JAS

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by cdk4219:
<strong> The air that BOV pushes back into the area between the MAF and the blower inlet will need to displace some of the air that has already entered through the MAF. When you close the throttle body all this stuff happens and the MAF will actually read some of the air twice before it reaches the engine, because it actually pushes or displaces that air back the wrong way. Sounds silly, but with the finicky nature of the LS1 MAF it could be a problem. JAS you are right with it not being a problem with idling. </strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">Thanks. Yeah, that has been discussed in the past that the MAF is too close to the bypass valve. The Vortech's have more tubing between the blower and the MAF. So, why do some experience it and others don't?

sscamaro387

iTrader: (1)

Ok, I pulled a couple plugs to see how lean i was. And they can out pretty tan, So when U die when u come to a stop, could it be cause it's running to rich????and just bogging it's self down?

Just thought I'd throw it in.

Hopefully we can figure the thing out

Black LS1 T/A

Thanks, guys, dad is better.
I'm back home, now (just this morning).

The PY3600 basically lets your motor stall a couple hundred RPMs higher and will stay in the power band better. It probably is at least as streetable as the SY3500. I find the PY3400 is not much less streetable than stock, with this 422.

Black LS1 T/A

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by JAS:
<strong> </font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by cdk4219:
<strong> The air that BOV pushes back into the area between the MAF and the blower inlet will need to displace some of the air that has already entered through the MAF. When you close the throttle body all this stuff happens and the MAF will actually read some of the air twice before it reaches the engine, because it actually pushes or displaces that air back the wrong way. Sounds silly, but with the finicky nature of the LS1 MAF it could be a problem. JAS you are right with it not being a problem with idling. </strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">Thanks. Yeah, that has been discussed in the past that the MAF is too close to the bypass valve. The Vortech's have more tubing between the blower and the MAF. So, why do some experience it and others don't? </strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">Maybe it's just an "on the threshold" problem. It's not severe enough to worry me. I only noticed a significant stumble once this whole weekend, and it has not died on me but once... the first time I mentioned. Note, like I said... I have bumped the idle speed back to 800 in drive.

JAS

Chris, please explain further.

Thanks

CHRISPY

When the throttle body blade snaps closed at lower rpms the air reverberates back through the compressor blades causing turbulence and what is called "compressor flutter". It isnt really enough to cause a BOV to open but it is a enough to make the MAF go a little wacky on the intake side from the turbulence. Hope this helps
Chris

JAS

Chris, yeah, that was a concern when I had the MAF in the stock ATI position before the TB. That's why a bigger bypass valve mounted at the ATI plenum box would of been better. However, at the relocated position I don't see MAF flutter flow numbers. Which one were you talking about, stock ATI location or relocated position?

CHRISPY

Compressor flutter can cause what you are describing when the T-body blade snaps shut with the MAF on the intake side...
Cheers,
Chris

02BlackWS6

Hey Mike, I broke down and ordered the 7# ATI kit today <img border="0" title="" alt="[Big Grin]" src="gr_grin.gif" /> I need to reduce my stall and get a few other things before the blower arrives in 2 weeks or so. What head gaskets do you recommend with this kit plus S1 heads at 10.3:1 CR and 216/220 cam? I have a buddy who's having trouble with his Cometic's leaking antifreeze..eek!! So i'm asking around for good gaskets. I'm gonna use ARP head bolts for sure. Well i'll post back as the project unfolds <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" />
P.S. Good to hear your dad is doing well.

Den

1dirtyZ

iTrader: (1)

hey 02BlackWS6,
welcome to the dark side!
don't you think that your compression is a bit too high?
definatly go with the cometics. they are the best head gaskets around.
your buddys problems are from the o-ring not seating properly in it's layer ( the o-ring overlaped it's layer) causing the leak.

why are you lowering the stall speed?

Black LS1 T/A

Cometics, man... <img border="0" title="" alt="[Big Grin]" src="gr_grin.gif" />

I, too recommend a lower Static compression, if that is something you can do... You'll never get to go much beyond 7 PSI without running race gas or dropping the timing WAY down, with the compression you plan. (My opinion... I guess anything is possible.)

02BlackWS6

I'll only be seeing about 5#'s because of the ported heads, cam, and longtubes. So with 10.3:1 CR and 5#'s I should be ok. I'll be running 38# injectors too. My converter flashes to 4,300rpm with my heads and cam. When i add the blower its gonna flash even higher. Besides blowers don't like the real high shift extension the big converters provide. With a Vig.2800 i'll flash around 3,500rpm and shouldn't drop below 4,700rpm between shifts at WOT. A Vig.3200 would flash around 3,900rpm to possibly 4,000rpm which is alittle high for a blower setup. But i could get away with the Vig.3200 i guess. I'm still on the fence on which stall to be at.

Mike,
I know what you mean. But i don't plan on going any higher than a 7# pulley which will only show about 5#'s cause of my current setup. But I was talking to a buddy of mine lastnight and since i have to pull the heads for the better gaskets and ARP bolts i might have the combustion chambers ported out to drop me to around 10:1 or lower. But even on ATI's chart it shows you can run almost 10#'s with a CR of 10.3:1.

02BlackWS6

Mike,

Before you installed your new motor weren't you running stock compression on 10psi? I'm gonna look into lowering my CR since i'm gonna remove my heads anyway. Thanks.

Den

Black LS1 T/A

Yes, with headers and stock compression on the 3.20" pulley I made 10 PSI. It was 12 PSI with the stock exhaust system.

I had to run TORCO Race Fuel Additive or add some 100+ when I was going to race it, though, or I got detonation. <img border="0" title="" alt="[Frown]" src="gr_sad.gif" />

1dirtyZ

iTrader: (1)

ok , i think after banging my head several hundred times on the wall, i came up with an idea!
(more like a thought):

on a stock motor ( applies to stock ATI setup too) the air goes through the maf when the throttle blade is open, but when the blade is closed close to no air flows through the maf (the air just hits the blade and stays there- ignore the IAC) so we can say that this is the normal scenario.

now lets look at the relocated maf setup:
at idle , when the throttle blade is closed , air is still going through the maf. why, because the blower is always sucking air in - even at idle ; which means unlike the stock set up , the maf will regester flow at idle .

now that we have air flowing through the maf when it shouldn't , we get a whole lot of fule but no air to burn it off. so that could explain why the car stumbles to life if you give it gas after WOT.

what do you guys think of this theory?

Black LS1 T/A

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by 1dirtyZ:
<strong> now lets look at the relocated maf setup:
at idle , when the throttle blade is closed , air is still going through the maf. why, because the blower is always sucking air in - even at idle ; </strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">So, in the stock-ATI position, isn't the air always going thru the MAF because the blower is always pushing it in?

1dirtyZ

iTrader: (1)

i don't think so, chause it's like blowing into a hose with one end closed. instead of the air moving in that section , it just circulates through the bov to the hat and MAYBE goes out through the filter if not sucked in by the blower.
what do you think???

JAS

Except that you forget that if the bypass valve is big enough, even in the relocated position, the air thats going back into the blower whould only be the bypassed air. In fact, the bigger concern is that so much air is being bypassed that it may even be going through the MAF backwards. Here's another: You think that the ATI one side bypass is big enough to bypass ALL the air instantly when the throttle slams shuck even in the stock ATI MAF position? You don't think there is air bouncing back and forth through the MAF off the trottle blade? <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" />

Now let me ask you what happens to injectors when you slam the throttle shut? <img border="0" title="" alt="[Wink]" src="gr_images/icons/wink.gif" />

Instead of guessing, do some logs and post them for analysis.

I'm thinking short bypass valve purge location to MAF proximity and less than ideal onesided bypass valve location. And in your case, huge cam and below stock idle rpm. <img border="0" title="" alt="[Big Grin]" src="gr_grin.gif" />

BTW, have you tried clocking the MAF differently yet?

JAS

Hey dirty Z, take the belt off your blower only and do a WOT run and let us know what happens.

1dirtyZ

iTrader: (1)

it's funny you ask about removing the belt, cause a couple of weeks ago the idler pully seized up and burned through the belt.

well what happened is the car got DANGEROUSLY VERY SLOW! <img border="0" title="" alt="[Big Grin]" src="gr_grin.gif" />

in all seriousness, if i remeber correctly , the car idles smoothly after WOT, no dieing (sp) at all.

i assume by clocking the maf you mean switch the direction of flow through the maf. why do you think that would help? ( if you mean rotate it so the top side faces left or right , i did that already)