Engine technology thread.

[Matador]

How the hell did this thread get to 4 pages?

Originally Posted by Exage

You should look at the older VTEC, i-VTEC, MIVEC, and VVTL-i systems (among others). You want kick in the seat? Single cam-shift... There is nothing that will replicate those systems in the coming years with Variable Valve Lift mechanisms (see BWM Valvetronic, Toyota Valvematic, Fiat Multi-Air etc...) being implemented. An interesting fact is that BMW Valvetronic and Double VANOS systems control the intake and exhaust valve lift so well that they don't need a conventional throttle plate to control the engine.

As is the case with Nissan's NEO VVL and Toyota's Valvematic. Mivec is old.. akin to Honda's VTEC. Not sure if Mitsubishi have updated it with new features/style of operation. i-VTEC is on the level of Toyota's VVTL-i.

Originally Posted by Dimman

DOHC eventually became standardized, when companies were using Twincam, and even Quadcam for some of their motors.

Variable lift with cam phasing, is how I would describe Toyota's application of Valvematic.

There's pretty much only the three mechanisms I can think of.

Variable Valve Lift (Valvematic).
Cam Phasing (VVT-i)
Cam profile switching (VTEC)

Most of the named systems like VVTL-i, iVTEC, Valvematic, etc... are just combinations of these.

It's just wishful thinking on my part...

Valvematic and Valvetronic are far more than just a variable cam timing and lift system. I see I'm late to the punch, that video should clue you into what it's all about.

Originally Posted by 1GoZoom

Honda wins in this category. VTEC is a household name. Impressive brand marketing for something as mundane as timing of intake and exhaust ports. lol.

The only thing honda wins at right now is the VTEC brand recognition. Not even sure if that's in a good way. VTEC kicked in yo.

Originally Posted by Exage

Back to more relevant thread topic... It would be interesting if Toyota/Subaru do a turbocharged version of the FT's engine with a variable geometry turbocharger rather than just a twin scroll.

But I must point out that if they start putting to many technological things on the engine it not only is more expensive but also harder to tune and modify for average joe without breaking the bank.

Toyota have been HARD at work with some interesting turbo technologies, including Variable Geometry (already found in some of their turbo diesels I think) and Electric spool assisted turbos. Good stuff. It is however, anyone's guess when they will turn up... probably late to the party as they have been these days .

[ichitaka05]

Originally Posted by Exage

Subaru Forester FB Engine


I personally don't have any experience with a boxer engine but I can hazard some guesses.

Bolt on modifications I think would be relatively easy. Consider the air intake manifold (and plumbing) being on top of the engine, exhaust on the bottom both of which I believe could be easily accessible leading to relatively easy installation of cold air intake, throttle body, intake manifold, header and exhaust components (cat-back and the like).

I think problems start to occur when you want to say swap camshafts, valve springs, spark plugs, (direct injectors,) and work on the head with the valve cover removed (valve lash) because of the limited space between the heads and the sides of the engine bay. I'm not saying that it's not possible, I think that it would however take a lot more time and swearing compared to a strait or small angle V engine.

This is with the engine still bolted on the car of course!

Perhaps Ichi or someone with boxer experience could shed some light for us?

Pretty much you got it. So when you wanna do internal mods like cams, v-springs, resurfacing/port polish, & etc, I would recommend do it all at one... but some mods like injection, clutch, flywheel, intake mani, throttle body, pulley, and spark plugs can be tricky but can be done without pulling the engine out or pulling your hairs out. Now H6 in other hand (like EZ30 & EZ36), they're lil bit nightmare than FB engine imo

[serialk11r]

Oh I just remembered, with Valvematic since valve lift (restriction basically) and duration are correlated, mods to increase intake flow will actually benefit fuel economy as well. Regular engines need a throttle to restrict air, so restrictive intake doesn't hurt economy since the car needs to run at partial throttle anyways. The efficiency penalty from sucking more air in exceeds the efficiency benefit from less pumping loss at around 80% max. torque or so on throttled engines I think. Variable valve lift will lower this.

On fuel economy websites they do warm air intakes, basically trying to suck air around the exhaust to heat it up, to reduce the air's density and let the throttle open up more, reducing pumping loss. Variable lift could change this too, making cold air intake have less throttling loss at part load and since it's more thermodynamically efficient, possibly have increased fuel economy from cold air intake.

Not that people care that much lol.

[Dimman]

Originally Posted by serialk11r

Oh I just remembered, with Valvematic since valve lift (restriction basically) and duration are correlated, mods to increase intake flow will actually benefit fuel economy as well. Regular engines need a throttle to restrict air, so restrictive intake doesn't hurt economy since the car needs to run at partial throttle anyways. The efficiency penalty from sucking more air in exceeds the efficiency benefit from less pumping loss at around 80% max. torque or so on throttled engines I think. Variable valve lift will lower this.

On fuel economy websites they do warm air intakes, basically trying to suck air around the exhaust to heat it up, to reduce the air's density and let the throttle open up more, reducing pumping loss. Variable lift could change this too, making cold air intake have less throttling loss at part load and since it's more thermodynamically efficient, possibly have increased fuel economy from cold air intake.

Not that people care that much lol.

As an owner of a high-performance turbocharged car, you can probably understand how the concept of deliberately warming intake air hurts my brain.

[aliphian]

Originally Posted by RRnold

That's what made GP fun to watch when I was a kid. Highsides were plenty!

Randy Mamola!!

Two words, Garry McCoy. /threadjack

[serialk11r]

Originally Posted by Dimman

As an owner of a high-performance turbocharged car, you can probably understand how the concept of deliberately warming intake air hurts my brain.

So it should be good news that in the future, warm air will have absolutely no benefit whatsoever even fuel economy Future's looking pretty good, I just hope I can afford it when the time comes :O

[Exage]

Originally Posted by serialk11r

On fuel economy websites they do warm air intakes, basically trying to suck air around the exhaust to heat it up, to reduce the air's density and let the throttle open up more, reducing pumping loss. Variable lift could change this too, making cold air intake have less throttling loss at part load and since it's more thermodynamically efficient, possibly have increased fuel economy from cold air intake.

Not that people care that much lol.

I don't see the point in doing that when you could slightly increase exhaust gas recirculation (EGR) to decrease oxygen (and thus fuel) during the intake stroke and lower emission levels. I guess they're just being frugal.

The problem I see is; What happens when they decide to take their car up the mountain on a nice summer day?

You're engine is sucking in hot low density oxygen (air) probably past the ECM or ECU recommended parameter and it is trying to reduce the chance of detonation (knocking) by running a richer mixture (more fuel) to cool engines intake mixture which shouldn't be happening in the first place. Not to mention you're going up a mountain so you're going to have to throttle it even more because of the loss of power and your less dense hot air intake suddenly not only becomes useless (because of wider throttle opening) but actually hurts the environment (increased fuel consumption and emissions due to rich mixture) and may cause damage to the engine (knocking).

[serialk11r]

Exactly, thermodynamic efficiency is also down under all conditions due to the higher intake air temp, so under acceleration it loses efficiency since you do need most of the available torque. The only scenario where it does anything good is when you're under cruise, you can open the throttle more and reduce pumping loss by a good deal due to the decreased air density.

Surprisingly I don't think fuel economy oriented people try to make their exhaust flow better. Back pressure in the exhaust directly cuts into power, and reduces efficiency. Maybe it's not cost effective. Maybe a loud exhaust and eco friendly image don't go together >_>

[Dimman]

Under cruise, couldn't you just lean out the fuel with a controller? If there's no load, there should be no detonation correct? I've heard this is what planes do.

[NESW20]

Originally Posted by Dimman

Under cruise, couldn't you just lean out the fuel with a controller? If there's no load, there should be no detonation correct? I've heard this is what planes do.

if you don't have a catalytic converter, then yes, you can run lean under cruise conditions. i run 15:1 or higher a/f ratio under cruise conditions.

[Dimman]

Originally Posted by NESW20

if you don't have a catalytic converter, then yes, you can run lean under cruise conditions. i run 15:1 or higher a/f ratio under cruise conditions.

Much more sensible than an intake air heater (shudder...).

[Matador]

Originally Posted by Dimman

As an owner of a high-performance turbocharged car, you can probably understand how the concept of deliberately warming intake air hurts my brain.

[Allch Chcar]

Wow, way to go guys, you turned this into a fuel efficiency thread .

The warm air intake works by reducing engine power. In most cases this means better mpg for a given gearing. Hypermilers take it easy so a lack of power isn't a problem. Cold air intakes are designed to increase power by increasing density, this is done for power not MPG. A smaller exhaust is better for MPG since it helps with velocity and therefore torque at a lower RPM. If you keep below 3k rpm where the exhaust isn't restricted a "pea shooter" exhaust would work without a problem. A bigger exhaust would only help upper RPM torque and even more so with a turbo car.

+1 for NESW20 for mentioning the catylictic converter problem. Lean burn might be good for fuel economy but it burns more oil and I'm pretty sure it can be bad for the cats too.

Hypermilers that drive OBDII(post '96) cars get a scangaugeII and watch their throttle, load, and fuel consumption. Anything over 2/3 throttle or so is open loop. Below that it's usually stoich(neither rich nor lean) so fuel economy is better than open loop even though full throttle(less) should be more efficient and more powerful. With regular grade Gasoline at the compression ratios an economy car has it would detonate at high loads without a rich mixture but at low loads and low throttle the efficiency is better with a higher compression ratio.

Now who wants to discuss spark advance and air:fuel ratios! :P

[Exage]

Originally Posted by Allch Chcar

A smaller exhaust is better for MPG since it helps with velocity and therefore torque at a lower RPM. If you keep below 3k rpm where the exhaust isn't restricted a "pea shooter" exhaust would work without a problem. A bigger exhaust would only help upper RPM torque and even more so with a turbo car.

With that being said I'm surprised they (the environmentalists) haven't tried making their own custom eco headers! Or have they and I just haven't bothered researching it?