100+ MPG CRX HF VREX - help needed! - Page 3

benfrogg · 09-28-2010, 09:31 PM

My 2 cents':
Lose the altenator! I was reading someone else's post on the site a while back about MPG increases and the altenator. It's something like 10% potential gain. I forget the user that posted it; he has a geo with a bunch of aero mods and such.
Anywho, well worth thinking about. You could dump the altenator altogether or leave it installed with a break switch for when needed. A pair of deep cycle batteries and fexible solar panels on the roof and hood should be more than adequate. The panels, controllers, batteries, and related components would be pricey, but not that bad considering your goals and budget. You might be able to get some of this stuff donated too.
You could also keep a 110 charger onboard (perhaps wired to your block heater for winter) that could top off the battery with grid power when you were at home (or Mcydy's outdoor power outlet!)
Range wouldn't be limited if you kept the altenator. Weight would be more of an issue with those batteries and related components. I think your 10% gain would offset this easily.
At this point, you are getting to the land of diminishing returns.

Anyway, one other question I can shed some light on is the question about lean burn low threshold. My vx will stay in lean burn anytime over 1000 rpm's at basically any practical speed in any gear. The throttle position is the most important factor, it seems. One thing I want to do is put in some kind of an indicator to let me know where that threshold of pedal is. I dont have anyway of doing that just yet.

B

HeadlessNorseman · 11-11-2010, 09:21 AM

have you made any progress with this? subscribed and very interested! i have a 91 HF, why choose the 88 besides the lowest weight? i think i could easily take about 100lbs out of mine but then after that its compromise weight, interior pieces, passenger seat, etc. im working on improving the aero first cause my main goal is to get my highway mileage up without spending so much it takes 2 years to "pay off" in mileage gains

HeadlessNorseman · 11-11-2010, 09:25 AM

Also just a thought on running with no alternator. I have a diagram somewhere for a 2 battery system. With the ignition on, the car works like normal and the spare battery is wired into the charging system. turn the key off, and the backup battery takes over and drains slowly. It was designed for car PCs so the computer could stay running 100% of the time, no starter interupt or anything

HeadlessNorseman · 11-25-2010, 09:52 PM

the second battery is only wired to the car PC and the alternator. there both never actually connected at the same time, its an A or B mode based on the engine running or not

imzjustplayin · 11-26-2010, 03:11 PM

Quote:

Originally Posted by HeadlessNorseman

the second battery is only wired to the car PC and the alternator. there both never actually connected at the same time, its an A or B mode based on the engine running or not

If you only have one battery hooked to the alternator, how do you charge the one that isn't hooked up? With an external battery charger?

panamacolin · 01-26-2011, 07:34 AM

Wheres this project at currently?

101mpg · 08-06-2011, 05:54 AM

Sorry for the delay everyone, my wife & I have a new baby - so this has been on hold for a bit.

The reason I'm going with the '88 1/2 (I know - first half) frame is a) slight weight savings but b) even more I HATE door mounted seat belts.

Pgfpro - thank you publicly for your donation of the mpguino. It's very much appreciated.

The transmission on this is going to be the manual out of the Wagovan. I haven't read anywhere that you need to cut a hole in the firewall to make it fit, it's supposed to be a direct-fit bolt-up. I'll keep you posted when that happens.

I am not going with no alternator in the vehicle. Part of the goal is to get maximum MPG with a vehicle that can be a daily driver. I'm actually thinking of beefing up the alternator as well. I'll be replacing every single lubrication fluid, grease, etc., so as much savings as I can get will be needed. I need my tunes. =)

c_rex90 · 08-30-2011, 09:55 PM

I'd love to see this thing come along. Keep it going.

The 89 Hf's also had pillar mounted seat belts, if you didn't know already. Though I think they weighted slightly more than the 88s for some reason. But it'll give you another option while looking for a shell.

As for the suspension, the Si shocks and springs are the same as the Hf. The only difference between the Si and Hf suspension systems was that the Si came with a rear sway bar and had a thicker front sway bar. The 90-91 models also came with rear disk brakes. It would also probably be in your interest to lower the car for better aero.

In regards to the alternator delete suggestion, the Vx has a sort of "smart" charging system that only charges under certain engine conditions in order to improve gas mileage. I'm sure getting rid of it would increase mileage but it would likely not be as much of an increase as with other vehicles.

You might head over to crxcommunity.com and have a look around if you haven't already. You'll find just everything you need to know about the Crx.

Also, find the user "Mista Bone", he's the community d-series transmission guru. He might be able to help you out with the transmission details.