911 aircooled developments

[Neil Harvey]

Originally Posted by PeteKz

Neil, thanks for the update. Still watching this thread.

IN addition to weighing the different cases that you listed above, have you or anyone else weighed the cranks? Is the 70.4mm crank in the 2.4/2.7 engine the same as the 3.0 engine? Or were those cranks beefed up too? Does 74.4mm/3.2 crank weigh more? I'm pretty sure the 3.6 crank does.

I have the weights of 66.00mm, 76.40mm and 80.40mm cranks. Only 70mm crank I have here is inside an engine. I do have 2 new 74.40mm cranks here so I can weigh those.

It all has to go down the road. So the less weight to move the quicker the car. But some parts do get heavier by design. The oil pump is heavier due to more scavenge sections.
The rest is lighter so far. The unfortunate downside is weight saving does cost money. Titanium parts cost more to make than steel parts.

My hope is the potential customers that have asked for this level of engine will pay the difference.

If it's successful.

[Neil Harvey]

Over the past few years we have designed new Cam motions for the air cooled 911 engines, Early 911, 964 and 993.

Regardless of how accurate you make the designs; the rocker arm accuracy is always suspected. Wrong radii repair, too much material removal on the contact pads etc., all resulting in ratio inaccuracies. On the engine testing shows how these results with the swivel pad sliding across the valve stem instead of its proper motion. In many cases we found a loss in lift numbers.

Deflection and bending are another problem. Arm stiffness is required, as deflection is quite high with the stock arms and some others we have tested. The street customer wants the ability to lash these engines simply with an adjuster.

We have designed our own Rocker arm that is stiffer and has the correct geometry. We have added some features that we feel are important as well. The 993 arm is adjustable and has a added oil feed to the contact pad.

These parts are in their first stages of manufacturer and will be available after we have conducted on engine testing.

[JoeMag]

Clever idea Neil on the oiling hole to the pad.

Would it be advantageous to move the hole to the location shown below? That way the oil is spraying on the cam then that freshly sprayed cam area moves to the pad during the entire lift process.

[Neil Harvey]

Yes Joe.

We added the hole so it can be seen. You know how small the hole we added to your Rockers, it would not bee seen.

nh

[Neil Harvey]

Having designed a new Rocker arm for the 911 air cooled engines, it has become evident that stiffness has never been a high priority with some. We have tested many and found many to be quite weak.

Its kind of like valve springs where you don't want more force than you need. For rockers you don't want more mass than you need. You want to remove as much as you can without it affecting your valve motion. Its touchy.

Here is the formula for calculating rocker stiffness with an example added.

RS = real springs force at full lift (300 pounds)
FS = flow bench springs force at full lift (8 pounds)
RL = max valve lift with real springs (.495")
FL = max valve lift with flow bench springs (.500")

(RS - FS) / (FL - RL) = stiffness (lb/in)
(300 - 8) / (.500 - .495) = 58,400 lb/in

If the loss was only .002" of lift with the real spring,
(300 - 8) / (.500 - .498) = 146,000 psi

That's a big difference.

The work continues. As I have said before, the cam designs we have done have to be used with Rocker Arms that have the designed ratio and stiffness. Otherwise they are a waste of time.

This goes for any cam design you may use. If the Rocker Arm geometry is wrong and the arm flexes, you lose the valve motion designed into the cam lobe and ultimately lose engine performance.

The largest error we have seen in many Rocker Arms is the pad radii. Completely wrong and possibly caused by incorrect repair often done on a valve grinding machine with an attachment. These attachments are not designed for this kind of pad repair.

[cgarr]

Most accurate and actually faster grinding method is to use the holding fixture on my CNC grinder and check it with my optical comparator.


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[Black 993]

Great stuff Neil. Always enjoy reading your updates.

[Neil Harvey]

The air cooled parts we have developed over the years have all come together in this first "real" finished engine heading to our customer in UAE.

Based on a 964, the only parts that resemble anything stock are the Chain Housings and covers. Everything else is either highly modified or custom.

This engine has extremely limited sales potential. Not many will step up and pay for something like this. However, most of what we developed for this engine project will filter back into the earlier engines that are lower in cost.

We are finishing up a late 80's engine now that has some of these lower cost alternative parts fitted, made in steel instead of higher cost materials and also includes the Crankshaft Damper for the earlier 911 engines, 6G Serp Alt belt system with tensioner etc.

Another "skunk works" project we are involved in for a US customer is a very special 964 engine that is receiving some new parts that we have still in the development stage. These parts will be made available to who ever wants them once they are tested. This includes the new adjustable Rocker Arms, single Valve springs we have had made, some custom heads Bill has produced for us that use both 6.0mm and 7.00mm Valves, along with some new Camshafts.

[LukasM]

That is a very trick looking engine Neil, lots of goodies on there!

Is the damper still a modified Fluidampr or are you now having them custom made, and does it fit with the tapered 964 crank snout now? That would be very cool, as removing the damper to run a normal pulley with a serpentine belt is certainly not ideal, even if street useage doesn't seem to be a problem. I have a list of people for you who would be interested, as there was no equivalent alternative solution until now.

Looks like your own belt tensioner bracket, is it self adjusting like the Clewett one or simply done with an eccentric pulley?

Cheers,
Lukas

[Neil Harvey]

The Damper is a custom part made for us by ATI. At present the only dampers we have are for the straight snout cranks.

I did look into the 964 and we did draw up a new hub for these cranks but although there are some demands, we have to look at the total to recover the cost of design and manufacture. More and more are fitting the Gt3 cranks to these engines which makes the decision easier as well.

If the numbers were there we would re consider making the hubs on a custom order basis, cost divided by the number plus some profit.

The tensioner is mechanical. I looked at the self adjusting types but they are bulky and ugly. I hate to look at an engine where one part catches your eye and you focus only on that one part. Good or bad.

That said, we have this huge blue thing strapped to the top of the engine that does exactly that. Unfortunately the carbon Plenum we designed for this engine is still away off. Tooling and fabrication take time.

[Henry Schmidt]

Hi Neal
Those look like heat exchangers on the headers but I don't see how you're feeding in fresh air. What am I missing?
We've struggled with coming up with a reasonable heat exchange for the 964/993 engines but most are pretty ugly. I agree with you. " I hate to look at an engine where one part catches your eye..."

[dannobee]

Originally Posted by PeteKz

Neil, thanks for the update. Still watching this thread.

IN addition to weighing the different cases that you listed above, have you or anyone else weighed the cranks? Is the 70.4mm crank in the 2.4/2.7 engine the same as the 3.0 engine? Or were those cranks beefed up too? Does 74.4mm/3.2 crank weigh more? I'm pretty sure the 3.6 crank does.

3.0 SC crank weighs 31 lbs 13oz. FWIW

When I was racing Super Late Models, some 350 SBC cranks were down to 23 lbs.

[Neil Harvey]

Those are some Titanium parts supplied by our customer for dyno work. They have cats included. I believe where this is going they are required. Not the best for performance but we often have to work with what we are given.

Same for the Plenum. It fits and closes the Intake but is far too small for these big engines. Like a Dyno room too small and the engine sucks all of the air out before it can be replaced.

The company making the carbon Plenum is way behind and had issues with making it. My fault as I designed a one piece part that I wanted to "stretch" a little as the engine grows but the runner to chamber sealing cracked and failed. Now its a completely new piece with O rings.

These things appear really simple when in your hand but making them is another story.

You try, you fail, and you try again. Story of my life.

[JoeMag]

Any general specs on the motor? Intake looks like maybe modeled off 7Cup; multiple res flaps? ...on ATPowers. Is blockly looking things on fuel lines filters?

[LukasM]

Originally Posted by Neil Harvey

The Damper is a custom part made for us by ATI. At present the only dampers we have are for the straight snout cranks.

I did look into the 964 and we did draw up a new hub for these cranks but although there are some demands, we have to look at the total to recover the cost of design and manufacture. More and more are fitting the Gt3 cranks to these engines which makes the decision easier as well.

If the numbers were there we would re consider making the hubs on a custom order basis, cost divided by the number plus some profit.

The tensioner is mechanical. I looked at the self adjusting types but they are bulky and ugly. I hate to look at an engine where one part catches your eye and you focus only on that one part. Good or bad.

That said, we have this huge blue thing strapped to the top of the engine that does exactly that. Unfortunately the carbon Plenum we designed for this engine is still away off. Tooling and fabrication take time.

Hi Neil,

I'll PM you separately on the 964 crank damper, maybe we can put a big enough group together.

Is that a 996 GT3 or 997 plenum? I can put you in touch with somebody that is developing a plenum center section that allows you to use the 997 one, which supposedly has quite a bit more intake volume than the 996, if that is what you are looking for.

Cheers,
Lukas

[Neil Harvey]

Rocker Arm FEA testing is now completed successfully. We made some minor changes to strengthen the arm sacrificing some tiny extra weight. They now go into production but I have no dates of completion yet.
The new Arms are allowing us to bring more Cams to the market as the stock arms limit the lifts.

Project 24 is moving along with many new parts completed and more about to be as started. This is a high RPM early 911Mag case engine. Many issues in these early engines have been addressed. More Flywheel bolts holding the Flywheel onto the crank is one. Cylinder Heads is another. Many of these upgrades will filter down into parts we will make available.

A new Crankshaft Damper has been drawn for the 911 air cooled engine. Unfortunately this is not an easy conversion. The existing Damper requires the Front Bearing Sleeve (#8 bearing ) to be modified so this can only be done when the engine is apart. The new Damper will fit to a series of new Crankshafts with a completely different attachment.

More to come.

[Neil Harvey]

I wanted to update the air-cooled parts some time ago but am involved in 992 GT3 street, Cup and Turbo development that has taken a lot of time. I know water engines have their own place here but will post some pic’s of what we are doing. Even though these are different engines, a lot of what we are doing will find its way back into our air-cooled parts. Lots to do so the air-cooled stuff got pushed back.

Posted about the Rocker Arms and the new Damper earlier today. Catching up on what we are doing with this post and others coming.

Working with these engines we come across issues that make you think, how can we make this better and easier. When you get positive feedback that the parts made the assembly easier, it is gratifying. The added features made a difference in the exact way they were intended.

In both cases I speak of, both customers bought our Head Studs and 1 piece base Gasket set. The Base Gasket makes it simpler as you fit 1 per side.

The Head studs allow you to adjust the height when required with the heads are attached. This is a feature no other Head stud supplier has. I recommend the Head Studs are installed with grease and not Loctite. This allows the Stud to turn when tightening the nut. This movement removes any added friction and often that snapping when the Loctite lets go. If the stud does turn, you loosen the nut and with a ¼” socket, turn the Head stud. We have Head studs with 10.00mm and 12.00mm case threads both with 3.8” x 24 upper threads using our Titanium Nut and Washer. The Titanium Washer helps insulate the Nut from transferring the temperature into the nut.

Thank you for the kind words and I am pleased we helped.

[Neil Harvey]

So far base Gaskets fit 90.00mm head stud spacing. Smaller Head Stud spacings coming.

992 Damper shown is the only printed part so far with the new 911 attachment. We have new Cranks on order now with this front nose detail.

[JoeMag]

Few thoughts on the harmonic damper... I got one for my current build (gt3 nosed crank) from Neil. The degree markings on the wheel are excellent. I'm actually using it instead of my 24" degree wheel. Setup a mark so TDC is correct (based on dial indicator drop of piston around TDC). Tip of the line is correct location. You can see fan shroud mark in first pic; off about a degree.

I put a phone holder on the motor and zoom in with the camera. Second pic is about how far I zoom in and you can see he space between degrees is actually more than with the 24" degree wheel.

[Neil Harvey]

Very busy with 992 GT3 and Turbo upgrades. Many engine issues that need attention. The air cooled development has taken a back seat somewhat. I can say this, if you own an air cooled engine you are one of the lucky ones.

A new oil/air separator is in the works for the air cooled engine. These engines have needed this for years. If we can rid the oil of some air the oil cooling will be faster and more efficient. Maybe less oil coolers are possible. Testing will tell. At least the oil will be more consistent.

Project 24 is underway and I should be able to show off some of the new parts we have developed for this engine. This engine will include many of the parts we have to date, including the Case Through bolts, Head studs, Crankshaft, Connecting Rods and Pistons. These parts will be available individually soon.

A new modern ITB system will soon be available for those that wish to use mechanical Injectors. This system will incorporate a TPS sensor and a MAP sensor so a modern Ignition control system can be used. Keeping the distributor but having the advance, base timing etc all controlled electronically. No more points and better timing control. A simple conversion from an existing EFI ITB system for those that do not care for the original look but a more modern and adjustable unit.

Have an air cooled project we are involved with presently that is very different and has many unique changes and features. We are consulting and helping with the project so we cannot give up any details as its not our project. As soon as we are given permission we will and hopefully photos. This is a project I am particularly interested as it incorporates modern technology in an older engine.

Have had a lot of positive feed back regarding out Head studs. Telling us, how easy they are to install with the upper hex, the quality and the use of high quality nuts and washers. Adjusting the stud height can be achieved with the heads installed. Its does make a difference when we get positive feed back as it tells us we are doing something right. We sold many sets and have more in production so we keep inventory all of the time. Also, we have these with 12.0mm case threads for Turbo applications and if required, std case repair where a larger size may be required.

I have viewed some of new parts offered by other vendors. Its great others are doing this as it gives more choices and life to these older engines. Hopefully more vendors will get involved offering more and better solutions.