I have a 94 si with a d16z6 all stock and s20 which I believe is the A000 model. I'm not interested in making it a race car or anything and mpg is important to me but my gears are ridiculously long. At 70 mph I'm not even hitting 2k rpm in 5th and going up an incline in 5th and even 4th at times is just a joke. I find myself downshifting constantly and I almost never get into 5th, and even when I do its not for extended periods of time.

So my question is what kind of rpms would I be looking at in what gear and at what speed (like 5th gear at 70mph at 3000rpm) if I swap my tranny to B000 model, and how would it affect my mpg (I'm getting about 34-36mpg)? Any help with this would b greatly appreciated

 

What size tires?

 

14 inch

 

For me when I had my Frankenstein trans. With a d16y8 5th and fd I believe I was close to 3000 at 60mph on 17's.

 

Look in the small circle cast in the case next to the axle above the drain plug. P20/A00 is either a DX/LX or VX, the P20/B00 is the EX/Si model. It sounds like you may have a VX trans with very long gears and FD ratio in the car.

 

I know where to look, It's just that I live in an apartment and I can't really do anything. I got in trouble last week for cleaning my tb. I'm 99.99% sure it's the A000 model, I'm just trying to find out how much higher my rpms would be if I went with the B000 model and if I would see a difference in mpg and if so how much of a difference

 

Depends on which trans you have and which one you get (for the US, there are three possible B000 5th gear RPM).

 

Is there a way to tell which B000 tranny I'm looking at? If so how? And how do the gears differ from each of those 3? I'm really just looking for a tranny that doesn't have really long gears but at the same time I don't wanna b at 3 rpm doing 60, that's just gonna be bad on gas. A tranny that puts me at about 3k at 70-75mph in 5th would be ideal if one exists

 

Only way way to know for sure, and that is to split the trans and count the teeth. One of them you can run the VIN number on, the other two don't have VIN plates.

Z6, Y8 EX = .702 5th, 4.25 FD
Z6 Si Del Sol = .750 5th, 4.25 FD
Y5 HX = .702 5th, 4.058 FD

Higher RPM doesn't mean worse fuel economy. At 80mph I'm at 4,950 RPM with my D16Z6 (1.000 5th, 4.058 FD) and get 41mpg (47mpg with the same transmission on a much lower mileage Y7 longblock). If you have the D15Z1 then keep the transmission you have as it is specifically setup for the matching transmission.

 

How are you getting such good mpg with your z6? I have a stock z6 and it's only getting around 34-36mpg and that's when I'm driving it like a grandma. Could it be that the longer gears are actually making the engine work harder and therefore it's loosing some mpg? My si currently has about 230k miles on the body but the engine and tranny were both replaced by a previous owner so the true milage of either is unknown.

 

Higher RPM = less throttle needed to maintain speed = less fuel used.