So everythings working well in the turbo setup except one thing, It may just be me but it seems like my turbo takes forever to spool. Its a T3/T4 .48 hotside, 40 trim compressor. It starts making boost around 2krpm but doesnt make it up to 6psi (where i have the wastegate set) until a little over 4krpm, ios this normal? Im thinking since im using an internal watsegate which probably has a pretty soft spring, its probably slightly opening the wastegate during spool, if I added a cheap manual boost controller to this so it wouldnt open the gate at all until 6psi would i see a dramatic diff or none? Just thought i would ask around as the car seems to have a ton of power now that im starting to get the tuning dialed in but it still doesnt do to well off the line due to the fact that it doesnt build full boost until over 4k. BTW its an auto, as i know that matters due to gear ratio.

 

normal.

boost controll will help, but not much

Turbo lag, downside of turbos

 

No this isn't normal for that size of turbo.

You should have full boost by 3000rpm at WOT. Are you running extremely rich under 4000rpm? You should also make sure you have no exhaust leaks before the turbo.

With internally gated turbos, it's actually more common to overboost initially (boost spike). The lag makes me think you're either not tuned right and/or you have some sort of leak preventing the turbo to get enough exhaust to spool.

 

Hmm no leaks before turbo, might have a VERY SLIGHT leak after turbo but thats it. Also heres a weird one. Not really a good idea, but done under a very controlled accelaeration I disconnected the wastegate and when i gave it any gas at all it almost instantly went up in boost over 5 psi. Also afr wise is very stable, thinking the same thing i lowered how much fuel i was putting in under 4k so that my afr stays around 13.5 in this range and same result

 

Ok - try changing your boost reference source going to wastegate.

 

Yea right now its on the compressor, ill try t-ing it into my manifold line (same one boost guage, fic, and bov are on) when i leave work

 

Your turbo spools when the car is started and idling. Boost threshold is is the lowest rpm at which the turbo system creates boost (1 to 2psi).

4k does seem a little high. Even the smallest leak will be detrimental for your boost psi. That small leak at 1-2 psi will make more of an impact when you reach full boost.

Pressurize and test the whole system. After you fix the leaks and still have problems...head over to the tuner he will be able to help you out.

 

wastegate is opening too early, is it stuck?

 

Checked wastegate the other day its def not stuck, its an internal WG, spring holds it fully closed and im able to pull it open against spring normally.

 

then it sounds like a boost leak

 

Any updates, thendawg? Did you get to try a different boost reference?

 

Well here's what i figured out after changing the lines going to my wg and connecting them to manifold vac did nothing, i tried adding an air pressure regulator, allowing the pressure to build slower on the wg than is actually building in compressor, so in the end result it didnt really change boost, but what it did do is now the turbo is making full boost by a tad under 3.5k, the air pressure regulator isnt really ideal for this but it does make me think it has to do wwith the wastegate starting to open at partial boost. Looks like ill be trying to pickup a cheap manual boost controller sometime soon

 

Ah yes - I forget how sometimes this may happen on an internally gated turbo.

 

0.48 is WAY too small for the Tc motor. With such a large displacement and long stroke you need at LEAST 0.63 on the hotside housing. I prefer 0.84 or 1.01 myself.

 

Just thought I'd share my graph...I'm running a 54trim .63 a/r and boost starts building a little after 2k.
Boost Controller set to 6psi reaches full boost around 3500 and at 9psi, reaches full boost after 4500.
This is also a slower spooling bushing turbo, not a BB turbo:

 

Just to think, you have a boost controller, which is keeping the WG shut longer and helps spool. Imagine without it and just on the WG spring.

 

meaty you got your crack pressure at 2 right? i got mine set at 5 and it spools super fast but i have to put it down to 3.. not bad though for a long runner manifold, but yeah tuning, boost controller, checking for exhaust and boost leaks will help.. that small turbo should spool fast

 

True...I have my boost controller set to crack at 2.

But I think thendawg is talkinga bout getting a manual boost controller, not an electric...will a MBC help at all?