Can I put the 5th gear from my HF trany into my Si? I hate being on the interstate going 80 MPH and 3500 RPM's....or at least 300 RPM's. This sure would help with gas mileage!

 

will fit right in, won't help with the mileage. Might even get WORSE mileage.

 

I agree that around town It might not make that much of a difference but on the highway I would have to help. Two cars traveling the same speed with the same engine only one of the engines is spinning at 2000RPM's and the other at 3500RPM's...the higher one will have lower MPG's.....but all that could be offset by the difference in city MPG's, which might be lower then a stock SI trany setup...then again I'm just thinking out loud here.

 

well, the HF motor is tuned to be more efficent at the lower rpms, the Si isn't.

Me and _TJ have tried, and I've posted about this before.

 

I doubt the gear alone will lower rpms very much. The SI final drive is the big difference in gearing.

 

I thought about the same thing but if the final drive is different than i dont know how much it would change

 

I'm just worried that long term highway driving at high RPM's would be bad for my engine...that is one reason I use fully synthetic oil.

 

i notice last time i was at the oval track with my freined and his DX. i hit a top speed of 210 ish KM/hr at redline in 5th gear on an Si CRX

he hit 220 issh KM.hr at only like 5000 RPM in 5th in his CRX DX and we nboth had stock rims fror the track.

i got a DX tranny too but dont wanna put it in what a PITA

 

Like they said above - the HF motor was designed to run at lower rpms than the Si.

Running it at 3500rpms in 5th isn't too bad. The motor was built for that, and I think it should handle it quite well, long term wise. Besides, you could prolly mess something up if you take apart your tranny.... I know I would!

Fully Synthetic oil =


[Modified by MrTodd, 10:50 PM 9/23/2002]

 

OK, I'm sold. I leave things alone....but you know how it is ...it's never good enough. Just when you think it's fast enough, you lose a race....etc.

 

Heh. Yeah I know what you mean. It's okay, you'll find something else to tinker with later on down the road...

 

That is what the DOHC swaps save when I beat them with a SOHC.

Power to da D!

 

if u ask me , u might get worse MPG>..
since the RPM's goes down, the engine has to do a little more strenght with less momentum... its like riding a bike on a flat st.... the top gear and u pedaling slow its going to get u more tired than spining at a constant more faster pace speed....
plus the final drive might messs that gear and make it heavier...

 

Isn't the HF supposed to be an economic friendly car in the first place? The Si is more of a sporty decent.

 

Heck I wish I was taching 3500 at 80 I am solid at 4000 at 75, course I have a ZC tranny in mine, not the Si. But then lower RPMS would equate to less get up and go when I needed it.


[Modified by virginia_dude, 3:10 PM 9/25/2002]