Hi guys, First off, I\'m a bit of a rotary newbie, so please bear with me :) I\'ve had a search around the forums but couldn\'t find exactly what I was looking for.. I bought my first FC about a month ago (my first proper turbo car, really), its an \'89 model. When I bought it, it already had fitted a pipercross air filter, fujitsubo (i think?) exhaust and a baileys dump valve as the only engine mods. Not being a fan of the noise, I decided to remove the dump valve. I had also been told it may have been leeking slightly anyway, but not that i could notice. After taking out the dv, blocked the pipe off with a rubber cork and ran a vacuum hose from the side of the engine to the sensor for the standard boost gauge, everything seemed well secured and tight so took it out for a drive. Started and idled fine, seemed to pull ok with no noticeable loss of power, but coming off throttle, no "flutter" like I\'ve heard in pretty much most turbos with an air filter. The exhaust is really quite loud (baffles are missing i think), and i know a standard turbo is relatively small, but i\'d have expected a bit more chatter from it de-spooling? You\'d only hear it if you were really listening. Anyway, sorry for such a long post for a really simple question, but I wanted to give as much info as possible :) Any input would be much appreciated! Cheers
The blow off valve removes the air pressure in the system when you let off the throttle, as you have removed it when you close the throttle plates the presurised air rushes back in a pressure wave and smashes into the turbo causing that fluttering sound. It is NOT GOOD and is damaging the turbo every time you do it. I have a spare OEM recirc valve if you need it.
I think the turbo was causing the fluttering due to it being too tight and not opening quick enough, what sort of blow off valve was it?
welcome to the club by the way :D remember to post up photos :)
Hi,
Cheers for the reply! I will be sure to post some pictures up soon :)
Not sure why my original post came out as 1 paragraph, so it may have been a bit difficult to read..
My question was, after removing the dump valve (baileys) I\'m getting no noticable chatter at all. It might sound a bit odd, but I actually prefer the flutter and am aware of the side-effect to the turbo.
Or if it is making any sound, then I can\'t hear it.. As I know nothing about the stock turbos on an fc, I\'m unsure how loud it should actually be?
Is it a Baileys super sound? I have that sort, I found that it did make that kinda sound, but I think it was cause it was sticking slightly, now its letting off as it should, what blow off valve have you got installed at the moment? you thinking of putting the recirc valve back in, BOVs are there to protect the turbo, else the turbo won\'t last long. The only cars that run without a BOV are Pro drift cars, as they can afford to change their turbos and are always on boost lol
How are you finding your FC by the way? Have you been told all the things you need to do to care for the engine and such yet? (please don\'t say you rev the car when its cold)
I think you\'re talking about compressor surge, fantastic sound:mmmm. You will only really get it on medium to large single turbos.
Have a read here http://mazdarotaryclub.com/forums/showthread.php?t=45966 (http://mazdarotaryclub.com/forums/showthread.php?t=45966) a good debate on whether it\'s bad for your turbo or not.
I don\'t think its a Baileys SS, but just to make myself clear, I currently don\'t have a bov installed (i have taken it out and bunged up the hole), its not the bov sound I\'m concerned with, its just that im not getting much sound (practically none) from the turbo despooling (eg "flutter"), so I was checking if maybe I could have done something wrong?
But anyway, apart from that yeah I absolutely love my FC. Its probably the best car I will ever own :) I only use it for a bit of weekend fun (so by the time the turbo blows I will be looking to upgrade anyway). And dont worry, I use 10/40 mineral oil and always let the car warm up / cool down when driving :)
Quote from: mukumu kurubushi;565750And dont worry, I use 10/40 mineral oil and always let the car warm up / cool down when driving :)
Good im glad you have done some reasearch :D
Hi JohnnyP,
Thanks for that, you might be right the standard fc turbo is maybe a bit too small and might be drowned out by my exhaust.. Thanks for the link, interesting read :)
My turbo sound like a hairdrier when it spools, it really is quite loud lol unless you have a nur spec exhaust im sure you can hear it lol
Oh I can hear the turbo spooling, definitely.. its just the de-spool "compressor surge" as JohnnyP called it that is missing.
My exhaust has the baffles missing, so it is seriously loud at the moment. Put it this way, a mate of mine is running a 180sx with a blitz nur spec and said he thought it sounded louder :3Confused
But unless I have done something obviously wrong, then the car is idling fine with no problems under hard acceleration, so maybe its just the size of the turbo thats causing the lack of noise.
I went from a standard twin fd with no chatter to a medium size single fc with loads of chatter!! Addictive sound. You just need to swap it for a bigger one!
do you have a de-cat..?
that makes a BIG diff to how loud it is!!
Compressor surge in any spooled engine is bad, it can actually have the force to bend the blades over themselves. As in aero blades a aerofoil is designed to move/compress a volume of air in one direction as efficiently as possible. When it surges or even flutters this is a sign that the air is stalling and not flowing as it should. Its these forces that will do the damage and potentially take the engine with it as well. I would put a BOV back on if you value your engine.