Another hot rod

As discussed in a prior post, the ANDIAL engine, originally built as a longstroke 2,5 was treated to a displacement boost about five years ago.

At that time, a set of ANDIAL 2,9 pistons and cylinders were installed. ANDIAL developed the 93mm pistons and cylinders in conjunction with Mahle to satisfy their customers who wanted the largest practical displacement from engine cases with the early cylinder head stud spacing. These pistons are 1mm larger in diameter than the 92mm 2,8 RSR pistons, which give 2808cc.

Here is a pic of one of the 93mm Mahle forged pistons with its matching Nikasil coated cylinder. Like all of the Mahle pistons made for high compression racing applications, these are forged aluminum.

The prior owner of the engine, after deciding to increase displacement, was faced with a choice as to how to make the old 2,5 heads work with the increased bore. Essentially, there are two choices: either chamfer the heads to accomodate the increased bore of the piston domes or alternatively, chamfer the pistons. He chose the latter of the two.

Here you can see the chamfering around the circumfrence of the piston dome. This allows the heads to remain unchanged from their original configuration and would allow them to be used again with pistons of 86.7mm diameter if it was decided at some point to go back to a 2,5 displacement.

These pistons are over five years old but still look new. The one illustrated only needed to have its dome wiped clean with some brake cleaner to make it look like this.

It is our intention to use pump gas so we will need to measure the compression ratio of this head and piston combination. Although twin plugged, it will have a compression ratio of no more than 10.5:1.

Here is the flywheel that was on the Andial engine.

As you can see, the flywheel has been subjected to a weight reduction program and looks very much like an RSR flywheel with its outer circumference liberally scalloped in the identical distinctive pattern.

However, the hub has not been drilled as was done on the RSR flywheel.

The flywheel has a 930 part number so perhaps it has its origins from 934? Or perhaps a modded turbo bit?

An image of an original RSR flywheel (not mine), with its extensively drilled hub, is shown for the sake of comparison.

Earlier on in this thread it was mentioned that ANDIAL 129 had the first version of the factory's high butterly mechanical fuel injection.

This system is referred to today as the "2R" system. The ports on these 2R stacks measure 41mm at the bottom of the stack where it mates to the head, port matched with the 41mm intake ports on the ST twin plug heads.

The 2R system was fitted as original equipment on Typ 911/70 (long stroke 2,5) and Typ 911/73 (short stroke 2,5).

Here is an image of one of the magnesium stacks. You can see clearly the 911.110.107.2R casting number with the ST unique 2R suffix.

This from Matt Blast of Eurometrix from the Competition Throttle Body thread:

"2.5 ST High Butterfly, 50mm top throttle plate, bottom size presumably 41mm. Three sets I've measured or had someone measure were 42-43mm on the bottom. At least two of these had been modified for sure. Anyone with an unmolested 2.5 houising casting #911 110 107.2R please measure the port side diameter. Throttle plates, shafts and bushings same as 2.8-3.0.

And further:

"Yes the casting number for the 2.8/3.0 is the 5R (911.110.107.5R)"

Note that the shaft couplers are of the early original style and remain in fine condition.

Although this hot rod is being re-manufactured to factory competition specs, we wanted to remain sensitive to its original production car origins.

The paint tag on the driver door hinge post was left intact. It shows 3939-S, the MY 71 paint code for Olive.

The manufacturer's tamper proof sticker on the driver side lock post was similarly left intact. Note that the original Olive paint can be seen in the little perforation in the center of the tag. The DOT tag shows the build date of the car in the upper right hand corner. It shows that this car was built 02-71. The chassis number is stamped into the tag along its lower right hand quadrant: 9111300694.

Up front, the guys made certain to leave a nice sharp looking chassis number imprint when the fuel bay was sprayed.

re: "Ollie's updated the heads with beryllium seats for exhaust valves."

what are the advantages of the exhaust valve beryllium seats?

and did Porsche ever use these on production or factory race cars?

thanks.

I guess the surprisingly graceful shapes of the flares are what make the ST such an alluring theme on which to base a hot rod.

It has been a good long while since we had a look at the old steel ST flares, so here are two gratuitous images of the hot rod flaunting its "revised wheel arches."

All those purple bandaids in the fuel bay are to keep the satin black overspray down in the footwells.

Quote:

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Originally Posted by 37yrold911

re: "Ollie's updated the heads with beryllium seats for exhaust valves."

what are the advantages of the exhaust valve beryllium seats?

and did Porsche ever use these on production or factory race cars?

thanks.

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Hi 37yrold911

The function of the beryllium exhaust valve seats is to dissipate the heat faster from the head of the exhaust valve. I am not aware if Porsche has ever used this type of insert on their race engines. However, the engine designers were certainly cognizant of the necessity to dissipate heat from the head of the exhaust valves. That is the reason that the exhaust valves are sodium filled (the sodium filled cavity of the valve ends just beneath the dimple in the center of the head of the exhaust valve). I should have described this as a modification, rather than an update, as update implies an evolution of factory design.

The shop recommends this modification primarily for pure race engines. In particular, this treatment is used on all their turbo race engines and also full race 2.0 liter engines for class racing. These are the types of guys who are stressing equipment to the max.

In the case of ANDIAL 129, this treatment has two benefits. First and foremost in my case, it allowed the exhaust seats to be cleaned up on the old 2,5 heads, which I wanted to save along with all the engine's other old original race components that we could make serviceable.

The heat dissipating properties of the beryllium seats for the exhaust valves are a bonus for me but as it is not my intention to be stressing this equipment under racing condiitions, it would otherwise have been unnecessary. This is just a hot rod.

Beryllium adds strength (or is it stiffness?) to Copper and Copper alloys like Bronze, in addition to the more efficient/faster heat transfer.

Thanks Flieger.

This from Martin Brickwood:

"Beryllium Copper Valve Seats
Another great idea from the NASCAR and Formula 1 communities, beryllium copper has become the material of choice for valve seats in high-performance cylinder heads. The key advantage to this material is its exceptional ability to dissipate heat but as a bonus, they offer a cushion to the valve that is not provided by the new unleaded gasoline or the ultra-hard seats typically required with this fuel."

Shared some pics with a friend in England.

He remarked that the hot rod was "wearing more paint than an old tart in Whitechapel."

So now the car has a name, "The Olive Tart."