Jump to content
SAU Community

Recommended Posts

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. post-52441-1273888340_thumb.jpg

Link to comment
https://www.sau.com.au/forums/topic/320720-is-this-too-much-lag/
Share on other sites

  • Replies 53
  • Created
  • Last Reply

Top Posters In This Topic

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

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?

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.

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

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

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 :)

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.

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

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!

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.

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?

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now



  • Similar Content

  • Latest Posts

    • You just need to remove the compressor housing, not the entire turbo. I would not be drilling and tapping anything with the housing still on anyways. 
    • So, I put my boat on a boat. First of all, I'm going to come out and say it. Why is Tasmania not considered a holy goal, an apex that all road-legal modified cars go to, to experience? This place is an absolute wonderland of titanic proportions. If people are already getting club runs for once in a lifetime 30 person cruises to Tassy then I've never seemed to see it. It is like someone replaced the entire place with an idyllic wonderland for cars, and all of the people living there with paid actors who are kind, humble, and friendly. Dear god. After doing a lap of almost all of the place I've found that it's a great way to find out all of the little things that the car isn't doing quite right and a great way to figure it all out. All in all, I drove for 4 hours a day for a week and nothing broke. I didn't even need to open the engine bay. This is by all means a great success, but it has left me with a list of things to potentially address. I also now have a 3D printed wheel fitment tool which annoyingly hasn't got any threads in it to actually assemble it. I might be able to tape it together to check the sizing I actually want to use, but it'll likely involving pulling the shocks out to properly measure travel at least at the front, and probably raise the car while I'm at it, at least in the rear. I scraped on quite a few things and I'm not sure how else to go about it. I was taking anything with a bump at what felt like 89 degree angles. And address those 10 other tasks. And wash the car. God damn it is dirty. And somehow, the weather was perfect the entire time - And because I was on the top of Mt Wellington it turns out it was very much about to freeze up there. I did something I typically never do and took some photos up there in what must have been -10 and the foggy felt like suspended ice, rather than mere fog. If you own a car in Australia, you owe it to yourself to do it.
    • Damn that was hilarious, and a bit embarrassing for skylines in general 😂 vintage car life ey. That R33 really stomped. Pretty entertaining stuff
    • Hi, I have a r32 gtr transmission. Does any of you guys have an idea how much power it will hold with the billet center plate and stock gearset? At what power level and use did yours brake with or without billet plate? Thanks, Oystein Lovik
    • Saw this replica police car based on a Mitsubishi Starion XX parked next to a 'police box' (it's literally a box) in Hirohata, Himeji City in Hyogo prefecture the other day. It's owned by Morii-san who is a local Mitsubishi Starion enthusiast. According to a local radio station blog post, he always wanted to make a police car himself based on ones he saw in his favourite Manga comics.  As it's illegal to modify a car to look like a police car and drive on the road, Morii-san tried many times to get permission from Aboshi police station headquarters nearby. They refused initially by after they got tired of that they granted him permission. However, the car can only be displayed on private property and obviously can't be registered as long as the police livery is present. The car was completed at a cost of 1.5 million yen (US$ 10,000) in addition to the car cost. A location was chosen outside Hirohata Police box where the car can easily been seen from the street. Morii-san has two other Starion road cars, both widebody GSR-VRs.
×
×
  • Create New...