"Hurricane" To Use Pushrods?

Wot goes around, comes around.... just got through looking at a page on porting new aftermarket FE heads...

Nothing wrong with the old basic designs... new alloys and casting refinements... Imagine an all aluminum FE 427!!!

Then slap a sooopercharger on that thang!

No need to imagine:

Heck yeah.

It's about freakin' time. You'd have thought Ford would've picked up the hint from the LS2 and the new Hemi a bit sooner...

Joe Calypso Green '93 5.0 LX AOD hatch with a few goodies Black '03 Dakota 5.9 R/T CC

Backyard Mechanic wrote in news:Xns95B8ECE17EE05BkMch6d@207.115.63.158:

about freaking time!

MadDAWG

A little more compact, yes. Weight? The FE blocks weigh 650 to 670 lbs dry in cast iron. If they made this new motor aluminum it'd probably save about 80 to 100 lbs off those numbers but I'll bet it winds up close to that if they are going for large displacement. The cast iron

5.4 DOHC weighs 540 lbs and the cast iron 5.4 SOHC weighs 525 lbs. With a supercharger and intercooler (dry) you'd add about 150 lbs. Make those aluminum block 5.4's and you've got about the same weight even with the huffer. The 6.8L Modular V10 weighs in at 640 lbs (cast iron, I believe). I don't see the weight benefits jumping out at me.

Cheaper to build? Possibly, it will depend on the engineering that goes into the heads and block. However, the Ford OHV Windsor-based crate motors that are out there are so inexpensive because there are so many folks, inlcuding Ford, making and using a ton of them: well over 50 million Windsor/Cleveland 302 and 351's have been built by Ford alone since 1961. The design and tooling are very well established. Ford only made something like 6500 of the original FE 427's. If this "Hurricane" is a brand new design there's no way it'll come in at equivalent pricing. Where's the tooling for this one at? Australia? I don't see where the cost is going to improve on this one without most of the process already existing somewhere.

It'll be interesting to see since they just put a new cammer Modular motor with larger displacement on the market and it's more than powerful enough normally aspirated. Certainly another offering would be a fine thing but it's clear that the fleet companies have already accepted that they can service cammers as well as pushrod motors. I'd be interested to see what the long term reliability numbers are on the cammers versus pushrod motors. It's a given that it takes a little longer to service the top end of a cammer because of the care that has to taken in aligning the cams and chains. But it they are doing this less often, then they may be seeing an actual benefit instead of a cost.

I dunno. I actually don't care. It's clear the Modular family is here for a long while so I'll just keep my cammers :). . Dan

2003 Cobra convertible With some stuff and things

It means that old fossil CobraJet was ahead of his time.

Erich

It means that Ford can't do modern engines. How high can you rev a pushrod compared to an equivalent cammer?

"Imants" wrote in news:l59xd.543621$%k.345892@pd7tw2no:

I don't know about generalities, but according to that C&D comparo between the '05 Mustang and the '05 GTO, the Ford cammer redlines at

6000, whereas the LS2 redlines at 6500.

Joe Calypso Green '93 5.0 LX AOD hatch with a few goodies Black '03 Dakota 5.9 R/T CC

Advertised redlines aren't an appropriate measure since those are based on a combination of crankshaft, piston, and rod material, stroke/bore ratio, piston speed/acceleration, head/valvetrain design, actual head/cam flow capacity, desired mileage, and reliability factors. My guess is that the new Mustang GT redline is limited by its cast crank, pistons, and rods more than anything. In the end, all else equal and with the bottom end to support it, because there is less mass in the valvetrain to overcome, an OHC design will out rev an otherwise equivalent OHV design.

I am curious to find out the capabilities of the new heads and cams with a better bottom end. The 32 valve Modular (Cobra) can hit 7500 rpms reliably on the stock valvetrain. The oil pump is the weak link but the crank is forged and the top end is enough to get there. With some work it'll hit 9000 rpms. The SOHC has similar redline capabilities with the appropriate build down low but the heads can't keep up. I don't know what VVT has done to the valvetrain that might limit this and I don't know the details of the rest of the cam drive so it'll be interesting to see what it can do, but it should be close with some effort.

As to whether or not Ford can or cannot do modern engines, that's a pretty specious comment. Every domestic manufacturer has produced both OHV and OHC designs that were "modern" and successful. Ford's Modular

32 valve is used in some of the highest performance arenas in the world and it does well. And since Ford is not abandoning the Modular family this "Hurricane" is simply a different engineering approach for some set of goals or needs that Ford perceives. We'll have to learn more to figure out what they are thinking. . Dan 2003 Cobra convertible With some stuff and things

While some of the things you mentioned above might limit the redline of a motor, the major one is the lift and duration of the camshaft. A higher lift and/or duration will result in a higher redline. I went from a basically stock cam in a 84 302, to a .554/.558 lift and .298/.306 duration and my redline went from approx. 6000 rpms to 7000 rpms. Nothing else was changed, except to replace the pedestal rocker heads with a stock set of 351w heads. As for a OHC out revving a OHV motor, that's not necessarily true. The redline is the point at which no more fuel/air can be delivered to the cylinders. One way to get more fuel and air into the cylinders is to increase the lift and/or duration of the cam.

Gary

Yes, you are talking flow characteristics and it's relationship to VE and making enough power to spin the motor at high rates. But you can't even contemplate that flow rate at that engine speed if the crank, rods, and pistons can't support the rotation. You can put all the optimal lift and duration you want in order to make more power, but if the bottom end breaks at that speed it's meaningless.

Certainly, it's possible to make high revving OHV systems, the NHRA has oodles of them :). In the end, however, assuming enough power to turn the systems, the OHC version of a motor will out rev the the otherwise identical OHV version. It's simply because there is more mass and contact points in the valve train that absorb energy. This is one of the reason that small motors using OHC systems make alot of power relative to their size. Yes, there's head design and cam design and all that but in the end the OHC motor is pushing less around against fewer surfaces.

. Dan

2003 Cobra convertible With some stuff and things

Hmmmmm...Ok, your talking about contact points in the valve train that absorb energy. In the OHC motor, the crank has to turn 2 cams, vs. 1 cam in the OHV motor. Also, you need to take into consideration that the cam itself, in a OHC motor, has to open the valves, where the OHV motor, the rocker arms open the valves, which act as a lever, and require less effort. If the rod and main bearings are at proper clearances, and in proper tune, an OHV motor will rev just as high as an OHC motor. If you don't believe me, ask CobraJet, or any engine builder. Back in the late 70's I built a .030 over 289 with forged pistons, stock crank & rods, and a .535 lift .288 duration cam, and it redlined at 7500 rpms. It was still running when I sold the car it was in, and as far as I know, is still running today.

Gary

Shoot, this might turn up as a double post, sorry. I did something weird while writing my original post.

Anyway, take two...

Everything I've read and my own dabblings in kinematics indicate the opposite. The OHV system has to move a large cam, the pushrods, the rockers, and the valves. The total mass can be less than a typical four cammer plus valves but the overall energy used by the system to overcome the inertia through multiple linkages is measureably larger. Also, the pushrod length in a typical OHV is enough that the piece itself absorbs some energy, much like a spring. Finally, while the rocker arm may assist as a lever for the pushrod it isn't near the leverage that a cam lobe has in direct contact with a valve stem as found in OHC systems. Far less effort is required to move the valve against a given spring rate in an OHC system since the torque the crank is applying to a camshaft is "passed" through fewer links.

Think about using your torque wrench with and without an extension between the wrench and the socket. The actual applied torque is less due to the extension. The longer the extension the greater the difference between the torque created by the wrench and the torque at the socket. The more joints in the extension the greater the difference as well The same principle is at work here.

I have no doubt OHV systems can be built to rev relatively high. But a similar OHC system can be made to rev higher. Your 289 hit 7500 reliably with a little work. With an oil pump change I know several 281 cammers that each have done more than a hundred full quarter mile passes at 8000 to 8500 rpms while being daily drivers in between. Stock bottom ends, too. With pistons, rods, and the right cams a couple I've met are turning 9000 rpms every run. It's hard to compare because the flow characteristics are so different and these are forged cranks. Absolutely one could put in ultra lightweight, super strong pieces and make an OHV hit 9000, probably fairly reliably. But at what cost? The NHRA and NASCAR motors do it all the time but they get rebuilt every race and those motors have valve trains that cost almost as much as a whole Modular crate motor.

There's nothing inherently wrong with pushrod motors. They work and they work well and in some situations have advantages. But they do have limitations that cammers do not. . Dan

2003 Cobra convertible With some stuff and things

Aaaaah....Same applies to the mod motors. Look at whats available in after market parts for both. Some day the list of parts for the OHC may catch up with the OHV motors, but for now, after market parts are more plentiful for the OHV motor, and cheaper. I think for the time being, I'll stick with my OHV motors. When it becomes cheaper to build a OHC motor, then I'll switch.

Gary

There must be more to it than redline. My '02 Ranger 4.0 SOHC redlines at 6k. I'm not sure what the reason for OHC in a motor like that would be. Surely can't be cost or weight savings.

Brian

On the mod motors at least, the cams operate the valves via a roller follower that is nearly the same as a rocker arm. It too I believe has a similar input/output lift ratio to a 5.0L for example, like 1.6 or 1.7:1. This is an interesting discussion. I remember reading in an engineering magazine some years ago about a car maker that had a valve train dyno essentially. Perhaps its fairly common. But it involved a high $ carefully calibrated electric motor that could drive the valve train on various OHC/OHV engines. They did constant speed measurements to log frictional losses and did acceleration type tests to measure inertia. Neet stuff but it was too long ago to remember details.

Yep, yep. I left that out. My apologies :). These are roller followers with the cam lobes applying force between the pivots and the valve stems. There's a hydraulic lifter under it as well and they provide a

1.8:1 "rocker" ratio. The GM Northstar uses the same setup, I believe.

I recall an article on that test bench as well. I have no idea where I put it though :).

I was looking over some F1 stuff too. I realized that the rules don't limit head/cam configuration other than the number of valves. Those are

3 liter motors turning 18,000 to 20,000 rpms with, typically, five valves per cylinder. Pushrods aren't excluded explicitly but they simply are not viable in such an environment both because it would be almost impossible to design the cam, pushrod, and rocker arrangement just to drive all the valves, and because the compliance in the valvetrain linkage would cause them to fly apart dramatically. But there are still issues with valve springs and cam contact and such. They have been exploring solenoid activated valves in those motors: no cams, all computer controlled. Pretty cool :). . Dan 2003 Cobra convertible With some stuff and things

Yep, yep. I left that out. My apologies :). These are roller followers with the cam lobes applying force between the pivots and the valve stems. There's a hydraulic lifter under it as well and they provide a

1.8:1 "rocker" ratio. The GM Northstar uses the same setup, I believe.

I recall an article on that test bench as well. I have no idea where I put it though :).

I was looking over some F1 stuff too. I realized that the rules don't limit head/cam configuration other than the number of valves. Those are

3 liter motors turning 18,000 to 20,000 rpms with, typically, five valves per cylinder. Pushrods aren't excluded explicitly but they simply are not viable in such an environment both because it would be almost impossible to design the cam, pushrod, and rocker arrangement just to drive all the valves, and because the compliance in the valvetrain linkage would cause them to fly apart dramatically. But there are still issues with valve springs and cam contact and such. They have been exploring solenoid activated valves in those motors: no cams, all computer controlled. Pretty cool :). . Dan 2003 Cobra convertible With some stuff and things