1989 CRX aero mods

[ultimx]

Originally Posted by coyoteX

slownugly, Look at the diffusers under F1 cars to get an idea of how small they can be and still be very effective. The important aspects are; fences on the sides, roof has to face the ground, angle of the roof 3*-5*. If you can find wind tunnel tests, it's amazing how the diffuser under the bottom changes the air flow over the wing on top. Belly pan vs. no pan, are you headed to Bonneville? Get a vacuum gauge and learn to use your right foot first.

Do you have pictures of what your talking about?

[coyoteX]

I am running an AFR gauge also, it lets you know what the computer is seeing in the exhaust. The Vacuum gauge watches the intake side. The AFR gauge watches the exhaust side. Being a Tech, you know the Intake Event is the most critical. Read some of Bisimotos stuff, the Honda single cam master. When climbing hills, I try to keep the AFR pulsing with the best possible Vacuum. Usually only 1"-2", on the Vacuum gauge. When the AFR pegs out rich, that's unburned fuel out the tailpipe. Letting off the throttle, ever so slightly, gets it pulsing again. On downhills, If you crack the throttle, you can actually pull more vacuum and see no pulse or very low AFR reading. I use a ScanGauge II on my '01 Tacoma and it's cool to watch the MPG go to 9999. When you get the technique down, you can actually let off the throttle slightly as you are cresting hills, watch the Vacuun actually increase and be accelerating at the same time. This is completely contrary to how most people drive.
As far as good engine mods, a 4-2-1 header is necessary, so the exhaust pulses hit the main pipe in sequence. As far as exhaust back pressure and harmonics, I did the math and Honda already has that taken care of. A full exhaust, header to tailpipe tip the stock size would be ideal, but you won't be able to come up with a small tube header. It's not a problem though, because as long as you go back to the stock pipe size behind the header, you regain exhaust speed. Big tubes are only good for astronomical RPM's, racing only. No good in the real world. Hey, you can always sell it to Ricky Racer.
Good luck Dude.

[slownugly]

Yea I need most help on the uphill part. I use dfco a lot. I can read that on my afr because it pegs lean. I know exactly what you mean with the cresting a hill thing. Right before I hit the highest spot I drop into lean burn and that pulls me over the hill. Good advise on the afr uphills. I need a good medium on uphills where it's enough engine load to maintain speed but not so much that it drops my mileage.

[coyoteX]

It' a good thing we don't have to go uphill both ways!!!!
ultimx asked about pictures and I don't know how to get to the album with my cars pictures, can you assist? I think he wanted to see pictures of the rear diffuser.

[slownugly]

I created a photobucket account and use that. I take a pic and send it to the account. The. From there you copy the link and paste it on the post you want the picture. Very easy if you have a smartphone. I have photobucket on an app so it's very simple

[some_other_dave]

Originally Posted by slownugly

I use dfco a lot. I can read that on my afr because it pegs lean.

DCFO is a way to slow down while using no fuel, but coasting without slowing down (engine on or engine off) is even more efficient in the long term. Unless you are actually coming to a stop, or have a downhill stretch that is so long that even if you crest the hill at 5 MPH you still get too fast.

-soD

[slownugly]

That's what is great about the Vx transmission. ( hf transmission too) the final drive keeps the rpms so low if the hill is steep enough I can use dfco and gain speed without touching the throttle or using eoc. Or shifting to neutral. If the hill causes a decrease in speed I blip the throttle a little to get back up to speed and continue dfco.

It's all about averages and weighing them out. I could shift to neutral and go 5 miles at 20:1 afr. Or I could dfco 4 miles at 99.99 mpg and 1 mile accelerating at 14.7afr. Or eoc for 5 miles. Eoc obviously most effective but I'm wanting to prove hybrid mileage from this car without hybrid techniques (shutting engine off)or expensive battery packs. I'll save the eoc for my last goal

[ultimx]

Originally Posted by coyoteX

It' a good thing we don't have to go uphill both ways!!!!
ultimx asked about pictures and I don't know how to get to the album with my cars pictures, can you assist? I think he wanted to see pictures of the rear diffuser.

I was referring to the f1 cars underside. Iv looked for the. A while ago and didn't come up with anything.

[coyoteX]

ultimx, Just google F1 race car diffuser images and click on the images 100's of them come up.

[ultimx]

Awesome thanks! Any more modifications in the future for the crx?