I wonder what style of sensor it is. I would consider it if it would spit out a 0 - 5v signal... and if I had money

Ref the nut holding the comp wheel coming off- Arent these cars running left hand threaded shafts? Thought that was a given on performance turbos, and would solve the nut loosening issue?

From what I can tell, it's optical, might need to put a dab of paint on one of the turbine blades.

http://www.dwperformance.com/kommerc...GAR781328-0002

http://www.turbobygarrett.com/turbob...d_sensor.html#

They offer a kit without a sensor for datalogging only, so I'd guess datalogging is also an option with the sensor. If they put out 0-1v for some reason (I don't see why they would), you could always build a stepper circuit to get it up to 0-5v.

I have a turbo tach on my car.


PEOPLE ARE JUST SO THICK AND NARROW MINDED.

BOV is a waste of money. DONT WASTE YOUR MONEY.

If your front nut on your turbo came loose, it was built by an idiot. Seen it happen many times.

What's your current turbo spooling to? And how does shifting gears affect the rpms of the compressor w/o a BOV? Please give solid numbers, preferably a specific log showing the values or a graph showing compressor RPM's from WOT/full boost to 0 Throttle back to WOT/Full Boost.

Are you logging it at all or is it just a gauge of some sort? Do you have any information you can share about blowoff vs no blowoff?

Consider me ruffled.

The holset speed sensors are magnetic.

pfsssh
 

I'm glad someone else is doing this and not me.lol.It always fun to what if...lol.U should start a fund for a replacement turbo.I'd donate.lol

proof or fail

turbo hasn't exploded yet. i've been driving it all weekend

i want to resurrect this thread. i have facts, so its not hearsay :-D

1) i bought a used single turbo gt35r ~9k miles on it. (previous owner had BOV)
2) got turbo and no play in shaft any direction
3) installed and idled - no shaft play
4) put 4 hours into street tuning - no shaft play
5) drove to DGRR and around the hilly streets up to 10 psi (1300 miles total trip)

i did steps 2-5 without a BOV. lol partly lazy, and part courage from this very thread.

Im working on installing my WI and get my elbow welded for my BOV and i noticed: i have ridiculous shaft play. if i spin it by hand, i can hear the bearings make a lub dub sound.

Deals Gap obviously caused A LOT of compressor surge. the most i think a car can be subjected to.

I dont know if shaft play and bearing sounds equals bad things. all i know is that the turbo is not the same lol. something's different. not performance wise, just spun by hand.

Of course, these facts dont say jack squat, but its interesting at least. the turbo could have bad bearings, 1300 miles on it could be bad either way. idk. just sharing my findings

I have been driving my lotus almost daily lately,

since january I added 3k more so total 35k hard miles on stock
10yrs old t25's, no bov and they still have lightning responce

So here's the first and most important question: are you sure there's something wrong with your turbo?

I can't say I've ever run a ball bearing turbo without a blowoff valve. They could be more sensitive to this and maybe the lack of a blowoff caused a problem. Or you could have an oiling issue, or you could have just gotten a bad one, or there's nothing wrong at all. Now let me ask you this: is there axial shaft play? Can you push and pull the shaft in and out? You would think running no blowoff valve would cause that kind of play if any. And axial shaft play is the worst kind.

Also, a lot of the larger (and ball bearing) turbos do seem to have a little bit of radial shaft play (as you have been now noticing) even when new or almost new. Is the shaft play so bad that your compressor wheel contacts the outside of the housing? It seems strange to me that you had zero shaft play when brand new, when a lot of people have a little bit of play out of the box. Maybe you should keep driving it and see what's up. It's kind of hard for anyone else to offer definite opinions without seeing the turbo firsthand. I wish I could have made it to DGRR this year. I went in 2006 and since I am in NC it's just an afternoon trip. With the economy though the budget just won't allow it.

btw, still no problems with my turbo.

If anything the BB units should take the punishment more then the journal bearings.

thewird

That is the question. :-) i dont have any problems. the only reason i played with it was i took the air filter off to mount the water injection.

shaft play is NOT far enough to touch housing
shaft play is a little axial as well.
I didnt text axial shaft play before hand

the oil feed is an excellent question, i can verify that my oil feed was operational since the first moment because i didnt have my return line completely tight and it leaked oil onto the mani.

the only concern i have is the sound of the bearings. they sound like bearings that are worn down a little. like one ball is sub par. i think you know roughly what i mean.

ill gladly run the beast for a while more. im installing WI, so thats only one more thing to complicate the situation lol

i don't know, my turbo makes a little bit of a sound when I spin it by hand. I wouldn't write it off as a damaged/blown turbo when it doesn't have any symptoms. There is usually an acceptable tolerance for shaft play on a turbo, although I can't say what that would be on your specific unit. Check out this shaft play inspection procedure on a Porsche 944 turbo (which are externally wastegated from the factory, interestingly enough):

https://www.rx7club.com/attachment.p...1&d=1271828516

It's a cryin' shame there aren't more "8 months and counting with a blow off valve" threads. Wonder why that is...

I would also like to try this setup with my new single turbo swap. It saves weight and simplifies. Also, the single kit I got came with a Turbo XS RFL (Really Fucking Loud) bov which I have no interest in running.

My question is, are there any additional concerns running bov-less on a road course or under race conditions?

hm... not really.

if you wanna be an individual, put the TB before the compressor.

Some people argue that running without a blowoff valve will result in less response as you change gears. Based on firsthand experience I don't think it matters either way.

Some people also argue that running without one increases response between shifts since you don't have to re-pressurize the intercooler pipes etc.

Anyways, because of this thread I decided to not upgrade my little Greddy BOV so I'll keep having my butterfly noise from my turbo :D

thewird

http://www.youtube.com/watch?v=9DR5pPwGOkk

1st gear (1/2 throttle) and 2nd gear (WOT) pull without a BOV. 16.5psi

1st gear (1/2 throttle) and 2nd gear (WOT) pull without a BOV. 16.5psi[/QUOTE]

how much power does your car put down? do you have big ass wide wheels and very good tires?

I haven't dyno'd the car on this engine and turbo, I don't have wide wheels, I don't have good tires, and I don't have money for any of that right now due to the economy.

j/w bc it didnt spin the tires at all. usually second is completely useless

It spins badly in 2nd when it's colder outside

One of my previous cars was a 83 Callaway turbo rabbit gti. A small amount of rabbits were sent to Callaway for a turbo charge setup. It included a big t4 turbo external wastegate and intercooler. It did not come with a bov. It was like that since 83 and it had countless miles on it with same turbo. I finally ended up selling it in 2001 and the motor and turbo were all in good condition.

From this experience I’m probably not going to run one on the rx7

im suprised were still talking about this. Blow off valves are a waste of time.

I will not be using a BOV on my new setup, this thread is motivating

No Bov? wtf it sounds like you're running one lol

haha i hear it too.. wicked surge. im going to try the no bov theory tomorrow see if i notice any change in response between shifts.. im replacing my turbo soon anyway


but another thing to consider is most stock turbo cars with no bov have very small compressors.. maybe having no bov does not cause much damage simply because the compressor is not big enough and less momentum to cause any damage to blades and bearings. most of us on the other hand are running compressors a lot bigger and have a lot more momentum when they hit a wall of air when throttle is snapped shut.. which may cause more damage?

My turbo has an actual flutter sound when it surges though..doesn't sound like a bov like his

The sound changed a lot when I switched air filters. I had a 4" inlet 3.5" length shorty filter (same one that is in that thread). After some careful measuring I realized that I could fit a 7" long cone filter so I switched. After that the sound of pressure relief changed a lot. There's a small amount of flutter at part throttle low boost but that's it.

Bizzare how you can hear a chuff on your car with no BOV? Where would a chuff come from, i mean a flutter makes sense, but?!

Ive ran maybe 10 cars with no BOV and they all chatter, makes no sense for them to do anything else.

My FC chatters like crazy, but no damage in nearly a year so far, and runs pre-comp water injection and prior to that it ran for ages with no air filter- literally ALL the things people claim will kill your turbo, lol.

Ill try and get a video before next weekend.

Here's a quick vid of mine running no BOV if anyone is interested...
http://www.youtube.com/watch?v=BSSuppCnFWw

Mine kinda sounds like that with my little Greddy RS BOV lol.

thewird

I'm just curious, and maybe this has been covered and i didnt see it, but y are bov's evened used, and are the stories of turbos coming from together just wives tales?
is it just precautionary?
are these breaks from 20-30psi systems?

and in my case; would it be appropriate to run my car minus bov?
its stock internally, but im going to be running t04e w/ .82 a/r about 8-10 psi,
also has 3'' ex. from housing back, 2.5 intercooler piping. 550 1's and 750 2's and rtek 2.1
(just a quick rundown)

i'm just very intrigued by this and ARGHX's word is pretty influential to my build.

I wouldn't consider running without a BOV unless the turbo is ball bearing. I remember reading somewhere where there was information about the Garrett turbo's and they specifically mentioned that the non-ball bearing units will not last without a BOV long term.

thewird

IMHO, from experience, thats not true.

Almost the only turbos ive seen break easy with no BOV were garrett gt series, as seemingly they had fairly thin shafts compared to other turbos. As the only fails I could 100% say were no-bov related were shafts snapping, which ive seen a few times on GT35Rs.

Ive ran 30psi boost for at least 12 thousand pretty damn hard road miles on a non-bb garrett t3/4 turbo with no damage, 25psi on another slightly smaller garrett non-bb, and know countless other that have done similar too.

Its always a risk and a complex issue you can never be sure of. But ive always (for 10yrs now) had perfect luck with big boost and no BOV and know countless others in same situation, so personally, i never bother with them.

Don't know if its true but I remember reading it a while ago. It didn't say the non-bb's would break, only not last as long as the bb counterpart. I'll see if I can find anything on it tomorrow.

thewird

I am running a Garrett T04R (non ball bearing) which I purchased used off this forum. Most of the turbos people use on Rx-7's "big shaft" turbos, not the smaller "standard shaft" As for ball bearing vs journal bearing, I can't really say whether it makes a difference.

I stopped using a bov on my 87 TII after I installed my E6K. No air flow meter no problems.


http://www.autospeed.com/cms/article...estions&A=1457
Is there any performance gain to a blow-off valve?


"We've tested one on a manual gearbox performance car run at Winton Raceway. I think it was running 1 minute 40s back then, but it would lose 2 seconds a lap putting the gobble-gobble valve on. When you look at data acquisition, what you find is - as you change gear - the blow-off valve dumps all the pressure built up through the intercooler and pipes. It then goes back to zero manifold vacuum when you get back on the throttle, you have to build all that boost back up.

"The fact that people think that they keep the turbo spinning is a problem. The people that suggest this have never had an engine on the dyno and never had a turbo tacho in their hands. What people don't realise is, when you shut off the throttle, you shut off the air supply to the engine - this shuts off the exhaust gasses coming out of the engine. When there is no exhaust flow, there is no energy to keep the turbine spinning - the turbo slows down at an alarming rate.

"If you change gears at quite a good speed, you can actually get a boost spike on changes; if you're trying to hold a constant 30 pounds, when you do a racing change you'll get 32-33 pounds when you crack the throttle open again. If everything's working well, you've got a full head of stream waiting to go into the throttle as soon as it's opened.

"I've done this on a rally car and it was quicker through every timed section without a dump valve. You'll never hear a World Rally Car going pssshhht because they don't use a dump valve - you get the woof-woof-woof noise instead."

I'm getting closer and closer to removing my blow off valve lol.

thewird

What more proof could anyone have.

I think it's important to remember that none of us are running a MAF sensor, so there are no potential driveability issues to worry about due to a messed up airflow signal.

OEM has MAP, not MAF, sensor, right? Mine is OEM (whichever that is). Am I OK to run bov-less?

FD uses a MAP sensor only (Bosch D jetronic style, aka speed density), FC uses a vane-type volume airflow sensor (Bosch L Jetronic style) for load calculation although it does have a factory MAP sensor as well. Only the Rx-8 has a factory mass airflow sensor.

damn that sucks, make sense but sucks..
Rtek needs to hurry up and update to get rid of the maf!

Actually, away from the reliability issues (or lack of IMO), we did some timed with and without a BOV performance tests this time last year on a 400bhp SR20 engine running 1.5bar boost BUT still with the AFM, so it was actually making the car stutter between gearchanges without a BOV.

BUT even with that issue messing things up hugely (i mean the stutter was audible and even visual watching the car, the 20-80mph time (with a ultra close ratio box, starting in 1st and ending in 4th) was 0.7 of a sec faster with no BOV.