Import Tuner Magazine : Project Sipper ('92 Civic VX)

[pgfpro]

Originally Posted by serialk11r

Ehhhh...
Forced induction often does not result in a lighter engine. Often times they throw in heavy iron blocks which ruins any sort of weight saving. For example the iron block 3S-GTE weighs more than a 3.5L 2GR-FE (with a cam swap easily makes well over 300hp). Turbo/supercharger hardware can add 100 pounds to an engine that was only 250 pounds to begin with.

To get a high power/weight ratio engine you first want a small stroke, maximum possible revs, and then very high boost (hey what do you know, F1 is running the smallest possible stroke, as many rpms as the regulations allow, and when turbos are around, as much boost as possible). With the <1 bar boost that most cars have the turbo barely adds to the power/weight ratio of the powertrain, especially because of the increased torque which needs a stronger transmission.

Now you can nitpick and say certain setups such as a centrifugal supercharger are extremely light, but forced induction is typically going to lower the engine's thermal efficiency under load.

Anyhow my point is naturally aspirated engines are used in racing for a reason.

My real example using the same exact engine.
Engine: Honda D15 1.5L
Car: My sons 92 Civic Hatch


Accelerating Test Used:1/4 mile Spokane Raceway

N/A D15 1.5L 16.11 @ 84 mph
Turbo D15 1.5L 13.7 @ 102 mph (50 lbs heavier then N/A from turbo kit)

Using a 1/4 mile calculator I would need a 2.9L that weighs the same weight as the N/A D15 to run the same time as the D15 with the turbo???

[BongoBennie]

Originally Posted by serialk11r

I know that. However to make it worth the extra piping you have to run significant boost pressure, preferably at high rpm. The engine block may be smaller but the extra exhaust piping, intercooling, etc. will add weight back. A small 4 cylinder engine weighs barely over 200 pounds, so a 40-50 pound increase from a turbo kit is very significant.

You can't say you know how much all these things weigh as there are 4 cylinder engines that weight more than V6s etc, you are also not considering the rotating/reciprocating mass.... turbo are actually used MORE for efficiency than max power, thats why just about every big rig, tractor, train, bus etc in the world has one

There is a theory that an engine with low enough yet still positive manifold pressure will actually get better MPG than the same sized NA motor because the motor doesn't have to 'suck' the air in...... Im not too sure about that since our atmosphere is technically under pressure, but it might.

[BongoBennie]

Originally Posted by serialk11r

If you look at the 1ZZ-FE development paper for example, you'll see that connecting rod mass does affect fuel economy on the order of ~0.5% for a ~10% increase. For the ultimate eco engine, you could have a low rev limit like a Prius (4000rpm), extremely thin titanium (you can go titanium MMC if that cash is really burning a hole in your pocket) or maraging steel rods or something that weigh 1/2 of stock (might not be able to go this light because of stiffness problems), extremely delicate and light pistons, knife edged crank, extremely weak valve springs, titanium valves, reduced deck clearance, 14:1 compression ratio with 280 degree intake cams that have very low lift. That would be like the dream efficiency engine, given a well sorted combustion chamber and direct injection and other goodies. Oh, multipoint laser ignition as Mazda is developing would help a little too, but you can't buy that.

As tempting as it is to do a build like this, I'd am saving my big money for an electric build..... I have a K24 civic to build as well..... I need a damn sponsor

new accord 4banger is direct injected, looking into its possibilities as well, also that new Fiat car is cam less, very interesting as well.

[BongoBennie]

pgfpro, is that civic engine/tranny still the VX? is there any more info on this? VERY interesting!!

[pgfpro]

Originally Posted by BongoBennie

pgfpro, is that civic engine/tranny still the VX? is there any more info on this? VERY interesting!!

This engine is just a D15B8 that we pick up used with 175k miles on it. Still running strong and back to N/A. It was 100% stock. We then bought a foreign exchange D16Z6 the Japanese type, and ran it for a couple years. Then we put my Vitara built D16Z6 engine into this hatch, that came out of my Del Sol.

My hatch the black one next to my sons white one had a major built D16Z6 that ran 11.8 @132 mph


Then we switch to a B16 VTEC


I never had a VX engine just the trans. I converted all these engines exc.B16 to my own design lean burn.
I started with Haltech stand alone then CROME, then CROME PRO, then Neptune using a P28ecu.

[BongoBennie]

pgfpro, i hate you..... (not really)... My plan is to drive the crx vx to work and back (75 miles a day), so I can take my 04 off the road and rebuild it..... but I would so love to turbo the crx run 13s and get 60mpg..... but with lean tuning, what can you get out of a k24 3000 pound civic? I average 30 with it now. I still have the K20 and was thinking about turbocharging it. I did run E85 in it for 2 years when I lived close to work, if I could get 30mpg on E85, I would be very happy!

[BongoBennie]

also, do we know how strong the VX internals are compared to other d series?

[pgfpro]

Originally Posted by BongoBennie

pgfpro, i hate you..... (not really)... My plan is to drive the crx vx to work and back (75 miles a day), so I can take my 04 off the road and rebuild it..... but I would so love to turbo the crx run 13s and get 60mpg..... but with lean tuning, what can you get out of a k24 3000 pound civic? I average 30 with it now. I still have the K20 and was thinking about turbocharging it. I did run E85 in it for 2 years when I lived close to work, if I could get 30mpg on E85, I would be very happy!

I would think you would be able to run 13's in your CRX pretty easy with a turbo.

I messed with a customers K20 that had a generic turbo kit. We had it getting around 32 mpg avg with k pro. I just didn't get enough time to see what it really could do? So I'm not to sure on that one.

Running E85 you will lose some fuel mileage do its lower btu content. You might be able to get it back to a petrol base by increasing the compression?

BongoBennie also, do we know how strong the VX internals are compared to other d series?

The D15 rods look like they should be in a lawn mower. They are extremely small in size compared to the D16Z6 rods. So i can't imagine the VX rods being any smaller? lol

[serialk11r]

Originally Posted by BongoBennie

You can't say you know how much all these things weigh as there are 4 cylinder engines that weight more than V6s etc, you are also not considering the rotating/reciprocating mass.... turbo are actually used MORE for efficiency than max power, thats why just about every big rig, tractor, train, bus etc in the world has one

There is a theory that an engine with low enough yet still positive manifold pressure will actually get better MPG than the same sized NA motor because the motor doesn't have to 'suck' the air in...... Im not too sure about that since our atmosphere is technically under pressure, but it might.

Those are diesel engines, not the same thing. A spark ignition engine running 1.1 equivalence ratio, max possible compression with minimum possible pumping and volumetric efficiency, and a turbo to recover the very slight amount of blowdown would be more efficient than a diesel at peak load yea. Efficiency depends on application and operating conditions.

[BongoBennie]

Originally Posted by serialk11r

Those are diesel engines, not the same thing. A spark ignition engine running 1.1 equivalence ratio, max possible compression with minimum possible pumping and volumetric efficiency, and a turbo to recover the very slight amount of blowdown would be more efficient than a diesel at peak load yea. Efficiency depends on application and operating conditions.

More than anything, it depends on how you drive, and while diesels do operate differently, they are still pumps. The same vehicle with a turbo motor will almost always come with a smaller engine that makes more power and if you stay off the gas, it will do better on gas... those are the facts.