FAST intake installed, valvetrain louder?
03-09-2009, 05:27 AM
#1
FAST intake installed, valvetrain louder? Got the intake put on yesterday and now it sounds like the engine is making more noise.
Seems to be coming from the rear of the intake area and sounds like the sound the valves would make when closing. Not a sharp clacking sound like most valve train noise so much as it has a "gargling" quality. Hard to describe.
I seem to kinda hear a sucking sound from inside the car as well, but I don't seem to have a vacuum leak. The car idles better now than it did with the ls1 intake both at idle and in drive.
The fast 90 throttle body had a large hole drilled that caused the car to run like **** at first but I put a bolt/washer/locknut (with locktite) through it as a test and it made it run great.
I used the correct lifter valley bolts.
Another curious thing is I drove 2 hours to Redline raceway outside dallas and ran. Got great fuel mileage on the way (23-24mpg). Ran 3 runs and filled up and drove 150 miles with the same mileage. Topped off the tank so I wouldn't have to stop again later (we were hungry) and from there my mileage dropped to ****...11 gallons in 160 miles. Car doesn't seem to run any different whatsoever and I can't see any leaks or smell fuel anywhere.
Seems to be coming from the rear of the intake area and sounds like the sound the valves would make when closing. Not a sharp clacking sound like most valve train noise so much as it has a "gargling" quality. Hard to describe.
I seem to kinda hear a sucking sound from inside the car as well, but I don't seem to have a vacuum leak. The car idles better now than it did with the ls1 intake both at idle and in drive.
The fast 90 throttle body had a large hole drilled that caused the car to run like **** at first but I put a bolt/washer/locknut (with locktite) through it as a test and it made it run great.
I used the correct lifter valley bolts.
Another curious thing is I drove 2 hours to Redline raceway outside dallas and ran. Got great fuel mileage on the way (23-24mpg). Ran 3 runs and filled up and drove 150 miles with the same mileage. Topped off the tank so I wouldn't have to stop again later (we were hungry) and from there my mileage dropped to ****...11 gallons in 160 miles. Car doesn't seem to run any different whatsoever and I can't see any leaks or smell fuel anywhere.
03-09-2009, 09:15 AM
#3
TECH Junkie
iTrader: (5)
Join Date: Feb 2007
Location: Key West, Florida
Posts: 3,183
Likes: 0
Received 0 Likes
on
0 Posts
the "gargaling" sound is the same thing i've been dealing with on my car.
doesn't appear to have a vacum leak, but i'm waiting for the cable to plug my scanner in and check the fuel trims
doesn't appear to have a vacum leak, but i'm waiting for the cable to plug my scanner in and check the fuel trims
03-09-2009, 01:56 PM
#4
I am going to scan mine today.
The fuel trims looked good before though, so it might just be the nature of the intake sitting so close to the valley.
I will likely pull the valve covers to inspect for issues though, if I find anything with my scan or visual inspection I will let you know.
The fuel trims looked good before though, so it might just be the nature of the intake sitting so close to the valley.
I will likely pull the valve covers to inspect for issues though, if I find anything with my scan or visual inspection I will let you know.
03-09-2009, 01:59 PM
#5
i got the same noise after i put my fast 92 intake on. it's not like an OMG it's alot louder but it's deffinitly noticable. i am going to pull the intake back off and install those foam pads that the factory intake has on the bottom. when i bought new intake gaskets from felpro, it came with those peices of foam. i thought about putting them on before i installed the intake but i said f' it. hopefully it will hinder the sound but if it doesn't and probally won't, i'm not going to lose sleep over it
03-09-2009, 02:06 PM
#6
i had that sucking noise from the inside of my LS6 intake when i first installed it, turned out to be vaccum leak for me, leaking from the brake booster hose..... but in your case thats strange...
03-09-2009, 03:12 PM
#7
I can only hear the sucking sound from inside the car which is odd. So it might be a lose vacuum line on my climate control pod or something under the dash.
Also aside from the gargling and the typical ls1 "diesel truck" noise there is another new one that sounds like whining gears coming from the upper rear of the engine that increases speed with rpms.
I get no codes, car actually seems to think its fuel tune is good as the trims aren't compensating much, both o2s are reading normal. No oil burning smells, no coolant in the oil. Engine isn't getting abnormally hot.
So I'm stumped. If my fuel mileage doesn't go back to normal I'm going to be upset though. I used right under 11 gallons in 160 miles of interstate doing 70-75. Only got on it hard twice.
Also aside from the gargling and the typical ls1 "diesel truck" noise there is another new one that sounds like whining gears coming from the upper rear of the engine that increases speed with rpms.
I get no codes, car actually seems to think its fuel tune is good as the trims aren't compensating much, both o2s are reading normal. No oil burning smells, no coolant in the oil. Engine isn't getting abnormally hot.
So I'm stumped. If my fuel mileage doesn't go back to normal I'm going to be upset though. I used right under 11 gallons in 160 miles of interstate doing 70-75. Only got on it hard twice.
Trending Topics
03-09-2009, 04:47 PM
#8
11 Second Club
iTrader: (34)
Join Date: Feb 2005
Location: Ft. Wayne, Indiana
Posts: 3,158
Likes: 0
Received 0 Likes
on
0 Posts
Welcome to the world of FAST intakes.....it is normal to hear more valve train noise (no foam pads) and for the the sucking sound (moving more air).
Easiest way to check for leaks is to spray something around the various hoses, TB, Injectors, and Intake base, while the car is running(should free rev if there is a leak). If your car doesn't idle search (free rev) or idle stays excessively high after warm up... typically it's not a vacuum leak.... I'm sure you know this already though.
Same octane fuel since the cam change?? I would almost vote bad gas unless you have run more than one tank since going to the track. Have you replaced your fuel filter lately??
Easiest way to check for leaks is to spray something around the various hoses, TB, Injectors, and Intake base, while the car is running(should free rev if there is a leak). If your car doesn't idle search (free rev) or idle stays excessively high after warm up... typically it's not a vacuum leak.... I'm sure you know this already though.
Same octane fuel since the cam change?? I would almost vote bad gas unless you have run more than one tank since going to the track. Have you replaced your fuel filter lately??
03-09-2009, 05:44 PM
#10
all hoses are hooked up, sprayed starting fluid around all ports, hoses, ect and found no leaks
turns out after close listening and trying things it's not a "sucking" sound, it's a scraping sound...coming from the torque converter area...noticed because the sound is only there when the car is in gear and only when no throttle or very very light throttle is applied (cruising 65 on the interstate for example)
my fuel mileage (at least in town is back to normal if not a little better than pre-intake swap), I just went for a drive with several heavy throttle runs and the gauge is still on full
so if the intake noises being louder are normal then it looks like all is well as far as the engine goes and its time to find out why the tranny is making noise...fluid looks and smells perfect and its not getting hot though so that's a good sign
turns out after close listening and trying things it's not a "sucking" sound, it's a scraping sound...coming from the torque converter area...noticed because the sound is only there when the car is in gear and only when no throttle or very very light throttle is applied (cruising 65 on the interstate for example)
my fuel mileage (at least in town is back to normal if not a little better than pre-intake swap), I just went for a drive with several heavy throttle runs and the gauge is still on full
so if the intake noises being louder are normal then it looks like all is well as far as the engine goes and its time to find out why the tranny is making noise...fluid looks and smells perfect and its not getting hot though so that's a good sign
03-09-2009, 10:41 PM
#12
Had the same increased valvetrain noise with mine, ill soon be swapping in a forged shortblock and been considering finding a thin peice of foam to install on the bottom, its pretty close though. The noise really isnt that bad id just rather not have more noise than I need.
03-10-2009, 08:45 AM
#19
I know when we installed the FAST intakes on the CTS-V's at Katech, is made the car sound like a diesel. There might be a little sound dampening from the foam, but the majority is from the use of a different plastic for the manifold. I think because it is more dense than the factory intakes, it transmits the sound easier. It's almost like GM already thought of this and that is why thier intakes are made from the material that they are!!!!!
This is the price you are going to pay for performance. It does sound way better at WOT fwiw.
This is the price you are going to pay for performance. It does sound way better at WOT fwiw.
03-10-2009, 01:21 PM
#20
I just wanted to assure it was normal and I didn't need to be freaked out looking for a broke or loose rocker or something.
Thanks guys! It does indeed sound like a diesel now even more than before. But it pulls so much harder above 4000 rpm I don't care if it spewed Fran Drescher laughs out the tailpipe.
Thanks guys! It does indeed sound like a diesel now even more than before. But it pulls so much harder above 4000 rpm I don't care if it spewed Fran Drescher laughs out the tailpipe.