01 Jeep Wrangler 4.0L ~1900 @60 mph

apples to oranges compared to most of your engines though.....

I will look when i go to school. Al I know is 1,600rpm=30mph in the saturn.

Thanks to all for the replies!

Based on the numbers from DaX it looks like I definitely don't have the FE trans.

It looks like some of you have much better gearing than I do, but I'm not sure if spending $300 or so for an HF tranny will be worth it in the long run...

[QUOTE=MakDiesel]'85 CRX Si: '85 Si tranny w/ HF 5th gear = ~2750RPM @ 60mph

Makdiesel, could you tell me- where did you get your HF 5th gear? Junkyard? That might be a better start for me, but I am curious as to why your engine (12valve d15 just like mine) turns faster than mine at 60mph when you even have the HF 5th gear .:confused: Did the HF 5th gear swap give you much mpg improvement?


DaX- did you see a big improvement when you switched your civic (much newer than mine) from auto trans to the FE trans?

Thats wrong 1,500rpm =35mph. 2,500rpm=60mph (I don't see that kind of speed to often :) )

Sure did. Check out my Gas Log HERE. The rise in FE about halfway through the graph is when I installed the HF transmission. It does, however, take FE conscious driving. If I try (and I have tried to test it), I can get worse gas mileage than before by driving the car hard.

Change transmissions? Gear ratios? What a pain! Bring money! Time! Patience!
I'm with "clencher" on this one...find some taller tires / wheels / both? Bolt-on beats R&R (remove & replace) any day!:thumbup:

I took a look while driving my car today. It's at 2335rpm at an indicated 60mph. I have a taller 5th gear in my tranny. The stock 5th gear spun the motor about 500 rpm higher.

Thanks again
 

Thanks again to all for the info. I might keep my eye out for a cheap FE trans or an FE 5th gear set for my trans. I don't mind the labor of swapping the transmissions out. I've done at least 4 Honda D series clutch jobs.

Someone mentioned that upping the tire size would be an easier mod to change the gearing slightly.

On my previous car (87 Acura Integra D16 MPFI), I tried increasing the tire sizes in an attempt to change the ratio slightly to get better FE. In that car, at 60 mph (5th gear), the engine was turning at 3000 rpm :eek: . I went from the stock 195/60 14 up to a taller 175/75 14 (the 175/75 14's would rub the fenderwells when I turned sharply). I did all the speedometer correction calculations and ran them for several years, and then went back to the stock size when those tires wore out. It ended up that I got slightly worse mileage with the taller tires than with the shorter tires :confused: (more ground clearance/air under the car?). Again, I did all of the corrections for odometer inaccuracies. I was really surprised that the shorter tires were better for my FE. It would get 32-34 mpg on the highway (60 mph). I always wondered how much better it could have done with better gearing (2 months ago someone hit me and totalled it) :( . It was still running strong at 254,000 miles (it had 148,000 when I bought it).

Erik: On my 89 civic wagon, which is fundamentaly a DX, box, I am turning about 3000 at 60mph.
On the transmission, I have a HF transmission I was able to pick up for free. However, it has a piece of the case missing, so I am going to need to pull my transmission and rebuild it, using the HF gearing. Their are several points worthy of note.
First, as has been noted, the people who have made a change to a taller transmission have all had pretty significant positive results. Consequently, if you can get a transmission for a low enough price, it would probably be a worthwhile change to make.

Second, if you look at the gearing on an HF transmission, most of the drop in engine rpm actually comes from the taller gearing of the differential gears, not the 5th gear. The 5th gear contributes, but it's probably a 30/70 percent ratio, or so in my evaluations.

Third, if your getting 38mpg, with the engine, carb and transmission you have, you are doing pretty well. I also have a 87 DX, and I typically get 35-37mpg from it. Personally I'd like to get rid of it, but I have to get another car running for my daughter to drive, before I can do so. My primary reason is that the carburator set up is very complicated, a real pain to work on and the cost for a replacement carburator, rebuilt, is worth more than the car is worth, if I sold it. However, it has been a phenomenal car. It had 155,000 on it when I purchased it and it is at around 230,000, now.

Last: I believe that on the 87 you can actually replace/exchange the 5th gear with the car in the transmission. Their is a CRX web site called Redpepper which has loads of information for the 87's and it is almost all relevant to the DX, as well. I wouldn't advertise that your driving a DX, though, since it's largely dedicated to making CRX's go fast.

If you decide to make the change, be sure to post your conclusions, after you get some idea of how well it worked out.

2100 at 60mph
2480 at 70mph