Is This Too Much Lag?

[Get EPIC]

Hi all.I just put a AX53b70-25 turbo on my car and had it tuned.Made 299.2 rwhp on 16psi but i reckon boost comes on later than it should.I have attached a photo of the dyno sheet.Im thinking it may be an actuator problem as it doesnt seem to hold boost very well up top as seen in the dyno sheet.

[Pal]

need more specs on the mods you got??

[Get EPIC]

need more specs on the mods you got??

Pod with CAI

Power fc

Walbro fuel pump

Tomei fuel reg

3 inch turboback exhaust

Front mount intercooler

Boost tee

[paulr33]

yeah i would expect it to come on a bit earlier

what car? manual? auto

how is it tuned?

how do the AFRs look ?

8psi by 3300rpm hmmmm

it just looks sluggish - theres no real whack

how is your boost control?

try it on the dyno on unlimited boost mode

what did the tuner say

does it knock

[Fat_Tony]

Check to see if your wastegate actuator is adjustable. Looks like it might be soft.

[R31Nismoid]

Boost control is poor - Fix that and you'll improve the setup.

it takes 1000rpm to go from 14-17psi or there abouts.

You can see it climbing perfectly then slows up, and then noses over... issues there for sure.

[Get EPIC]

Check to see if your wastegate actuator is adjustable. Looks like it might be soft.

Actuator is adjustable,so i'll have my tuner have a look at it.

[Get EPIC]

Boost control is poor - Fix that and you'll improve the setup.

it takes 1000rpm to go from 14-17psi or there abouts.

You can see it climbing perfectly then slows up, and then noses over... issues there for sure.

Would the boost tee be responsible for it being laggy or more likely the wastegate actuator? I noticed that the mechanic hooked up the boost tee to a nipple on the elbow of the turbo where as before it used to go to the intake manifold.Would that make any difference?

[StealthX]

I think you need a bit more pre tension on the wastegate actuator, the boost is too soft and fluffy, needs some more aggressiveness, a few winds of the wastegate arm should change some things, take it for a spin and experiment with different tensions, then once your happy with the boost, take it back and get a final tune/run I reckon.

[libardi]

i had a similar set up on a RB20 and i just assumed the lag was just coz it was a 20

[paulr33]

yeah there isnt enough pretension on the actuator

ie its either loose or just on the edge

so when its ramping on boost , its probably part leaking / part open

which means you are loosing out on the backpressure in the housing

bassjunky had this on his GCG hiflow with a new actuator (from memory)

end result was it was sluggish and took ages (like yours) to get on boost and full song

he bent the actuator rod (temp fix) and instantly it would ramp to full boost around 3000rpm

i forget how he fixed it in the end, but a quick bend of the actuator rod was enough to give it some tension so it wouldnt leak/bleed off

[paulr33]

for those who are reading a general tip

if you are trying to debug boost build / wastegate / boost controller issues

the quickest way to find out if its leaking / stupid controller / wrong settings / wrong control etc

find the VAC line or signal line to the boost controller (or actuator) or gate and unplug it

tape up the VAC line so you aren't leaking to atmo from the manifold and then drive

ramp the engine on full load in say 3rd gear but be prepared to back off as its running unlimited boost

you should be able ramp past 1 bar pretty quickly (be careful and dont run much past this)

ie back off when you go near 3000rpm. if you are able to build your ideal boost early, this is your "quickest possible boost build map"

ie the quickest possible time your engine can load up the required pressure

the next step is to setup your controller / gate / boost controller / etc to run with that desired ramp rate (ie work correctly) and control when target boost is met

[Get EPIC]

I think you need a bit more pre tension on the wastegate actuator, the boost is too soft and fluffy, needs some more aggressiveness, a few winds of the wastegate arm should change some things, take it for a spin and experiment with different tensions, then once your happy with the boost, take it back and get a final tune/run I reckon.

Thanks for that mate.I just had a crack at it and all the sudden when it came on boost i heard a loud pop and the car died on me.Started it back up but wouldnt idle.I thought-oh no ive blown something.Got out and looked around the engine bay and found an intercooler pipe joiner had popped off! I think i have just found my culprit with the boost problem.I believe its been leaking at high pressure for quite some time.Haven't taken it for a test drive to test the actuator again yet,i'm changing my undies from when i shit myself when i thought i had blown the turbo or something

[Get EPIC]

So would shortening the length of the actuator rod bring on boost faster or slower or neither?

[darrinspencer]

I use to run the same turbo on a Neo rb25, poncams and power FC etc.

15psi only netted 250rwhp

The tuner (godzilla motorsport) had problems with boost control. We concluded the actuator was not much good.

I never solved the problem and have since removed the turbo and put a bigger one on

I have heard of the same apexi turbo's having similar problems when you try and run 15++psi

This turbo should be no laggier than the stock. They are only rated at 380ps and still run a ceremic exh wheel for faster spool.

They can handle more boost than the stock turbo. The only one I have heard of spitting the exhaust wheel hit 25psi.

[Get EPIC]

for those who are reading a general tip

if you are trying to debug boost build / wastegate / boost controller issues

the quickest way to find out if its leaking / stupid controller / wrong settings / wrong control etc

find the VAC line or signal line to the boost controller (or actuator) or gate and unplug it

tape up the VAC line so you aren't leaking to atmo from the manifold and then drive

ramp the engine on full load in say 3rd gear but be prepared to back off as its running unlimited boost

you should be able ramp past 1 bar pretty quickly (be careful and dont run much past this)

ie back off when you go near 3000rpm. if you are able to build your ideal boost early, this is your "quickest possible boost build map"

ie the quickest possible time your engine can load up the required pressure

the next step is to setup your controller / gate / boost controller / etc to run with that desired ramp rate (ie work correctly) and control when target boost is met

Thank you Paul

[rad100]

yep mine was seeing 14psi at like 3000rpm.. and wouldnt boost more than 15psi due to the actuatuor being blah..

so we fitted a big can one and fixed it!

great turbo.. made a very responsive 250rwkw!

[WHITER33GTS-T]

Lag is to give the V8s a head start

[StealthX]

Thanks for that mate.I just had a crack at it and all the sudden when it came on boost i heard a loud pop and the car died on me.Started it back up but wouldnt idle.I thought-oh no ive blown something.Got out and looked around the engine bay and found an intercooler pipe joiner had popped off! I think i have just found my culprit with the boost problem.I believe its been leaking at high pressure for quite some time.Haven't taken it for a test drive to test the actuator again yet,i'm changing my undies from when i shit myself when i thought i had blown the turbo or something blush.gif

bahahah yeah I've done that soo many times! and every time I shit myself just as hard lol Good luck man.

[Get EPIC]

yep mine was seeing 14psi at like 3000rpm.. and wouldnt boost more than 15psi due to the actuatuor being blah..

so we fitted a big can one and fixed it!

great turbo.. made a very responsive 250rwkw!

So what was the new actuator you put on and where can i get one,if you don't mind me asking?