DOHC 300 Head

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Has anybody contemplated the idea of fabricating a head that has dual overhead cams for a 300? I wonder if an existing DOHC V8 head could be welded together or if there are some foreign inline heads that may be modified to work? I am currently in the preliminary stages of developing plans for a 300 head that will take maximum advantage of the inlines potential. Right now I am exploring all possibilities before committing to one design. Once I have made a decision I will begin the tedious task of designing a cylinder head that meets my specifications for a 300 head. I would eventually like to produce plans for such a head and produce it using a local foundry.

On a side note: The head would probably be a four valve design with a hemispherical style combustion chamber. It could even be possible to use direct port injection for this new design.

However, before I design a brand new head I would like to make a prototype, hence, the question above.

Any feedback would be greatly appreciated.
 
i know it can't be adapted but how about taking design ques from the bmw inline??
 
i was working with a machinist friend to try to make a new auminum head for the 300 but his shop got busy so its on hold right now but the foundry that was going to do first runs told us to either mold or mill the design in a hard plastic or mill a billet block so that a sand cast could be made for reproduction sand casting is the best way to do it. as i was told. unless you can find a computer wiz that can right a cad design for it. just thought it might be helpfull news
 
Your best bet is to plagerise a Olds Tech 4 DOHC, and cut and shut to fit the Ford studs. The Pontiac OHC was a 4.4" spacing Chevy engine with a head conversion. The real idea is to find something with the same bore spacings.

The Landcruiser 4.5 is a neat engine, but I thought it was based on the modular plat from from which the Supra3.0 and 4.2 Diesels were based on.

Guys, sectioning an exsiting head with a similar four bolt per cylinder, 4.48" bore spacing is a good idea.

The Daimler Chrysler OHC V8's found in Jeeps run off a Mercedes tooling platform. From memory, about 112 mm bore spacing, or about 4.41". Thats close to the mark. If they have four bolts per cylinder, you can do it.

Forget BMW, Aston Martin, MB sixes, Jags, Nissan Z car in-lines...the bore spacings are too small. (About 3.8" in bore spacing)

The extra length of a cam drive on the front of the engine is considerable, and even a 260 Z sohc is longer than a little 250 six. The 300 is way longer than a 460 big block, and a DOHC 300 with the cam drive, it'll exceed a Jag V12 in length.

The Ford modular V8's and V10's sit at 3.937" bore spacing, similar to a V12 Jag, but even a V10 truck engine will be sorter than a DOHC 300.

Remember, its 10% inspiration, 90% persperation. And a bit of bakground info thrown in for good measure!

http://fordsix.com/forum/viewtopic.php?t=6557
 
i remember reading of a guy in STREET MACHINE who already made a dohc head for a ford six and the same head could be adapted to a holden 202 also.

This guy helped ford in ways and i think convinced them to put a twin cam into the new BA's

This was mid to late 90's this guy finally got the head up and running but proved to be very good on old 250's

hope this helps
 
Yep, thats the Krogdahl heads. The application was simple. Both Holden L6 and Falcon I6's have always had the same 4.08" bore spacing.

Funny thing is Krogdahl's application on a Big Six, like the 292 Chev and 300 Ford, could allow just the economies of scale to get it into production.

The 300 is about the same bore spacing as the Oz Chrysler Hemi L6. Duggan made SOHC heads for the 250 Chevrolet L6, same bore spacing.

See? Just find a dohc four, vee-six or Vee-eight which has a simlar bore spacing and bolt spacing. The rest is simple hard work.

So long as the block is strong and the crank is prepared right, theres no reason why the big six won't see 8 grand. Heck, even Aussie Hemi L6's could do 6500 rpm with pushrods. A dohc head alone could add 25% more power and torque everywhere with the same same kind of rev range. With the potential to hit 25% more revs without damage to valve gear, I'd say 50% more power on what a good race 300 is giving isn't unrealistic.

For an idea of the costs, see the Slant Six guys and check Florida phatmans posts on the CHI head prospect.

http://www.slantsix.org/forum/viewtopic.php?t=6915


and
http://www.slantsix.org/forum/viewtopic.php?p=20976&highlight=#20976
 
SOHC, DOHC beautiful for an exercise in design. Not putting anything or anybody idea down, but a bit of over kill for the 300. An OHC head would exceed the volumetric needs of an engine that is by design limited to 7,000 rpm max.

A cam drive will also have to be designed and would increase the engine length thus limiting which vehicles it could be installed in.

A simpler conventional crossflow pushrod head using off the shelf valves, springs, rockers etc would be easier to design and do. Present head design; Yates, Twisted Wedge, AFR and others would meet any performance need of the 300.

As far as design---plagerise the SBF head of your choice. Flip over to put valves in right order. Cut/ paste/ space. Rearrange cooling water ports to match block, draw in opening for water pump mounting.
 
Yeah, but if a 4 valve DOHC unit were developed, then it could also be set up to stage valve operation, so that low RPM running only used 2 valves. Variable cam timing could also be employed, and a la Honda V-Tek, the result could be better performance & lower emissions at all engine speeds.
Ford is also doing that on some of its newer engines.

J.R.
 
Way too much money to be spending on a 300 in my opinion.

Why not stick with a motor that comes with a 4v head, or at least is an option.

Hey, i hate the 4.6L, but with the cobra heads it can turn out some real hp numbers. Of course i would never replace my 300 with a 4.6L in a truck, not ever, man... i really can't stand that damn motor. I don't know what it is about it...

I need to seek psychiatric help.
 
Just thought I would comment. I have an 87 Toyota Supra Turbo. It has a 3.0 liter Inline Six. It is DOHC and 24valve. In the normally Aspirated motors it puts out 200Hp and 255Tq. My Turbo'd version (stock) use to put out 232Hp and 260Tq. And thats only at 6lbs boost. Buy just adding a few goodies she now puts out 450Hp and 512Tq. So in review. If you could ever get a Ford 300 Inline in a DOHC setup with the proper 24 valve config . it would be a Beast. Then start boosting it. It would dominate all.
 
that goes the same for all motors, as long as the bottom end can withstand the added cylinder pressures.

When you double hp like that, you're more than doubling the downward force the expanding flame front has on the piston (lots is lost to friction and rotation) and most manufacturers don't make bottom end parts twice as strong as the need to be. Hell most manufacturers don't make the motors strong enough to last to 200k.

The production costs of a new head, especially a DOHC, and not to mention the added stresses of rigging up the valve train, distributor gear, etc. would be nuts.

The heads on the 300 are horribly restrictive from the factory, but if you want high hp numbers, there's always extrusion honing, which doesn't come cheap, bigger valves, and professional race port and polish jobs. Look at FTF for example. That head isnt the stock 300 head, but it might have been. And look at the power he's making!
 
Another idea might be to use variable valve actuation. Such as, servo's or hydraulically controlled actuators in order to reduce the cam linkage requirements and increase the overall mechanical efficiency of the engine. This would eliminate the need for a camshaft, pushrods, and lifters plus you would have total control over valve timing. This design would also include a crossflow head with four valves per cylinder and a hemispherical combustion chamber. I believe using a system like this would eliminate alot of the production woes associated with a DOHC design. There are currently many auto manufacturers already experimenting with variable valve actuation and I have read a great deal about it in the SAE SP-1523 papers. It is very doable and with the right budget could actually be produced. This type of cylinder head is currently what I am trying to design. I decided what is the point of designing a DOHC when you can increase mechanical efficiency and retain complete control of the valve timing.
 
The Aussie DOHC 4.0 Falcon sixes run a simplex chain with variable valve timing. It is thiner and narrower than the former Intec SOHC 4.0. These earlier Falcons ran a duplex chain, and still had a variable valve timing option. These newer chains won't like 8 to 9000 rpm, though.

Holden is using the same kind of full variable valve timing and fly by wire ECM mapping as Ford. It removes the need for external EGR on the latest Alloytec 3.564 liter Holden 60 deg V6. It's bore spacing is not any wider than the Ford's 4.08", so there's no point reverse engineering a quick 24 valve head.

The reason forthe Oz Ford Falcon going to the simplex chain was space and drag and the need to fully operate the hydraulics. When modified, it seams to work okay on 1200 hp XR6 turbo engines!

The thing is that its fairly easy to pirate the factory Ford DOHC gear and alter the US 200 or 250 block to fit the Aussie head. Stud patterns are the same, and the water path can be changed with a 180 thou block plate and and a few smarts. Heck, Lotus shoved Harry Munday and Cosworth the BDA heads on little Kent ohv blocks, so doing it to a little 200 or 250 isn't out of the realm of possibility.

The only thing is, there are no blocks around with 4.48" bore spacings and 4 v per cyl twin cams. So you've gotta make one which fits into a 4" bore! It's a case of scaling up against and existing narrow angle pentroof OHC. The best bet is the Duratec 3.0 V6 used in the Jag and US Fords. These are turned into the V12 Aston Martin engine by joining them together. If I recal, thats a 4.32" bore spacing. Nissan Skyline six is 3.858" with centre cylinders at 3.799". The quad cam V series Nissans, Toyotas and Mitsubishis are about 4.25". Still way off 4.48" bore spacings and the good old US 4" bore. Dang!

I'm not worried about the 300 block. At all! Without a cam to look after and a steel crank as big as the old related 262 I6 that fathered the famed engine, it'll do fine at 9000 rpm.

Just remember, you've then gotta scratch build the remaining bits. Hmm, grab a couple of 944 2.5 heads and weld them together? 928S4 heads.

Good luck!
 
As strictly a design reference look at Honda's CBX motorcycle from the late 80's or early 90's. I simply can't recall when these were produced. The CBX was 1013 cc's (I think) and was an across the frame inline six cylinder air cooled engine that was primarily a tribute to Honda's six cylinder GP racers from the 1960's. The CBX had six carbs on the rear of the engine and six pipes out the front so you have "cross flow" as we sixers would wish. These were four valve dual overhead cam engines with the cam lobes pushing dirctly on the end of the valve stem with the lash adjusted via shims. So no extra nasty valve train components thrashing about at high rpm. There are also some inherent flow advantages even with conservative lift cams from four valve engines versus two valves that would benefit low rpm, high torque users as well. Again, all this is offered as reference. That said, if someone starts with a blank sheet of paper, I would suggest they look closely at Japanese motorcycle engine designs as there is much to be had. They not only produce high horsepower, they have good driveability and run well on today's sometimes questionable fuels. Oh yeah, the last Honda six cylinder Gp racers had a redline in excess of 20,000 rpm.
 
Does anyone know about the company that is building heads with rotary valves in place of poppet valves? I'll see if I can find it. If what you want is the most exotic Ford six, that's the kind of head to have.
 
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