Aftermarket part pains

March 7, 2015 Jeffrey Jones

Sometimes ‘upgrading’ to aftermarket parts creates unintended consequences. In the process of removing and reinstalling the engine a couple of times I’ve found there are some aftermarket parts that are not conducive to an efficient pain free process.

Two items that are particularly noteworthy in this respect are shown below.

The Apikol transmission mounts use a very long bolt to secure them in place, this creates problems when trying to install the mounts.

I’ve found that it can take as long to get these bolts into the mounts as it does to install the engine. I’ve wrestled with these bolts for up to an hour each time during two engine installations. The best method I have come up with is to bend back the heat shield over the Apikol transmission mount, put the motor back in place so that the holes in the bracket and mount are aligned, raise the front of the engine with the hoist, and then put my floor jack under the car to raise the rear of the transmission. If I lift the engine and transmission a couple of inches I then have enough clearance to wiggle the bolt through.

Upgrade Work

Engine Pull Déjà vu

March 6, 2015 Jeffrey Jones

Once more the temperatures cooperated and I resumed the work pulling the motor back out to identify where the intake leak was at.

It was the clamp shown below.

It had not been pushed back far enough onto the compressor inlet, so that when it was tightened it merely started to wrap the silicone connector around the inlet, allowing some air to escape during the intake pressure check.

Tomorrow I’m going to hook up the rest of the intake, Intercoolers and Bipipe, and run another pressure check to verify that all of the clamps are now tightened correctly and adequately – then back to work putting the motor in the car again.

Misc.

Running out of breath

February 25, 2015 Jeffrey Jones

Falling on it’s face… dying up top. Words to describe how some turbocharger is inadequate in the view of the person commenting on the turbochargers performance.

Shown above are sections of the compressor maps from three popular turbo compressors in use on the Audi B5 S4. This section is the top right corner of the map. What I am trying to illustrate is the difference between a turbocharger that dies up top, runs out of breath, and falls on its face, compared to a turbocharger that does not.

See the difference? Notice how the one turbocharger compressor does not have a drop in volumetric flow rate at the maximum speedline PR even as the flow rate continues to increase? (PR is the vertical axis and flow rate is the horizontal axis.) No? You don’t see that? Neither do I, in fact all the compressor wheels show that with increasing flow rate the pressure ratio declines, and by a certain flow rate that PR drops quickly, as the turbo ‘falls on its face’.

So what’s behind this phrase that gets thrown around? It’s a description for a result that any compressor wheel eventually reaches, a point where in order to try and increase flow rate through the compressor requires a drop in the PR. Where you will find the phrase being used is in a comparison that pits a large compressor wheel against a smaller wheel, one where it should be quite apparent the larger wheel should be capable of flowing a greater volume of air, beyond what the smaller wheel is capable of, up to the point where the larger wheel also falls on its face, dies up top, and runs out of breath, just like the smaller wheel does.

If you have not figured out which map belongs to what turbocharger, the top is for the K04, middle the K03, and bottom the RS6.

Audi B5 S4 Information and Testing