thoughts on 993HE vs ssi(turbo HE)
 

I am debating changing out my 930 ssi set up for 993 HE. differences are the following.


ssi Longer runs but small primaries(quality far superior )
ssi nice packaging

993HE short run large primaries (unequal length)
very inexpensive

Now keep in mind cost is not a factor as I own both setups but interested in thoughts. Also remember I will be using dual wastegates and a volute setup(twin scroll) either way.

we I see gains either way? please justify your response Thanks for your thoughts . Either way I will produce a Y for the 993 HE for regular consumption

here is a basic pic of my setup currentlyhttp://forums.pelicanparts.com/uploa...1226704060.jpg
note the oil drain was for mocking it has since changed to aero quip lines

Here's my 3.5 with SSI's and custom sump plate by JW.http://forums.pelicanparts.com/uploa...1226704622.jpg

Equal length primaries are mandatory to optimize the twin volute design. Each pulse must arrive at a different time.
SSI developed their version of the twin volute system some 15+ years ago. A modified GT30 now sits in the turbo spot. Twin 38mm waste gates balance the two banks. The system was optimized for torque and boost response.
Sense you already have the SSIs installed I would give that a go first and then compare it to the 993 based H/E system you plan to develop.


http://forums.pelicanparts.com/uploa...1226721728.jpg


Here is what a 930 engine looks like with 993 H/Es mounted. The stock turbo orientation may be tricky on the driver's side.


http://forums.pelicanparts.com/uploa...1226721965.jpg

Yeah Brian I hear you on the advantages but the 993 set up offers a more compact design. And boy do I remember chucks set up:)

There is a set of used B&Bs on EBay now -

I have no real world experience to base this on, but it seems like shorter, unequal length primaries would make more power due to getting more energy to the turbo.

Ben, good for you! I asked someone about this set up who will remain nameless SmileWavy but was informed that it wasn't a good solution.
In addition to the benefits mentioned by others, I think that 933 HE's will have much better durability than aftermarket HE's. I have no interest in spending major dollars on an aftermarket system that cracks after 2-3 years of service.
When you are ready to market this I'll be first in line.

Guys 1st not interested in buying anything else(no offense intended) as I am less then impressed with quality and really don't need to do anything but want to try some different things but not out of necessity .

Paul I am planning to have this ready for the market by then end of the year but I need to get rolling. I have to find a stock braket and Brian is supplying and old stock turbo for fitting. Stay tuned I suppose and if you have a stock braket anyone let me know I need one for this project

lots of Pm's and interest on this so I will post anyupdates on this thread.. start looking for your 993 HE (bischoff):D

Sorry no real updates on this but I do hope to have a final example ready before christmas

Ben, have you figured out if you will be able to retain the stock turbo orientation with the 993 HE/pipes you are designing?

I have my 993 HE's already, so just trying to figure out how much additional fab might be necessary.

I still think I can make it happen without moving the turbo but I would susspect we will need to do dual wastegates with the design

dual 38mm vband wastegates and the bracket are here. I expect completion by the end of next week How many would be interested in this? I will intially make 2 sets 1 for me and 1 for 911nut anyone else want in? these will be priced at cost of materials plus time@$60 but looks like this will be a simple project .

Personally, I would go the SSI route for the following reasons;
1.) Like you said the primaries on the 993 HE's are bigger, so you will see a increase in spool-up time due to the loss in exhaust gas velocity. Not really an issue for a track car, but for the street...noticeable.
2.) I don't know how long the 993 HE's will remain "cheap".......
3.) The SSI's are known to produce good power and are very reliable. A friend of mine runs that setup on his track car and hasn't had any problems over three years.
4.) The 993 HE's operating under high turbo temps is an unknown factor. What's their longevity?

On the other side of the coin.....I do think a nice polished set of 993 HE's look better than the SSI's.

There may be some tradoffs with this system:
Pro
* shorter exhaust gas path, therefore more energy available to spool up the turbo due to less thermal and friction lossess.
* Reduced backpressure vs stock system due to shorter path and bigger primaries
Con
* Larger primaries reducing gas velocity, increasing turbo spool time

Some experts indicate that large primaries are desireable on turbo applications as heat energy is responsible for 80% of the energy driving the turbo.

The only way to know how it will all work is to build a set.

The 993 H/Es should hold well as they are made from a far more robust material (409 SS) than aftermarket headers. For me, that is one of the attractions of this system.
As for 993 H/E cost, I don't foresee a big demand for them unless all the SC/Carrera owners decide to put 3.6 engines in their cars :D

Paul,
I agree, the 993 have shorter primary lengths which equates to a lower energy loss. The larger primary size lowers gas velocity at lower RPM's. The two probably cancel each other out when comparing to the SSI setup. So it's probably a wash there.
Trying to remember my days of studying thermodynamics...... :rolleyes: When there's a loss of gas velocity, heat energy goes up or down? I think it's a direct relationship, so energy should go down.

Ben, are we going seat of pants, subjective or objective with dyno runs? I'm not here to question/critique just purely wondering?

Sadly, I've been finishing other projects (MG, GS and new shop) along with waiting 6 months on my replacement Carillo rod for the 3.3 TT build-up so I have no feedback regarding my 993 HE's.

How much should you have to pay for a set of 993 HE, used?

I've discussed this setup shortly with my mechanic as well, he likes the 993 setup better because of durability, short runs, and primarys, but has not put it to the test on a dyno, I think he wanted me to be his first victim...

He did mention that most smog inspectors will probably wont even question the system due to the porsche part number stamped on the 993 he. Something for us smog guys to think about.

I'd be really interested if this can be developed for a single stock wastegate.