I want more power! (MG ZT CDTi)

[Jakg]

I want to get some more power out of my CDTi...

Current state of play is 160.4 HP / 264 ft-lb torque...



So far I've done:
Synergy (set to 10) + PB MAF
EGR Bypass
Decat (standard exhaust)
Venom remap
Pipercross air filter
Custom air intake (70mm tubing)
Intercooler O-Rings replaced
Intercooler cleaned
Top intercooler hose replaced
Inlet manifold / MAP sensor cleaned
PCV filter replaced 14k ago

Since the last run I've cleaned the intercooler out, tweaked the air intake slightly and replaced the top intercooler hose, but I can't see a point in spending £ re-dyno-ing it until I've actually done a proper mod (although it does now feel slightly faster).

What next? Willing to try pretty much anything...

All I can think of is a new exhaust (really want a duplex system), the turbo wastegate adjustment thing and maybe another remap.

Ideas?

[Dakta]

It's difficult to say really, it depends how far one's willing to go. I wouldn't go for an exhaust myself for a performance increase, (though it'll make it sound more sporty at least!) but I wouldn't do it just on the grounds of performance because they don't add much (generally speaking).

You've already covered the most common bases, but if you haven't adjusted your boost yet then maybe you can squeeze out that bit more (stock boost is usually set quite conservatively). when mapping vw's and the like with electronically managed boost we normally increase the boost slightly.

But obviously it's something you need to be careful with and not go mad with, a lot of people just up the boost blindly, it's always worth doing a bit of research find out what you can about the turbo you have just to make sure the boost you run 'is safe' for the engine displacement you have, with our GT15's on the L series we find the best compromise between reliability and performance is about 19-20psi I don't recommend going higher than that. Those figures aren't 'concrete' and I suspect have come about to be the widely used standards because of people's experience over time rather than anyone's explicit say so. It's always delivered in terms of performance and reliability, and testing has shown on the L series increasing the boost further has a negative impact.

I'm not saying this to suggest a level of boost, because each engine is different but if you do do a wastegate adjustment, don't go mad with it and see what other people with tuned 75/zt's are running at the very least.

You might need to adjust your remap with the boost adjusted, depending on how much fuel you're pushing. You need both air and fuel to make power, so a boost adjustment will add air, the remap will help with the fuel. result should be power providing the turbo isn't maxed out - if it is then it's time for a turbo upgrade but to be honest I wouldn't go too mad, wouldn't want to stress the DMF :P

Just my very quick 2 cents. Always worth a look in the 75 section to see what people are doing as thats where most people with this engine hang about.

[ramdonice]

upping the boost is a must really, you got a funny curve early on the graph like a flat spot at about 2.2k revs what setting you got the synergy on?

[radion_auto]

Robdrinkwater had one of these pushing out 180bhp. might be worth digging.out his project thread to find out where the extra power came from.

[finyuk2005]

im sure i have read that upping the boost to 19psi is generally what folk do, this can only really be done with a boost controller like the GBe one.
i am looking forward to start tweeking my folks new zt-t, great engines that bmw unit.

[PrimeTime]

I don't have any facts, but i would say a BMW intercooler and injectors may be worthwhile upgrading, if you find out what the differences between the Bimmers 150bhp and the Mg's 136 are you can try upgrading the bits to get you extra power

[Jakg]

Originally Posted by finyuk2005

im sure i have read that upping the boost to 19psi is generally what folk do, this can only really be done with a boost controller like the GBe one.
i am looking forward to start tweeking my folks new zt-t, great engines that bmw unit.

I've never really understood where you fit a boost controller?

Originally Posted by PrimeTime

I don't have any facts, but i would say a BMW intercooler and injectors may be worthwhile upgrading, if you find out what the differences between the Bimmers 150bhp and the Mg's 136 are you can try upgrading the bits to get you extra power

The BMW has a different turbo. The intercooler wouldn't fit

[Rik420SDi]

Originally Posted by Jakg

I've never really understood where you fit a boost controller?

In the line that supplies air pressure to the wastegate or similar, at a guess. Plus appropriate power connections etc if it's a fancy one...

[mad]

is there not a spring mod for the cdti, cant remember exactly were i read it, but basically makes the actuator spring "stronger" increasing boost. And as darren says, its not a very good curve, bit more tweaking on snergy/remap required.

[Rik420SDi]

Not read it, but there is something along those lines mentioned on Ron's site...

http://tuning-diesels.com/75Zt/R75tu3.htm

[ramdonice]

looking at the actuator on mine its the same as the L-series so will be easy to increase the boost, i'll be happy to lend ya a hand as your not to far from me.

is your synergy set something like mid/high as that would cause the curve needs to be on mid/mid or high/high if you know what i mean

[finyuk2005]

yeh i have heard of the helper springs, but i think the boost bleed screw controllers are the easiest, for some reason i'm not sure why, but i dont think its actually possible to adjust the waste gate actuator, other wise im sure more people would do it

[pervavore]

I would remap the CDTi again because the torque curve is terrible Looks more like a roller coaster track Smooth it more out.

[Jakg]

Originally Posted by pervavore

I would remap the CDTi again because the torque curve is terrible Looks more like a roller coaster track Smooth it more out.

The two runs you can see were before / after the remap...

[Dakta]

indeed but there is a funny dip around the 2200rpm mark, that's an area with potential gain

[ramdonice]

Was the remap done on the rollers?