mpsig226

OK my friends, it is Friday. Everybody should be checking in since "our time" has begun for the fun during the weekend. PS: except for those who can't cuz its the "house boss's" time! i.e. your significant other.


I removed what I believe to be the "factory" wastegates and installed a set of Turbosmart wastegates. I purchased the 24psi units and removed the "blue" spring to reduce the effect from 24psi to 11psi (2 remaining springs) in each unit. 11psi is about .8 bars according to Turbogate's chart. The car has an all stainless GT2 exhausts and Evomos intake. This is what I did:

1. I loosened the "preload nuts" leaving the locknuts in place.
2. I finger tightened the preload nut until the just touched the gate lever dowels.
3. I measured the free space between the lever dowels and the undisturbed lock nuts. They both had a 21mm gap.

Turbosmart's instructions states to set the preload at 2mm's. A whole lot less than 21mm (19mm difference).


After installing the Turbosmart wastegates, I road tested the car and this is what I noticed:

1. The boost gage increases to .9 bars at mild pedal depressions with mild "g" / torque force effects.
2. At full pedal, the gage will go up to 1.4 and 1.5 bars but immediately go down to .9 bars with moderate "g" / torque forces.

I feel that the "factory" wastegates geve me a little more "g" / torque forces than the Turbosmart units at the settings mentioned above (2mm preload vs. 21mm) and factory boost (0.7 bars) vs. the new readings (0.9 to 1.4-1.5 bar) boost readings.


So, I wonder if are the 2mm preloads are not enough? or is the ECU reading and controlling the turbo pressures, timing, fuel, etc. and therefore giving the impression that I might have been better off leaving the stock units on? I also wonder at what boost readings am I getting too close to comfort before blowing the engine?


Lets see what my colleagues have to say .... Thnx. MPSIG226

32krazy!

you need to use a mityvac to properly set any w/g . if your upping the boost you need to retune as well

911mhawk

If car was running fine before, put it back, then figure out what you're doing before you do it.
You are entering very expensive territory if something goes wrong.
Not sure what you're familiar with, so I could be wrong, however your post is indicative.

Third-Reef

1.4 and 1.5 is expensive territory. I would not do that anymore or you may be replacing a very expensive motor. If you are going to start messing with boost pressure, get a Cobb AP and start logging things to know what is going on. Call Sambo and get the AP from him and he will help you out and keep you safe.

mpsig226

Understood 911mhawk. Since I am monitoring the post, I guess I need to inform the next posting friends where I have been since you made a fair observation. My first gas toys where r/c planes at the age of 6-7. At the age of 9 my 1st go-cart. At the age of 12 my first dirt bike (Bultaco). At the age of 16 my 1st road bike (400 F Super Sport). Nobody touched my engines. I figured these all out myself. 1 Associate Degree in Automotive Technology and another in Diesel Mechanics. Worked at Nissan, Cadillac, Chevy dealerships. Bought a new Nissan 300 ZX turbo and modified the turbo to 15psi boost. Sold car without ever blowing engine, was careful. ECU's weren't controlling boost then. Bought and sold a Texaco Service Station with 6 bays, 4 techs. Rebuilt many engines, carburators, etc. Loved working on Bosch injection systems. After that, a Mechanical Engineering degree. Worked for tier 1 supplier to Ford and made several contributions to drive train division in the US and Europe. Worked in the medical industry and made several contributions to endoscopic instruments. Owned and a MB AMG 55 that nobody ever touched (175 mph many trips). Owned a Ferrari 360. Replaced clutch (engine out) myself, saved about $12,000. Plugs, wires, oil changes all myself. Currently own and have made simple mods to 2002 1200R Eddie Lawson replica (160 mph many times). Worked on a couple of planes and helicopter belonging to friends (tune-ups, brakes, oil changes, etc.) and inspected post annual mandatory service inspections. Found loose bolts (not safety wired), loose cowlings, etc. Built and currently own a chemical manufacturing plant producing industrial detergents for transportation/food/building-construction/oil production industries creating innovating delivery systems at client sites. I have owned many new cars that I no longer serviced because it got boring for me as well as got too busy working and family. I have not modified any ECU's or ECM's or done any flashings. I bought this 996 tt with only 12,500 miles to have fun .... I do have respect for this car. The main reasons why I decided to join this forum are fun and information. To Third-Reef, I hear you. Can you please tell me how to contact Sambo? Thanks to all of you guys for your replies. MPSIG226!

jeanmarcboilard

So you obviously know what you're doing but I agree with others that you need a new tune if you're changing the wastegates. You're ECU is probably confused because the boost pressure it's asking your n75 valve for isn't being met. You might be better off keeping the old wastegates and getting a tune. You can get all the boost pressure you need with the old wastegates, since the n75 valve bleeds off more reference pressure to increase boost.

911mhawk

Glad to hear I was off on my estimation of your skill set.
With your experience, you'll probably have lots to offer the group here.
Kevin at UMW can help you with the tuning part, he's the man.
Look forward to the MPH reading your new toy!

mpsig226

OK, w/g's off an tune it will be. I do need to post an alternator replacement. I didn't find anything out there. So I went for it. Semi breeze job. Thanks to both of you jeanmarcboilard and 911hawk !