Supercharger - Imagine Auto

[ohioboxster]

I found a used kit on E-bay that is like new. Let me clarify, I dont know how much Imagine autos kit cost. That was just a guess.

[oliverg]

In case anyone is interested I heard back from Imagine Auto. Response below. As you can see, they were prompt and friendly. I'll be weighing up the advantages / costs of buying a 3.2 from an S and dropping it straight in vs the SC. Is there anything else that needs to be changed during a 3.2 upgrade? EG I assume the tiptronic is common between the earlier 2.5s and the 3.2s?

Thanks alot to Vin as well for his kind help!! Front page of our main newspaper in Australia reads "Discovery: Major Celebrity to drive Porsche Boxster in up and coming film XXX3"

Regards

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FROM IMAGINE AUTO:

Oliver,

Yes we can ship to you.

Not as of yet. Lots of inquires but no actual sales as of yet to your area.
Yes, the ECU has to be sent to us to be flashed.
No, the system is designed to run on a stock motor.
Shipping would be several hundred dollars for air freight.
Sorry, the kit available is the 2.5. It can be shipped any time.

Hope this helps. Thanks for the questions and let me know what concerns/questions you may have. The kit is a wonderful addition to any Boxster and delivers very favorable results. I know you would be pleased with it.

Best,

Stephen

[ohioboxster]

Did they give you a kit price?

[oliverg]

The pricing I've found is $6995.

I'm seriously thinking of importing a bunch of these into Australia as I think there's a market for them

I'm torn though because I've been talking to Turbowerx:

http://turbowerx.com/page1/page3/page3.html?gclid=CIumy4i3-4YCFSI7GAodCkULIA

Their twin turbo kit looks like its the duck's nuts - it's the same price and takes 1/2 the time to install.

Hmm supercharger .. or twin turbocharger .. hmm supercharger .. or twin turbocharger

Its like being torn between one's current wife and one's future wife

[Gary Gaukler]

I am not affiliated with either of the companies, and I am not advocating one system over the other, but here are my two cents:

The iA supercharger (non-intercooled) is supposed to increase rwhp from 150 to 230. That is an increase of 53% (not 38% as claimed on iA's web site). That's a very large increase. The following estimate of supercharged hp can be used (e.g., see Corky Bell's book):

HP_super = HP_na * PR * DR * VER * DPE.

PR is the pressure ratio, DR is the air density ratio (boosted/na), VER is the ratio of volumetric efficiciencies, and DPE is the drive power efficiency (100% if belt is transmitting power perfectly).

For illustration purposes let's use DR=0.85 (ballpark for a non-intercooled system), VER=1.1 (better VE after supercharger install), DPE=1 (perfect power transmission). You can plug in other values and see what you get, but the values I used are a good starting point, IMHO.

Then, you can find that in order to go from 150 to 230 hp, you need a PR of 1.64 (someone please check my math). That corresponds to roughly 9.5 psi of boost (again, please check). Why is this important? The Boxster is a fairly high compression ratio engine. That means you want to have low boost levels. 9.5psi to me seems too high to safely use on a Boxster engine with stock internals. YMMV.

Based on what turbowerx say on their website, their kit provides 6psi of boost, intercooled. They only claim an hp gain of 60 hp (to 210 hp). Plug in their numbers into my equation above, and you will find that this makes a lot more sense (PR=1.4, DR=0.9 due to intercooler, VE=1.1, DPE=1):

HP_super = 150 * 1.4 * 0.9 * 1.1 *1 = 209.
(The last term is approximative, as there is no belt efficiency in a turbo system)

Of course, this is just physics, so real world results may vary

Bottom line: I don't see how iA can get 80 hp out of a non-intercooled supercharger kit at safe boost levels. Judging from the numbers on paper, turbowerx seems to offer more realistic power gains. Ask for dyno charts including A/F ratio and boost levels before buying.

Gary

P.S. Useful books:
Corky Bell, Maximum Boost
Corky Bell, Supercharged!
A. Graham Bell, Forced Induction Performance Tuning

[oliverg]

Can you / Should you decompress the engine before doing either procedure?

BTW thank you Gary for your write up - that was pretty incredible!

[Gary Gaukler]

Originally Posted by oliverg

Can you / Should you decompress the engine before doing either procedure?

Theoretically, you can lower the compression ratio by installing different pistons. However, I am not aware of anyone who makes / sells these for the Boxster. So, practically, the answer is, no...

Low boost levels with proper chip mapping should be fine without lowering the compression. I personally would start to get concerned at anything beyond 6psi or so, but that's not a hard-and-fast rule.

If you are seriously interested in forced induction, read Corky Bell's books - it's a small investment, and you'll be a much more educated buyer!

BTW, please do not think that I advocate the turbowerx kit over the iA one. An intercooled twin-turbo certainly sounds better to me on paper, but a lot depends on the kit maker's ability to tune the system, and I have no first hand experience with either of these kits.

Best,
Gary