turbo questions

[mean88]

I have a franken motor 1.6.  Engine is new.  Pump is turned up 40% from stock, and governor is shimmed tight.  I am running a mercedes t3 with a front mount intercooler, 3"DP no exhaust.  I have a mls head gasket and arp head studs.  My car is a daily driver for work.  I am getting a best of 56MPG with it.  I am looking for possibly better boost at low rpm. 

I can get up to 30psi(after intercooler) with the current turbo(wastegate closed tight)  But it seems as though it takes too long to build boost.  With the pump where its at it will smoke like a freight train in higher gear/lower rpm.  I can only get it to build boost relatively quick if I hit it in 1st gear.  My turbo overspeeds at 30 plus so its at its limit. 

My question is this, would a larger vnt be a better option?  I ultimately am trying for best MPG and seeing the black smoke at mild throttle/lower rpm means I am leaving economy on the table.  I spend most of my time light throttle lower rpm driving around and the car feels sluggish unless I fuel the boost.

[theman53]

A vw T3 or KKK K24 would solve your problem. The merc turbo is a bit on the laggy side for a 1.6. Other option is turning up the pump more to spool it with the extra heat, but if you are already belching black you may be maxed out for that option if fuel economy is your concern. The K24 I think is relatively stable at 24psi intercooled, but closing the wastegate isn't the best for them, you should do a manual boost controller.

[RabbitJockey]

instead of going to the straight vw t3, u could do what i have done(but not driven yet), which is use the mercedes compressor, with the vw hot side.  this should give much better spool up while still keeping the efficiency up at 30psi.  you could also take your merc turbo and get a newer staged turbine wheel installed (like turbonetics), honestly i can't say how that will change things, but i think it will improve flow, and possibly spool up because it is a much newer design, vs the 70's turbine wheel the mercedes came with.  the mercedes diesels had the older t3 turbine wheel that had a larger inducer, which was actually worse because it was heavier.  the vw turbos, and most any other t3 had the newer smaller wheel that had better spool up and the same flow.  so u could possibly improve spool up just by swapping to the later .48 wheel and housing from a saab, volvo, or turbo dodge.

u could also go the vnt route, check out what the tdi guys use for what ever your power goal is, the same turbos will apply to your 1.6

[R.O.R-2.0]

A vw T3 or KKK K24 would solve your problem. The merc turbo is a bit on the laggy side for a 1.6. Other option is turning up the pump more to spool it with the extra heat, but if you are already belching black you may be maxed out for that option if fuel economy is your concern. The K24 I think is relatively stable at 24psi intercooled, but closing the wastegate isn't the best for them, you should do a manual boost controller.

unhooking or sealing off the wastegate is BAD for a K24..

i had mine hooked up like that for about a month, until it started puking oil..

[RabbitJockey]

i had mine like that for 2 years haha no issues with the turbo.

[CrazyAndy]

R.O.R. didn't you once say that the K24 wastegate when left unhooked from boost source pops open from drive pressure at 24 PSI?  Or was that said in that month's time that the turbo WG was unhooked before it started leaking oil?

[RabbitJockey]

R.O.R. didn't you once say that the K24 wastegate when left unhooked from boost source pops open from drive pressure at 24 PSI?  Or was that said in that month's time that the turbo WG was unhooked before it started leaking oil?

that can't happen on a k24 only on a t3 because the the valve opens in towards the manifold pressure.

[R.O.R-2.0]

R.O.R. didn't you once say that the K24 wastegate when left unhooked from boost source pops open from drive pressure at 24 PSI?  Or was that said in that month's time that the turbo WG was unhooked before it started leaking oil?

that can't happen on a k24 only on a t3 because the the valve opens in towards the manifold pressure.

my K24 is off a 2.0TD, so the valve seals against the pressure/pre turbine exhaust housing side, and opens into the low pressure side of the turbo outlet. so yes, my particular K24 DOES have a "magic" wastegate that pops open from drive pressure.

i forgot that my wastegate is set up differently than regular K24s..