3800 post-sc swap KR

[sgtp]

a few wkends ago I swapped in a p/p sc and a polished lim, and of course, I now have more KR than I started with. Before, I only got about 2-3* and not till 80mph....now Im getting highs in the 14* range. I pulled the blower belt and scanned and couldnt get any KR, (and the car felt so slow with 0 torque ) and then I scanned again with the belt on. At first I got high kr that slowly came down, till one wot run where it hit 14* and went away right away. I think I need to start looking at sources of false Kr after seeing that, and need some idea's.

Heres a little more info on my swap: The ported housing had maybe 60k on it with original needle bearings that I relubed. I replaced the rotors as well with some I had because my stock ones had no teflon left, due either to ?a coolant leak? or some agressive top engine cleaner addministered thru the vac line on top of the blower (two cans, back to back). I torqued the sc down with 14lbs + quarter turn, because Ive read 17lbs can mess up the rotors. I did a mild polish on the TB since it was off the car. I just widened the outlet some and polished everything. I did do something that I dont know yet if it may be related. I put a spacer under the egr needle valve as a way of blocking the exhaust gases. Is the needle rattleing against it? I checked everything I touched during the swap but didnt find anything obvious. I get 3* just reving it up past 3K in neutral :huh:

give me some idea's....racing season is close to half over and I havent raced yet

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[syP]

tuning... you need tuning....

its like me adding a cam, ported s/c inlet, polished heads and LIM... and i got KR also.. i think you need to adjust a/f

 

[alexgtp]

You ported your TB?

Even mild porting to a TB not done properly will cause all sorts of problems (turbulence)

I would 1st swap a stock TB back in. To rule that out.
Which ported SC did you get? Some have been known to cause problems. Due to poor porting procedures. which had now been rectified

When you refer to "needle bearings" what are you referring to?

Also did you change out the entire "SNOUT" assebmly with your old unit or did you keep the one that came with the ported SC?

 

[sgtp]

I ported the sc myself. what are the problems reported? Ive only heard people say the boost drops slightly.

I installed my snout on the ported case. Most people replace the bearings inside the blower case, but I did not. Arnt they called needle bearings?

If the TB porting was causing a problem, Id expect a rough idle and crazy fueling problems. I dont have any problems like that. The car runs fine. It was more of a polish than a port job anyway.

Oh, one more thing. I just remembered it. During all of this, I noticed an idler pully for the sc belt was noisey. I cleaned and repacked the bearings instead of waiting to get a new pully. It turned smoothly after repacking it, but I dont know anymore....can a idler cause kr?

 

[alexgtp]

How did you port the SC?

Did you do inlet or outlet porting?
Also what guidelines did you following in porting an m90?

By porting improperly you can do more harm .. I beleive ZZP actually ports in order to reduce inlet temps and to improve efficiency..

I think you should look on ZZP website and also take a look at winterhalter's ported blowers.. They go into detail about porting M90 blowers. What worked and what didn't It took them a cple yrs and many blowers to come up with the mot effecient blowers they could make..

Remember turbulence will cause KR. Improperly ported inlets will cause KR. Improperly ported outlets will cause KR.

 

[Mike K]

Turbulence around the throttle body can cause KR as the MAF is no longer able to get an accurate meter of the incoming air.

ZZP (and the rest of us) port our blowers to lower outlet temperatures. Anytime you're porting the blower (correctly) you're going to lower outlet temperatures and you should see no loss in boost really. In fact we saw a gain with our first blowers. The outlet temperatures are direclty related to the amount of energy the blower requires to spin. If we can reduce the amount of energy required to turn it (open up inlet so it's not "sucking" as much) we can lower the outlet temperatures and lower KR.

This is the clifts notes version of all of this.

 

[sgtp]

looks like im SOL....thanks anyway

 

[syP]

aww cmon you cant give up.... throw on the stock TB and scan... you might be surprised... i went from 9 kr to 0 kr ... ported to stock... ask suprchrgdgp.. heh

 

[sgtp]

Ok, I tried some more tuning and that seemed to help some. If I floor it from 20 to ~35 I get no kr. If I floor it from ~35 and up I get 14* of kr, but if I ease into WOT from a 35mph cruise, I dont get the 14* spike but do get some more manageable kr to tune out with a afc. I will post some scans to show what Im talking about. (these scans are after a fresh fill up, I thought I had bad gas before, but the 14* spike is still there)

I am looking for a 2000 tb to swap in to see if that could be the problem. If anyone has one to sell or lend, shoot me a PM.

 

[Mike K]

Are you using a PowrTuner? Increasing the Acceleration Enrichment function in the PCM will aid in removing that burst knock.

 

[sgtp]

I guess I have some belt slipping going on as well....heres a scan.

my kr filled scan

I am just using a afc 2.0 to tune, and have things rich right now....no PT here. I wonder how this crazy burst knock was non existant till after the swap.