DIY Duratec balance shaft delete

Some Duratec blocks are equipped with a balance shaft. As most sports car owners are more concerned with weight and rotary mass than ride comfort that is something that needs to be removed. A balance shaft are a quite big lump of iron situated below the crank, inside the sump, and a dry sump doesn't have room for it anyway.

Plug before punched in place.

The only problem is that there is an oil supply to the balance shaft that needs to be blocked. You can find kits for that from Cosworth among others. They're not expensive but as usual Cosworth's delivery times are not from this earth so I decided to try a DIY solution.

A M8 cap head bolt and some grinding made a perfect fit. Degreased with acetone and then Loctite cylindrical bonding. Unlike my VCT Delete stub this plug does take load from the oil pressure. Therefore I filed the plug on the cap head side, making the hole a bit deeper than the plug. Then I carefully deformed the block with a punch so the plug would be kept in place.

VCT Delete

Using aftermarket cams on a VCT Duratec head requires that the VCT valve is removed. Unfortunately this opens up an oil passage which must be blanked, and doing so without eliminating the oil supply to the no 1 cam journal.

This is also known as "VCT Delete", and hardware for this can be bought from massivespeedsystem.com in the USA.

But importing stuff from the USA is not very cheap after adding postage, VAT and customs, so here is a sketch for a DIY solution.

I went to a local mechanic in the neighbourhood and got this part manufactured in aluminium.

Glued it in place using Loctite for cylindrical bonding. It won't take any load, in fact the oil pressure will generate forces in both directions and keep it in place by itself. But just to be sure, I made a punch mark that definitely will keep it in place.

Duratec Front Pulleys

Some of the more recent Duratec versions uses a larger front pulley trigger wheel than before. The trigger wheel diameter must match the style of the engine front cover, at least if you plan to use the standard crank sensor and mount.

Also, if the pulley size is large on high rpm engines it may cause the alternator to over-rev, and the water pump could experience cavitation that causes cooling problems. It is also said that unnecessary power is lost. For these reasons aftermarket under-drive pulleys are available in various models.

On the picture above there is to the left a 164mm under-drive pulley, in the middle a stock 146mm old style pulley, and to the right a stock 164mm pulley.

Aftermarket underdrive from TTV Racing.
Weight: 776g
Trigger wheel: 164mm
Pulley: 100mm
Alternator rpm @7800: 13000 rpm.
Waterpump rpm @7800: 7428 rpm.

Stock old pulley
Weight: 1529g
Trigger wheel: 146mm
Pulley: 137mm
Alternator rpm @7800: 17810 rpm
Waterpump rpm @7800: 10177 rpm

Stock large pulley
Weight: 1949g
Trigger wheel: 164mm
Pulley: 155mm
Alternator rpm @7800: 20150 rpm
Waterpump rpm @7800: 11514 rpm

The alternator pulley above is 60mm, water pump pulley 105mm.

According to the book Four-Stroke Performance Tuning by A. Graham Bell, a water pump's maximum efficiency zone is usually between 4000-6000 rpm.

A good article/calculator addressing how the pulley weight affects power output can be found here: http://hpwizard.com/rotational-inertia.html#flywheel

Damper position sensors

I've written before - I have a thing for measuring things. I also have a new set of adjustable Penske dampers and wanted to see how their behaviour changes when turning those adjusters.

So, I've bought a pair of position sensors and made 3D printed suspension mounts for them. So far just for the rears but plan to do it all around.  They're wired into my data logger.

For reference - rear right.
The same five runs with Mid/mid setting.

Rear left, five runs with different settings.

I've made an attempt before with strain gauges on the pushrods. I'm looking forward to combine the two methods and see what that gives.

This weekend I got the chance to do a few test runs. I drove the same piece of road five times and adjusted the damper on the left rear between each run.

The X axis is the damper velocity (input voltage derived by time). The Y axis is the probability.

There are theories that the best suspension settings are when the diagram is symmetric around the zero. Regardless if you believe those theories or not, one can note that the rebound adjuster moves the curve sideways, and the compression adjuster mostly changes the peakiness of the curve. The Mid/Mid setting, which is the default setting from Penske, is very symmetric and that is probably a good sign?

The usefulness of this can be discussed but at least this gives me something to look at, as I don't trust my butt-dyno at all. 

Penske dampers

When I bought my car it was equipped with Caterham CSR race spec dampers, non-adjustable Bilsteins. They're now 10 years old and not serviced once, and therefore I now think I finally got an excuse to replace them. They've always worked great but I've always been longing for adjustable dampers. Also, my rear droop travel has been limited.

After being in touch with different damper manufactures I chose a set of double adjustable dampers from american Penske - their 7500DA. The reasons I chose Penske were:

• Good reputation, high end dampers
• Very helpful and service minded
• User serviceable! And equipped With Schrader valves to allow control of nitrogen pressure.
• Affordable (but certainly not cheap)
• Custom built for my car, not an off-the-shelf product.
• Plenty of information about their products on their home page.
• Black and gold... What could possibly go wrong??

I was disappointed that the Swedish Öhlins couldn't help me. A lot more expensive (about twice), and still they couldn't tell me anything about their products that made them better than the others. In fact they couldn't tell me much about anything at all. They were not the least helpful. 

I sent them information about the car and let them decide what would work best. It took some trial and error, a bit of thinking and a mechanic workshop for the mis-alignment spacers before the dampers was finally mounted on the car with the adjusters accessible. Now I got adjustable dampers with a lot more droop travel without sacrificing bump travel. Not sure what it will do on the lap times. I guess it will depend on myself and how I manage with the setup.

Damn these salty roads. I can't wait until spring!