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The Buchka 242 Daily Driver

Spinning another accessory using engine power will always rob more engine power. Even with a larger alternator, since you having less rotating accessories.
Steve

This assertion smells funny.

A well engineered belt drive can be 98% efficient.

80% efficiency is a good number for both and alternator and a small DC motor.
Considering that the alternator is also belt driven you have, optimistically,
98% x 80% x 80% or 63% efficiency if you generate electricity and then turn a
shaft with it in a typical automotive situation.

Electric power steering pumps can be more efficient than a belt driven pump, but
for other reasons, predominantly that assist is only needed when actually turning,
and the assist required is inversely proportional to road speed.

Belt driven loads need to be able to cope with a wide range of input speeds, and this
leads to inefficiency also.

Comparing watts to watts, it is more efficient to drive a hydraulic pump directly
from the crank versus generating electricity from the crank then driving the pump
from an electric motor.
 
This assertion smells funny.

A well engineered belt drive can be 98% efficient.

80% efficiency is a good number for both and alternator and a small DC motor.
Considering that the alternator is also belt driven you have, optimistically,
98% x 80% x 80% or 63% efficiency if you generate electricity and then turn a
shaft with it in a typical automotive situation.

Electric power steering pumps can be more efficient than a belt driven pump, but
for other reasons, predominantly that assist is only needed when actually turning,
and the assist required is inversely proportional to road speed.

Belt driven loads need to be able to cope with a wide range of input speeds, and this
leads to inefficiency also.

Comparing watts to watts, it is more efficient to drive a hydraulic pump directly
from the crank versus generating electricity from the crank then driving the pump
from an electric motor.

It all seems pretty academic to me until someone actually starts measuring amps used to run the electric pump, etc. But in quick google searches I'm finding info that suggests dyno testing on engines with belt driven PS pumps show it can lose as much as 8 ft lbs at peak torque.
Dave B
 
I’m interested to hear some more colored feedback after you’ve driven it a bit. I’ve not yet driven a car with any level of electric assist that had satisfactory steering feel. I haven’t driven a new 911 but all of the modern BMWs et al are number than the back of Lindsay Lohan’s throat on a Saturday night.
 
Electric power steering pumps can be more efficient than a belt driven pump, but
for other reasons, predominantly that assist is only needed when actually turning,
and the assist required is inversely proportional to road speed.

Pretty much exactly this. There is no efficiency to be gained from bolting on an electro-hydraulic pump and running it full blast all the time. It will, all things being equal, always use more power due to conversion losses. That being said, I didn't do this for any perceived efficiency benefit, it was only for packaging. The car has fairly heavy steering now which I am actually a bit ambivalent about, I have no need for effortless parking lot steering and feel at speed is about the same as before.

Thats not true at all. Plenty of people with power racks are still using EPAS

Exactly. We put a prius EPAS column in our E36 lemons race car. The thing kept nuking power steering pumps and tossing the serpentine belt. All we did was loop the lines on the rack and mount the column. The torsion bar isn't even locked out in the spool valve and it works great. Steering feel is slightly worse but it's not exactly razor sharp from the factory so :e-shrug:

In preparation for dyno tuning I added some instrumentation to the car. I wanted exhaust gas temperature and fuel pressure monitoring in the ECU to make sure things weren't going pear shaped. Bought a Setra transducer on ebay and made a short M12 to D38999 jumper harness that connected to one of the spare I/O bulkhead connectors Karl set up on the engine harness.

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I didn't get any pictures of the EGT probe work but the engine now has 8 K-type sensors on it. One for each cylinder, one in the collector, and one in the downpipe. I connected everything to an 8 channel thermocouple to CAN interface box from AEM. Apart from an intial SNAFU where I had to learn the hard way that the AEM box does not support grounded sensors, everything went together pretty smoothly.

I took last Friday off work to meet up with my ace calibrator friend Neel at a shop in the inland empire called Nine-11 Design. It's a high-end Porsche shop that graciously allowed an old Volvo to besmirch their Dynapack for a day.

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The Dynapack absorber unit was a very tight fit on the passenger side of the car. While bolting up the hub adapter I was nervous about clearance but it just about fit.

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Their cooling fan setup is highly optimized for air cooled Porsches so we had to be careful to keep temperatures in check. There just wasn't enough airflow to keep up with steady state operation above about 4000rpm so for everything after that we just did transient pulls from 2500 to redline.

The fuel map was already 90% good from road tuning so we focused on timing and boost control. From a baseline of 220whp at 8psi we ended at about 320whp and 325lbft of torque at 14psi. The day was cut short due to some scheduling conflicts with Neel so we ended it there. I'm going back in a few weeks to continue dialing in timing, boost control, and knock detection. There were no signs of detonation at 14psi so I'm confident the car is capable of 350whp or more on 91 octane pump gas.

I couldn't get the stupid embed function to work but here is a short clip I took of one of the pulls we did.

https://youtu.be/DeyrS2Kk1yY
 
Probably making 365 - 375 at the flywheel right now. This thing scooted before, should be a rocket now. Will need to verify!
 
Looking forward to the post describing accidental 4th gear wheelspin...assuming traction control hasn't been set up yet.
 
Thanks dudes! Pretty happy with the results so far. I'm confident the combination has considerably more power in it. Going to add some pressure sensors to the manifold and downpipe before the next session to keep an eye on total delta P across the engine and turbine.

Looking forward to the post describing accidental 4th gear wheelspin...assuming traction control hasn't been set up yet.

The car still has a stupid open diff so it's a one tire fire party in 1st through 3rd. I don't think the engine in it's current state will ever have enough power for a 4th gear rolling burnout.
 
Kicking a bunch of cans down the street as usual so progress is slow.

Went to the VCOA national meet in San Luis Obispo a few weeks ago. To be quite honest I was a bit disappointed with the whole thing, the show wasn't organized all that well and the 240 showing was pretty lackluster. It was mostly stock pushrod cars which don't really blow my hair back all that much. Karl snapped this photo of my car next to Homer's sweet 5-cyl 244.

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Making headway on the axle build, rotor hats and outer axle hub flanges are done and I 3D printed some male/female press tools to make brake backing plates. I think I got a little greedy with the punch radius on the dimples so they're not quite as defined as I would have liked but in general I'm pleased with how they came out.

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Got the tab-and-slot bits for the axle tube welding fixture in. I think I got a friday afternoon waterjet operator on these since the slots are very tapered and undersized. Kind of annoying to have to file all the slots out, but such is life.

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Wheels version 2 that were alluded to years ago now are finally getting some attention. The design is pretty much where I want it so I 3d printed a partial slice of the wheel center to check for caliper clearance and to verify offset. Going for a Ronal Turbo-esque design with BBS Motorsport 17" rim shells. The wheels will be 8" wide front and back.

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Those wheels is going to look great

+1 Pretty cool you?re making the centers yourself AND the fact they?re going mimic Ronal Turbo wheels in 17x8 form, is awesome. The picture of your 242 and Homers 244 is great, 2 outstanding 240s. Wish I were closer to see these things in person.
 
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