911 aircooled developments
 

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Some images of the new 92.00mm Piston and rod we did for Jeff and now used in both the 93.00mm kit, along with other kits.

Very nice - what does the top of the piston look like?

What do you use to retain the wrist pin?

Is Jeff's engine up and running yet?

Makes me wish I had't sold my old 2,2.....

Std type round wire lock.

These rods are currently available in all of the std sizes and lengths. There are two levels of rods dep[ending which material they are made of.

The "standard" grade is 34CrNiMo6 which is higher than 4340, commonly used in domestically made aftermarket rods. This has a tensile strength of 1400Mpa, where 4340 is 1200Mpa. The other material used is 35ncd16 which is higher than 300M. It has approx. 20% more fatigue strength over 300M. I'm not sure is anyone builds rods unless custom, with materials this higher grade.

These are offered as a alternative to the other well known aftermarket rods currently sold and used in these engines. The "35" versions are lighter than anything else sold currently unless you move into Titanium. They have added features including the relief shown above the BE so the compressive loads are transferred over a larger part of the upper bearing shell.

We are also making available these rods in some custom sizes and lengths along with custom Pistons. These kits will be available for all of the std air cooled rebuilds where the std deck heights are in play along with all of the std CR numbers. Top guided and longer CCL rods, shorter piston compression heights with smaller piston pins. giving better control of the piston, better gas exchange, and less weight over the pin will help these older engines that have been supplied with age old designs for years. We feel its about time someone offered something new.


We are currently in production with rods and Pistons, so initially there will be some lead times for these parts. Stock length rods are currently available now along with std pistons for those that are not inclined to wait.

Our customer base has taken us back into the air cooled world after many years not seeing one of these engines. Upon some research we found the same old parts designed back in the 70"s still been sold today. This gave us cause to re look at what is available and make new parts for these engines, including these Rods, Pistons, Camshafts, Intake systems, exhaust systems, etc.

Some more updates on some of the parts soon to be available.

2.8L upgrade.
The photos attached above are the parts available for the earlier 911 engines to upgrade to 2.8L. Included in the 2.8L kit is a new camshaft. The Rod is longer and lighter than any other currently available for a 2.8L upgrade. Same for the piston. The piston pictured is for a dual plug head. These are the parts we supplied to Jeff (home built) for his 73 911 engine.

2.9L upgrade.
These parts are currently in prototyping and we should see these in the next 2 weeks. A new longer, lighter rod, a new Piston for dual plug head, and a new camshaft are included in this upgrade kit.

3.4L kit
This upgrade kit includes a new rod, and a new Piston. We have also designed a new piston for single plug heads to be an alternative to the early wedge type piston design. A new camshaft design is in development for this kit. This engine upgrade has been lacking for modern components for years.

3.8L upgrade
This is currently in development and should be completed by months end. A new Rod, Piston and camshaft will be available.

964 Camshaft.
This camshaft will be our new version of the venerable 964 cam used in so many engine upgrades.

We felt that many of the current kits available for these engines have not kept up with the changes in modern design. Many of the substituted parts are copies of factory parts giving no increase in the engines efficiency. We have focused on component weight, friction reduction and air management to gain back some of the engines performance lost in these air limited engines. Customers have been limited to choices with most engines built using the same parts. We felt its about time these earlier 911 air cooled engines had some new parts.

All of the kits can include upgraded cranks, cylinder heads and other options we currently offer.

How does someone purchase from you? thanks

Interested in the 3.4 pistons and rods.

Best to email me with what you need.

neil@performancedevelopments.com.

same. Email with what you need.

Would need your cylinder head volume so we can establish the CR you need and the cylinder heights you have. These kits are "custom" to a point. Although most will end up the same, there is some leeway we have to obtain exactly what you need.

Neil

Some updates.

The 2.9L engine parts are almost completed. This engine config uses a different piston forging as the 93.00mm bore allows the use of the lighter bridged forging. This forging also allows for a much shorter compression height making the piston lighter as well.

The biggest gain had in this engine is the connecting rod. Its a lot longer than stock and lighter. They are coming in, sub 480 grams. The first prototypes are close to been finished and tested. Once we have this completed they will go into production.

There is only so much you can expect these small displacement engines to produce. Heads have limited port sizes, valves sizes are dictated by cylinder bore size etc, so component weight and friction are two areas that gains can be had. We know how much these engines can theoretically produce with the energy contained in the fuel, and by subtracting all of the loses known in 4 cycle engines we end up with a number between the actual measured BHP and what the calculated HP is. This amount of HP is what we can influence with component design, component weight and lowering parasitic losses.

Friction is a huge loss in small engines so anything that can be done to lower this is a huge help. Anything that slides against something creates friction and heat and this energy is lost is just turning the engine over. http://forums.pelicanparts.com/uploa...1570815562.jpg
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The work involved and these parts come at a cost. They are not cheap and not intended to take the place of current parts sold by other vendors. They are intended for those that what a more modern interpretation of these earlier 911 engines with components that are engineered and designed to extract more performance.

There are new pistons in design for single plug versions of both these engines and as soon as they are completed I'll post photos. Included are pistons for the 98.00mm bore as the 3.4L conversion from 3.2L seems quite popular. The new design is a compete departure from the ancient wedge type sold currently for these engines.

Forgot to add, the new head studs we have in production go along with these upgrades as well.
I have included here a better photo of the camshaft and the stock cast rocker arms. http://forums.pelicanparts.com/uploa...1570816631.jpg
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Neil, excellent stuff!!

Not that I am in the market, but more of a curiosity question. Do you plan on boosted applications with flat top or slightly dished pistons with your connecting rods?

Just really curious what that combo would result for RPM wise on a 3.2 based 3.4? Redline basically.

PM sent.

Never received any PM. Send it again and I will respond.

An update also.

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An update also.

The cam inventory is getting larger. We now have non symmetrical cam designs for air cooled NA engines up to 2.8L, 2.9L to 3.4L, 3.4L to 3.6L and 3.6L to 3.8L. All these new designs will only be available on new billets, with DLC lobes. The existing 1/2 step designs and some of the older Turbo designs can be regrinds.

These designs are all matched to our new spring. This spring comes in two favors, each having a slightly different rate and installed seat pressure.

I'm happy to announce that Steve Becker, ex Andial race engine builder has joined PD, is up and running and will be taking care of the PD stock/upgraded engine rebuilds and also offering our Signature machining service including Cylinder head rebuilding service. In the past PD has not offered this service at the price of many other service suppliers. Our work was never intended for those customers requiring a cost based product, rather for the more exclusive customer wanting quality over cost. Steve is now able to offer a cost competitive service for those wanting a quick turnaround, quality work and will be selling our line of Connecting Rods, Pistons and Cylinders, Camshafts, Valve Springs, Head studs and fasteners.


Above is an example of what you will receive.

Neil... what's weight of that assembly? Very nice appearance.

As pictured, Rod with bolts, Pistons and Pin, 914.50grams.

No clips or rings included in picture.

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Would it be possible to have the wrist pin even higher up in the piston? If you had a hole where I marked on the picture, and slid the wrist pin in, and then had a tight fitting plug that locked in place, with grooves for the piston rings, you would have a much better geometry. You would have to put the piston rings on after the rod was installed.

You would get less piston slap, a lighter piston, and a longer rod to stroke ratio. All making more HP... Or am I in the wilderness here?

Pin position is always limited by the forging. In this case the forging was determined by bore size.

Its not uncommon for the pin to interfere with the oil groove. I'm not a huge fan of doing this as you have to use a support rail which adds weight.

What you are suggesting is something not done to my knowledge.

Good luck on that one if you do.

Good engineering practice is to center the wrist pin location with respect to the piston skirt length. Re-locating the wrist pin near the ring belt as suggested would result in piston cocking in the bore, driven by rod angularity and dynamic forces. This would create a noisy, short lived engine. The parts as shown look beautiful, well thought out, and designed correctly.

Congratulations Neil - I'm saving up for a set!

Thanks Neil :)

You are welcome.

I figured I should clarify the direction we have taken and the parts we are offering.

Two "things" every engine upgrade should be preempted with are, your performance goal and your engine budget. You may have to come off your performance objectives some to meet the budget. In other words, don't over buy parts that will not make any difference to the performance goal.

Performance Developments builds many high performance engines, used for off road purposes. These have a single objective, to produce a reliable performance level. Component design include features that produce higher levels of torque more efficiently, lowering frictional losses and the ability to rev quicker resulting in the engines torque band reached quicker in less time.

But when we looked at the street business, most of what is produced and sold is age old copies of parts designed in the 70's and 80's. Not a lot has changes. So we went about including features that will make a difference to a street engine in areas we consider extremely important.

The parts designed offer a modern higher level of technology to those customers wanting something engineered to recover some of the lost performance that has been considered normal and acceptable for years. The cost is higher as the quality and technology is higher, therefore, not for all.

We are not trying to compete against what is already available for these engines. If what is currently available meets your performance goal, our parts should not be considered.

Our on going parts development continues. Weight has been our focus here along with modernizing the components.

This is the new 2.9L rod that will be an addition to the existing 2.8L steel rod. This rod is a little more expensive as its designed with weight as its main criteria. Shown here is without bolts. The new bolts for these rods weight 24.5 grams ea.

This rod fits the stock crank journal but is longer in length and uses a smaller pin size. This lightens up the piston as well. Once we have the assy all together I will weigh as a comparison to the stock parts.

We are offering all of the stock Porsche and BMW rods sizes as an alternative to the commonly sold versions. Coming very soon are lightweight steel versions for the 74, 76 and 80 mmm cranks. The 76.40mm lightweight rods are designed for the 3.8L engines along with the GT3 variants.

We are currently involved in several high end air cooled projects and some of this technology is filtering back into main stream sales. The new head studs, exhaust and thru bolts, camshafts, valve springs etc are all coming out of these projects. The new head studs are in stock now and we expect to have the new "964 fit to everything engine cam" available soon. The design is completed and its undergoing Spintron testing now with its new Valve spring and retainer. This will add to our increasing cam inventory. http://forums.pelicanparts.com/uploa...1575489599.jpg

Neil, have you entertained the idea of smaller rod journals, like the 1.85" journals currently used in nascar cup cars? They would likely help with the oil pump clearance problem on the long stroke cranks along with weighing less. And better and cheaper bearings are readily available.

Indeed we do, but the 2.8L and 2.9L rods were designed to run with a stock crank. The issue with the stock crank is the oiling holes. This limits the journal been cut undersize. The larger journals on the 3.2L and up cranks can be cut undersize. I think the max on them is 2.00". However, both of these rods have narrow beam widths than stock.

Custom engines we build use a lot smaller journal and a narrower beam thickness. But these use a non stock crank they have different pin oiling.

Neil, ignoramus question here: are these rods created by that process whereby they're cast (forged?) as a whole but the segment that is to become the big end cap is forcefully whacked/cracked/split off? Or is that only done with components mades from sintered metal? Thanks in advance for the lesson! John

Also to add to your question, the BE radius is designed to clear the biggest oil pumps using stock journal diameters.

To compare against the Titanium rods we use, they weight 403 grams with steel bolts but cost 3 x as much. So 461 grams for a longer steel rod with bolts, larger BE and longer CCL, we feel we have achieved our primary objective.

variants No, these are made from a forging with typical parting lines with dowels. Material and after processes will remain confidential at this time as we have a huge amount of time and many prototype sets involved in these first finished parts.

These are special lightweight variants but we offer all of the stock Porsche sizes as alternatives to those commonly sold in the aftermarket. We wanted to also offer a more "custom" line of steel rods for those engine customers who want something special over the standard parts sold in the aftermarket.

Dumb question. If I use light weight rods and pistons do I need to modify the crank for optimum performance? In other words, with light weight rods are the counterweights on the crank too heavy and should they be knife edged to compensate?

opposed engines aren't balanced with bob weights like V engines are, so as long as the pistons and rods all weigh the same, you won't have any problems. If you cut down the counterweights or knife edge the crank, it will need to be rebalanced.

Yes, but I am wondering if the stock counter weighs are now more than needed with lighter rods/pistons. Then again, Porsche added more counter weights when they went to the longer 76mm stroke motors, including the GT3s.

Good point and you are correct in your thinking. These engines and their layout with narrow cylinder spacings do not lend themselves to a great crankshaft design.

The 993 cranks that have a 0.750' wide rod journal in difference to the earlier cranks that have 0.866' wide journals, were done to add width and mass to the mid sections, to help stiffen the cranks due to the added stroke.

All cranks including Porsche cranks twist back and forth from torque pulses. The longer the stroke, the heavier the masses reciprocating and rotating, the higher the combustion pressures all add to the stresses and movement placed on that bent piece of steel spinning at 7000 RPM.

The more you can lighten up the masses helps. Going in this direction as opposed to going heavier, certainly helps. But, as you suggest, calculating the counterweight required is important. The % of counterweight on all Porsche cranks allows you to lighten up the masses without having to remove weight, unless you are turning the engine at very high speeds. In just about every air cooled version I can think of, the engines ability to pump air for those speeds is zero. Counter productive.

What I can tell you is this, if you do remove counter weight material, (knife edging) you are not doing the engine any favors. This is the wrong way to go. You need what weight is there to help counter the flexing. If you had larger counterweights with a higher % number, then yes, but this is not the case with Porsche flat six opposed crankshafts. This is why we choose to go in the other direction and lighten up the rod and Piston assembly. Effectively, we are increasing the counter weight %, helping to lower the crank movement.

We have the 1st lightweight 2.9L kit ready for assembly. This kit uses the new lightweight, longer rod we designed for both the 2.8L ,2.9L and up to the 3.4L applications. These all use the 74.40mm crankshaft.

The combined weight of the 2.9L lightweight kit is 920 grams with rings, clips, pin, rod and piston. The other kits may be slightly different due to piston size. I have the 2.8L piston weight somewhere and can weigh the 102.70mm piston along with the 104.00mm pistons we have in stock. Weights to follow.

A standard Porsche IRP rod can be substituted if required, along with standard spec piston. We are offering these kits as an alternative to all of the existing rod and piston kits that have been sold for many years.

PD is offering IRP rods as an alternative to the aftermarket rods, commonly used. All stock Porsche applications are available as well as the lightweight "custom" kit versions. These are more expensive and are designed for those applications requiring a more engineered solution.

We also designed lightweight rods for the 76.40mm and 80.40mm strokes that will be sold for the 3.6L, 3.8L and 4.0L engine kits. Pistons are available as well. To go along with all of these kits we have new Camshafts, Valve springs, Head studs, Ex studs with more parts in development.

At present, until we can catch up, the Rods and Pistons are available with a min 4 week delivery time. Our intention is to carry these in inventory, but we have a lot of development underway and our resources are stretched to the max. http://forums.pelicanparts.com/uploa...1576011743.jpg

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Pictured is the "standard" rod and the new lightweight rod, to give a comparison.

Are you sure the Rod pictured as your 2.9 package is not the BMW rod you manufacture, the reason being the sipes on the side of the big end which is common but not always used for pairing rods on one common journal such as a V8

regards

I can guarantee the two rods shown are for a Porsche air cooled engine.

The lightweight rod (2.9) has taken almost 1 year to get to this stage. My bank balance tells me this every day!!!

It very difficult to lose weight, retain strength and stiffness.

This rod weighs 412 grams without bolts. It will lose another 20 grams as we have trimmed some more weight where it’s not needed.

Just curious as to why the sipes in one and not the other

I was thinking the same as racing97. Usually the sipes on the thrust surfaces are used as squirters for the pistons? We don’t need those since the case has the squirters, right?

We are removing all added weight that serves no purpose. I’ll take from wherever as long as it doesn’t affect strength.