Does anyone know the true reason why TPC's supercharger has problems?

[HB.]

Just like the title says, I'm only looking for detailed, techincal facts as to why ppl have problems with their kit. I've spoke to a couple of ppl who have not had any problems at all, but then hear gobs of horror stories from others who haven't had the kit installed or have their own theory as to why the problems occur. If you know for sure, please share. Thank you.

[insite]

There are four problems as I see it:

1) The actual compressor itself is designed to be mounted straight up and down (it has a rectangular cross section). In actuality, it doesn't fit in the car that way and must be installed at an angle. Because of this, there are questions as to whether a steady supply of cool oil can be supplied to the bearings.

2) The Boxster's engine already has a fairly high compression ration of 11 : 1. Forced induction on an engine with this much cylinder pressure adds tremendous stress to the internals; these stresses will far exceed the design parameters of the structure and material used for these parts. Generally, any normally aspirated HIGH compression ratio engine that is going to be force fed properly will need to be modified to lower the cylinder pressures by lowering the compression ratio with custom pistons and by profiling the camshafts for a safer duration / lift. The TPC supercharger attempts to ignore these constraints by simply lowering the overall pressure output of the compressor (VERY modest boost).

3) The system is obscenely expensive: $4700 + 2 to 3K installation for a modest power gain, shortened engine life, questionable reliability, overstressed internals and NO modifications to the stock engine to compensate any of this (not to mention the STRONG possibility of leaning out your motor under boost and overheating your components). That is a ridiculous amount of money for a bolt-on kit of any sort, especially a bolt on kit for an already highly stressed high performance and LIGHT motor.

4) Since you want to do this to your car, it won't be too long after you install the TPC that you decide to swap pulleys on the supercharger for a bit more boost. When you do this (and you WILL be tempted), engine failure becomes a virtual certainty. All it takes is punching the throttle before the engine is warm and sending a nice, dense, cool blast of air into a supercharger to be further compressed and then ignited, turning your beloved pistons into swiss cheese.

5) It's roughly $7K for the supercharger / install. It's roughly $10K for a 996 engine / install. That yields at LEAST (depending on what you do to it) 300HP of normally aspirated power from an engine performing WELL within its design limits that all dealers know how to work on. The supercharger is a cute idea. Maybe a great idea for a chevy or something with a carburator and an 8:1 compression ratio, but a 'bolt on' design for an 11:1 compression ratio in a late model Porsche is a disaster waiting to happen (although it will be fun for awhile). These are the exact reasons that there is no viable turbo kit for this car that does not require engine tear-down first to beef up the components and lower the compression ratio.

If you want info from a shop who's done a TPC supercharger and five 996 conversions, call Cars II / Racer's Image in Melbourne / Palm Bay, Florida. Have fun. (Hint: The supercharged car met an untimely demise and was swapped for a 996 motor. The Boxster's trashed motor sits on their shop floor to this day).

[HB.]

Thank you for your reply, my only question about your statement is you view of the supercharger on a high compression car. I know a lot of NSX owners who have placed a positive displacement blower on their cars, and have had no problems what so ever except changing the belt every 10-15k miles but that is normal. Given these are two totally different motors, the blower mounting, and the blower used, could be as to why it works wonderfully on the NSX and not the Boxster. The NSX's supercharger from Comptech has two kits, both running higher boost, and there are plenty of oweners of these kits who have put well over 10k of daily driving and track miles on their cars.

I can see how the oiling would cause a big problem. Is this kit bolted to the bottom or the side of the engine? Also, do you know what type of fuel management was used with this kit?

Thank you for help
HB

Edit: also, I sent you a PM

[Brucelee]

There is a another way to look at this. The Boxster is a brilliant design but IMHO, a fragile one. These cars cannot be hammered in the way that say, a C-5 Corvette can be. The tolerance for stress above what is designed in by Stuttgart is minimal.

If you trade them for a living like I do, you get to appreciate just how much maint. and repair these cars actually require. This is not a bad thing, just what a Porsche is all about.

I for one am NOT surprised that a SC would not be a good thing for a Boxster.

Now if you want a faster Porsche, they do exist. They are called the 911 and I have one in stock!

[jfmillr]

actually there is another way to have your fast boxster. The shop I frequent does Twin Turbo Boxsters 3 or 4 a year. Want 450 hp? get a twin turbo kit, bolt on, from TTP. But again you will find yourself in the 20 k range installed. Only one person I have met with the twin turbo kit has had any trouble. And I wont mention his name since he might frequent this board as to not embarass him. But the one and only problem case I know of...the blame is on him why he blew his turbos a few hundred miles after having them installed.....Dont race EVOs the same day after an install and not wait for a DYNO tune! If you go down the road of adding turbos make sure you allow for a break in period! FYI The EVO he blew away, 4 or 5 straight runs was dusted in the 1/4 miles by 4-6 car lengths consistantly. mid 11 second times. very fast! I should hopefully have my kit installed by spring
www.09860.com

[Lux]

Insite, very good post.

But on that note, you can run very low boost on a high compression motor and get away with it. Sure you're adding more stress. But so does constantly driving in high rpms. Dinan has been strapping superchargers on BMW's for years and they seem to be fairly reliable. But they're also using centrifugals and not positive displacement so that makes a little bit of a difference.

HB, I still wouldn't supercharge a Boxster. Heatsoak is one issue. I might be wrong, but the supercharger for the Boxster doesn't come with any type of intercooler, correct? I'm guessing the NSX Comptech guys are running coolers? Once heatsoak sets in, you're losing power. That's no fun. PD blowers are great for creating torque. But they're also great at creating heat...

For that amount of money, I think a 996 motor swap is the way to go. There's no replacement for displacement. Well, except for high boost but we won't go there.

[Brucelee]

There is no way I would put a normal Boxster engine under the stress of TT or SC. However, the larger disp idea has been done very nicely and in fact, this larger engine is "less stressed" is the somewhat lighter Boxster.

Way to go. Find a Box with a bad motor and go for it.

[HB.]

Guys, thanks for chiming in, but I was really seeking the real facts as to why they have had problems. I believe Insite's reason for how the blower is mounted is one major issue.

Lux
No they are not inter/after cooled, but they do use a srew-type blower that conducts it's own compression vs. the roots type that just moves air. Both, the NSX and Boxster are virtually running the same compression ratio. Heatsoak would also be a good factor for any related failures. Both cars have very tight engine compartments, so I'm just wondering why it works for the NSX and not the Boxster? Better engine maybe???

Brucelee
There are plenty of 996 onwers who are running centrifugal superchargers, and have had no problems thus far. Does the 996 use different engine internals then the 986? If you can run a centrifugal blower that spins almost twice as fast as a PD blower and not have problems, why can't these motors handle less boost, less CFM?

[HB.]

jfmillr


I just visted your site, I like I like

question for you...what year is your boxster, and is that a spoiler purchased from FVD? Sorry, also...where did you get it install. I bought one just like it for my '99 Boxster and the shop I go to around here said it wouldn't fit . I've had this spoiler sitting in my house for months. Now I truly know it does fit.

[Brucelee]

Brucelee
"There are plenty of 996 onwers who are running centrifugal superchargers, and have had no problems thus far. Does the 996 use different engine internals then the 986? If you can run a centrifugal blower that spins almost twice as fast as a PD blower and not have problems, why can't these motors handle less boost, less CFM?"

Good question. To my understanding, the engines in the Boxer ARE different internally from the larger Turbo motors in the 911. More interestingly, a tech at my local dealer told me that they have always had MORE service problems with the non turbo 911s than with the Turbo 996.

That might suggest that the Turbo model has a more robust set of internals, ie materials, construction, etc. than the regular 911 motor.

I will do some digging and see what I can find. In the interim, I will just say that I would personally not add any breathing supp, like SC or Turbo to a base Boxster. But then, I am a tad conservative and cheap, dont want to pay for a new engine, etc.

[Lux]

Originally posted by HB.


Both, the NSX and Boxster are virtually running the same compression ratio. Heatsoak would also be a good factor for any related failures. Both cars have very tight engine compartments, so I'm just wondering why it works for the NSX and not the Boxster? Better engine maybe???

I don't think it has to do with the NSX having a better engine. Like I said, running a relatively low amount of boost should most likely not yield any issues.

Keep in mind that Comptech is a very reputable company. Since I'm familiar with BMW, I'll give you an example of what I'm trying to say. Dinan has been known to produce a very reliable system for the E36 M3. A lot of competitors produce essentially the same system with the same Vortech blower. However, the difference is in engine management and boost. I've seen people have major issues with these other company's systems and not with the Dinan. Granted, there are also success stories with these other companies. The difference is that you never hear of any issues with Dinan. It's not rocket science. It's just whether the package as a whole is designed well. Know what I mean?

When you hear about engines grenading, there's only a few reasons that could make that happen. Run low enough boost, have proper fuel delivery and proper engine management and you should have no problems.

There are plenty of 996 onwers who are running centrifugal superchargers, and have had no problems thus far. Does the 996 use different engine internals then the 986? If you can run a centrifugal blower that spins almost twice as fast as a PD blower and not have problems, why can't these motors handle less boost, less CFM?

Centrifugal works totally different than a twin-screw. You get hardly zero boost below 4K rpms. Max boost occurs at redline. And if all you're getting at redline is a low 6psi or something, then that's actually less stress than a PD's constant boost. How fast they spin vs a PD is irrelevent.

So you're saying there are 996 motors running over 9psi of boost on bone-stock internals running high compression? I'm skeptical.

I know you want real life stories and not theory. But since supercharging a Boxster is not that popular at the moment, all we have are theories.

[Ad Sach]

Originally posted by HB.


Brucelee
There are plenty of 996 onwers who are running centrifugal superchargers, and have had no problems thus far. Does the 996 use different engine internals then the 986?

The 996 engine block is made out of a different alloy than the 986 engine block. External component similarity aside, these are different engines.

[insite]

More thoughts:

The NSX has a compression ration of 10.2:1. That actually makes a significant difference in this scenario for multiple reasons. One, the overall cylinder pressures achieved even after boost are acceptable (they will be similar after boosting to the boxster's NA pressures). Two, octane. While it's accepted that high compression engines require high octane, most forget that it's finally the maximum cylinder pressures that really matter in this scenario. Cylinder pressures achieved under even low boost in the boxster will be high enough to cause detonation with pump gas. This will result in an uncontrolled burn and localized rather than steady state dynamic loads. (Steady state dynamic sounds like a contradiction. what i'm getting at is not the dynamics of the engine itself, but the dynamics of the combustion phase. a controlled combustion results in fairly even tempreratures and pressures throughout the cycle. detonation results in local high pressures and temperatures, like on one spot of a piston crown as opposed to even pressure / temp on the entire crown. this is one reason why we see pistons with holes in them).

lux -

you are right in that heat soak could be an issue. you are also right in that high compression engines can run with high boost. there are requirements for this though: plenty of fuel and an engine management system that knows that you are doing this. the spark curve on the boxster will be adjusted if the engine starts to knock, but it changes other things, too. the bottom line is that the TPC system does not account for enough of these variables and as such is an incomplete system. all they do is apply the pressure. with something like a boxster engine, more work is needed to ensure a usable and long lasting engine.

because porsche took these things about as far as they can go without pressure, some of that work has to be UNDONE to use pressure properly. this is costly, and imo not nearly as effective as just dropping in a 996 motor. if you're going to pressurize, don't cut corners. tear the motor down and build it for pressure. the results will be great. the bill will be high.

[HB.]

Originally posted by Lux


Centrifugal works totally different than a twin-screw. You get hardly zero boost below 4K rpms. Max boost occurs at redline. And if all you're getting at redline is a low 6psi or something, then that's actually less stress than a PD's constant boost. How fast they spin vs a PD is irrelevent.

So you're saying there are 996 motors running over 9psi of boost on bone-stock internals running high compression? I'm skeptical.

I didn't say the 996 motors are running twice as much boost, I was saying that they are running centrifugal blowers which have the capabilities of spinning at a much higher RPM then PD blowers. How can you not say that a blower spinning at 60k RPMs could not present more of a problem then spinning at 40k RPMs. With centrifugal blowers you really have to make sure that the belt tensioner keeps the belt tight around the supercharger pulley to avoid slippage. Belt slippage has been known to cause major problems in a reliability stand point when it comes to supercharged vechiles. You are correct about maxium boost at redline making for a reason that a centrifugal blower to be more reliable. And, yes I am aware of all the differences between the 3 different blowers.

At one point of time a few months ago, I was looking into the option of supercharging, but not anymore. Just for a thirst of knowledge I wanted to know real life facts as to why owners experience problems with TPC's supercharger.

Thank you Ad Sach I didn't know they were any different. The only thing I fear with the 996 swap is the notorious 3 little letters problem. If you think about it, you would spend what 10-15k for the swap and then what 6 months to a couple of years having to replace the RMS, sometimes over and over again. I think it's less likely (I'm hoping) for me to not have the RMS replaced on my +72k mile engine then an owner with lets say 20k miles.

[Fletcher]

I have been hearing alot about motor swaps these days. Are they really only 10k for conversions (does this include labor, headers, ecu etc, etc..).
I also have read many negatives about the TPC supercharger in fact doesn't the european car mag project car have one of these they can't get sorted?

[Brucelee]

My concern about motor swaps is one of future valuation. In general, is very tough to sell a modded out Boxster. You can sell them but USUALLY you lose your shirt!

Why not hot rod a cheaper car that would NOT devalue greatly or, simply buy an S and do some breathing and chip work?

How fast do you need to go?

Just some thoughts before someone spends that 10K!

[Fletcher]

I agree. A motor swapped car is going to be Tough to sell. I think I will stick with a few tweeks that can either be taken off for sale of car or left on as a negotiation tool. Intake, exhaust headers and ecu are all bolt on type stuff and can be sourced a little at a a time.
Now...who makes the best headers...?