Fuel Economy, Hypermiling, EcoModding News and Forum - EcoModder.com - View Single Post - Building a FE D-Series trans for my CRX VX

SuperHatch · 08-09-2010, 04:32 PM

I'm planning on building a transmission for my CRX this winter when I swap in the D15Z1 I picked up last week.

I made an Excel spreadsheet that shows Vehicle Speed versus RPM for a stock HF transmission (49 State with 2.954 Final Drive). This is essentially what is in my car right now:

I've read some people talk about putting Si 1-3 gears in a HF trans, but I want even shorter 1-3 gears. The JDM DOHC "ZC" transmission has a 1.944:1 2nd gear, a 1.346:1 3rd gear, and a 1.033:1 4th gear. The 1.033:1 4th is too tall, but the DX/Si has a 0.937:1 4th gear.

Below is a graph with a Stock 1st (All D-Series transmission have the same 1st), ZC 2nd and 3rd, DX/Si 4th, HF 5th, and stock HF final drive.

This really tightens up 1-3 and the DX 4th is a nice bridge between the ZC 3rd and HF 5th. This should liven up the car a little on acceleration but still retain the superior cruising fuel economy.

Thoughts?

08-09-2010, 04:32 PM	#1 (permalink)
SuperHatch EcoModding Lurker Join Date: Jul 2010 Location: NJ Posts: 53 Civic - '99 Honda Civic CX 90 day: 37.39 mpg (US) Thanks: 7 Thanked 16 Times in 7 Posts	Building a FE D-Series trans for my CRX VX I'm planning on building a transmission for my CRX this winter when I swap in the D15Z1 I picked up last week. I made an Excel spreadsheet that shows Vehicle Speed versus RPM for a stock HF transmission (49 State with 2.954 Final Drive). This is essentially what is in my car right now: I've read some people talk about putting Si 1-3 gears in a HF trans, but I want even shorter 1-3 gears. The JDM DOHC "ZC" transmission has a 1.944:1 2nd gear, a 1.346:1 3rd gear, and a 1.033:1 4th gear. The 1.033:1 4th is too tall, but the DX/Si has a 0.937:1 4th gear. Below is a graph with a Stock 1st (All D-Series transmission have the same 1st), ZC 2nd and 3rd, DX/Si 4th, HF 5th, and stock HF final drive. This really tightens up 1-3 and the DX 4th is a nice bridge between the ZC 3rd and HF 5th. This should liven up the car a little on acceleration but still retain the superior cruising fuel economy. Thoughts? Attached Thumbnails