Blackflag

Those reports are all based on dyno testing. That's how you compare engines - back to back on a dyno, measuring fuel consumption, in a lab. Not according to what two mpg "window stickers" say for two different vehicles, different weights, different engines, different years. Seriously, give me a break.

And the Ford engine is a smaller engine. Or are you saying 5.4L vs. 7.0L is apples to apples now? Why do you want to ignore vehicle weight and engine displacement? Again - give me a break. I mean, in your previous post, you wanted to compare an Impala (though we dont' know what year) with a 5.7l engine to a new S Class with a 4.6l, and is 1000 lbs. heavier, different transmissions, different gearing... Give me a break. If you want to compare vehicles, then compare vehicles. But if you want to compare engines, it's done with dyno data.

If you want to be scientific, then be scientific. If you want to be a clown, then be a clown. But you know the difference. What you're trying to do is like saying the tires on a Cadillac must be less efficient than those on a Neon, because the Cadillac gets worse fuel economy. It's just a little more complicated than that.

Nero

Ok, lets face it the only thing that improves the fuel rating is the air flow, compression, spark, flowers, headers, fuel flow. shocks, psi for the tires, weight, and airodynamics. The number of ports only helps with the injection and and extraction. It realy does not help fuel rating only performance.
Also let it be know that if we learned anything from the cars from the 70's it is that you can not make a big block v-8 have a better fuel rating by lowering comprestion and de-tuning them. Its like giving a jet a muffeler to decrease nose.

lear4406

Blackflag you need to keep it above the table. If you have a point of veiw.. good. But personal attacks show that you are running out of material. That is what happens when a person does not get their way, they revert to name calling. 4V and 3V = performance, that is a given. Fuel mileage... no way. More fuel VE and more is used and at a higher RPM. Case closed and end of discussion as for as I'm concerned. Just use common sense and the answer will come. The more fuel put in the more that is used.

Blackflag

Whatever. "a greater valve area reduces any losses that may have been incurred through pumping, and there is also an increase in compression ratio, leading to a higher thermodynamic efficiency." You can lead a knowitall to water, but you can't make him drink.

RLSH700

Give me a break. First of all, I provide you with the information that those LT1 powered cars weight was less than one thousand pounds difference. The Cadillac version weighed only 18 pounds less and it still got the same mileage as the Impala SS did (weight difference of 429 pounds), and the newer Impala's (which was not what I was originally comparing) weight difference is less than one thousand pounds (754 pounds to be exact). If you read what I wrote you would know that. I provided gearing info on the Impala SS and Mercedes S-Class you ignored it. Also you need to get your facts straight, the new S-Class that I compared had a 5.5L not a 4.6L (infact I don't think they even have a 4.6L engine). The fact is the Mercedes has the advantage of more updated technology such as a better transmission, larger rims (15, 17 vs. 18s & 19s), a higher compression ratio, VVT system, from all appearances better arrowdynamics, etc. and it can't beat ten year old technology. It's especially sad that an old design routing back to the 50-60s gets better fuel economy than a current design with all the modern high tech advantages helping it.

You have been wrong over and over again on these engines. I provided tons of examples of both 2 valve pushrod conversions to OHC 4 valve engines and 2 valve OHC to 4 valve OHC engines on the same line and you ignore it and dismiss it. When you tried to dismiss it, I provide examples of other cases using the same engines in other models with evidence that disproved your attempts to dismiss it and you ignored that as well. You don't even know enough about the current engine market to know that there are still a few examples of 2 valve, 3 valve, and 4 valve headed engines on the same block line in production today. You even thought that Ford's VCT system was a multidisplacement system when it is nothing other than a VVT system.

One reason why many of these cars weight goes up sometimes after they switch from 2 valve to 4 valve is partly due to the increase in the engine's weight due to the changes. If the 4 valve system did have an advantage, it's lost by the weight and then some. If it is truely the path to pursue, this would not be an issue. The simple fact is that if 4 valves was the way to go, the most fuel efficient V8 cars on the market would be 4 valve engines, the problem is they are not 4 valve engines despite the displacement advantage that most of them have over most of these 2 valve pushrod models. Also the 2 valve pushrod models would be at the bottom of the fuel economy ratings. According to all the "official" sources, these 4-5.5 liter V8 engines should be the best in fuel efficiency and they are not. If it is a fact the evidence would be somewhe

Nero

I believe the qote is "You can lead a horse to water, but you can't make him drink."

Blackflag

But you do have a choice. The OEM's won't release their engine/dyno data. But you can read books on engines, and you can read the technical papers published by universities and research organizations, like the D.O.E. You can even read the little bit of stuff that the big 3 engineers do decide to publish. The engineers at the big 3 read all that stuff ... to see what else is going on in the world. They also look at what's being done in Europe/Japan, which you poo-poo. Believe me, they look at those engines in depth, buy them, run them, tear them down. But you'd have to want to be a hard core engine guy to go through all that stuff, it's a lot of work. Have a sweet weekend, baby!

RLSH700

I have read enough information that lead me to my view on this and have been able to actively defend my perspective without using multiple other examples I have that could weaken any of your other points that you have made thus far. Obviously those books and universities have trouble educating people on the simple fact that certain 2 valve OHV engines and 2 valve OHC engines are from the same family as certain 4 valve OHC engines and that in the process that the fuel economy has dropped during the transfer. Not too suprising since most of our country doesn't have any clue about our own national history (or anyone else's for that matter), I wouldn't be surprised if universities are incapable to see that your theory is incorrect no matter how much evidence there is to prove that 4 valves are less fuel efficient. There are a few other theories out there that supposively improve fuel efficiency that simply make it worse as well.

Your missing the point of why the Japanese and Europeans use such engines. It's primarily for marketing purposes. Generally a 4 valve OHC is more refined and quite than a 2 valve OHV engine, plus its the bragging rights purposes (I can get 268hp out of this engine while there engine of the same size only produces 224hp). Performance is the factor that drives this, not fuel economy.

Hmmm. They have all this information and GM and Chrysler still chooses the 2 valve OHV path. That must say something about that design.

Blackflag

I think you're probably right. The people who actually design these engines - the big 3 engineers - are all wrong. The european and japanese engineers are wrong, the government researchers are wrong, the universities are wrong, all the engine textbooks are wrong, all the SAE papers are wrong, and the DOE is wrong. But you're right on this point. Because... well, because you read the MPG on window stickers. That is AWESOME. I wish I were that bold about everything I 'know.' Ha ha.

I don't see anything 'american' or unamerican, or national history about it this question. Americans have done 4V as long as they've been done.
It's no secret that Chrysler fancies itself the low cost producer.

Tell you what, I gave you a quote from the Department of Energy, and UC Irvine, saying 4V has a larger valve area, and therefore lower pumping losses and better fuel economy. If you can find me a quote from anybody (reputable) saying that 2V gives better fuel efficiency, I'll concede the point. While you're looking, get the Heywood text and read up on what pumping losses are.

lear4406

If you have gained anything from this discussion, it should not be that Chry. and GM are low cost producers. The HEMI and LS1 and LS2 are quite technical. In your world they should just OHC and 4V it, that should make up the difference. But they have taken a tried and true engine design and added technology from there. I have a twin cam 4V and enjoy the free high reving of the engine. But the sound and torque I get from my OHV 2V 340 is another feeling all together. The discussions brought up on this thread have been covered completely. And everyone who has read it goes away with enough information to make up their own mind. So I say let it be and I hope that is the way you guys feel also. Lets have a great week end and to leave you guys with a compromise. I will soon have my 2.6 liter 4 cyl. completed and its a OHC 2V HEMI I will post pictures whan we get the motor in.