Automotive X Prize - would a modded Civic VX make it?
 

Is anyone familiar with the "Automotive X Prize"?

Basically, it is an X prize to produce a production vehicle that gets 100 mpg.

Seeing as you all have a lot of experience with some cars that come close or meet that bogey, I wonder if you would critique my idea for an entry.

I'd be starting with a '92 to '95 Honda Civic VX with the manual tranny (44 mpg EPA highway).

If you are familiar with the Import Tuner space, you know that there are a ton of performance mods for this car. I would be applying as many weight saving and efficiency enhancing performance mods as possible.

For example, you can get carbon fiber doors, fenders, hood, spoiler, air dam and hatch for this bodystyle. You can get weight saving polycarbonite windows. You can get weight saving aluminum control arms. You can get springs that lower the car dramatically. Lightweight seat are also available.

On the efficiency front, you can get underdrive pulleys, headers, freeflow exhaust systems, cold air intakes, larger throttle bodies, and freer flowing intake manifolds.

For some more unique items, I would be looking to replace the side view mirrors with backup cams (eliminate the drag due to mirrors). I'd be looking for some other more... unique hacks of the ECU to enable start-stop, cutting fuel on deceleration, and alternator cut out on acceleration.

It goes without saying that I would use low rolling resistance tires and a low drag suspension alignment (those aluminum control arms have a lot more adjustment). Also, some of the tuner items like adjustable fuel pressure regulator and cam phaser would offer more tuning ability.

My question to you experts is, do you think that this would be enough to get in the 100 mpg ballpark? Lighter weight, less drag, more engine efficiency, optimal tuning and setup?

Or would I just be wasting my time?

Welcome to the site. I am indeed familiar with it, and you have some interesting ideas.
These all sound like they would influence the weight quite a bit, but at a huge cost burden, I would say to hold off on this until the end. Especially the spoiler bit, :p

I would be careful before adding any of these things to be honest. You have to remember that a fuel efficient engine does not a fuel economical car make. It's no help to use 20% less fuel per HP if you're making 30% more HP....you'll end up using more fuel in the end.

When working with the vx, it's best to take your design queues from honda, I think.

It's good that you've thought of removing the mirrors, but that's nothing compared to the whole world of aeromods out there. I honestly don't think you'd make it to 100mpg without tapping most of them a decent amount.

Can you hack the p07 yet? The last time I was on pgmfi.org it was not doable still....

I think if you looked more into the aeromodding part of things, you would be well on your way to the realm of possibility.

:turtle:

Thanks for the feedback.
 

The point of the engine mods would be to make the engine more freer flowing. Less drag in the intake and exhaust system. Lighter engine components (how about an aluminum flywheel, for example).

I think that you are right that, without some tuning, this could just increase HP without a corresponding increase in fuel efficiency.

That's where the adjustable fuel pressure regulator, cam phaser, and dyno time come in. You need to do your time tuning the thing on the dyno.

Maybe I mis-spoke by sayiing ECU hack. It could be that these features would be enabled by outboard systems.

Regarding the carbon fiber, no doubt they're expensive parts. The doors along go for $1600. The hood is like $500, the fenders like $600.

One reason to use them is that the vehicle needs to be production ready. To go into the competition with a readily available production car (even one currently out of production) modified with readily available aftermarket parts (no matter how expensive) would give you a huge leg up on some of the competition.

The CF parts do lend a sort of... technogeekishness to the car. That's not for nothing.

Aeromod wise, first pass is the lowering springs, front air dam, mirror delete, and rear spoiler (a small ducklip on the hatch, not a big, stupid one like you see on a lot of the imports). There is a radiator blocker for the VX as well. Maybe an underbody pan (might be moot if the thing is low enough!).

What else is out there for aeromods? Are they really worth the extra weight at 55 mph?

What's the methodology for the X-prize testing? Is it just - throw it on a dyno, then multiply by a scalar correction factor? (which I believe is how the EPA does it - or maybe did it)...

If that's the case - focus only on mechanical, not aero. Yes, I know aero is just as important - but that's not how one wins a competition as this :p And you know, if the above scenario is the case - the big players will do just this (and might have a cool looking exterior)...

I guess I'll echo treb's comment here...it would very much depend on how the testing is done. Can you tell us that?

And if it's done with real driving (ie wind) the extra weight for aeromods will be well worth it.

According to Wired...
 

There's going to be a road test. Aerodynamics is VERY important.

But... The VX hatch is pretty aerodynamic to begin with. What's its stock CD? 0.25? Something like that?

What would the modifications I'm considering get you? Under 0.2? There are probably diminishing returns to aeromods at some point.

Here's the homepage of the prize:

http://auto.xprize.org/

I've seen the guy on this site that has a heavily aeromodded Civic, with the nose-cone and tail-cone. I can't say that it looks right to me.

And he "only" gets 70 mpg. It's not a VX though.

Another good site
 

I would actually call the hatch very unaerodynamic. CD is .36, I believe, :p

So it's 100 mpg across country? That could be done with an insight and driving mods...I would think it could be easily accomplished with an aeromodded and otherwise stock vx.

Keep in mind that while cruising on a highway weight is going to mean very little to the feul economy of the car.

Check out this link
 

This is a paper from 1992 on the VX

I was wrong, the CD of the VX was 0.31. So aeromoding would do a lot of good, huh?

I was also wrong on the highway fuel economy. The VX was good for 55 mpg!

According to this paper, the VW had a weight reduction of 80 lbs., which was good for a 2.5% improvement in fuel economy. Going from 0.32 to 0.31 on the CD was good for 1.5%.

I think that you could get a pretty significant weight reduction with the carbon fiber, etc.. 100 lbs. would be easy. 200 lbs. might be possible. Would that be good for a 6.25% improvement in FE?

Could you get down to 0.25 on the CD by lowering it, an air dam, mirror delete, and a spoiler? Would that be good for another 7.5% improvement?

Engine mods maybe get you another couple of %. Let's say 2%.

That's a roughly 15% improvement. You'd need a 81% improvement.

Can that gulf be bridged by the electronics mods (start-stop, engine cut off on decel, alternator cut off on accel)? And driving techniques? And tuning?

Ah, I have seen that paper before, but it's worth another read.

Really, .31? Every source says something different...But yeah, you would get a lot of good out of aeromods.

You weren't "Wrong" on the fuel economy, but there are different tests used by the EPA these days compared to the old tests.

I think if you could get 250+ pounds removed it would be worth it. I would strip the interior and things as well.

I'm not sure on .25 out of just that. Compare to the insight, which is rather definitively known to be a stock .25...Some wheel covers and a boattail would definately help. Mehbe treb will chime in, but he has a breakdown of where aero drag occurs and I think about a 1/3rd is after the car in the wake.

I doubt how much electronics will help on a highway trip. It's already doing fairly well with the lean burn and you won't be stopped too much. However, combined with good aeromods and LRRs, I think driving technique could bridge that gap.

I think I'm something like 80% over epa in my car, but then I started with an auto...darin has done 130+ mpg circuits with his metro. *shrug*

Fundamentally - there's no diminishing returns for cD - it's actually the opposite :p .1cD versus .2 cD halves for the force... .2 vs. .3 is a third :p

But, the mechanics half has to be able to keep up. Less force to overcome isn't any good if you're power plant is too big to begin with.

It's just exponentially more difficult to lower cD the further down you go. Not diminishing returns - just exponential investment :p

^^ For everyone... Keep in mind that cD isn't anything like HP.... Unlike something like a WAI etc. it's a bit more difficult to predict a number (even a range) of cD reduction. And of course, no one thing will be the savior of poor aero design - it's a package deal.

Common misconceptions about the EPA test
 

Guys, the EPA mileage test has not fundamentally changed since it was first instituted in 1975.

What has happened is that in 1985 and 2008 the EPA has appled "reduction factors" to make the mileage more realistic.

Look at that paper that I linked to, they discuss the 1985 reductions.

The CAFE standards written into law use the original 1975 standard, BTW. So my Saab 9-3 2.0T, which got 28 mpg under the 2007 standard and gets 26 mpg under the 2008 standard, has a CAFE number of 34 mpg.

Neither here nor there, but I did want to clear up that misconception.

Interesting point. Maybe 97 hp is too powerful for what I want to do.

Anybody ever turn a 4 cylinder into a 3 cylinder? Plug off the ports, take out the piston and con rod? Probably throw some wicked codes!

Another alternative might be the industrial diesel engine route. Briggs and Stratton makes a 3 cylinder industrial turbodiesel that makes 37 hp.

The B&S honestly sounds like a great idea. Match it to some ridiculously tall geared 5th that has it plugging away at 1k rpms at ~50 mph and you'd be set.

Sweet - my outdated knowledge hasn't let me down :p

2 relevant Ecomod rides
 

Well, I looked through the garage, and there are 2 Civics that could be templates for my AXP ride.

Aerocivic is a DX hatch with heavy Aeromods. He averages almost 70 mpg.

Thrifty McGasaver has a VW with some of the mod's I mentioned (carbon fiber hood, lowering springs), yet he can't even hit the EPA numbers!!!!

Damn it! This is going to be harder than I thought.

Looks to me like his lifetime AND 90 day average are over the New EPA Combined number of 43mpg. These cars need to be driven gingerly to achieve these numbers. It doesn't happen by just slapping together top shelf parts.

Yes, it looks like you have your work cut out for yourself. But if it was easy, everyone would do it. ;)

Don't get me wrong...
 

... I knew there would be work to be done. Hacking the electrical system to make it a mild hybrid, for example.

I'm a mechanical engineer, not an electrical engineer. So the hack would tax my skills.

But it looks like waaaay more engineering is needed is needed. More than just buying some parts and installing them (for which I am fully competant).

I'm now thinking that I might have to custom fabricate some carbon fiber suspension components. Carbon fiber halfshafts, anyone? Carbon fiber control arms? Front Subframe?

How do you cut 500 lbs. from a car without gutting the interior?

Engine swaps? Especially gas to diesel swaps? That's tough stuff. A diesel doesn't help the lightening process, either. They're all cast iron. Very heavy.

What does the VX weigh compared to the CRX? SVOboy would know. Why not start with a lighter vehicle in the first place? Swap in the VX Engine/Trans etc.

Just a thought

The crx does make more sense. If you get an 88 HF you have an instant ~250 bonus over the VX and the owners manual lists the drag at .29 for the HF. :)

You guys are frickin' GENIUSES
 

Very good idea. VERY good.

The CRX body is totally the way to go. Why didn't I think of that?

And there was a JDM VX engine on ebay a couple of days ago.

Still would probably was the VX tranny as well, with its ultratall gearing.

HF tranny would be better gearing wise. If you're going vx engine talk to jdmresource.ca or something like that...they've got good deals.

Also, a custom 5th gear might be good for the highway.

No carbon fiber doors for the CRX :(

Okay, I obviously have a thing for CF.

lighten up a CRX, the 90-91 models have a lot of CF available, but then you'd be spending a lot of $$ to end up at the same weight as a 1st gen CRX.

Seriously though, get a HF, toss the engine and replace with a small diesel.
This one might work, but turbo-diesel would be better I assume.

You wouldn't be getting 0-60 any time this decade, but man the MPG would be killer.

Don't buy a first gen crx though, there be dragons in them waters.

What dragons do the 1st gens have? The main thing I don't like about them is the lack of the lower rear "window" that and the kinda fugly front end. But they're light weight as hell, plenty of autoXers run them for that reason alone.

^
Not really, Here's a quote about the "approximate" fuel mileage that it gets. Looks like he drives fast, if your gonna be in the contest, you're not going to be driving fast, you're probably gonna be driving the speed that the car gets when it is shifted into last gear and no faster. probably around 50mph.

Not sure on the drag, but the first hf was only 1713 pounds, only about 100 less than the 88 hf, and it's much more troublesome to put a VX engine in there.

Actually, you do want increased engine efficiency
 

Just because a modification increases the engine's MAXIMUM POSSIBLE power output doesn't mean that it decreases fuel economy. Underdrive pulleys, lightweight flywheels, free flow exhaust systems, etc...make the engine more efficient because they decrease the drag on the engine...so it takes less work (work...as in calories, joules, foot pounds) to turn the engine...therefore LESS fuel is used. Its true that these types of modifications increase horsepower...but you only see that increased horsepower if you have a lead foot...and even then the engine operates at maximum thermal efficiency at full throttle since the cylinder pressure is maximized (not that maximum FE is achieved by maximum power at max thermal efficiency).

Actually, if I were you I would use the smallest engine displacement possible. The best way to do this would probably be to destroke it (if the corresponding piston and rods to maintain piston to head clearance are available) and either turbocharge it or go with a higher compression ratio, but only turbocharge if you can significantly reduce the displacement....and even then use only a few psi of boost so you don't start guzzling gas. That would maximize your thermal efficiency. Turbo engines have high thermal efficiency because they take waste energy (exhaust heat) and convert it into useful work. High compression engines have higher efficiency because the increased cylinder pressure maximizes the PV (pressure-volume) work extracted from burning a given amount of fuel. A small turbo engine uses less fuel than a large NA engine of the same power output. Same with a high compression engine. Diesel would be best though...and turbodiesel is the best of both worlds...maximizing cylinder pressure at a given power output with both high compression and boost, and harnessing waste energy with the turbo.

You could also use themal barrier coatings in your combustion chambers and piston heads...so there would be less heat loss into the cooling system. Using a thermostat that raises you engine temperature would also increase efficiency...my grandpa was a mech engineer and did this big study on thermal efficiency when he was in school...always said engines run more efficiently at higher temperatures.

I guess the whole point I'm trying to make is that to get maximum fuel economy at a given power output, you want to minimize engine drag and maximize thermal efficiency. Coincidently...this will also increase your full throttle horsepower if you ever choose to go there.

Actually...if you were to pull out 2 of the pistons and rods on a 4 cylinder engine in such a way that you kept an even firing order (such as 1/4 or 2/3) and removed the rocker arms on the dead cylinders so the valves stayed closed, that would cut your displacement in half (Should probably modify the counterweights on the crankshaft to keep it as balanced as possible). If you removed pistons 1/3 or 2/4, etc...you wouldn't have an even firing order but the crank would be better balanced as far as mass is concerned. This would probably require the best crank damper available either way. Then if you turbocharged it, used thermal barrier coatings and minimized engine drag and rotating mass...that would probably get you about the best fuel economy possible without making the thing too unbearable to drive.

Removing pistons like this is a pretty extreme way to modify an engine that I've never seen done, so I'm not sure the thing would run smooth...but it would cut the displacement in half which should help in theory.