This is a good read. I haven't finished my build yet but it's making me reconsider running my TiAL BOV, mostly because I've had headaches with past builds with leaking/malfunctioning BOVs.

Cant remember if I ever posted these, but this is what mine sounded like, no BOV, 23psi on a T04E 57trim

http://youtu.be/TS8ov36gpHM

http://youtu.be/qwwGTm8prwM

StavFC - are you running external waste gate that's dumping to atmosphere?

Yeah. Some rusty old HKS thing venting straight to the floor by the front wheel. Though that only affects exhaust noise of course.

Good stuff, looks and sounds great!

Hmmm. I might have to join the no blowoff valve club. Great info!

Here's five right off the top of my head, that I have personal experience with:

JR Isuzu Impulse (had one) - IHI RHB5 turbo
WK-engine Audi 5000 (have engine for one) - KKK K26 turbo
EA82 engined Subarus (almost bought two) - IHI RHB5 turbo
Ford 2.3 Turbo in many various cars - IHI RHB5 or Garrett T3 depending on year
Buick Grand National (work on them for a living) - Garrett T3

I have never seen a BOV on a GN, either. The sound a GN makes when you let off the throttle after hitting 25+psi with a huge turbo is glorious :)

I have a friend whose daily driver is a beautifully stock XR4Ti. (They run up to 18psi in stock form, and they are non-intercooled) When we're talking on the phone after work, I can tell when he's merging on the highway because the noise cancellation on his cell doesn't quite do a good job of preventing the surge giggle from coming over the line. And that should be the clue why the OEMs started using recirc valves: noise, noise, noise.

I know there are more out there. Audi didn't start using recirc valves for quite some time, and I am uncertain on the status of Turbo Dodges. I know the early ones didn't have them, but they don't count because they had the throttle body on the turbo INLET. Never played with a blowthrough style one.

^^^^^^Most common...300zx.

The nissan RB30 motors in our Australian GM/Holden commodore turbos in the 80s didn't have them either.

Famous in the western sydney "hectic habib" community for "Dose" sound, they all run alloy/metallic turbo inlet piping to carry the noise out louder.

All lotus esprit turbo models even the track versions don't run one

If we're playing the 'what comes with no BOV' game, here are some more...

All 80s and 90s Renault Turbo engines.
Nissan CA18 and FJ20 turbo engines.

TBH, almost no top level (ie works team, not privateer) turbo race and especially rally car has ran one, barring a few unusual exceptions.

Still no BOV
 

Havent been on here in a while, and bought the so called no BOV car and can say that its still fine. Ive run no BOV on 1200hp mustangs with no probs. Arg your tune was spot on, on the rich side but still spot on. Dynoed the car as it sit on 18 lbs and it did ok 384 hp at 7100. second run 432 at 8k and rich as hell into the 9s. Ill be playing around with it a little but so far so good. Its not usual to buy a car and it performs as stated, KUDOS to u its and awesome little car. You werent lying about the boner tires, 225s are not enough

Great to hear!

It was tuned so that you could turn the key and drive it without having to [hopefully] worry about it just randomly blowing up. That was #1 goal: rotary that's quick on pump gas only and doesn't blow up, even when the weather changes or you drive it hard... the air temperature fuel compensation table was tested in all 4 seasons. AFR and timing were set that way intentionally for a wide safety margin: the turbo and ports were spec'd larger than absolutely necessary, so that intended horsepower range could be achieved with this wide safety margin on pump fuel only. I also retained the 8.5:1 compression ratio of the 87-88 engines (instead of switching to 9:1) due to the higher safety margin and the tougher casting of the earlier rotors. The horsepower numbers you got are roughly what I expected on a dynojet. I'd be curious to see the dyno sheet if you can scan it.

You will notice that it runs leaner in the winter--up to half a point on a wideband. It will also run a little leaner on a hot start--the fuel and timing safety margin had to take this into account, so that there would be minimal risk of engine damage during heat soak conditions. Target AFR range was roughly 11.1:1 +/- .5 during year-round operation.

I assume you haven't touched the boost control settings on the PFC Commander. When it gets cold out, setting #1 does tend to spike a bit and could hit fuel cut, especially when the engine has only been running for a little while and air temps are very low. Setting #2 is intended for cold weather. One thing I never did was change around the pressure source for the solenoid. I think sourcing from after the intercooler would probably help stabilize boost in colder ambient temperatures, below 50F or so.

I had almost 6 years of my life in that car, please take care of it.

^DUDE. Didn't know you sold it.

I'm another no BOV guy. Mostly because I redid my intercooler/piping, and never bought a new straight pipe with flange for one on it :) I don't intend to either unless I find that pipe randomly. Haven't passed 5500RPM yet either because of bad wastegate. It's just a different sound, no damage to anything that I know of.

Instead of "pssshhhhh" it's "doootdoootdoot!!!"

Hey guys,

I had an old blitz bov on my t2 fc but it was stuck. I used to hear the same sound as the sound in Stav's vids. One day i was racing an slk and during my 5th gear change the hot turbine side broke to pieces! I wish i could find that old foto to show you the "shaved" turbine flywheel. the turbo had 140.000km on it but the engine was stock. I believe that the stucked bov was responsible for this, i am not sure though. Just be careful with those no bov setups!

I've spent 2 weeks trying to eliminate the leak in my Turbosmart BOV and have run out of patience. Tomorrow I'm going to remove the BOV and step over to the other side.

Personally I think a BOV just makes sound, nothing more. While I enjoy the sound I am not going to waste any more time/money on another BOV that can ultimately leak again and get nothing in return.

I blew 2 turbo's without a BOV, fyi. It's fine on the street but once it goes to the track, boom after a few sessions.

thewird

How do you know the cause was related to lack of a bov? Somewhere in this long thread I remember you mentioning your bov sounded similar to arghx, and were thinking of going larger. Perhaps if your original bov was small to begin with air might have been going back out the turbo anyway.

I took the BOV out and was running a different turbo altogether. If I had left the BOV, it would probably have been fine.

thewird

In my experience TiAL BOVs are pretty much bulletproof and are not prone to leaking.

:lol:

Are you suggesting higher duty and loading on a an occasionally tracked rotary than racing fueled turbo lemans 24hr/euro series racers from 70s-80s-90s running syncro closed throttle shifts at higher boost?

You have to be kidding. Your turbo failures were not as a result of not running a BOV. They were not manufactured correctly or you had a boost leak and over-sped them.

Ok there buddy, I believe you even though you have no idea what your talking about. Has it ever occurred to you that the turbo's used in those applications are not the same as the off the shelf one's we put in our cars?

On a more serious note, turbo change and the BOV elimination was the only thing changed. I have a custom 4" boost leak tester that mounts onto the turbo intake that pressurizes the whole system and no leaks up to 25 psi.

I had initially blamed the Precision turbo's but after some thought, its more likely that the lack of BOV was the cause. Precision stated that excessive load was the cause of the failure.

Honestly, it ran mint and shifts felt faster. But two different turbo's failed on the no BOV setup where previously my car was stupid reliable where I could be out there for 30-40 minutes (when I would get tired) for the entire 9-5 track day as my water/air temps are always golden with my vmount setup.

On the plus side, this whole experience made me decide to just pull the motor and go 20b as I didn't feel like buying another turbo and have been thinking about 20b for the longest time.

thewird

YES, maybe, no, I don't know. After reading this thread more possibly depending upon setup a BOV isn't need LOL :)

Tial wastegates are OK but they could use some more heat exchange material near the diaphragm because they get too hot and the diaphragm gets damaged. I've lost two like this. When using HKS I haven't had this problem YET lol.

No bov
 

In my experience on the street running under or around 20 psi you def dont need the BOV. Ive had cars driven every weekend for years without one at 25psi most all were turbonetics and thrust bearings at that(long ago). BUT to be honest i DO run one on my Eclipse because of the 35psi its running but took forever to get the damn thing to seal and it doesnt even blow off at low boost it still has a little sound under 8 psi or so but its a trade-off either that or leaks at high boost. Now I know ill get a rash of sht for having an Eclipse but hey ive been a DSM guy for a long time. It demolishes the RX7,,,,,,,,,,,,,,,,,,IF the tranny and axles dont break

You won't get a 'rash of shit' for being a DSM guy, but you will get laughed at mercilessly for saying absolutely retarded crap like the above.