not sure if the final drive (rear end) is different or not.

 

5th gear is steeper, for acceleration over cruising.

i believe the top speed of a JDM FD is 182 miles an hour while the theorectical top speed of a USDM FD is 202 miles an hour.

 

Regarding the later JDM trannys, I have some interesting info about updated parts but I don't know when or if the change took effect.

Mazdacomp has some P/Ns for updated 2nd and 3rd gears but no descriptions. (F128-'s) When I called they didn't know why those parts were listed either, but they asked japan and the answer is these are single-cone synchro versions of the gears. Both the parts guy and I agreed these were less desirable than the original double-cone synchro versions. So if anyone has torn down a late-model JDM tranny, has series 8 parts or FSM info I'm really curious whether the 2nd and 3rd gears are double-cone synchronized or not.

 

That's what the guy whom I bought my car from said it had 300hp! He's an import dealer. But I also Know that not every Import Dealer knows what he's talking about!

 

missed the 2nd page! that last response was to the last reply on the 1st page

Sorry

 

JDM's have a speed limiter in them that prevents them from breaking just over 180KM
Unless you cut the right wire!

 

yeah that was already stated...

 

[QUOTE = i believe the top speed of a JDM FD is 182 miles an hour] (by: Hitokiri_Gensai)


JDM cars are in KM's per hour, which is different then MPH.

Now did you mean after you snip the speed limiter cause then they might go 292.9KM per hour which is 182 MPH.

But wouldn't you'd need some mods to get that fast !!

 

ok... i dont understand what you point is here... obviously JDM cars measure in KM/h while US cars measure in Mp/h but thats not a performance difference.

and an FD is capable, atleast in the US, STOCK, of about 165 - 170 miles an hour due to the lack of a speed limiter.

 

What was inaccurate about his statement? He's right. "Right Hand Drive Rx-7s have their speedometers in Kilometers vs Miles". And before you whine...again...about Canada not being recognized as using the Metric system, remember the OP's original post:

 

The commonly accepted number is 155mph, on a very good day. 170 is absolutely out of reach with stock gearing and power.

 

By the diagram, visually, the hubs, selector rings and syncros, look pretty much the way they always have in the late boxes, if you take prefix changes as major changes, 1st-2nd, 3rd-4th have had major changes, 5th-reverse minor. Not sure the part #s will be of huge significance because of slight changes to the main and countershafts in version V from the NA cars and start with "R" predominantly.

3rd gear is changed in some major way (2nd changes to 250B, a nothing change?), but doubt it is numerically given minor change to the countershaft. Of interest, RS/RZ (presumably, Spirit R??) had a change in top gear - if I'm reading this right - over the povo packs, and, at a guess, to compensate for the final drive installed in those cars. So might still end up with an overdrive(??) 5th if the wrong import replacement box is selected.

 

Looking at part numbers is interesting but probably of limited value. I've shopped for and bought numerous transmission parts and in nearly every case the part number has updated (often a couple times) since 93 with no functional improvement. Many of those updated part numbers were more "major" than the alpha character at the end. (I'm guessing that alpha character might be as simple as the production run or change in supplier, which has no effect on the final part). 5th synchro and the shift select spindle are the only ones that come to mind as significant changes.

Dave

 

ok so stock power maybe not, but ive seen a stock transmission FD go 175 before.

 

The transmission is almost never related to top speed capability.

 

well i wasnt saying it was, but its capable of more than 155 mph.

 

Would you guys agree that by removing the EGR and the cat you would increase HP?
Because the JDM cars did not come with and EGR and the pre cat. Also there is no Air Conditioning Control Module. These are differences aswell. I know the pre-cat was already mentioned but these are emission controls right? With them not in the system, wouldn't it increase HP!