Turbo lag Question

As some of you guys know this car lives at nurburg, I fly over 6/7 times a year and just drive it on the Ring

3 years ago I fitted a PHR stage 1 turbo running 1.35 bar with 550 injectors and with a lighter than standard car provided ample power

last weekend i noticed clouds of smoke from the exhaust on the overrun, the local turbo engineers diagnosed a worn turbo cost to rebuild little over £400

now my dilemma is I have been offered a second hand stage 2+ 1000 miles (road used only) for £600 the question is do I buy and fit it, for an extra £200 seems a good opportunity.

As the car is only used on track my main concern is turbo lag The way i figure it although having slightly more power, more lag could make for a slower lap, altering the character of the car, I have absolutely no problem with the stage 1 it works perfectly and provides very little lag once it is up and running, but the stage 2 is tempting

So the question is will i regret it? is the stage 2 that different from the stage 1 and how will it alter if any the driving chararistics on a track, and has anyone changed from a 1 to a 2+ and what diference have you found

The other issue will be injectors, having possibly to upgrate will be more money and is all realy worth it.

before commiting your comments will be greatly appreciated

I think the stage 2+ is the same size as a BL T67? if so that would be fine on track.

Hi George!

I'm sure experts will be along shortly to tell you if a battered turbo would only cause smoke on an overrun is likely or not (doesn't sound 100% definite to me, but I'm an amatuer not an expert)...

...but to answer your question about lag, it's only a problem at low speed, surely? I think my turbo is slightly bigger/laggier than yours, and the ONLY time it causes me a problem is heading out immediately after leaving the cones; once I hit 4,000rpm I'm making plenty of boost and I simply use the 6 gears to make sure I never drop below 4k rpm during a lap - I know yours is a 6 gear too, so I wouldn't worry unless you fit a huuuge turbo the like of which the drag racers like.

Have you got a dyno printout of your current setup?

P.S. Thanks for the lap earlier this year

I'm sure the Whiftbitz track drivers (Ben and Steve) would be able to help out here, one has the PHR 1 and the other a PHR 2+ IIRC

You will need to change your injectors with a 2+ turbo, 650's would be the absolute minimum you'd need, though most use 720's. Then you have to remap, etc so it could work out costing a few £££.

Take it off and bring it back here, and take/send it to Turbo Technics or similar, they quoted me £250 for a rebuild on a GT4088 which is not a BB type, don't know if the PHR is?

George, the other thing I would say is that you really need a proper ECU that is up to the job, haven't you still got the stock one at present?

On a side note whats your best lap time at the ring?

George, drop by anytime and your welcome to try mine, I changed from a PHR stage 1 to a GT4088(I'm only 10 mins from you)

Hi Steve

Agree regarding the problem, I also am no expert but the engine has just been stripped down with new piston rings, race bearings, and and High lift cam shaft fitted, it has been suggested it could be valve stem seals but they have all just been replaced so unlikely. JPS motorsport and the local turbo people have suggested the turbo, as on the overrun they say the shaft will move slightly on a worn turbo causing the oil to seep into the manifold so I am at the mercy of the experts on this one

Still on stock ECU and agree should be replaced with a programmable one but to costly at the moment so still relying on boost and fuel controllers to map up but seems to work OK but of course cannot fine tune as with a programmable one

Jamie

the car has done 7.54 with Gareth driving there are 2 videos on youtube one being filmed by a biker on an R1 just type in supra at the nurburgring to watch if you wish.

As you say Steve, will accept any advice from experts on this one, as we are only assuming its a badly worn turbo

George' date=' drop by anytime and your welcome to try mine, I changed from a PHR stage 1 to a GT4088(I'm only 10 mins from you) [/quote']

 

 

thats very kind, perhaps you could send me a PM with your address and we could meet up or just pop into my place if you are driving by

I think you'll get a big a gain from adding a decent ECU & mapping session to your spec list, regardless of whatever turbo you go for George. You have most of the ideal big power track car setup, the stock ECU copes bizzarely well but it is the achilles heel on your car IMHO.

Smoke on the over-run is normally rings mate, if theres smoke at idle when hot thats the give away turbo sign. Even an Emanage Ultimate will give better results than stock, plenty about and cheaper than full stand alone, also Ryan can map it for you

Good luck with the rebuild though and keep at that 'ring!

Hi george, mines a phr 2+, lag is minimal, like steve says only really noticable when coming through the cones at the start,allthough if you`re happy with the stage 1 i`d just get that rebuilt atleast you are used to it and it runs well, has the turbo had any work before,if not its probably due.

Hi george, mines a phr 2+, lag is minimal, like steve says only really noticable when coming through the cones at the start,allthough if you`re happy with the stage 1 i`d just get that rebuilt atleast you are used to it and it runs well, has the turbo had any work before,if not its probably due.

Thanks Simon I agree cheapest option is repair the stage 1 but the 2+ was tempting (to be or not to be that is the question)

I have the 2+ and I found that at Knockhill its a little laggy but only because it is a fairly slow track I would imagine on the ring it would be awesome and would be a great set up for that sort of track. Not had mine on the ring since the single conversion but will do one day.

Smoke on over run can indeed be turbo seals caused by worn bearings.

On boost the high pre-turbine exhaust pressure keeps the oil in the housing as the pressure differential between the exhaust gas in the turbine housing and the oil pressure is not huge.

On overrun the oil pressure will be high (as high as the oil pressure normally is at the rpm the engine's turning at), but the exhaust pre-turbine pressure in the turbine housing will be near zero as no combustion is taking place and the throttle is closed. This means that the pressure differential between the oil in the turbo bearings and the exhaust housing will be big..... resulting in the slightly worn seal on the turbine sided leaking a small amount of oil into the hot turbine housing. This is the smoke you see.

Rebuild with new bearings and seals is not much as long as the turbine shaft is not scored on the bearing face.

You may also need to look into why the bearing started to wear and allowed the seal to deteriorate. Oil supply is one area, as is oil drain back to the sump as there are limits to the angle of the drain.

Also look at the oil you're running. If you're synthetic it may be that you're running too low viscosity or running the oil too hot? It may also be the balance of the turbo or the fact that its overspeeding? Get the turbo balanced on a VSR balancing machine to a high tolerance.

I have the 2+ and I found that at Knockhill its a little laggy but only because it is a fairly slow track I would imagine on the ring it would be awesome and would be a great set up for that sort of track. Not had mine on the ring since the single conversion but will do one day.

I am sure you will enjoy it why not tag along with Steve and Simon next year I sure Steve will organise another trip

Smoke on over run can indeed be turbo seals caused by worn bearings.

 

On boost the high pre-turbine exhaust pressure keeps the oil in the housing as the pressure differential between the exhaust gas in the turbine housing and the oil pressure is not huge.

On overrun the oil pressure will be high (as high as the oil pressure normally is at the rpm the engine's turning at), but the exhaust pre-turbine pressure in the turbine housing will be near zero as no combustion is taking place and the throttle is closed. This means that the pressure differential between the oil in the turbo bearings and the exhaust housing will be big..... resulting in the slightly worn seal on the turbine sided leaking a small amount of oil into the hot turbine housing. This is the smoke you see.

 

Rebuild with new bearings and seals is not much as long as the turbine shaft is not scored on the bearing face.

 

You may also need to look into why the bearing started to wear and allowed the seal to deteriorate. Oil supply is one area, as is oil drain back to the sump as there are limits to the angle of the drain.

Also look at the oil you're running. If you're synthetic it may be that you're running too low viscosity or running the oil too hot? It may also be the balance of the turbo or the fact that its overspeeding? Get the turbo balanced on a VSR balancing machine to a high tolerance.

Thanks for the info that may well confirm what others have said,

you may well be right regarding oil. I had an oil change done in Germany about 2 months ago and they put in a castrol 5/60, Leon at JPS told me off, said it should be around 10/40 so I,m sure that didn't help an already worn turbo,

also heat is a problem, this time of year all temperatures remain normal on the Ring. but during the summer on hot days they get far to high, which may well have contributed to the turbo problem, the cause of the warped head was pushing to hard on a hot day dicing with a couple of GT3's when the fan belt broke causing the water to instantly boil luckily the head was still scimable so no permanent damage and is a testament to how well built these engines are to take this kind of punishment year after year.

So I think the turbo has done well concidering its use and perhaps the stage 2+ may well take the punisment a little better