Howdy,

I need some input from anyone thinking about getting an intake plenum.

A little background: I have been talking with Scott Slauson about the Porsche intake plenum that he mentioned in the past. Scott gave me the part numbers, and I have gotten the parts and have been working on getting everything to install and fit nicely. Scott said he would not mind if I were to put together a kit to sell (I think he'd prefer to stick with the software side of it, and not get into modifying/selling intake parts).

So, the kit would consist of instructions, a modified intake plenum, a new PCV hose, a new elbow and pipe to connect the MAF, and a few other bits and pieces (clamps, plugs, etc). The kit would sell for about $400.

However, there is one "but". Because the Porsche plenum repositions the throttle body to the centerline of the engine, it is directly above the starter mounting boss. This means that the throttle body sits up high enough that it will interfere with the aluminum engine cover. So, the cover would need to be clearanced to make room for the repositioned throttle body, by hammering a "bulge" into the cover (approx 4" wide by 1" high by 3/4" out). I would include a template and instructions for the clearancing, or could offer a modified replacement cover for about list price (approx $330). If there was interest, I could do a core exchange with your old cover.

Would people still be interested in this kit? The kit would be all-inclusive, except for the cover modification (either you or your shop modifies your cover, or you buy/exchange a modified cover at extra cost).

I put a poll above, to judge the level of interest. Please don't vote in the poll if you aren't interested in getting any intake plenum (this one or the IPD one). Also, I have not yet finished the final details of the kit yet, so I can't give any data on performance, but it should be similar to the IPD plenum.

Just FYI, this is the same intake plenum that is used on the 3.8S engine swap into the Cayman. However, those swaps use modified engine mounts to lower the engine enough to clear the engine cover. I will not be modifying or replacing the engine mounts, but that is an option for anyone who feels like doing the extra work.

I guess my question would be: aside from being Porsche parts, what advantage does this plenum have over the IPD?

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It costs 60% less. And, the plenum is the same fiber-reinforced plastic as the other intake parts, so engine compartment heat soak won't be as big an issue (or potential issue). Other than that, not much.

BillC,

I remember looking at this previously as I have one of the 997S plenums here (I think the cost was $45 from Suncoast) but I noticed that it doesn't have the same number of hoses hooking into it as the factory Cayman plenum does, do you have to tap into the 997S plenum somewhere for the extra Cayman hose or how did you work that out?

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I add a vacuum port on the side of the plenum, placed so that you use the stock vacuum hose.

Bill, Scott:

For the sake of all, please kindly clarify a couple of points in order to allow us to make an informed decision?

Scott previously indicated he had dynoed a stock Cayman S with modified 997 3.8S Plenum and had developed maximum 335bhp and 280ft-lbs torque, (345bhp with cat-back exhaust), with greater than 225ft-lbs from 1500rpm onwards throughout the rev range.

Furthermore Scott clarified that these performance figures were achievable using his software and the modifed 997 3.8S Plenum OR an RSS IPD Plenum.

Please kindly confirm the cost of the software? And cost of a software upgrade for existing Softronic customers?

Thanks

Just to clarify, I am doing this on my own, and not in association with Softronic (even though Scott gave me the part numbers).

You'll have to ask Scott for clarification on those numbers, or about any software upgrade. However, I believe those hp/torque numbers are an estimate, since he uses the word "should" in this post, and are based on simulation and his expertise -- I don't believe anyone (outside of Porsche, maybe) has actually installed this plenum and gotten dyno numbers yet.