Intake restriction
Thread Starter
Joined: Jan 2002
Posts: 4,069
Likes: 74
From: Casselberry FL
Intake restriction While touching up the PE fueling, I notice my WOT kPa is erratic, bouncing around between 94-102 during the WOT pulls in 3rd & 4th gears.
I have a Fram paper filter (new on 2/19/14),Fast Toys 85mm lid, LS3 100mm MAF w/ Saxon screen, 92mm Nick Williams TB & a Rick Crawford modified LS3 intake. I had a Fast Toys Ram Air system early in the cars life but removed it a couple of years ago for better cooling on an open track.
Am I losing much power with that restriction? How would I go about isolating and reducing that restriction without using a FTRA/SSRA/Chris1313 setup? I'd prefer to isolate cheaply before potentially spending big money for little to no gain.
I have a Fram paper filter (new on 2/19/14),Fast Toys 85mm lid, LS3 100mm MAF w/ Saxon screen, 92mm Nick Williams TB & a Rick Crawford modified LS3 intake. I had a Fast Toys Ram Air system early in the cars life but removed it a couple of years ago for better cooling on an open track.
Am I losing much power with that restriction? How would I go about isolating and reducing that restriction without using a FTRA/SSRA/Chris1313 setup? I'd prefer to isolate cheaply before potentially spending big money for little to no gain.
Well... That depends.
I ran a non AC chrs1313 here in south Louisiana. You should be able to imagine how hot it gets... LT1 radiator and 160 stat and she ran nice and cool.
I pulled 96kPa at WOT, and it was due to the stock MAF. Used a 4" piece of Aluminum pipe and 2 4" silicone couplers to connect to my SLP lid (4" OD) and my NW 92mm TB.
15 minutes later and at WOT she was staying at 100kPa. Picked up 8/5 on the dyno. In my case the MAF itself was the restriction.
Went closed loop speed density and never looked back. Car ran amazingly good. This was my 01SS.
I ran a non AC chrs1313 here in south Louisiana. You should be able to imagine how hot it gets... LT1 radiator and 160 stat and she ran nice and cool.
I pulled 96kPa at WOT, and it was due to the stock MAF. Used a 4" piece of Aluminum pipe and 2 4" silicone couplers to connect to my SLP lid (4" OD) and my NW 92mm TB.
15 minutes later and at WOT she was staying at 100kPa. Picked up 8/5 on the dyno. In my case the MAF itself was the restriction.
Went closed loop speed density and never looked back. Car ran amazingly good. This was my 01SS.
I am inclined to think that you may be seeing the intake
pressure pulses, decimated by the sampling rate, in the
MAP reading. Putting a 'scope to it and seeing whether
the output voltage bounces in sync with motor RPMx4
would put that plain.
pressure pulses, decimated by the sampling rate, in the
MAP reading. Putting a 'scope to it and seeing whether
the output voltage bounces in sync with motor RPMx4
would put that plain.
Thread Starter
Joined: Jan 2002
Posts: 4,069
Likes: 74
From: Casselberry FL
Thanks for the idea, Jimmy. Instead of buying a oscilloscope or taking it to someone who has one, I'll re-log with minimal PIDs to see if it's just a sampling issue.
Last edited by JimMueller; Apr 20, 2014 at 08:14 PM.
Teching In
Joined: Sep 2013
Posts: 43
Likes: 0
From: Straya
The MAP readings do seem to bounce around a lot more on big setups, I think it's just all the pressure pulses crashing around in the intake manifold like Jimmy says. If you take the average of the high rpm WOT readings, and subtract from the key on engine off (atmospheric) readings, you get an idea of the restriction. Your intake setup is pretty big all the way through already though, and it would be hard to improve on it. A bigger lid wouldn't hurt, but I doubt it would make much difference.
