Finaly I finished my throttle body conversion but I'm disappointed because they produce a loud chirping noise at light throttle and load.
The strange thing is that when I put the pedal to the floor, It isn't there, just sucking the air in the horns and that sounds great
I checked everything, no leaks, alternator belt is checked, etc
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Building: racing style pick-up with Vauxhall 2.0 'tec
posted on 20/10/14 at 05:07 PM
Just sounds like air rushing through the slightly open butterfies to me? Quite normal. Cant change physics, but an Air box or air filter might quieten
it a bit,
If that is normal, I can't accept it, it is too loud and a highly irritating noise. People where looking when I drove through the streets...
Just easy and slowly cruising
In the video it is not so loud as when you drive the car specifically at high load on low rpm.
When I first heard it, I thought it was a vacuum leak.....
Have you ballanced them and what about mapping as throttle responce doesn't sound very crisp compared to mine, also as said trumpets and filters
will help smooth air flow
As already said, get them balanced properly.
I'm embarking the same project, GSXR throttle bodies.
If the same happens to me I will drill a 1mm hole in each butterfly to allow them to close more fully.
Then maybe up in 0.1 increments till the butterfies are shut at tickover.
Or close the butterflies and utilise the MAP sensor tappings to feed the tickover air via an IAC valve.
quote:Originally posted by will121
Have you ballanced them and what about mapping as throttle responce doesn't sound very crisp compared to mine, also as said trumpets and filters
will help smooth air flow
have balanced them not yet, haven't a decent synchronizer
Mapping has to be done but want to have the car drivable. It actually drives
good, much too rich at idle but at wot it goes like hell !!!
Had trumpets fitted but didn't make any difference in chirp sound.
I must be the only person who actually likes that sound!! It reminds me when I put a K&N 57i kit on my Vauxhall Cavalier, I deliberately drove
round at just the right throttle to get that noise going!
It seems to be that the sound comes from cylinder nr. 4 so I changed the bodies 180 degrees to see if it changes...
Still the same noise from cylinder nr. 4
Is it possible that it has to do with valve clearance/timing ?
or maybe flow from exhaust?
Sounds like the engine is boggin down rather than the TB's. All sorts of fuel enrichment happens when the car is mapped correctly. The throttle
response seems way off what it should be. Before you can really second guess any noises, you really need it mapped and set up correctly.
Of interest, there can be a strange air leak through the bleed screws then 'fully' tightened....this was demonstrated to me by a very
knowledgeable Troy at Northampton motorsport whith clever use of a vac cleaner!.
Stupid question but what coupling between TB and inlet adapter are they hard mounted? (could not tell from image) The engine note lags the throttle
jab (perhaps it is just cold). As suggested remapping/jetting may help.
quote:Originally posted by Jenko
Sounds like the engine is boggin down rather than the TB's. All sorts of fuel enrichment happens when the car is mapped correctly. The throttle
response seems way off what it should be. Before you can really second guess any noises, you really need it mapped and set up correctly.
Of interest, there can be a strange air leak through the bleed screws then 'fully' tightened....this was demonstrated to me by a very
knowledgeable Troy at Northampton motorsport whith clever use of a vac cleaner!.
Thanx, appreciated.
Please explain more about the bleed screws ?
I blocked the injector holes form the bodies with screws and the o ring from the injectors.
Wasn't sure about that so I replaced the std. injectors from the bodies, but again no problem solving.
I have my injectors directly at the intake manifold.
[Edited on 21/10/14 by Pinarello]
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On most TB's there are also bleed screws that can be used for fine tuning. Most (but not all) tend not to use them for car conversions, and if
this is the case, the logical thing to do it to screw them all the way in, thus blocking off the hole. Only, on some models, screwing them all the way
in does not block the hole, we had to unscrew them a few turns to actually stop air leaking through on my gsxr 750 TB's....Obviously, with a
small air bleed, the balancing will never be right, on your set up, the first thing to do before you even think about any other tuing is is to ensure
the balance is correct across all 4 TB's. Only when this is done can you then do on to look at the light load parts of the map.
I still think the issue you see here is simply down to the TB's being poorly set up and the mapping. I could not recommend enough that the car
goes on a rolling road to someone who knows........
quote:Originally posted by jeffw
Balance the TBs (put the correct trumpets on)
Map the ECU
Sealed Airbox
All of these will reduce the noise to an extent.
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