Why remove A.I.R. pump?
Thread Starter
Intermediate
Joined: Sep 2018
Posts: 37
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Why remove A.I.R. pump?
I am tossing up whether or not to remove the A.I.R. pump from my '89 L98 Corvette.
I am told that by doing so I can expect an increase of between 20-30HP. Is this so?
I am also told that there is a 'restrictor' in the air intake system that was put there to 'de-tune' the engine,
and if you remove that 'restrictor' you can make significant gains in HP by improving the air-flow. Is this true?
I am told that by doing so I can expect an increase of between 20-30HP. Is this so?
I am also told that there is a 'restrictor' in the air intake system that was put there to 'de-tune' the engine,
and if you remove that 'restrictor' you can make significant gains in HP by improving the air-flow. Is this true?
Popular Reply
Jun 3, 2019, 01:23 PM
Melting Slicks
Joined: Oct 2016
Posts: 2,024
Likes: 363
From: Central Alabama
My 92 had the restrictor, but I got tired of hearing "slow your a$$ down", so I removed her it..
Safety Car
Joined: Mar 2003
Posts: 3,583
Likes: 504
From: Indianapolis IN
Finalist 2020 C4 of the Year - Unmodified
C4 of Year Finalist (stock) 2019
I am tossing up whether or not to remove the A.I.R. pump from my '89 L98 Corvette.
I am told that by doing so I can expect an increase of between 20-30HP. Is this so?
I am also told that there is a 'restrictor' in the air intake system that was put there to 'de-tune' the engine,
and if you remove that 'restrictor' you can make significant gains in HP by improving the air-flow. Is this true?
I am told that by doing so I can expect an increase of between 20-30HP. Is this so?
I am also told that there is a 'restrictor' in the air intake system that was put there to 'de-tune' the engine,
and if you remove that 'restrictor' you can make significant gains in HP by improving the air-flow. Is this true?
Race Director
Joined: Aug 2000
Posts: 11,470
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Last edited by Joe C; Jun 2, 2019 at 09:11 PM.
Safety Car
Joined: Mar 2003
Posts: 3,583
Likes: 504
From: Indianapolis IN
Finalist 2020 C4 of the Year - Unmodified
C4 of Year Finalist (stock) 2019
been into C4's for about 25 years now, and can't recall anything about a restrictor. the air intake is somewhat restrictive, and there not much that can be done with stock components. gasket match, a little pocket porting, and long tubes is about all you can do to a stock system. L98's are L98's - more torque than horsepower.
The ONLY restrictor I've ever known of in the L98's is the restrictor in the rear coolant passage of the intake manifold... that's there to keep coolant at the rear of the engine a little longer. Removing that would do nothing for your engine's performance...removing that simply allows you to remove that small bypass hose that runs to the coolant return line from the heater core.
Team Owner
Joined: Aug 2004
Posts: 21,543
Likes: 3,216
From: Park City Utah
The ONLY restrictor I've ever known of in the L98's is the restrictor in the rear coolant passage of the intake manifold... that's there to keep coolant at the rear of the engine a little longer. Removing that would do nothing for your engine's performance...removing that simply allows you to remove that small bypass hose that runs to the coolant return line from the heater core.
The only "restrictor" that I'm aware of is the entire TPI system.
Le Mans Master
Joined: Oct 2004
Posts: 6,314
Likes: 508
From: South-central Missouri
Restrictor plates apply to certain racing rules (NASCAR, etc) intended for "normalizing" horsepower of all competitors. Such restrctors in reference to the standard (i.e., street driven) cars is pure internet BS.
Last edited by Paul Workman; Jun 3, 2019 at 11:19 AM.
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Team Owner
Joined: Dec 2007
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While you are at it...
All smog items, ac, and heat, radio, speakers, frisbee, spare tire, cruise control, stock exhaust, etc. The car will feel a lot better. j/k.
The car is a detuned 350, that is done with emissions, excessively restrictive intake, exhaust, heads, small cam, ECU,
A good running / breathing "hypo" 350 on pump gas is capable of 425ish chp. Basically you heard right. It is choked.
LT1 intake
Heads
Cam (if auto need stall / gears)
Headers/ exhaust
1.6rr's
24+lb injectors
Tune
So that recipe will get you some where around 425ish chp. Pricey though!!!
All smog items, ac, and heat, radio, speakers, frisbee, spare tire, cruise control, stock exhaust, etc. The car will feel a lot better. j/k.
The car is a detuned 350, that is done with emissions, excessively restrictive intake, exhaust, heads, small cam, ECU,
A good running / breathing "hypo" 350 on pump gas is capable of 425ish chp. Basically you heard right. It is choked.
LT1 intake
Heads
Cam (if auto need stall / gears)
Headers/ exhaust
1.6rr's
24+lb injectors
Tune
So that recipe will get you some where around 425ish chp. Pricey though!!!
Last edited by pologreen1; Jun 3, 2019 at 01:32 PM.
Team Owner
Joined: Jul 2004
Posts: 28,473
Likes: 3,291
From: Hartford WI
As mentioned, there's little if any meaningful performance increase as result of removing the A.I.R. pump. However, removing the pump can negatively affect the efficiency of the cats - especially on start up, not to mention having to pass the smog station inspection of factory emissions equipment!
Burning Brakes
Joined: Dec 1999
Posts: 984
Likes: 154
From: Columbia MD
I removed my A.I.R. pump and I noticed that the engine compartment was a lot quieter when the engine is running. I never realized that the pump made so much noise.
But the main advantage is having more access to the front of the engine. The water pump in particular. There's a lot less clutter on the front of the engine now. And you loose about 15 pounds of hardware and plumbing.
-Wes
But the main advantage is having more access to the front of the engine. The water pump in particular. There's a lot less clutter on the front of the engine now. And you loose about 15 pounds of hardware and plumbing.
-Wes
Team Owner
Joined: Jul 2004
Posts: 28,473
Likes: 3,291
From: Hartford WI
I removed my A.I.R. pump and I noticed that the engine compartment was a lot quieter when the engine is running. I never realized that the pump made so much noise.
But the main advantage is having more access to the front of the engine. The water pump in particular. There's a lot less clutter on the front of the engine now. And you loose about 15 pounds of hardware and plumbing.
-Wes
But the main advantage is having more access to the front of the engine. The water pump in particular. There's a lot less clutter on the front of the engine now. And you loose about 15 pounds of hardware and plumbing.
-Wes
Drifting
Joined: Dec 2000
Posts: 1,785
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From: Leander TX
The only other benefit I'm aware of that hasn't been mentioned yet is it gets it away from from your alternator a bit. I've recently done this mod for this reason as I'm getting tired of fried alternators, but since I just recently did this I can't personally confirm it helps but it did move it away from my headers.
Thread Starter
Intermediate
Joined: Sep 2018
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Thanks, Guys. From what you have said, I have decided to leave the A.I.R. pump where it is, (at least until I decide to install headers).
As far as the 'restrictor' goes, if there is not one to remove, then I cannot remove it.
Actually the car performs better than any car in my (small) collection as it is, so I think that I will just be happy driving her as she is.
Thanks, again.
As far as the 'restrictor' goes, if there is not one to remove, then I cannot remove it.
Actually the car performs better than any car in my (small) collection as it is, so I think that I will just be happy driving her as she is.
Thanks, again.
Team Owner
Joined: Jul 2004
Posts: 28,473
Likes: 3,291
From: Hartford WI
The only other benefit I'm aware of that hasn't been mentioned yet is it gets it away from from your alternator a bit. I've recently done this mod for this reason as I'm getting tired of fried alternators, but since I just recently did this I can't personally confirm it helps but it did move it away from my headers.
Team Owner
Joined: Jul 2004
Posts: 28,473
Likes: 3,291
From: Hartford WI
Thanks, Guys. From what you have said, I have decided to leave the A.I.R. pump where it is, (at least until I decide to install headers).
As far as the 'restrictor' goes, if there is not one to remove, then I cannot remove it.
Actually the car performs better than any car in my (small) collection as it is, so I think that I will just be happy driving her as she is.
Thanks, again.
As far as the 'restrictor' goes, if there is not one to remove, then I cannot remove it.
Actually the car performs better than any car in my (small) collection as it is, so I think that I will just be happy driving her as she is.
Thanks, again.
Of course there is. Intake. Tune and headers with intake would be great
Burning Brakes
Joined: Dec 1999
Posts: 984
Likes: 154
From: Columbia MD
Team Owner
Joined: Jul 2004
Posts: 28,473
Likes: 3,291
From: Hartford WI