A Hemi 6 project begins

Posted by: Ray Bell

A Hemi 6 project begins - 09/17/09 06:25 AM

Dave, a friend of mine, runs a nice hot Hemi 265 in a drag car his wife drives. While he is currently putting together a 440 to go into another car (a gutted PT Cruiser), he is still keen on developing the Hemi 6.

There is an aftermarket alloy head available for the Hemi, but it's naturally enough quite expensive. So Dave has given the go-ahead for my nephew, Ben Simpson, to start on a project to see what he can get out of a regular head. The purpose of this is that it might be possible to actually do better than the aftermarket head and save some of the expense.

Tomorrow I deliver a head to Ben for comparison. He has two 265 heads there already, so now he'll have three to inspect to see how the cores might have moved and to determine the best one to start work on.

He has some good facilities at his disposal, including a flow bench (two, actually...) and all the gear needed to do the job properly. He does, after all, do this stuff for a living.

What I'll try to do is put up a photographic record of the work in progress here and report from time to time on how it's going.

It's not going to be done in a rush, so this thread might still be going in a year's time.

The Hemi 6 is, of course, the US-designed and Australian-built inline six that replaced the slant 6 in Australia in 1970/71. It was built for about ten years in 215, 245 and 265 sizes, all with the same stroke (3.52", 3.76" and 3.91" bores, respectively, stroke 3.68").

They were built to upgrade the Valiant profile in a market where the inline six had been ruling the roost for twenty years. The Valiant was Chrysler's biggest seller in this market as it was a similar size to the most popular cars here, the Holden and Falcon. The 245 was also made in a truck version while the 265 went seriously racing in production cars wearing three dual choke Weber carbies and producing over 300bhp at the flywheel.
Posted by: Drew, II # 4211

Re: A Hemi 6 project begins - 09/17/09 12:20 PM

Ray,It's a great project to follow even for a Chevy guy.Looking forward to it. And a 440 in a PT Cruiser. You're kidding right? Probably not. How will that ever not get airborne? LOL
Posted by: Ray Bell

Re: A Hemi 6 project begins - 09/23/09 08:15 AM

The PT Cruiser was burned out after a crash, so Dave's got the body and put a chassis into it, the 440 will fit up under the scuttle and drive the back wheels through a 727.

I think the 440 lump will be good enough to help keep the wheels on the drag strip.
Posted by: Ray Bell

Re: A Hemi 6 project begins - 11/09/09 05:18 PM

Things are slow getting under way...

But I now know a lot more about the aftermarket head scene for the Hemi 6 engines. And I thought it might be of interest here.

There are pics that have been posted on the Moparmarket forum on the subject, so here's a link to those pics and discussion about the heads.

CHI did the original head, on which the ports were raised a little. George Rallis got one of their heads and did some more work, commissioning a new casting with the ports raised by 20mm.

So it will be tough for Ben to get the kind of power these aftermarket heads will give, but at least he'll get some serious development work done that will pay off for those who don't want to go to the expense of the alloy head. The Rallis head, by the way, sells for $AU3,000 bare. Still valves, springs, keepers and rockers to buy after that. And the rockers, because of potential interference between adjoining cylinder exhaust and inlet valves, have to be fairly special.

Now for another treat, here's a thread on that forum with pics of one of these heads in a car. To be honest, I don't know if the rocker cover is included in George's price either, or even necessary, but isn't it nice!
Posted by: Ray Bell

Re: A Hemi 6 project begins - 11/15/09 05:48 PM

Yet another dimension being added to this story...

Dave now wants to do a really fat 215 version of the Hemi for a class where they compete with 215s agains Holden 202s and Ford 3.6s. With the smaller bore it might not be suitable to use the Rallis head because the inlet valve is moved further from the centre of the bore... it might be shrouded by the cylinder wall in a 215 block.

So it might be a bit more interesting than we thought.
Posted by: Ray Bell

Re: A Hemi 6 project begins - 05/23/10 04:57 PM

Well, again I'm reporting very slow progress...

Ben is, however, about to start work on it. Impetus is now coming from a potential marketing operation to sell modified Hemi 6s and performance parts internationally. For people who want something different.

One thing we're likely to do is make up a cast timing cover with inbuilt oil pump. The Hemi 6 has a bad habit of chewing out the oil pump skew gears on the cam, so this will obviate that. It also has a camshaft float issue that can be addressed at the same time.

And it will look neat and 'racy'!

We've found an H-beam rod that goes very close to fitting the Hemi 6 that will give a better rod/stroke ratio. This is 1.56:1 in the original setup, we'll take that to 1.70:1 with these rods. They only need to have a very minor shave from their big end cheeks (0.011") and require 0.008" off the journals to fit in with standard bearings. We've found that Ross make a forged piston that will take that rod with a custom pin position.

So let's see what Benno's flow bench says as he works on this over the next few weeks...
Posted by: Ray Bell

Re: A Hemi 6 project begins - 05/25/10 03:06 PM

Something to help Ben along the way with his porting...

A friend with a very strong 265 is going to provide us with the flowbench figures for his head, done by a reputable engine man in Sydney.

This will give us some 'benchmark' figures to start with.
Posted by: Ray Bell

Re: A Hemi 6 project begins - 06/22/10 01:06 PM

Still being delayed in all of this by Ben's other involvements... but he has started on the flowbench to get some initial figures.

What he'll do is work away, logging the flow rate at each change. Tomorrow I expect to pick up a damaged head that we can afford to cut up to see what's inside and where any weaknesses might be in the porting process. There's a block too, two legs out of bed in that, we can cut a single cylinder off that to use on the flowbench to be sure the cylinder is concentric with the chamber being tried at the time.

Some further development with this. We are now looking down the barrell of marketing these engines in a variety of stages of tune some time in the new year, options to be included range right up to steel cranks. The H-section rods and forged pistons will be core components, looking at getting about 320 streetable horsepower from the 245 at 0.040" oversize bores. A lot of work to do, though, new manifolds included... manifolds that will clear the master cylinder in LHD applications, by the way.
Posted by: Ray Bell

Re: A Hemi 6 project begins - 07/15/11 03:26 AM

Another year down the track...

Now the information from somebody about camshaft flexing (and how he deals with it) leads me to decide that we'll change the firing order.

Instead of 1-5-2-6-2-4 we'll have 1-2-3-6-5-4, that will remove the problem of the two cam lobes each side of the distributor gear on the camshaft opening and closing simultaneously. This means we can probably retain the gear drive for the oil pump on the camshaft and save outselves some trouble with oil plumbing.

We're getting close to finalising a piston design and getting our first batch made.
Posted by: Drew, II # 4211

Re: A Hemi 6 project begins - 07/15/11 05:21 AM

Development work including constant modification to original ideas always takes time especially when other more important everyday priorities need to be addressed. I admire your tenacity in this project. ray, with the size of the valves,especially the intake side, is there really a lot you can do to improve the flow. I would think it would be minimal contouring at best. And, in the previously attached pics, is the TNT 265 block aluminum too or is it just the side plate I see?
Posted by: panic

Re: A Hemi 6 project begins - 07/15/11 07:39 AM

For those not familiar with the engine, it's called a hemi to distinguish it from more common in-line valve L6 engines.
The valve stems are inclined toward each other but the angle is very low (similar to BBC, Cleveland, 385 etc.), the chamber is almost flat, and the inclined axes are at right angles to the crankshaft (90 away from Chrysler hemi V8).
Posted by: Ray Bell

Re: A Hemi 6 project begins - 07/17/11 03:30 PM

No new block...

To date nobody has made an aluminium block for a Hemi 6. And you really need tenacity when you lack captital!
Posted by: six gun

Re: A Hemi 6 project begins - 07/17/11 05:00 PM

What is the bore spacing on a Hemi-6, would that head fit a big ford-6 (240/300)????
Posted by: panic

Re: A Hemi 6 project begins - 07/17/11 09:40 PM

It's 4.400", same as SBC or Gen-3 L6 250, 292 etc.

Re: A Hemi 6 project begins - 07/20/11 04:48 AM

Big Ford six is 4.480, or .080" wider.
Posted by: Ray Bell

Re: A Hemi 6 project begins - 11/17/12 08:50 AM

We're still having a hard time getting some serious progress down on this!

One major detrimental factor has been the death of David Friend, mentioned right at the beginning. Dave died early in January after a sudden relapse of a cancer he thought he'd beaten fifteen months earlier.

But while this thread was begun with mention of Dave's plans, we've taken our project well beyond his ideas.

We have established a plan on how to go forward with rods and pistons. We will be working with two lengths of rods, one is 6.0" long (standard they are 5.7") and the other is in the 6.25" range. I have been told that going too long with rods has proved too harmful to low end torque with these engines so I want to offer the engines with these two options. The piston blanks we will be drawing from can be machined to suit each option.

Soon we are hoping to be in a position to supply ATI harmonic balancers for those who want to reduce the harmonics problems found around 6200rpm.

Ben keeps on getting himself more and more tied down with other things and hasn't yet really done much work on the heads. But he now owns a full engine reconditioning machine shop, so his ability to get things done is enhanced. On the other hand he recently got married!

I really do hope I have a lot more to report soon...
Posted by: Ray Bell

Re: A Hemi 6 project begins - 03/01/14 12:56 PM

At the point when I last posted on this thread I had a motivating partner in this project in the US.

He subsequently died (as did Dave Friend), so things have been further slowed. Ben, too, has been slowed down because he bought a new business that's keeping him tied down. Complicate that with his marriage and now the birth of his first child, I don't know when he'll find time.

I have been pressing on as best I can. My visit to the US enabled me to talk to a piston maker, my next task is to actually make a model of the pistons so they can be measured to get the compression ratio right. They will be very complex in the crown and I can't see any way to get the measurements other than to make them up.

I want to do this before I go to the US again in May, I will take the models with me for the piston manufacturer to work from.

In the meantime, we have had (as mentioned on another thread here) harmonic balancers made for the Hemi 6. These come from BHJ in California and the first shipment of these left the US yesterday.

They are not as complex as ATI's dampers, but BHJ have done a lot of work with 6-cylinder dampers the past year or two (again, further info on this is seen in another thread) and they have separated the alternator/water pump belt pulley from the inertia ring. This enables the inertia ring to properly do its job.

They have also done some work with the elastomer and have aimed this damper at cutting down the 6,200rpm harmonics and working well with the engine to about 7,500rpm.

The separation of the pulley and inertia ring can be seen in the pics, a keen eye of someone familiar with Hemi 6s would also note that this damper still enables the fitment of the factory pulleys for power steering and air conditioning.

I will be posting progress on the piston models over the next month or two.
Posted by: Ray Bell

Re: A Hemi 6 project begins - 07/11/15 07:44 AM

Month or two? Yeah, right...

When I was in America last year I had further discussions with a piston maker and as yet I haven't been able to progress anything further than to say I have a good idea of what I want.

There are now a couple of the harmonic balancers on engines that are out and about, however, and I'm hoping to get some good reports back on them. We did alter the design in that the bolt holes for the removal pulley are now ⅜" instead of " and have UNF threads instead of UNC.