THe Cobra R 5.4L was kind of a gas hog too. VVT would help fuel milage. I willing to bet that the Cobra R 5.4L was tuned too agressive for the avg. Joe, based on how mauch gas it uses and the fact that Ford kind of marketed it as a factory Race car. Of couse I'm not really sure of this since I have never driven one of those cars. Maybe someone that knows more about the R's cam timings can help here.
4.6 3v cutaway
- Thread starter numenor27
- Start date
-
Sponsors (?)
Ray III
New Member
shatner saves said:
Now where did you get that from? Large turbodiesels that can benefit from it have four valves running off a single camshaft. Two valves wee used on the 5.0 because it maximizes cylinder swirl and inertial supercharging for torque, not to mention how much stronger the heads are without pecking all those damn holes in it, not because they just couldn't get four valves in the head.
Variable cam timing could be pulled off much more efficiently on an overhead valve motor, because there is only one camshaft to fool with.
And VTEC on a Ford motor... sheesh. Have a seat.
Ray III
New Member
I heard about the valve solenoids a couple years back. Not something I would put in MY motor because it relies on electricity and we all know how much we can depend on things that need wires to operate. In addition they still have some serious obstacles to overcome like how to cushion the valve seating. Camshafts will move the valve with a specific amount of velocity with respect to its position, and (assuming the springs are strong enough to defeat float) will ALWAYS set the valve down gently on its seat regardless of whether you rev the holy piss out of it. Solenoid valves just pop open and then SLAM back onto the seat...
Ray III
New Member
Ray III said:Now where did you get that from? Large turbodiesels that can benefit from it have four valves running off a single camshaft. Two valves wee used on the 5.0 because it maximizes cylinder swirl and inertial supercharging for torque, not to mention how much stronger the heads are without pecking all those damn holes in it, not because they just couldn't get four valves in the head.
Variable cam timing could be pulled off much more efficiently on an overhead valve motor, because there is only one camshaft to fool with.
And VTEC on a Ford motor... sheesh. Have a seat.
Exactly what do you mean by "large turbo diesels"? There are gigantic marine 2 stroke diesels running 4 valves per cylinder and those things redline at a stratospheric 150 to 200 RPM. Highway tractors are around 2100 to (maybe) 2500 rpm. I'm pretty sure that the highest revving light truck diesel still has a redline of, I dunno, 4000 RPM? Reciprocating mass and high rpm stability isn't exactly an issue with these engines. And by the way, GM's 7800 duramax commercial truck engine is an overhead cam design.
GM has always maintained the reason they stuck with cam-in-block, 2 valve designs is that they are more robust, more economical, simpler and are still very effective in large engine designs. I agree entirely. However, I look at the cutaway of the 3 valve vortec truck engine, then the 3 valve mustang engine, do a parts/cost/weight/simplicity inventory in my head, and I really don't see any clear advantage. If someone can explain it to me, be my guest.
And I said "VTEC type systems" not "VTEC." Sorry I couldn't remember off hand what the trade name porsche, toyota , BMW or anyone else is using for their variable lift valvetrain geometry.
Not to single anyone out, but some of the anti-Honda sentiment on this board is getting downright Freudian IMO.
Clown.
shatner saves said:
BMW does not use variable lift, they use variable timing. Once again Ford doest NOT vary lift, only timing. BMW's name is VANOS or in the case of their engines that vary both the intake and exhuast timing, independently, it is called Duo-Vanos.
"Vtec like" would correctly refer to systems with variable lift.
"Vanos like" would correctly refer to systems with variable timing.
Although BMW gets the hype, I think Porsche had variable timing before BMW did. I don't remember what their trade name is though.
351CJ said:
As a matter of fact, BMW does do a variable lift on their 745 (V8) and 760 (V12) called "valvtronic". These cars also have dual vanos and variable length intake runners. BMW's system is unique because valve lift is steplessly variable. I think it works by altering the cam follower lever ratio. Crazy stuff.
Porsche's system is called "VarioCam Plus", which alters cam timing and valve lift. Like VTEC, it alternates between two different cam profiles.
Putting the VVT on a Cobra R engine could have some amazing results. Remember, that's a DOHC engine. Being able to change the timing on the camshafts on a DOHC engine will allow you to control the intake and exhaust timing SEPARATELY, not just one general shift. This then leads into being able to control the valve overlap, which is like changing one aspect of the camshaft profile.
Individually cam phasing a DOHC engine can give some very impressive gains into the torque curve. I think that one make one seriously badass engine.
Individually cam phasing a DOHC engine can give some very impressive gains into the torque curve. I think that one make one seriously badass engine.
nomuffler
Member
Valvetronic is cool, those cars don't have a throttle! The infinitely varible valve lift/duration handles all intake metering.shatner saves said:
I thought the new mustang had some system where it actualy moved the whole cam (both of them) to vary the valve lift
GinoGT said:Putting the VVT on a Cobra R engine could have some amazing results. Remember, that's a DOHC engine. Being able to change the timing on the camshafts on a DOHC engine will allow you to control the intake and exhaust timing SEPARATELY, not just one general shift. This then leads into being able to control the valve overlap, which is like changing one aspect of the camshaft profile.
Individually cam phasing a DOHC engine can give some very impressive gains into the torque curve. I think that one make one seriously badass engine.
Ford does not yet have a VVT system that does this. The Lincoln LS / T-Bird system varies only the intake cam timing - the exhaust cams are fixed.
But you have pointed out one of the major advantages of DOHC heads vs SOHC heads. That is, as you have pointed out with DOHC you can vary the intake and exhuast valve timing independently.
Time for Ford to get with the program and put this type of VVT in the 32 V mod motors.
351CJ said:
That would be the ultimate. I wonder; a 4.6, DOHC 4v, VVT on intake and exhaust cams, charge motion control and 11:1 compression. That thing would be lighter than the current 5.4, make an easy 400hp and probably get really good fuel economy as well.
Although, you might be able to get a lot of that advantage with a DOHC, VVT, 3 valve motor.
http://www.sae.org/automag/techbriefs/09-2003/1-111-9-26.pdf
Here is an article on GM's 3 valve head (pages 5 & 6). They claim the next Z06 engine will be 6.3 litres and "rev safely to 7000 rpm". Maybe if they do Ti valves and connecting rods and even then, I'll believe it when I see it.
Page 9 has an article on Lotus/Eaton solenoid valves.
For those of you with dial-up, it'll take a while to load.
Here is an article on GM's 3 valve head (pages 5 & 6). They claim the next Z06 engine will be 6.3 litres and "rev safely to 7000 rpm". Maybe if they do Ti valves and connecting rods and even then, I'll believe it when I see it.
Page 9 has an article on Lotus/Eaton solenoid valves.
For those of you with dial-up, it'll take a while to load.
Similar threads
