CRX HF reverse trike project

[Sven7]

Keep the small exhaust. More air running through means more fuel running through.

[Christ]

Use the header and the down pipe, mate it up to the smaller exhaust with a taper section.

Exhaust without intake mods just makes it easier for the exhaust to get out, and even if you mod both intake and exhaust, it doesn't "let more air in" until you put your foot closer to the carpet.

The only reason not to direct the gasses out in the most efficient way possible is if you have an engine that relies on residual exhaust to pre-charge the cylinder to limit intake charge.

You don't, that I'm aware of.

[some_other_dave]

Originally Posted by Christ

You don't need power brakes on a CRX as it is, and they already don't (mostly) have power steering.

The 88-91 CRXes did have power-assisted brakes. You want them to be power-assisted; I used the brakes on my CRX after depleting the vacuum. It takes an unreasonable amount of pressure on the pedal to slow the car down.

None of the US-spec CRXes had power-assisted steering. There may have been overseas (e.g., JDM yo!) models that did, but none that were intended for the US. The car is generally light enough not to need it, especially if it's moving at all.

-soD

[Christ]

Originally Posted by some_other_dave

The 88-91 CRXes did have power-assisted brakes. You want them to be power-assisted; I used the brakes on my CRX after depleting the vacuum. It takes an unreasonable amount of pressure on the pedal to slow the car down.

None of the US-spec CRXes had power-assisted steering. There may have been overseas (e.g., JDM yo!) models that did, but none that were intended for the US. The car is generally light enough not to need it, especially if it's moving at all.

-soD

You were also fighting a 4.5lb/in spring and a giant diaphragm trying to push the entire volume of air through a 1/2" hose while simultaneously pushing the fluid into the calipers and wheel cylinders.

I build and adjust manual braking systems pretty often. The CR-X doesn't need assisted brakes.

[some_other_dave]

You can switch it over to non-power brakes, but that means swapping out some important brake parts. If you keep the stock parts you definitely want to keep a vacuum source on it.

-soD

[Christ]

Originally Posted by some_other_dave

You can switch it over to non-power brakes, but that means swapping out some important brake parts. If you keep the stock parts you definitely want to keep a vacuum source on it.

-soD

Actually, you can just swap on a non-power MC, which can be had from earlier model Civics and bolts right up to the firewall pattern.

You can also just remove the MC and the actuator rod and use the brake pedal rod and an adapter plate to mate the MC to the firewall and push on it directly using the brake pedal rod. The thickness of the adapter plate is determined by the thickness of the assist rod in the brake booster.

Some people may consider re-drilling the pedal mount location to get a better leverage point when using the stock MC without a booster in place, but it's not really necessary.

The bike's rear caliper is probably about the same fluid capacity as both of the stock rear wheel cylinders, so there won't be a notable change in braking application force requirement.

If the bike's rear caliper is higher capacity, the pedal will travel slightly further and feel "weaker" for the same brake pressure application. If it's a lower volume, the pedal will feel slightly harder and travel less.

[some_other_dave]

Oh, good point! The rear brakes are being completely changed out anyway, so you're already into re-engineering the braking system. So a master cylinder swap (and maybe proportioning valve swap) may be needed anyway.

-soD

[Christ]

I detailed a manual brake swap setup somewhere on here with my VW Golf as well.

I made a quick adapter plate by cutting up the old booster housing, drilling it, and bolting those sections together.

It was quick and dirty, but it worked just fine. The pedal instantly felt harder and somewhat more pressure was required to work it, but the difference was easily manageable for a "normal" person, probably even better for someone already used to manual brake systems.

To alleviate that, I planned originally on shortening the push rod (to move the brake pedal further down it's travel and get a better angle on the pedal) as well as moving the attachment point of the rod to the pedal arm up some to provide more mechanical advantage.

I daresay that with proper engineering, one could develop a leveraged manual brake system for a vehicle up to 2.5 tons capable of standing with the best assisted systems on the market for normal use.

[groundflyer]

Originally Posted by Christ

Use the header and the down pipe, mate it up to the smaller exhaust with a taper section.

Exhaust without intake mods just makes it easier for the exhaust to get out, and even if you mod both intake and exhaust, it doesn't "let more air in" until you put your foot closer to the carpet.

The only reason not to direct the gasses out in the most efficient way possible is if you have an engine that relies on residual exhaust to pre-charge the cylinder to limit intake charge.

You don't, that I'm aware of.

I will use the header has 1.75 exit so close to the stock 1.5 exhaust
I found a muffler with a 1.75 to a 1.5 exhaust holes and a stright 1.5 pipe out the back

Oh, good point! The rear brakes are being completely changed out anyway, so you're already into re-engineering the braking system. So a master cylinder swap (and maybe proportioning valve swap) may be needed anyway.

As for the brakes will be using the stock set up the bike rear will be nothing but E brake.set up..

[Christ]

For safety and inspection reasons, you'll want to plumb the rear brake (if it's hydraulic) to the master cylinder.

If it's a mechanical (leverage) brake, you don't have to worry about it, but I'm not sure how that will play out for inspection purposes.

Might be a good idea to upgrade the front brakes. Upgrades are cheap and you can do it with all stock parts from other cars. Just check out any Honda forum.