The HOLSET Thread

avalaugh said:
It’s a M54B30 so a 3.0ltr engine. Of you look at pictures I posted you can see how the WG is plumbed back into the 3” downpipe, and yes a 4” just isn’t really possible.
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What's further down the exhaust system? Any mufflers or catalytic converters that could be partially blocked?
 
BenRice said:
What's further down the exhaust system? Any mufflers or catalytic converters that could be partially blocked?
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Nope, all new.

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So what's the engine doing and when?
You say choking, is it not making more power on the dyno or struggling to rev to limiter?
 
Andy318ti said:
So what's the engine doing and when?
You say choking, is it not making more power on the dyno or struggling to rev to limiter?
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Well when trying to increase boost using the controller mid range goes up but at high rpm it still about the same so I’m thinking it must be excessive manifold pressure forcing the WG open ?
 
Needs a genuine gate before anything else then.
Can't see it choking probably just the wastegate spring will be weak, you could try the stiffer spring and see if it holds boost up top.
 
avalaugh said:
That’s a very good point, I only tested to 10psi as only had 1 clip large enough and the test rig would pop off at anything over that, I’m actually in the garage now with another clip the right size and going to test to 20psi.

I have an AEM TRUEBOOST controller, what I’ve found is by increasing the duty cycle in turn the spike increases also, and obviously I don’t want to break this engine as it’s still in the mapping process.

Using softer springs and increasing the duty cycle I found boost still dropping off in the higher RPM range as the WG was getting forced open.

The controller is installed correctly and the wastegate has no leaks in the top and a slight leak in the bottom from the bush the valve goes through, this leak is only present when parts are cold, once upto operating temps it is almost completely sealed.
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Hey man, with regards to your boost spike issue - the tru boost manual says to set the "SPR" value to 3PSI less than your spring.
give it a go
 
beat_core said:
Hey man, with regards to your boost spike issue - the tru boost manual says to set the "SPR" value to 3PSI less than your spring.
give it a go
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Yeah that’s for building boost, I’ve got it turned done as spool is plenty fast enough, basically it’s the value at which the duty cycle starts to operate at, below set value all pressure is diverted to the top of the gate to keep it closed.
 
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Hi all, so as my build comes to an end (long overdue) I'm getting more and more concerned with engine reliability. I'm running a Holset HY35 on my RB25 with the usual supporting mods, link G4+ ECU and stock internals. It's running a single scroll manifold and 3" downpipe. My tuner has said if I want the car to be reliable he wouldn't push past 1.2 bar which he also doesn't think my Holset will respond well to. Any opinions from guys that have run one?
 
Tuner is right regarding stock internals. Would set up a low boost on 0.8 bar and high boost on 1.2 bar if you can. You'd be surprised how nutty it will be on 0.8 bar.

But your tuner is fucking retarded if he thinks an HY35 wouldn't respond well over 1.2 bar. If you'd read any of this thread you'd know HY35's can run over 2 bar efficiently, and that 2.5L 6 cylinders and HY35's are suited so well they should have been a factory option

Who was the tuner out of interests sake? Not a Garrett dealer by chance?
 
I think ive confused you, he meant it would want more than 1.2 bar to be decent. So what will be the difference in "feel" between .8 bar and say 2. bar for example. Less lag, more power? I've just been told that 1.2 bar will be enough to make me "shit my pants" so that's filled me with some confidence
 
The dynamics of the turbo as it builds from 0 to 0.8 bar doesn't change when run it at 1.2 bar, 2 bar or even 3 bar. The response stays the same, just more power because the rev range that previously saw just 0.8 bar is now seeing more

The fun thing about Holset's is you can run big boy boost and they just laugh at you and say "is that it?"

But they still respond just as well as anything else on low boost applications. The only proviso i'll add here is controlling low boost does tend to be the trickiest part. So if you do get boost creep you need to look at what is causing the back pressure. Small wastegate, dump pipe, partially blocked cat, bad fit between manifold and turbine housing are all things worth looking at if you encounter that.
 
Ah ok that good to know.

Well I've port matched the exhaust manifold flange and the turbo mounting flange.

The internal gate has been welded shut and I'm running a Tial 44mm wastegate with .8 bar spring.

Decat exhaust so no cat.

Hopefully that's covers everything. I guess time will tell. Been building for 5 years so hope it'll be worth it
 
Sounds like you've got it covered. How is the wastegate vented? Is it plumbed back or vented to atmosphere, or have the ability to be temporarily removed?

If it you do strike control issues, and the wastegate is plumbed back, being able to remove the plumbed back section and run it vented to atmosphere temporarily to see if it is causing the issue is worth doing first.
 
Not finished the wastegate pipe yet but the plan is to vent to atmosphere. Mainly for noise. May consider plumbing it into the exhaust if/when I get fed up with it.
 
The holset I'm running on my car as 1.2 bar for low boost and 1.7 bar for high.

I dont use high very often as it's scary enough on 1.2 bar, so I think the HY will do just fine at that boost for you too.

I only have a dyno reading for high boost (posted a few pages back with the spec of the car), but the tuner told me it should be somewhere around the 520/530 mark for low. I'll need to get a dyno run done someday to verify this as best I can, but Id say the HY will be perfectly crazy at 1.2 bar aswell.

From what I've read online, holsets only really start becoming "efficient" past 25psi, so even on high mine is still only at that boundary!

Looks like a really well put together setup you have there. Definitely looking forward to seeing how it performs, I think you'll be fine! Send it!
 
Benkid said:
Not finished the wastegate pipe yet but the plan is to vent to atmosphere. Mainly for noise. May consider plumbing it into the exhaust if/when I get fed up with it.
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Sussed then. Post up the results when she's had a beating on the rollers
 
Love your build @Benkid, very well put together. If there are any issues with response or mid range first thing I'd do would be to change to a bigger downpipe. Difference between a 3" and 4" made to Martin Wonnacots 1JZ was crazy.
I'd say it'll be awesome tho
 
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