Exhaust Manifold

[theunchosen]

I've been considering a somewhat custom build for a while now, as no manufacturer I know of makes tandem-seating or cars that are substantially lower than my Del Sol.

As I pieced together the chassis and frame, to make the car shorter I am considering rotating the B16(or D16) series engine and laying it down flat. In that configuration the air would come in from the top and the exhaust should go out the bottom. But the heads, or crowns or whatever, would be facing the rear of the car anyway(to keep the engine as close to the center of stiffness) and with a little work the exhaust could travel in straight line out of the cylinder and down the pipes.

Obviously there would be slight pumping gains because the gases no longer have to turn in any substantial fashion from header to muffler, but is it worth it?

[Funny]

Not to discourage you, but have you thought of the lubrication issue this will create? Most engines (all that I can think of) have oil sumps at the physical bottom of the engine. If you were to lay the engine down flat, without modification you will create oil pump starvation, blow the pump, then seize the engine. This could be remedied by creating a modified sump that makes a 90 degree bend off the original pan mount, but then you will have to modify the pick up tube in order to supply the pump, the oil dipstick will have to be sealed, and a host of other changes will need to be made to prevent pooling. Pooling on one side of the cylinder is going to create uneven wear and quite likely reduce the life of the engine, and much less improtantly reduce the mileage by having to push a puddle out of the way each rotation. In my opinion, it would be easier to create new mount points on a custom frame that is very low to the ground, and mount the engine in stock orientation. If you try to make that honda engine into a horizontal design, I think you may be in for a world of hurt. Just my $0.02.

[almightybmw]

take a look at opposed engines mass produced. The sump sits lower than the cylinders. In a few cases the cylinders have stops to prevent pooling and promote draining, mostly solving the uneven wear issue. But I have never seen an engine with cylinders other than upright last longer than an upright cylinder design. Some came close, but I doubt many are installing rotary cylinder engines in their cars, at least for practical reasons.

Leave it upright. Angle it maybe, but not more than 15 degrees without modifying the oil sump for a better pickup or a dry sump system. If you really want to shave a few inches go dry sump. That'll knock 6-8 inches off the height of you engine.

[Bullockracing]

If you can, the Subaru boxer engines are flat, aren't they? Or an air-cooled VW, although not very FE.

For a solution on mounting the engine lower, a dry-sump pan will let you lower the engine significantly. It may be costly, but it also reduces parasitic drag from the crank splashing in the oil, and you can use an electric oil pump, further reducing working HP required to turn the engine.

[cfg83]

Bullockracing -

Originally Posted by Bullockracing

If you can, the Subaru boxer engines are flat, aren't they? Or an air-cooled VW, although not very FE.

For a solution on mounting the engine lower, a dry-sump pan will let you lower the engine significantly. It may be costly, but it also reduces parasitic drag from the crank splashing in the oil, and you can use an electric oil pump, further reducing working HP required to turn the engine.

That's egg-zactly what I was thinking.

CarloSW2

[Shawn D.]

Well, how "low" are you and your passenger going to be? That's the frontal area issue, not the engine. If you put the engine upright behind you and your passenger, it will have a negligible effect on frontal area.

Even if your scheme was practical, there'd be no "pumping gains" to be had, really. Taking a few bends out of the exhaust is going to have a negligible effect. You'd be better off to fabricate a system with mandrel-bent curves instead -- gains from that are noticeable and well-documented.

[evolutionmovement]

The Subaru engine has the benefit of better low-end torque so you could get away with taller gearing with less of a penalty. But then there's the weight, which isn't bad for an engine with two heads (I can lift a long block with the intake manifold still attached and I'm not a big dude), but must be more than a 1.6 Honda. I wouldn't bother going dry sump for minimal gain unless you're really loaded. I looked into kits for various plans and they were more than the whole drivetrains I was looking at.

[theunchosen]

Ok I'll try and respond to everything at once isntead of 3-4 posts and quotes.

The idea is to get the car low, with the engine in the middle of the car, with tandem seating(to reduce frontal area), front wheel drive.

It could be a subaru engine except ideally I want all the crowns on the same side of the block. As I stated this is a future project for sometime when I don't have college loans, so consider expense less relevant than it normally is here.

The idea behind this topic is alot of time goes into engine design to figure out how to keep the exhaust as straight inline as possible. The less restrictions the air faces the less pressure needed to make it move(force,what I have to pay for, divided by area.) So obviously if I can create a system that has even fractionally lower pressure in the exhaust its worth it as far as stress on the engine and FE.

It doesn't need to be a 1.6 Honda but thats the only thing that I am very familiar with so thats whats in the model as far as proportions and heads. Something with more low end torque is always good. In a situation where custom trans can play you can make the gears about as tall as you like and more of them to avoid high rpms or lugging.

current model height is 45 inches with wheels and tires(4.5 inches shorter than my Del Sol) and 4 feet wide(a little over.)

The question is about the gains to be had from allowing very literally Straight Pipes from the exhaust directly out the top of the block with no twists or turns whatsoever.

[Frank Lee]

Something tells me this ain't gonna happen.

[theunchosen]

Originally Posted by Frank Lee

Something tells me this ain't gonna happen.

you're probably right ^_^

On the other hand I am definitely looking for a narrower shorter platform. I'm also looking for something reliant on CF and heat shielding to reduce weight to well under a ton. And lastly I don't need any of the other features in standard platforms.