Hemi Challenger

No kidding?

That surprises the hell out of me. It's absolutely amazing that dealers are able to ask (and receive) so much "blue sky" on these cars, with those numbers. It must be the "Shelby" emblem bringing in all the folks that P.T. Barnum told us about. :)

/raising glass/ Here's to the possibility that '08 will have as many produced.

John C. (MSRP...or bust) '03 Cobra (improved)

Reply to
John C.
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IMHO the 5 litre hemi is over rated, under powered and drinks gas like a dragster. I think that if they had used newer technology with OHC and such. Yes it has 40% more power than the Magnum in my Ram did, but gets worse mileage. A two door Dodge Ram Rumble Bee with the 345 HP hemi has loses by at least 2/3 of the length of my Titan against it's four doors and supposedly 305 HP and I get better mileage. Now I looked a some of the differences between the 5 and 6 litre hemis and without knowing it's real world mileage I'll say it's far more satisfying. However, at least one difference is something that *we* would do after market and replaces the cast manifolds with stainless tube headers. Also it's still OHV.

Reply to
WindsorFox

WindsorFox wrote in news:s2wLi.793$ snipped-for-privacy@newsfe20.lga:

You and your Titan are full of crap. Post some proof, butthead.

Reply to
Joe

Absolutely nothing wrong with an OHV engine. OHC is no panacea and involves more complex cam drives. OHC only comes into it's own with high RPM operation. A cam in block V engine wirh pushrods and either gear or chain camdrive is more durable than any cam-in-head design by virtue of the chain/belt length and associated wear issues. Hemi head complicates the push-rod/rocker situation a bit, raising the involved reciprocating mass, which limits high rpm performance. Same thing is true of 4 valve technology. Low RPM operation gains nothing from 4 valve tech unless you also have variable induction (shut down half of the intake at low RPM) to improve intake velocity at low speeds. The 4 cam setup on the Ford Duratec 6 is a potent arrangement above

5000 RPM without suffering from low intake velocity and poor cyl fill at low RPM because of the variable tuned intake. But what a MISERABLE peice of equipment to work on - and the 2.5 not only performs like a 3.8, but drinks like one too.
Reply to
clare at snyder.on.ca

I don't buy it. If there were such a difference Ford, Toyota and Nissan wouldn't have made the change. That may have been true in the past, but I think they are on equal footing now. As for "only in high RPM operation," that's no longer true either if you look at the torque ratings on the 5 litre truck engines by Ford, Nissan and Toyota.

Reply to
WindsorFox

And they could not attain those outputs with a cam-in-block engine? Or with 2 valve combustion chambers? Also depends what you call high RPM. ANything over about 3000 RPM (when cruising RPM is 2200-2500) At 5000 RPM 4 valves are an advantafe. At 5500 OHC is gaining the advantage. Either way, the reliability of the cam-in-block engine like the old SBC Chevy and the 260-289-302-351 Ford has not been eclipsed by the OHC engines. Not talking fuel, ignition, etc, but particularly cam-drive components.

Reply to
clare at snyder.on.ca

There are a couple of reasons most engines have gone the OHC route. The first one is reliability which reduces warranty repairs and gives the buyer better longevity. The second is to maintain performance while improving fuel economy. The current V-8 in the Mustang is a prime example. The OHC layout allows for variable valve timing (VVT) which improves engine performance across the entire rpm range, especially torque numbers. In todays world I don't really understand why any auto company would produce a new pushrod engine. Sure they can deliver performance with them but it is impossible to apply some of the current technology to them such as VVT.

Another good comparison, IMO, is the old 302 engine to the OHC 4.6L engine. The 4.6L is an order of magnitude better than the 302. Ford couldn't come close to the economy levels of the current 300 hp 4.6L engine. Especially considering the 4.6L with VVT can put out another

30-40 hp with a few tuning tweaks that don't effect its economy during normal driving. That level of performance with a 302 is possible but economy flies out the window.
Reply to
Michael Johnson

NO it's 500 factory horsepower for $43,000 MSRP! I could care less if Shelby or SVT is involved or not.

Reply to
My Name Is Nobody

That's all well and good, my comment was in regard to the people paying significantly _more_ than MSRP. At MSRP it's a good deal and a great starting point for a *really* strong runner.

-- John C. '03 Cobra (improved)

Reply to
John C.

Mike,

OHV (pushrod) engines engines can utilize VVT too. Check out the new Viper mill.

Cheaper to build and easier to package. OHV is too tall/wide.

Again, no it isn't.

That's a really, really bad comparison. A motor designed in the 60's vs a motor designed in the 90s.

Instead try the ZO6 mill vs the 4.6.

That's not even a fair fight. That's like tossing a 50+ year old ex- boxing champ in with a 25-30 year old champion.

Patrick

Reply to
NoOption5L

Michael Johnson wrote in news:ELqdnQC9a5nhvmLbnZ2dnUVZ snipped-for-privacy@giganews.com:

First, you might want to talk to the folks who make the Corvette and the Viper. VVT is also available for pushrod engines. GM's doing it and I believe the Viper's got it as well.

Comparing even the latest 302 to a current 4.6 is absurd given the difference in available technology. Try a comparison between the 4.6 and any current pushrod motor. You'll be hard pressed to see any clear advantage the 4.6 might have.

Reply to
Joe

I stand corrected. Are there any OHV engines with multiple intake/exhaust valves? This is another big advantage of OHC engines as is reaching higher rpm rates with less precise machining and less moving mass in the valve train.

I don't think I'm hard pressed at all. The 4.6L with a modest after market tune can match the Viper's hp/liter number and in stock form slight exceeds the standard Vette's hp/liter numbers. Not too shabby for a what some call a truck engine. Remember the Cobra R with the four valve 5.4L engine? It matched the Viper's hp/liter numbers and that is using its advertised 385 hp number and not the real world dyno numbers that indicated they were somewhat higher. Considering the cost of each engine this is pretty respectable performance from the Ford camp. I chalk up much of the credit for the Ford's modular engine performance to their OHC design. IMO, the OHC design makes it easier to achieve high hp levels economically and with very high reliability. The OHV engines do make for a more compact design though and somewhat lighter weight.

Reply to
Michael Johnson

Reply to
Michael Johnson

Ever put a twin screw on a Viper??????? Forced induction by it's very nature negates the requirements for variable/tuned intakes and pretty much makes VVT and multivalve technology redundant.

Reply to
clare at snyder.on.ca

I didn't mention twin screws in my post to Joe but I'll bite anyway. I look at a twin screw blower like an amplifier of the N/A power curve. The better the curve before the blower the better it will be with it. In other words the VVT, multi-valve design etc. only makes the twin screw more effective.

Try putting a twin screw making 9 lbs. of boost on a bone stock Viper and see what happens. The stock 4.6L will take that 9 lbs. of boost in stride and make 425-450 rwhp or over 500 hp at the crank. Try that same amount of boost on a stock Viper engine and odds are it will have a catastrophic failure due to its high compression ratio.

Reply to
Michael Johnson

Michael Johnson wrote in news:aN-dnc90EMowy53anZ2dnUVZ snipped-for-privacy@giganews.com:

Good point. AFAIK, there are no multiple-valve OHV engines (yet). However, 2 valves per cylinder is certainly not the death knell that some make it out to be. Witness current offerings by Chrysler and GM.

I basically agree with everything you've said, but keep in mind that I only said that the OHC design doesn't have a _clear_ advantage. It can be argued that the DOHC is more complex and has more moving parts to wear out and/or break, thereby possibly negating the advantages of the extra valves per cylinder.

All things considered, current technology enables OHV and OHC engines to be on par with each other. I believe it all comes down to preference.

Reply to
Joe

Patrick, apologies as I didn't see your post before I wrote mine.

Michael, I really don't think it's fair to compare custom tuned OHCs to stock OHV motors. If you're going to do comparisons, why not keep things on a level playing field? Either go with everything stock, or apply the same customization (relatively speaking) to each engine.

Michael Johnson wrote in news:aMmdnSW2DPJaxZ3anZ2dnUVZ snipped-for-privacy@giganews.com:

Reply to
Joe

I can't say for sure but I would wager that the Z06 and Viper engines are tuned pretty aggressively from the factory. I also believe Ford chokes back the Mustang engines to meet a certain target and after the Cobra hp fiasco go out of their way to make sure they provide slightly more hp than advertised. Even comparing stock to stock the hp/liter numbers between them are very close. My point is that Ford's OHC "truck engine" is at least a match (hp/liter wise) to Chrysler's and GM's flagship OHV engines. I chalk much of this up to the OHC design of the modular motor. It allows Ford to produce and extremely reliable, durable and economical engine that also can be scaled to produce some very respectable hp/liter numbers. I am curious to see what the upcoming Boss and/or Bullet engines produce. If the 400 hp figures from

4.6-5.0L is true then they are going to match the base Corvette numbers with over a liter less engine displacement. Why can they do that with the OHC modular motor? I think it is because of the inherent efficiencies/advantages in the OHC design to no small degree.
Reply to
Michael Johnson

The two valve engines make for good low end torque numbers. They can't hang with the high end breathing and high rpm redline potential of an OHC engine without some very expensive machining and/or compromises in low end performance. Matching VVT with a multi-valve OHC engine makes for some very potent potential regarding hp/torque across the entire rpm range to well over 7,000 rpm. IMO, Ford is getting hp from their modular motors very easily where GM and Chrysler can only get high hp numbers from their OHV engines by increasing displacement. Making hp through sheer displacement isn't that difficult or impressive, IMO. Saying that, don't forget I plan to put a 427W in the old Mustang. ;)

This is where I have to disagree. I think the OHC engines are less complex and are more reliable due to their design. Look at the complexity of the VVT on the OHV engines. If they ever get multi-valve technology then they will be even more complex. Whether these OHV engines with VVT are durable remains to be seen. We know for certain VVT is durable on OHC motors. One of the major problems for any OHV engine is the frailty of push rods, lifters and rocker arms. This is a lot of moving mass to account for, especially in the upper rpm range. The OHC engines don't have this issue. Although they may be percieved as more complex I think they are actually simpler. We perceive them as complex because we think it is new technology. It really isn't. All you have to do is look at the track record of the OHC engines in the cars that use them. It is stellar. The 4.6L is proving to be even more durable than the 302 and that is saying something.

I agree. The one big advantage I see with OHV engines is their smaller size. Take that away and, IMO, there isn't much of a reason for their existence in today's automobile world.

Reply to
Michael Johnson

Apples to apples my boy. Only a FOOL would put a blower on a Viper or other high compression engine without dropping the native compression ratio. Put a huffer on a stock 4.6 and see how long it lasts!!!!!

Reply to
clare at snyder.on.ca

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