Newbie from Phoenix

[tjyak50]

New guy from Phoenix AZ.
The project car is a 1988 Benz 560SEC that has been in my family since new.

Now it is mine and slowly getting modified.
The plan is to fab / install a supercharger for a modest power increase.
I have full access to a giant aerospace machine shop and all the resources.

Soliciting advice to select a good "starter" headunit.
I want something that is rebuildable, rugged and reliable.
I don't care if it is noisy.
I don't care if it is not the worlds best most efficient.

Only planning 5 to 8 psi installation.

Ideally I would find a rugged blower that needs rebuilt to start this project.

Thanks, I will scour the archives of this site.
TJ

[Michael]

Hi Tom, welcome to SCH!

WOW!!! A 560SEC... one of my favorite cars of all time! Classic elegance from a time when Mercedes ONLY made good looking cars. Very nice.

As for a good 'starter' blower for your application, I would suggest looking at any of the old Paxton SN units. They are rebuildable and easy to work on; parts are readily available from a number of sources, including Paradise Wheels and CUNDN Racing. Used units in need of repair/rebuild can be found for relatively low money as well (I bought an SN89 in desperate need of a rebuild a few years ago for $300). You'll obviously have to design your own mounting brackets and piping.

Before investing any money, however, you'll have to consider the engine's rotation direction vs. the supercharger's rotation direction. This is particularly important for centrifugal-type blowers. I know this was an issue during the early days when tuners where supercharging some import cars, which required complex bracketry in order to drive the blower in the correct direction.

[tjyak50]

Good point.
The Benz motor spins CCW as refereced from the driver seat.
I will check the blower.

Engine is a 9:1 compression ratio with a CIS-E that I am pretty adept at tuning now.
I also have a Wideband O2 already installed.3
IMG00095-20100803-1902.jpg


Others have already done this with success
12_1531221_7122005113807PM.jpg

Blower.jpg

[Michael]

I know that a small block Chevy rotates clockwise when viewed from the front of the engine, which means that from the driver's seat (behind the engine) it spins counterclockwise, the same as your 560SEC. That's good - it means blowers meant to work with a SBC's rotation are potential candidates for your application.

A 9:1 compression ratio is fine for a supercharged engine, so long as you're not planning to run a lot of boost. Any higher a CR and I'd be a bit concerned.

If others have successfully bolted up superchargers to the 560SEC then it's safe to say that you should have equal success. Based on the photos you've posted, it looks like a Powerdyne head unit will work and fit under the hood nicely. Powerdyne make some nice head units, however I don't know whether they are rebuildable, and their popularity in N.A. may not be high enough to facilitate finding a used unit for sale.

[tjyak50]

Agreed.
I just looked at an old Mustang and it turns the same direction as my Benz.

So maybe all V8s turn the same way.
Tj

[Michael]

Not all V8s. I believe the old Ford GT40 Mk I's (from the 60's) turned counterclockwise (when looking at the front of the engine). And it was only the 427 equipped cars. They had flat crankshafts and for some weird reason spun the other way.

Of course, that's a rather rare engine in an even rarer car.

[tjyak50]

BD11A?
SN93?

Either of these better than the other?
Parts / Service / Performance?

Tj

[Michael]

The BD11A is a far newer blower than the SN93, and it takes advantage of far newer impeller and scroll design technology. However, it's 'newness' may force you to consider getting a new unit rather than a unit in need of repair/rebuilding. I will guess that parts and service availability would be about the same for either unit.

As far as performance numbers are concerned, I think both are similar in the way of boost/output. Both will produce about 6psi of boost, however, the BD11A will go as high as 9psi with just a pulley change; the SN93 (or any SN blower for that matter) will require an upgrade to what's called a 'VR4' in order to see some serious boost increases. VR4 upgrades aren't cheap, but the output is considerably higher than a stock SN blower (6psi stock vs. 12psi for a VR4 upgrade). Changing the pulley on an SN in search of more boost will produce more internal heat with only marginal increases in boost. This is largely due to the older, less efficient impeller and scroll design of the Paxton SN unit.

Check out the SN Series section of the forum - there's a series of 'stickies' at the top of the forum section which outlines the history of the old Paxton ball-drive (SN) superchargers. It's an interesting read, and one that will help you to understand the technology behind those old blowers.

[tjyak50]

Extremely helpful, thank you.

Some forums frown on newbies asking stupid questions that have been addressed 1000 times previously.. so for the record, I have searched..

Detonation:
Exactly how can you detect it? Just the sound only?
Would you see anything on a Wideband indicator?

Running 7psi with 9:1 CR and an intercooler - should that be safe?

Problem with the Benz is the ignition timing is controlled by a German mafia module and isn't open to much discussion.

[Michael]

The only stupid question is the one not asked (even if it's been addressed before).

To answer your detonation question, to be honest I don't know how it's detected outside of the 'pinging' noise you hear people talk about. I'm sure that your MB came with a knock sensor and that it will measure the knock/ping counts and adjust timing accordingly, but how you would be able to access this information is beyond my knowledge.

7psi with a 9:1CR should be fine. In fact, with a 9:1CR you could run 10psi of boost without issue (assuming the engine's mechanicals and head gasket are in reasonably good shape).

A word of caution, however: using an air-to-air intercooler with a supercharger system that's producing less than 8psi~10psi of boost will cause a drop in system pressure. This is a result of the intercooler's physical volume. In systems with boost pressures below 10psi it is typically more beneficial to use a gaseous intercooling system (i.e. water/methanol injection) instead. There is a great write-up on the forum here under the "Charge Cooling Systems" section written by one of our moderators, speedytang. It explains a lot and is definitely a worthwhile read.

As for the MB's mafia module, can you run an add-on ignition controller like an MSD 6BTM? Accel and Jacobs also make similar multi-spark discharge/timing control boxes, maybe they have one that will plug into your stock wire harness?