Fuel Economy Improvements.

[vr4-fan]

I can buy a no. 7 ???

[Turbo_Steve]

Yes. They will be fine. If you have any problems, gap them a little smaller.

[MarkSanne]

What would typical gap-related issues be? I replaced my plugs for NGK iridiums "7" last weekend together with decat and apexi BOV and now the engine had an occasional shudder. Doesn't matter if the car is at idle or driving, in N or D, but it's most frequent in the morning at cold start.

I checked all the vacuum hoses. Yesterday I replaced the the apexi with the modified original mitsu recirc bov (which is not connected 'back' anymore so it makes the 'pssst' sound already at 2000 rpm when you take the foot of the gas). Not really closer though... maybe it's the gap from the new sparkplugs?

[Turbo_Steve]

At a gap of 0.7mm you shouldn't have any problems, and that's how mine arrived.
The only times I'd expect to see problems with a bigger gap is at high boost (i.e. when you hit max boost, or if you're running above std boost) or when the car is really cold it might be a bit "chuggy" when you start it. But that's it.

Have you checked the HT leads are on properly? They may not be...or may simply need replacing. Mine did.

[vr4-fan]

the number 7 , WORK fine , with 8 psi , and 1 time a month with 15 psi ???? let me know because I want to buy a new spark

[Turbo_Steve]

Yes. They will be fine. If you have any problems, gap them a little smaller.

-ahem-

[Turbo_Steve]

And if you really have a direct and simple question, you should start a new thread and not HiJack others, really. It makes it a lot easier when people USE THE SEARCH FUNCTION!!!!!

[vr4-fan]

ok thanks

[VRNew]

I just posted some questions about Ecotek on a different forum. I got one of these valves in my VR4. The result is ..hmmm.. disputable.
More economy, more torque but not sure if the car does 0-60 in the same number of seconds...any thoughts?

[Turbo_Steve]

They mostly work by allowing a little leanness.
The reduce the continual load of the brake servo...but I don't think it's very significant. The unmetered air probably makes more of a difference on a vr4

[VRNew]

They mostly work by allowing a little leanness.
The reduce the continual load of the brake servo...but I don't think it's very significant. The unmetered air probably makes more of a difference on a vr4

I guess you right ^^.The Ecotek guys think it improves the efficiency of the fuel burn by creating an air vortex effect in the manifold (you probably heard that many times before). I had it on a WRX 5 years ago when i used to do 100 miles daily... I must admit I had cca 12% to 17 % fuel economy on normal motorway drive. That's why i put one in the leggy. I'll keep on eye on it at the moment...

[MunkyWrench]

Surely cruising at 80mph the turbos are not boosting the engine simply using exhaust waste energy to overcome the pumping losses and give only slightly over atmospheric pressure, but not a vacuum. Therefore that should easily make up for the loss from the compression ratio and then some. So the engine should be more efficient than the normal v6 surely?

I don't think you understand pumping losses enough.

If you are interested you should research Brake specific fuel consumption and the effects it illustrates.

Essentially, it shows that WOT at a certain RPM is the most efficient at turning fuel into output energy (power!), and turbo charged cars are paricular prone to the effects.

Cruising is innefficient because the throttle plate is not all the way open, it is a large restriction and causes much pumping loss.

In a cruising turbo charged car the turbos main effect is a quite severe exhaust restriction that harms the pumping efficiency further.

In a turbo charged *performance* car I think you would see the lowest BSFC is no where near the power output required to cruise - I would think it'd be at a higher output - unfortunately this more efficient energy production being only available for higher output means we have to accelerate to take advantage of it
We have heard it before: "can't have the best of both worlds".

When you plot BSFC against RPM at several throttle angles you will see the lowest curve is WOT, and for a production car it starts high and falls in the mid range and rises again. (Google BSFC for reasons)

Race cars have lowest BSFC at WOT at very high RPM due to appropriate cam profiles and porting etc.

The honda insight has low islands in the BSFC surface at two points -idle and the RPM that the engine runs at when generating electricity.
The two islands are made possible by the use of VTEC. ie. dual cam profiles!
cam switching is the easiest way to change the BSFC of an engine on the fly.
VVti,Cylinder deactivation...



An N/A friend of mine once spoke of turbos as " leaving more power in than they take out". Which I agree with.

Anyway end rant.

BSFC tells us what most of us already know - that that the approptiately sized engine for maximum efficiency is the smallest one that will do the job.

Google BSFC!