Pumped993

I have a '95 993 with a Protomotive Stage 1 twin turbo conversion with intercooler. The wastegates are set to max out at 5.5 PSI. Does anyone have any experience with increasing the boost to 7 PSI? The CR is still stock (factory pistons) but my mechanic says I could go up to 7 to 9 PSI.

David T.

Sorry, I don't know answer to your question but do you mind answering some of my questions

How many miles do you have on the setup?

How is the power increase?

How much $ was the conversion?

Tone

Yes, could you please post?? I'd like to know those answers as well about your turbo.

Pumped993

Here is info on the Protomotive 993 setup. If anyone has had same type of enhancement done please post as well.
Car had 58k miles at conversion time, now 70k. Protomotive advertises 390 BHP for pre-varioram 993 but they do not dyno their cars before --or after-- conversion! After about 6 months, I noticed flat torque spots under full boost with strong raw fuel smell, so had it dynoed, and it did around 290 BHP at rear wheel (around 350 @ crank). Protomotive was unable to fix problem until I found a mechanic who found fuel pressure way too high and adjusted timing. My guess is fuel pressure setting had drifted. Car runs great now and feels significantly faster, I have not dynoed it again but expect it will dyno around 325 BHP at rear wheel, which is right where Protomotive claims it should be. Very tempted to switch to electronic boost control and go up to 7 PSI, should result in around 400 BHP at rear wheel --if engine does not melt--. Cost was $14.5k for all upgrades including very large intercooler but excluding body work.

Sam N

Sounds like a very nice setup. Did you consider TPC's supercharger kit? I live in Maryland and I am considering installing their Eaton unit with 4.5lbs of boost. The kit runs $6k without an intercooler and has been dynoed around 310hp at the wheel. Any comments would be greatly appreciated.

Regards,
Sam

David T.

Just curios how hard do you run your converted turbo car? Do you take it to the track?

Pumped993

Back when I was researching conversions the TPC kit was not available, and the Protomotive kit is actually one of the cheaper turbo conversions available at that price (installed) because it does not require a new ECU vs. Motec types. In hindsight I may have gone with a supercharger instead, but I wanted something close to factory setup and they don't seem to care for superchargers much (race teams don't either). The biggest concern I would have with a supercharger is the "always on" aspect. With 4.5 PSI you are looking at an effective compression ratio of around 14:1 --pretty much all the time--. Cruising at 90 MPH the twin turbos generate less than 1 PSI. How much does TPC charge for installation?

Pumped993

I don't take it to the track because it's a daily driver and any breakdown would be a huge logistics problem. I go full boost driving around town but nowhere near track levels. I was told the engine is rock solid and can handle a lot more stress than what the turbos put it through. Also I had a sports clutch (lightweight flywheel) put in.

David T.

Just to clarify: TPC supercharger has an intake vacuum/pressure controlled bypass valve (similar thing as a waste gate on turbos) to reduce the boost on idle/light throttle application.

My personal reason why I (think) prefer supercharger is an instant power. I enjoy a LOT the way my car drives on the track and I'm afraid I would not like turbo lag (even slight).

BTW - RealTime Racing Supercharged Acura NSX is doing well in Speedvision GT race.

Pumped993

Thanks for the clarification. It looks like the supercharger could indeed be a very viable alternative to turbo conversion. If TPC charges around $6k and you add a $2k intercooler, that still leaves you 6k for install which has got to be less than that. Anyone out there who looked at both options and could enlighten me?

Sam N

TPC charges $1500 for the installation, which takes approximately 3 days. The guys there have said that the supercharged 993 will out accelerate a 993TT until about 100mph and then the turbocharged car will pull away. I also like the idea of positive boost pressure from idle. In the past, some concerns had to do with the noise of the mechanical units and reliability issues. Seems like those may have been reduced with the newer units. Also, companies like MB have been installing them on their newer "sport" models.

cecil

I have about 300 miles on the TPC kit. I plan to drive the car to an event in North Carolina this weekend. The Eaton charger has a bypass valve that bleeds off the charge when running under constant throttle. It therefor is not always on. It is however almost "instant" on in that the supercharged car makes more torque at 2700 rpms than the stock car does at peak. Rolling along and stomping the gas is tire spinning sideways fun. The factory turbo setup would likely be a better track option due to the better power in the high rpm range but for the street imagine a 911 with the torque of a 60's muscle car. Fun. TPC is working on an intercooler. I will add it when it's ready. I won't increase the boost. The car is fast enough now. I should get a little more power from the denser cool charge that the intercooler will provide. I will put a full review on the main board after the NC trip. Right now my car has the analog "beta" computer program driving the charger. Mike will come down and put the "new and improved" digital program in after I get back from NC. [img]null[/img]

Sam N

Cecil,

Is the car stock other than the TPC unit? I am wondering about the clutch. I have a Fabspeed exhaust on my '95 with an Autothority chip that they said needs to be removed. (chip should be stock)

cecil

yes the car is a stock 97. my clutch has 50,000 miles on it and is starting to get a little weak. when i change it i may go with a lightweight one. you need the stock chip. the tpc chip is programed to work with the stock one.

David T.

Hi Cecil!

First let me express appreciation for your bravery and your feedback with this kit. Now - questions:

>> 'It (boost) is however ***almost*** "instant"'

So, is throttle response slower then before?

>> 'The factory turbo setup would likely be a better track option due to the better power in the high rpm range'

Are you saying that power drops in high rpms or turbo simply has more power?

(In search for more power)