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Old 01-04-2007, 12:30 AM   #1
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Default Rotor Coating loss

So now that I know the coating on my old L67 SC was 50% gone on one of the rotors, I figure that is why I could not see more than 10 psi even with the 2.9 pulley.

Do you think that makes any sense.
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Old 01-04-2007, 12:34 AM   #2
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well makes sence to me. doesnt it make 8 stock and its about 1 psi or so per tenth of an inch under. doesnt add up or maybe im wrong either way i dont think 10psi sounds right
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Old 01-04-2007, 01:46 AM   #3
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It makes sense because of your injection pre rotors. But how much boost did you see on other pulleys before you had your water injection running?
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Old 01-04-2007, 09:52 AM   #4
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It makes perfect sense. With a 3.2 I'm seeing close to 13-14lbs according to one aftermarket gauge I hooked up.

While the injection helped cool you, it hurt you at the same time. I like the new setup and think it'll do fine.
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Old 01-04-2007, 01:56 PM   #5
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I just ported SC on an intercooled 1998 GTP yesterday. His rotors had about 15% of the coating left.
He his mods consist of:
CHEAP DRYER DUCT HOSE (you know that aluminum foil duct that is very not smooth)
3.2" Pulley
Power Tuner
Harland Sharp 1.9 rockers
180* t-stat
3" DP
3" back to the stock y where every thing is stock after the y also.

Two major downfalls for him are his pointless intake setup, and his stock exhaust manifolds. Surprisingy he has no KR.

He was seeing a max load of 9-10 psi before the ported SC (ported/polish inlet, and lightly ported outlet).
With the addition of the ported SC, and lightly ported/polished 98 TB we saw his boost jump only 1/2 lb, but we didn't scan for KR because we were fighting a vacuum leak at the T we installed just before the MAP senor for his boost guage. Removal of the T fixed the vacuum leak and hesitation but we couldn't see boost on anything but his stock DIC boost guage (it maxs out bone stock). His Power Tuner wouldn't show boost levels on the laptop either.
The little time that we did have the boost guage hooked up we were peaking at around 10.5 lbs, but I suspect boost was being dumped due to the vacuum leak and bad readings at the MAP sensor which tripped the codes P0107 and P1107.


So yeah, it'* definitely safe to say that with all that coating gone you are losing a 1-2 lbs of boost, ***very possibly more***....

Reason I think you are losing more is 96BonnevilleL67 has very good coating on his SC rotors ( I think his SC was replaced as it isn't the correct color of SC that 1996 M90'* were) and with only a 3.5" pulley, Ported SC (inlet ported/polished, outlet lightly ported), lightly ported/polished TB, his 3" fenderwell intake (wrapped now), 180* t-stat, and wrapped his crossover pipe he is seeing around 11 psi, but then again he doesn't have 3" exhaust.

My old 1995 SLE SC I found to be missing about 50-60% of the coating from the rotors, which could very well be why that car wasn't as fast as it should have been at the track (between that and the SC gasket blocking the SC outlet).
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Old 01-04-2007, 02:28 PM   #6
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Please remember... Flow lowers boost and increases power since it'* using the boost and not stacking it.

With rockers or a cam you will flow more in and out of the cylinder. Therefore a 3.2" pulley on an engine may show 13lbs of boost with stock exhaust and once the motor is cammed or rockered the boost now shows at 7lbs. While being lower boost, the flow has created a lot more horsepower and torque.

Boost pressure is good and bad. Too much means you aren't using it when you could. Too little is more ialong the lines of vacuum instead of forced induction.

As well... porting and polishing an SC casing in our situation is more to reduce the resistance of the unpolished casing and keep the charge cooler as it flows. The slight changes do not have a dramatic flow amount effect. If flow amout was a large gain...Eaton would have cleaned and polished instead of developing the next generation blower.
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Old 01-04-2007, 11:52 PM   #7
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It will be interesting to see the difference in my boost level now since The Gen V SC was the only change made.

I don't know what my boost levels were prior to the injection and coating loss.
For all I know, the coating could have been lost before. It might even explain why the old Gen 3 SC was blowing its oil out its snout since day one.

I have more accurate boost readings now with my Aeroforce gauge.....but even with the 2.9 pulley, I never saw the readings above 11 psi.

......now if my final part would ever arrive, I could start this beast and find out.
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Old 01-05-2007, 12:03 AM   #8
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It would be interesting to see what our stock MAP sensors were even capable of reading. My gauge has been 'pegged' for two years. I have no idea what boost I actually run.

On the coating subject, it'll be interesting to see the coating on my Gen3 when it comes off. I think you and I did about equal amounts of WMI injection.
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Old 01-05-2007, 12:21 AM   #9
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By the FSM, the stock MAP sensor will read up to 15 psi.
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Old 01-05-2007, 01:04 AM   #10
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I know the gauge in my cluster has a 'hard stop' that will be coming out this winter, so maybe I need to dig into my FSM'* and check my MAP sensor specs too.
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