Turbo question td04/05
 

Hi quick question,I have a 94 classic running a td05,it's laggy as per norm for one of those with nothing happening until 3200 rpm,and is annoying me,not going for more than 300/320bhp currently have fmic,apexi induction no cats,straight thru system etc and z4 ecu,was thinking of swapping to a td04 to make it a better road car with better response,am I mad or should I just sell up and save for a bug or blob with it as standard and start from there again?
Cheers in advance :)

One option could be ported headers and a matched up-pipe (Harvey Smith) this gave me around 300rpm earlier spool on my setup.

I used to run a 05 on my old engine, 1.5bar boost with the gain right up on the boost controller, made 325/310 and I thought it was animal and perfect for the road, never did i think I needed less lag. as said though porting will help

Id say ported headers and up-pipe too.

i found that my turbo waste gate was worn and causing my lag on a td05,
a decated system and filter should help spool up, but then a fmic will add the lag.

To help diagnose couple qustions>
how are you controling the boost and what amount of boost you runing?
if you have a boost gauge at what rpm do you reach max boost pressure? (ie. 1bar at 3k)

a td04 will not give you the power your aiming for.

Cheers for replies so far guys,to answer a few questions,it's on a z4 ecu with 2 port boost solenoid,it achieves 12-13 psi at about 3900/4100 in 2 nd or 3rd at wot on a flat road,before this you get very little maybe 2-3psi and it just feels flat,it has -25 vac on over run so 99% there are no leaks and the boost is about right for the ecu targets it just feels very laggy,my old evo4 spooled very quickly,as did my sti3 but every early classic ive had has felt sluggish until on boost and it just makes it feel slow on the road especially as I do mainly town/b road driving,I might try an actuator is there a test I can do to check it? Cheers again,Neil.

What injectors are you running as the Z4 should be on 440 Yellows

I tried to look but they just look silver metal?

standard injecters are 380 u will be able to see some yellow if they are 440

No it shouldn't.
All pre facelift 1994-1996 are on grey 380's including STi, as do most 1997/98 models
The only model before 1999 runing 440's is an STi V3

agreed ,I ran a z4 on 380's fine

The front mount will make it laggy as well. Could also take off front mount and put top mount back which will help.

But TBH I always hated the early WRX's I had for just this reason. I always found them very laggy as a daily driver. I always found the later standard later UK classic with its TD04 a much nicer and arguably quicker car as a daily driver. Other thing that would help would be a polar performance chip which helped to reduce the lag a little.

Just keep the revs higher.... Simple