Big power starlets are nothing but a pain in the arse

[Captain Starlet]

The reason i thought i screwed the blades was my prev turbo did the exact same driving into fifth then when stripped down they were chewed.

rory i understand where your coming from.

 

[Captain Starlet]

so you staying td05 ??

aye mate fuck it am gana get chris on wednesday to sort out my base timing then get her remapped

 

[sx_turbo]

The reason i thought i screwed the blades was my prev turbo did the exact same driving into fifth then when stripped down they were chewed.

rory i understand where your coming from.

it's possible that ur last turbo died cos of this, the boost controller will keep the waste gate shut longer, sending the turbo into over boosting to compensate for the boost pressure being lost.

over boosting will bugger turbo's in no time, ask renault about the megane diesels they are prone to intercoolers splitting and the turbo's mashing up.

 

[pc18]

what sx turbo said. if you have a bad leak and your boost controller is keeping the wg shut to still maintain the boost level its been set at the turbo will be working extra hard to keep the boost level at what the controller is set at. surely this will kill the bearings in no time and then cause the blades to bash against the side of the housings.

 

[hardcoreep]

what sx turbo said. if you have a bad leak and your boost controller is keeping the wg shut to still maintain the boost level its been set at the turbo will be working extra hard to keep the boost level at what the controller is set at. surely this will kill the bearings in no time and then cause the blades to bash against the side of the housings.

Overspeeding doesn't normally destroy the bearings. It causes axial stress and the compressor wheel to snap off the shaft - its a test they do before turbochargers can be allowed for public sale. If you already have an imbalance then the overspeeding would make it worse, but it would still snap off the shaft along with blade damage.

Which IHI turbos did you refer to bro? Is their resistance in the design/specification or is it just to do with component strength

RX-6 TCW77. Its designed to withstand the stress of the surge pushing the compressor wheel backwards, while the exhaust is trying to move it forwards. If you drive around with massaive surge, then more power to you. As they say in Jamaica "Puss (cat) and Dog nuh have the same luck." I've too many machines fail, including my own, due to surge.

 

[Tim@TBDevelopments]

hardcoreep your right on this surge will kill turbo's. i've run those Rx-6 IHI turbo's on other cars and don't be fooled they get messed up from surge as well.

only disagreement i have is that the turbo,compressor etc will never spin backwards from surge its physical impossability down to exhaust energy always being more than intake energy in an engine. But yes it will act like an airbreak putting stressing on bearings, thrust and mains

most people don't run bov's for the sound, if your that bothered why not run a BOV and just tune the releace with the pressure spring, have it stall down low but vent when on high boost. atleast your giving it a token gesture of releacing the pressure on full load. or even get one of the earlier HKS ssqv's and you get that spring pressure right you can actually get the surge to flutter through the BOV release sound.

i see surge issues all day long, most don't snap off blades ect but it makes a mess of bearings. normally getting garrett GT turbo's to last about 25k at 1bar with surge and they have been designed to help maintain surge as well.

saying that i profer the sound of surge as well so let mine run that way, but i'm not arguing the fact i'm going to have to replace the turbo ever few years, but i do have the comfort of being able to get them cheap

Tim

 

[hardcoreep]

only disagreement i have is that the turbo,compressor etc will never spin backwards from surge its physical impossability down to exhaust energy always being more than intake energy in an engine. But yes it will act like an airbreak putting stressing on bearings, thrust and mains

Actually I've seen and heard a turbo spin backwards then snap.

There are different versions of the RX6. The specific units are by Apex'i and Power Enterprise.

The design itself is about as bullet proof as a turbo can get. Apexi doesn't even offer a BOV with the kit because they say it doesn't need one. Don't confuse it with the failure-prone Turbonetics stuff. If you visit the japan site, they have pics of the various configurations. I've been told that it'll take 6-8months to get a custom IHI however. If you have a "Japan" connection, perhaps faster. I believe their site is www.apexi.co.jp

According to IHI a normal turbine goes supersonic at 80,000rpm, their RX6 can hit speeds of 120K and the blade design resists surge, unlike other units that have to have anti-surge caps.

http://www.powerenterpriseusa.net/products/turbo/RX6R/rx6r.html

They can also withstand anti-lag.

 

[RGM1800]

Conclusion:

He ran 21psi on a 2nd hand turbo and blew it, big flop, no surprise. thread to be closed.

he said the turbo is fresh. many people using 2nd hand turbo had great success w/ them

 

[Tim@TBDevelopments]

Actually I've seen and heard a turbo spin backwards then snap.

There are different versions of the RX6. The specific units are by Apex'i and Power Enterprise.

mmmm i'm not quite sure how you've managed to get a turbocharger to spin backwards, i can't think of any situation where that can be possible, engine physics alone says exhaust pressure is directly proportonal to intake pressure, so exhaust should always be higher pressure than intake there for always spinning it the right way. you'd have to get a huge flow backwards through the compressor to overcome exhaust pressure. only thing i can think of is full boost then turn the engine off during stall might enduce reverse rotoation.

Yeah used alot of those IHI apexi turbo's in the past there not immune to surge and definitly not anti-lag. the supersonic compressor design just means that the edges of the blades start to cause compression as it approaches the speed of sound, they just have a special tip to help with compressability of air in that area. you get the same on attack helicopters as the edges of the totors do the same thing.

also with the resists surge and antilag just means there made from steel over ceramic which shatters on surge and anti-lag.

i know because i had one of htere PE1919 from the 3sgte which stated all this and i had it apart, there wasn't that much different about it from a normal hyrbid when it was all apart.

Tim

 

[weakboy2]

My Charade GTxx came from the factory without a dumpvalve... i am running a standard turbo hybridised with a vj17 compressor and housing from a mazda 323 gtx and it runs 1.5bar of boost with no dumpvalve.

Been fine for years and i recently stripped the turbo off to change all the exhaust gaskets, checked the turbo and there is no play at all.

 

[steveep82]

Many cars come from the factory without a bov fitted, i personally never run bov's on any turbo car, just somewhere for boost to leak out imo, also if you think about it, a bov releases all the pressure from the piping and intercooler, you have to build that pressure again. How many rally/race cars run them? Id guess at none to a very small minority.

 

[spuddy]

I don't think you can compaire road cars to race cars which are backed by huge budgets. They replace Turbos probably after every event.

There Starlets running 2.2-2.5bar, can't see 1.5 being an issue at all, thats very low boost in my opinoin.

 

[steveep82]

Yes but race/rally cars also take huge amounts of abuse, particularly rally cars, do you not think if a simple bov would increase reliablity so significantly, they would all be using them? Im not only talking about corporate racing either.

 

[spuddy]

Yes but race/rally cars also take huge amounts of abuse, particularly rally cars, do you not think if a simple bov would increase reliablity so significantly, they would all be using them? Im not only talking about corporate racing either.

I don't think running without a BOV will destroy a brand new turbo within 100-200miles before it's replaced.

For unsponsered racers I think its just the risk they take. I know with my own car I take risks and just accept the fact eventually its going to cost me.

Though I must admit I wouldn't run without a BOV above 1.4bar.

 

[hardcoreep]

1:A lot of factory cars have a secondary relief valve (pop-off).

Many cars come from the factory without a bov fitted

2:I know of no modern properly gas powered turbocharged car that comes without a BOV. Older pre-90s turbocharged cars used to come without the modern parts for reliability, such as BOV and intercooler, which is why many of them got their bad reputation in the first place.

i'm not quite sure how you've managed to get a turbocharger to spin backwards

It was done on a engine dyno to show reversion. The turbo began to stall first meaning you could see it literally slow and then come to a stop as it kept trying to recompress the same volume over and over. Eventually what happened was the engine could no longer absorb it. The turbo eventually stopped, there was a screech as the axial stress broke the shaft. The test was on a small displacement Japanese engine. It was to show what happens when the cfm in the intake and the turbocharger exceeds the engine displacement, a problem in Drag Racers at the time.

exhaust pressure is directly proportonal to intake pressure

Agreed. You may have 20psi in the exhaust housing, but 5psi on the intake side giving you a ratio of 4:1. However, the opposite can happen, where intake volume and pressure can exceed the exhaust pressure. Exhaust pressure/volume is fixed by the manifold and the exhaust housing + the ability of the downpipe to speed along that volume. The intake side usually has a larger volume to cross because it usually includes the compressor housing, the intercooler + piping, and the intake manifold. If you keep storing or pressurizing that volume it will eventually exceed the exhaust side.

This issue also comes up in high powered JDM cars and why they run fuel pressure regulators as explained to me by a Greddy Tech. The fpr is to ensure that during quick transitions from off to on boost, the incoming volume of air is met with a fuel forced through the injectors by the frp, as the previous volume may have already used up all the fuel.

 

[weeJohn]

Many cars come from the factory without a bov fitted, i personally never run bov's on any turbo car, just somewhere for boost to leak out imo, also if you think about it, a bov releases all the pressure from the piping and intercooler, you have to build that pressure again. How many rally/race cars run them? Id guess at none to a very small minority.

Thats not exactly true to the way you are describinbg it. The pressure in the system before the throttle body does drop, because the dump valve is leaking it off. But the turbo is still pushing the same ammount of air out of it as it was to produce that boost, so as soon as the dump valve closes the pressure is there almost instantly.

Compared that to what happens with no dump valve. The throttle is closed and the compressor wheel slows down, stops or even reverses in some cases, there is still X ammount of pressure in there but now no air flow. When the throttle is opened the prerssure drops very quickly due to engine demand sucking the air out of the cooler and pipes. You are then having to wait until the turbo gets back up to speed and builds boost again.

I know many people who have ran no dump valve and have not destroyed their turbos, I dont have an answer why not.

Its not a chance I would be prepared to take.

 

[hardcoreep]

Every rally car I know runs a BOV, what do you think that chattering noise is on a GrpA or WRCar. The chattering is because the anti-lag is keep the turbo spooling and pressure in the system.

Excellent point WeeJohn. The only reason you'd have a total purge is because you'd have a BOV with a higher flow volume than your car. I've had that with customer. He took his car to me telling me it wouldn't blow-off. At first we thought the valve was stuck, so i took it off and tested it. I then realized how much pressure it took to crack it open and did some research online. He'd just bought a HKS Racing BOV which is for cars in the 800hp range. The BOV has a terminal opening volume of 3bar. On a Civic running 10psi he wasn't pushing enough to open the valve for loud sounds. I get the same problem with wastegates. People will buy like a 40mm+ wastegate and wonder why there's response problems.

The BOV isn't supposed to vent the system empty and no good BOV does that, unless you do the above.

 

[Tim@TBDevelopments]

erm actually no rally car runs a BOV and the reason behind this isn't to do with responce or anything else, its down to homoligation rules. BOV's were banned in WRC back when group b was banned and went to the 300bhp rule, same time they brought in the 51mm intake restrictor

and the chattering is from the wrc car your almost correct, its just not out the BOV (as its not there) and it sounds different to normal surge we hear on the road because the antilag is keeping the boost up instead of it just dieing off when you change gear so its a constant surge because the antilag keeps it spinning at full speed.

Tim

 

[Jay]

But i will stick to my guns and say that the OP has a consistent problem with blown turbo due to thrashing.

Chill petal. He isn't blowing turbos consistently:

one pipe i didnt check had a split that had to get bent quite considerable to see, problem solved

Turned out to be an easy fix which is always a good thing.

 

[Jay]

It's amazing what a bit of labelling can do to a thread.

Chaps let's keep the namecalling out of it please. I'm here to learn stuff, same as everyone else. Don't ruin a perfectly interesting discussion.

Any posts from this point on that contain bitching will be removed. Even if they contain the Answer to the Ultimate Question of Life, the Universe and Everything.

Don't make me moderate.