Granatelli MAF causes performance degredation?
Thread Starter
Safety Car
Joined: Sep 2003
Posts: 3,558
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From: Cape Coral FL
Granatelli MAF causes performance degredation?
Any info/feedback on this. I am running one in my car. It made it run smoother, etc. But I'm not sure it actually has less hp/tq than the stock MAF. :U Or does it? :eek:
[Modified by ArKay99, 9:23 PM 10/21/2003]
[Modified by ArKay99, 9:23 PM 10/21/2003]
Race Director
Joined: Mar 2000
Posts: 17,602
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From: Palm City Florida
Re: Granatelli MAF causes performance degredation? (ArKay99)
Trust me on this..If you put your stock MAF back on you will immediately feel the difference...
You just ported your TB and you have the Vararam. You need to get the air velocity up and the stock MAF will do that...
Just polish up the ends real good before re-installing it..
I just had the ported maf ends and even tuned the car with LS1-edit.. It just never felt right.. I put my Stocker back on and it was like :eek:
You just ported your TB and you have the Vararam. You need to get the air velocity up and the stock MAF will do that...
Just polish up the ends real good before re-installing it..
I just had the ported maf ends and even tuned the car with LS1-edit.. It just never felt right.. I put my Stocker back on and it was like :eek:
Thread Starter
Safety Car
Joined: Sep 2003
Posts: 3,558
Likes: 2
From: Cape Coral FL
Re: Granatelli MAF causes performance degredation? (chuckster)
Trust me on this..If you put your stock MAF back on you will immediately feel the difference...
You just ported your TB and you have the Vararam. You need to get the air velocity up and the stock MAF will do that...
Just polish up the ends real good before re-installing it..
You just ported your TB and you have the Vararam. You need to get the air velocity up and the stock MAF will do that...
Just polish up the ends real good before re-installing it..
Pro
Joined: Apr 2002
Posts: 726
Likes: 2
From: Denver CO
Re: Granatelli MAF causes performance degredation? (chuckster)
Trust me on this..If you put your stock MAF back on you will immediately feel the difference...
You just ported your TB and you have the Vararam. You need to get the air velocity up and the stock MAF will do that...
Just polish up the ends real good before re-installing it..
I just had the ported maf ends and even tuned the car with LS1-edit.. It just never felt right.. I put my Stocker back on and it was like :eek:
You just ported your TB and you have the Vararam. You need to get the air velocity up and the stock MAF will do that...
Just polish up the ends real good before re-installing it..
I just had the ported maf ends and even tuned the car with LS1-edit.. It just never felt right.. I put my Stocker back on and it was like :eek:
I've heard similar things from two different tuners. The MAF ends hurt more than help, porting the stock MAF is a no-no (polishing may help), and that the MAF was probably the one thing GM got 'right' on the intake. The screen is a judgement call. I'd say leave it if you had the stock airbox, to help equalize the flow pattern over the sensing wires, but with the Vararam, you probably have close to laminar flow at the MAF and the screen is less necessary. Charles Probst recommends leaving it in place since the pressure drop is low, but GM chose to remove it in the later model Vettes (probably more for cost savings). I believe Lingerfelter estimated that the stock MAF is good for up to 500 HP (higher HP = higher intake flow). Leave it stock, with or w/o screen :cool:
Le Mans Master
Joined: Dec 2000
Posts: 9,909
Likes: 1,858
From: Hot Springs AR
Re: Granatelli MAF causes performance degredation? (ArKay99)
The only direct knowledge I've had on the G MAF was a friend who got one for his '99 C5. Only mods he had was intake and cat-back exhaust at the time. When he installed his GMAF he started getting a bunch of knock retard. Took it to a well known local tuner and they worked on it, but still had a bunch of KR. We took the stock MAF off my C5 as a test, all the KR went away.
I don't really understand what the GMAF had to do with the KR, but I do know that when we went back to stock the KR went away.
HTH, and have a good one,
Mike
I don't really understand what the GMAF had to do with the KR, but I do know that when we went back to stock the KR went away.
HTH, and have a good one,
Mike
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Race Director
Joined: Mar 2000
Posts: 17,602
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From: Palm City Florida
Re: Granatelli MAF causes performance degredation? (VetteDrmr)
The only direct knowledge I've had on the G MAF was a friend who got one for his '99 C5. Only mods he had was intake and cat-back exhaust at the time. When he installed his GMAF he started getting a bunch of knock retard. Took it to a well known local tuner and they worked on it, but still had a bunch of KR. We took the stock MAF off my C5 as a test, all the KR went away.
I don't really understand what the GMAF had to do with the KR, but I do know that when we went back to stock the KR went away.
HTH, and have a good one,
Mike
I don't really understand what the GMAF had to do with the KR, but I do know that when we went back to stock the KR went away.
HTH, and have a good one,
Mike
They lower the Velocity by increasing the volume. The lower velocity is seen as a lower engine load, and a lower engine load = higher timing..
Well, if you fake the motor out and let it think there is less of a load then there really is.. You open yourself up for problems. The higher timing MAP being used + the Load = Knock Retard
Thread Starter
Safety Car
Joined: Sep 2003
Posts: 3,558
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From: Cape Coral FL
Re: Granatelli MAF causes performance degredation? (ArKay99)
That's it, I'm putting the stock MAF AND airbridge back on tomorrow. I just gotta get a 4.7k resistor to trick the MAT sensor. Radio Shack $.02 each. Thanks guys, and especially you chuckster, helped me out a bunch, again! I'll let you know what the SOTP gains are :D
Le Mans Master
Joined: Dec 2000
Posts: 9,909
Likes: 1,858
From: Hot Springs AR
Re: Granatelli MAF causes performance degredation? (chuckster)
Chuckster,
But, isn't the GMAF supposed to be re-programmed for this? :confused: If the GMAF doesn't even attempt to compensate for the increased diameter (and associated reduced airstream velocity), how in the world did they ever expect it to work?
What you say makes sense with my observations, though.
One thing's for sure: I'm staying with my stock MAF until/unless I need some serious airflow increases.
Thanks for the info,
Mike
But, isn't the GMAF supposed to be re-programmed for this? :confused: If the GMAF doesn't even attempt to compensate for the increased diameter (and associated reduced airstream velocity), how in the world did they ever expect it to work?
What you say makes sense with my observations, though.
One thing's for sure: I'm staying with my stock MAF until/unless I need some serious airflow increases.
Thanks for the info,
Mike
Race Director
Joined: Mar 2000
Posts: 17,602
Likes: 20
From: Palm City Florida
Re: Granatelli MAF causes performance degredation? (ArKay99)
That's it, I'm putting the stock MAF AND airbridge back on tomorrow. I just gotta get a 4.7k resistor to trick the MAT sensor. Radio Shack $.02 each. Thanks guys, and especially you chuckster, helped me out a bunch, again! I'll let you know what the SOTP gains are :D
Your stock IAT is just fine.. With the Vararam you are going to see much cooler temps anyway.. Sorry but I have been down all these routes before and most are just a waste of time.
Thread Starter
Safety Car
Joined: Sep 2003
Posts: 3,558
Likes: 2
From: Cape Coral FL
Re: Granatelli MAF causes performance degredation? (chuckster)
Don't do the 4.7k resistor... I did that too.. It makes you run too rich... Especially in warmer weather it makes the car run like a pig..I pulled over to the side of the road, pulled the resistor and plugged the IAT back in.. And she woke right up!! Yes, it was noticable..
Your stock IAT is just fine.. With the Vararam you are going to see much cooler temps anyway.. Sorry but I have been down all these routes before and most are just a waste of time.
Your stock IAT is just fine.. With the Vararam you are going to see much cooler temps anyway.. Sorry but I have been down all these routes before and most are just a waste of time.
Pro
Joined: Apr 2002
Posts: 726
Likes: 2
From: Denver CO
Re: Granatelli MAF causes performance degredation? (chuckster)
Yep, thats fine for the relocated IAT.. should be ok. But use the stock MAF..
I know of the IAT, MAP, and MAF sensors, but what's a MAT? (Help, I'm in acronym hell :lolg:) Naw, just kidding, but newbies might be confused. I'm guessing that IAT = MAT, but the acronyms are from different cars or manufacturers. Chuckster, can you help us out?
BTW, sounds like I need to visit all your old threads b/c it sounds like I'll probably end up making mistakes similar to the resistor thing. :D
