tortuga

I had a look at the alternator today and it was definitely touching the s/c in one or two spots just barely. I had already grinded it when I originally did and still ended up using a washer on each mount bolt for additional space but I went ahead and took it off to grind it more today and now I've confirmed there's visible clearance now so I'm crossing my fingers this was the cause of my false knock.

KR is still there. If anyone's got any ideas, throw 'em my way. I've tried everything it seems like.

Codith, I know it;s basic but spark timing or a lean condition or a combination of both are about the only things that could cause this. Can you play with the tune in the problem area?

I know you have lots of tuning/data logging capibility to rule this out, but just throwing it out there...

I had a similar KR issue, was only at part throttle and just as boost was seen. WOT was perfect. Part throttle would kick the KR sensor, 7-14 deg knock and all the timing would dissapear killing the whole experience. I checked everything I could possibly think of for a year but nothing of the usual worked. Even though fuel pressure read ok and my trims were not that far off, it ended up being my FPR. I replaced that and suddenly my part throttle and part boost is amazing and KR free again.

Radically different engines at this point I know, but I'm just throwing it out there. I know you have some pretty custom stuff going on in your fuel system.

How are you tuning, exactly? In this scenario I think you absolutely need to VE tune until it's perfect.

Well this problem has been there since when I put the new engine in and a lot of stuff has changed since then, tuning-wise. The problem has not. I tried a ton of stuff. This KR is happening long before boost levels. I've even seen it on closed throttle under very light decel sometimes. I've tried retarding timing in the observed problem area. My fuel trims are pretty well tuned and fuel pressure is solid. AFR is rock solid where it should be. New denso O2 was freshly installed with the engine and wideband shows good reconcilliation with commanded AFR.

For tuning, I basically disabled KR until 2000rpm, disabled PE, and did some VE then maf using the "table modifier thingy". Based off what the graphs look like I'd say I still need to spend more time on VE. It's more spiky than the original VE graph was so I'm assuming I need to get more data and whatnot. James was saying that 97's might have some hidden VE involvment that 98+ doesn't since it's the oddball PCM.

I like to graph my VE table in excel as a 3D graph. It should look kind of like an upside down long serving bowl, or like half a football in shape. I had great luck after smoothing out my tune into that basic shape. Get out some of the out of place peaks since you know they shouldn't be there.

I prefer not to disable KR during tuning, if you have detonation happening you will throw your O2s all over the place. Address the timing and fueling issues together as you dial it in. Do some fueling/VE work, then do some timing work, then do some VE work, then some timing work. Don't be too aggressive in your timing settings until you have the VE stable.

I used the table modifier thingy a little bit at first, but it doesn't get rid of the spikes - it can only adjust based on the recent scan data. I ended up adjusting by hand based on fuel trims and O2s until I was satisfied. Once you get the VE table close, and in a nice smooth shape, you'll be surprised how well it transitions from one place to another on the tables.

It seems to be a debate as to whether the VE table matters. Some say it's just a contingent table used if the maf fails and it's being reference in the background to make sure what the maf is saying makes sense (fault checking) but normally, it doesn't do anything so there's no need to tune it. I also hear that, similar to what you're saying, things will change if you change it so it sneeks in there somewhere and does something... I really wish I knew one of the GM EFI engineers from this decade so they could positively explain what the heck is really going on!

I'll see if I can post my before and working VE graphs from when we were doing that.
When I was doing this I disabled KR under the pretense that I didn't have any actual detonation and I figured the 15* timing being pulled all over the place at random would reek more tuning discrepancies. Towards the end of the day, I was getting in just about 100% throttle without PE (tuning the higher end of the maf) and saw nothing but little blips of KR sometimes - enough to know it's working.

Still, I went and changed all this stuff, VE,maf, timing and observed no change in this part throttle KR condition. No aspect of tuning whatsoever has any affect on it which is why I believe it's false KR.

I'm no authority on it, but I don't think VE matters as long as MAF is working. I've tuned this car probably 100 times, never touched the VE table and gotten the results I need solely with MAF tuning. My friend Dyno Brian, who used to tune PCMs for INTENSE, once told me he agrees that VE doesn't matter.

Whats the Corn fuel you kids speak of?


I see Aaron still dislikes it

How so?

There are a number of factors in the timing and amount of fuel delivered. The calculations weigh each factor. The MAF will be the major factor, but if the VE table is way off, it will have an effect. In your case, the VE table is now way off. In any of our cars running E10 or plain old gas, the stock VE table will be close enough, for the most part. I believe my car runs that much better because my VE table is accurate to begin with. In your E85 situation I believe the VE table is a must-do step.

Its really not that hard to do and certainly worth a try.

Travis, nice troll.

AA wrote:

I don't understand. You have not even a blip of knock and E85 is sweet, but you are seeing 15 deg KR at cruise?!!! Lost me there.

Was just given you shit for hating on my hippy drink back when i used to run it lolz

I run it because it's better for the environment

turtleman wrote:

I run it because it's better for the environment

I ran it because i like the smell of alcohol, and bitches love alcohol

The smoothflow belt wrap is giving me trouble. Like other G/H body people do, I spaced it up from the blower with spacers so it could fit with my idler/tensioner setup. Problem is the bolt holes in the bar have enough room to let the bar wiggle a little so what happens is the tension from the belt makes the bar cock one way which puts the pulley at a slight angle. This angle is enough to make the belt start walking off under high load conditions which is why my 8rib belt is now a 7rib belt lol. I haven't heard of this issue with Eric's or other people so I guess I'm the lucky one.

I tried putting some rubber washers under the beltwrap to hold grip it and keep it in place. That didn't work at all. The only other thing I can think of is if I JB weld the spacers I made to the bar so the much tighter fit of the spacers is then holding the bolts and the bar in alignment, it can't move enough to be an issue unless the JB weld lets go or something.

Alternatively, I'm trying to draft up a rough blueprint to make my own at work using the smoothflow as a model. I can make it much tighter fitting than they did and then hopefully sell the smoothflow and make back losses.

Last worst case scenario would be buy a WBS beltwrap and switch to a W body coil bracket tensioner assembly but I don't want to do that because it's the most expensive and that coil bracket is heavier (cast iron)

youd be better off to drill and tap a hole in the smoothflow bar for a link from it to the alternator so it cant twist anymore.

or you could go blow tons more $ lol

I've already started making my own beltwrap at work today

gimme the old one for 10$ and some pocket lint...

Hertrich performance beltwrap V.1

started off with a piece of 1 5/16" T6061 aluminum stock




lathe work
The smoothflow s/c bolt holes were offset to center the bar away from the supercharger a little bit. Since I'm using a round piece, I offset the pulley boss instead off the bolt holes because I figured that'd look a little odd.

the legs


the rest on the mill










that's the area I clearanced for the gearbox area of the blower


I also clearanced the bottom part that goes over the wires

So yeah we'll see how it works out.

we could use one each on the 442's new engines

looks nice, still deflecting, im suprized you didnt look into a collar to tie it to the blower snout. all we'd have to do is machine the snout a bit more than usual for a smaller pulley and you can make a 1/4in thick "figure 8" tiebar

Turbocharged400sbc wrote:

we could use one each on the 442's new engines

looks nice, still deflecting, im suprized you didnt look into a collar to tie it to the blower snout. all we'd have to do is machine the snout a bit more than usual for a smaller pulley and you can make a 1/4in thick "figure 8" tiebar

Got it handled


That's pretty much what I've made now. two heim joints (one standard thread, one left hand/reverse thread), a union I made from 3/4" 303 stainless hex stock to connect the joints, a shank nut to connect the joint to the alternator stud nicely made from 3/4" T6061 aluminum hex stock, and then the carefully engineered clamp made out of 1" thick T6061 aluminum (usual stuff same material as the bar)

and the result..







So far, it works awesome. It's finely adjustable and install is a breeze. Took some tweeking to make the clamp tolerances right and whatnot but it's done!


In other news, I got a replacement nitrous bottle heater in today so I can probably start tuning that too but I kinda need a pressure gauge still.

oooo! fancy! Looks good!

That is what I call some serious pursuit of boost. Looks like you found it. (+)

PS - are you concerned about possible contact between the nut and IC cooling line?

looks tits