Turbo rebuilds

[EVOIV]

Yeah, that's a major problem with BB turbos...they are very expensive to repair, if they can be repaired. But I've heard that they can spool up to 30% faster than normal bearing turbos. I guess there's always a trade off.

[JimX]

Oh, one other thing about my turbo - the "bodgy" bit about the install wasn't the turbo itself, but rather the weak spring used to pull back the sticky wastegate pivot, as well as the welded-up and cut pivot. Once this is fixed I won't need the extra external spring and it won't look bodgy anymore It is a standard T04E turbo.

[Jay95R33]

JimX - you may have been asked this a billion times before, but whats the TO4E like on the 25DET ?

Was it ever working well enough to get a power figure and spool up time from it?

Just wondering if it was a lag king etc.

Cheers

J

[EVOIV]

I get a little confused. Are T04's large or small?

[JimX]

Actually Jay, you're the first person to ask This is probably because before today, I didn't even know what my turbo was. The engineer guy at Garrett instantly identified it as a T04E without even noting anything unusual about it, so I'd say it's the full standard unit and not a T3/4 hybrid. The previous owner advertised it as a "450hp T04" but I forgot to ask any more details about it before buying the car.

I've always liked this turbo, but there's nothing else I can compare it to really (aside from some poxy TX3 turbos I've driven from waaaay back). Benm's car with the factory turbo was slightly faster than mine when I got it, but he had a better intercooler and air filter. Since I upgraded my cooler and plenum I'd say they are at least on par again, and now I can also run higher boost due to the steel wheels.

My turbo seems to start spooling fairly low (maybe 2000rpm?) but it doesn't seem to hit maximum boost until 4500rpm or so. I always thought this was an anomoly of the turbo, but now I've found that the wastegate wasn't working properly it could just be that.

I'll re-evaluate it again once the wastegate is fixed. Maybe it is a lag monster relatively speaking, but it doesn't seem to bother me. I can still pull up a hill in 5th gear with a carful of passengers, so it must be doing something at lowish revs.

[Jay95R33]

Cool - thanks for that. Yeah with the wastagate stuffed it's a it hard to compare, but once it's fixed it should spool up a little faster hopefully.

It'd be good to see how you go when you get it back.

Cheers

J

[JimX]

Update: Garrett just rang me back, and quoted $140 to fix the wastegate. It's a done deal, I pick it up tomorrow morning.

[EVOIV]

Hehe...cool. It doesn't seem like a lag monster if it's making boost around 2000rpm...that's actually very responsive. I used to have a GT3037S on a 2L and that was laggy, like no boost until around 3500rpm!! Too laggy for street use, but when it came on boost it was great I think I'll try the GT2835PRO S for my next 2L.

[JimX]

Well that's the thing - it always felt like it was making boost early, but with my foot to the floor, it never got to full boost until around 4500rpm (maybe 5000). Going from what other people have posted here it should have been 500-1000rpm earlier than that to be considered an "early boost" type turbo.

I won't mind if it's around the same after it comes back, it was a gradual transition to max boost rather than a punch in the kidneys.

Fixing the wastegate should at least reduce the strain on my poor EBC, which has been fighting against this sticky pivot for well over a year now. If it brings full boost on earlier then that's a bonus.

[EVOIV]

I actually like the push in the chest effect that happens when a large turbo comes on boost After a while, a small turbo car just feels like an ordinary car but with more power. I actually prefer power curves to be more peaky than linear.

[JimX]

Well you can definitely feel it kick in, a lot more than getting to the sweet spot on a lumpy cam on a NA engine (as I get on my bike). It's just not as harsh as some cars I've been in, which makes cornering a little more predictable.

I dunno, "feeling" of turbos kicking in is very subjective. One person might think the turbo kick is excessive, when another will think that the car doesn't even have a turbo. If we are ever at the same cruise I'll take you for a spin and you decide

[EVOIV]

Yeah, it is subjective I guess. I've heard that some RWD cars running large turbos tend to wheel spin when the turbo kicks in. Can get very dangerous in the wet, but if this happens, you know that it's a pretty big thump!

Never been in a car that does this, because my car is AWD and traction is rarely a problem. Though my sister has a stock s15 and it feels a lot more dangerous in the wet, even when my car had 206kW at all four wheels. It's really easy to get the rear end outwards when turning a corner (s15). And I can imagine it would be very difficult to control with 200+KW at the rear wheels. But I guess 10" width rims would give a little more traction...

[JimX]

I got the turbo back this morning and put it back in the car this afternoon, it was a lot easier than taking it off because I knew where everything went and where to get the spanners in.

Including getting everything like the exhaust sealing compound on it took me around an hour. The whole wastegate was replaced, apparently the old one was pretty stuffed. The new one operates very smoothly and with no freeplay at all.

I noticed that the spacer for the turbo mounting isn't normal because it causes the nuts to not go all the way down on the studs. I tried taking it out but then the turbo touches on the engine, so I put the spacer back in and did the nuts up a bit tighter than they were originally.

I haven't gone for a test drive yet because after all this I took the fuel pump out, but it all starts up and runs ok. I did a big coolant flush and put new coolant in and bled the system. The new fuel pump should be in tomorrow afternoon so I'll see how it goes after that.

Oh, the big thing - the rattling noise is now completely gone! Obviously the dud wastegate was the entire cause of the noise.