[banditsc]

Tap in right at the fuel pressure regulator and I routed mine in thru the fuse block area.

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[flash]

be sure not to use tubing that will melt. it gets pretty hot back there.

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[flash]

well, i have now messed with every map that even remotely resembles a decel map. i've cleaned the MAF. no soap.



i'm changing out the O2 sensor tomorrow and then i'm taking some MAF voltage readings. the car runs fine, but it bugs me that it is doing this, and i think it should shut off the injectors. i wish i had a stage 1,2, or 3 car here to test, but i won't until the first of the month.



the only other remaining theory is that the off-throttle leftover boost that is being recycled back into the intake is creating a draw of air over the MAF that is confusing the system. not sure what i can do about that though. i'm going to conduct a test with the return hose disconnected and see if that changes it.



the only reason i am even bothering with this is because i don't know what's causing it, and that bugs me, and this is probably going to cost me fuel economy.

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[flash]

well, it looks like i have gotten to the bottom of this. it's a physics thing.



basically the supercharger is drawing air, even off throttle. this creates a pull across the MAF. the MAF thinks the car is under more load than it really is, and adds fuel. once the rpms drop enough, it falls below a preset threshold, and goes back to normal. unfortunately i cannot find a place to reset that threshold.



the other kits probably do this, but to a lesser degree, as they draw less air. i'll know that for sure when i get a chance to test one.



i know what i would have to create to resolve the problem, but i don't think i can make it happen. i think i'm going to have to live with this.



the bottom line is that this isn't going to hurt anything, and it doesn't affect the drivability, but it will cost me some fuel economy.

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[MB968]

You could put the throttle body in front of the SC. That and a vacuum operated bypass should fix it, but probably isn't worth it.



FYI, in case the info might be useful, I tested the bypass on the Eaton at one point. The bypass begins to open at about 5 in of vacuum, and at anything over 9 in of engine vacuum, the bypass is 100% open.

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[flash]

yeah - i thought about something similar. like i said, i don't think i can make it happen

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[flash]

solved the chop throttle enrichment issue. i was using the prototype 3" elbow, which had a smaller I.D. return insert. it was too small for the increased boost. i opened it up and now all is perfect. woohooo!!!!



now i just need to finalize the boost level, and wrap that tune up. another day or two and i'm done

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[flash]

arrrgh - best laid plans and all that



went to the dyno. complete waste of time. did the standard baseline run of where we left off last time. numbers were way off right away. couldn't figure out why. 20hp low across the board.



moved on to playing with some things to peel off a bit of boost. got that all tuned, and figured out what i was going to have to do next. i didn't notice it, but a clamp slipped and i was blowing boost to the atmosphere. all runs completely useless and will have to be done again.



then, on the way home, i put the windows up to make a call, and was reaching over to turn on the AC when i noticed that IT WAS ALREADY ON! every run we did had the AC on. that explains the even drop across the entire power line.



lol - well, now at least i i know that the AC costs about 10 lb/ft and 20hp.



so, now i just need to wait for a couple of parts to be made and i can go back and finally finish.



bummer. i really wanted to be done today.

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[DaveN]

Look at it this way. You are the only developer who can actually post dyno runs which include AC loss! Talk about complete engineering.

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[tamathumper]

Wow, 20hp! I remember on the 944S, I *really* felt it when the AC kicked in. Not so much with the 968 because we have stuff like VarioCam, but still nothing to sneeze at.

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[Rap]

So your still at 290 with ac hmm. Guess it will depend on just how hot it is!

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[jfrahm]

In a lot of cars the AC shuts off under <acronym title='wide open throttle'>WOT</acronym>. If the 968 does not it would not be difficult to bodge that. It is probably not a great idea to spin the compressor up that much anyway.

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[flash]

no worries - i don't run the AC when i am playing anyway, and if i nail it when i do have it on, it's only for a couple of seconds, and never at high rpms.

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[flash]

i've been pouring over data all night. based on what the results were from a couple of things i did yesterday, and everything else that i've been playing with for the last month or so, i think i can safely say that i will be able to pick up a few more lb/ft of torque in the middle, and end up somewhere between 355 and 375 hp at the crank. that's as far as i can go safely with these injectors. i could get more if i went to even bigger injectors, but i would also lose any chance of passing emissions. as it is, i am peeling off a LOT of fuel down low and at idle to get the mixture right. if i went larger in injector, i would run out of ability to adjust. my fuel economy would also likely suffer.



so, i think this is going to be about it. it's ironic that back when i started all of this over 2 years ago, i first predicted a max of a bit under 350. i'm not going to be too far from that. i also said that what i wanted was 325, and that the car couldn't handle or use much more. in reality, that is correct. while the engine will be able to put out more power than 325, i will only be able to actually use about that much. after that, i'm way up in revs, and i just don't see that happening very often.

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[flash]

the new parts will be done monday or tuesday. i am set for tuning on thursday morning. if all goes right, i will be all done thursday afternoon or friday morning, and i can finally disconnect all my sensors and junk, and button things up.

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[rxter]

Good. The engine bay looks like something out of an ER script....

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[flash]

lol - true enough. the OCD part of me has been going nuts for far too long now. this really should do it. the last time out, i was too high on boost with one setup, and too low with the other. i need to be in the middle, so i have a couple of setups being made and will choose between them. i'm going to go for as much as i can safely run, and leave a margin for socal summer weather (heat). i'm expecting to land at about 7lbs boost and 360hp peak. i think i've found a few lb/ft of midrange torque too. we'll see how it all goes. what i do know is that it won't take long to nail now. i've done so much advance work that this will be almost plug and play. it would go very quickly if i had somebody to drive the car on friday while i played with the laptop. unfortunately that is hard to come by, as i need somebody that can drive it as instructed. there is a "feel" thing that is hard to explain, and without it tuning certain areas of the part throttle map is tough.



no worries though. i'm confident i can nail it all down well before happy hour friday.

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[Eric_Oz_S2]

So are you running an 85mm sc pulley now?

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[flash]

nope. not changing the pulley.

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[rxter]

I'd love to help (any excuse to drive that beast <img src="/forum/images/smilies/968/smile.png" class="smilie" alt="" /> Unfortunately will be in Tucson Friday.

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