Jump to content
SAU Community

Recommended Posts

sorry guys, real quick q...

this is my tune:

dynoula220708.jpg

my hks adjustable actuator only goes down to 19psi... we tried all methods, its the lowest it will go... im running a stock dump/front... some ppl say its overboosting coz of that, some say it wont matter im sick of hearing bs, all i would love to know is if running 19psi n the occasional limiter bash at winton drifts next sat will be safe?

i ran this exact setup for a year n a half n a couple of weeks ago cracked first n 6th piston (looks like an over time thing)... i would rather not have a repeat of this if boost was the cause.

thankyou in advance!

emz

Link to comment
https://www.sau.com.au/forums/topic/233501-rb25det-hks2535-19psi-safe/
Share on other sites

I used to have the same setup on my R33 and to be safe I would turn the boost down on track days ad also run a quality octane boost.

Does it hold 19psi to redline? if it falls off towards the end of the rev range then it may not be to bad.

Is the motor built for 19psi?

why on earth would you run a larger turbo with std front and dump pipe?

no wonder you cant lower the boost, its trapped in the housing!!

change the front pipe/dump pipe even if you dont want more boost

We'll all heard this so many times from you...the solution to your overboosting is your stock dump...it has been told to you several times...whether or not it holds to redline is beside the point at this moment...

Now...as for 19psi at winton...its probably not the best idea...especially if your high boost is a result of a restriction...people usually wind boost down a few psi for safety at the track...couple of laps at WOT will have EGTs through the roof as well...and then risk of detonation will be another issue...its a bad idea if you ask me...and is an accident waiting to happen...

i had 2 different 3" dump/fronts

both different brands (i wont mention on the forums) one was the split n other the bellmouth design and both warped.. one from the turbo/dump n the other from the front/cat.

f**k buying cheap 300 shit.

does that answer ur question? sorry i dont mean to be rude but as a student i cant just go off n buy expensive shit, especially not a week before winton lol.

im just really after a quick fix for next weekend, then might sell my recaro seats n buy a proper jap dump/front.

cheers guys

first one was kinda my fault..

every1 warned me that the gaskets that came with the kit WERE SHITHOUSE... but some people said they will be fine. so instead of going to nissan n getting some, i just used the ones that came from the kit... my fault coz i got lazy.

2 weeks later, gasket failed, exhaust leak for a day or 2... ordered gaskets off nissan, pulled the dump off n realised the metal warped, no chance it was going back on so i returned it.

different brand kit, used the nissan gaskets... this time warped from the front/cat... looks like it was caused by shitty welding.

till this day i havnt heard anything bad about the jjr items... can they be trusted?

Edited by DjeMz

Well, I bought the Xforce bellmouth in mild steel and its been a treat for the almost 2 years i've had it.

Maybe get one fabbed up for you at a reputable exhaust shop. Shouldn't cost you a great deal more and at least you know the quality will be good. But yes being a student and funds and stuff etc etc....

That boost and those a/f ratios at the top end; you're asking for trouble.

RB25's are known to have weak ring-lands and the boost and leanness of the tune will generate more heat which can cause issues. I personally wouldn't risk it.

I consider anything over 12:1 a/f ratios, on a std RB25 and doing track days a BIG risk.

I ran 18psi, with 11.5:1 a/f ratios and still managed to crack a ring-land, pics below. All other components were in top nick, even the piston top, bore, etc of the cracked piston where completely undamaged.

Don't worry about split pipes or stainless; just get a custom made bell-mouth mild steel dump from a good exhaust shop. Should not cast you too much.

post-1811-1219909462_thumb.jpg

post-1811-1219909476_thumb.jpg

^^^ thats exactly wat happened to my old 25...

"I consider anything over 12:1 a/f ratios, on a std RB25 and doing track days a BIG risk."

drifting at winton isn't as bad as circuit, we do a few corners n line up for 5-10 mins then go out again...

i need something asap before winton, im not going to risk my new motor over it..

Edited by DjeMz
^^^ thats exactly wat happened to my old 25...

"I consider anything over 12:1 a/f ratios, on a std RB25 and doing track days a BIG risk."

drifting at winton isn't as bad as circuit, we do a few corners n line up for 5-10 mins then go out again...

i need something asap before winton, im not going to risk my new motor over it..

If your short of the $$, maybe someone close by to you would be willing to let you borrow one for a short time. Otherwise, maybe you'd want to check the for sale threads, there's cheap second hand goodies in there.

That boost and those a/f ratios at the top end; you're asking for trouble.

RB25's are known to have weak ring-lands and the boost and leanness of the tune will generate more heat which can cause issues. I personally wouldn't risk it.

I consider anything over 12:1 a/f ratios, on a std RB25 and doing track days a BIG risk.

I ran 18psi, with 11.5:1 a/f ratios and still managed to crack a ring-land, pics below. All other components were in top nick, even the piston top, bore, etc of the cracked piston where completely undamaged.

Don't worry about split pipes or stainless; just get a custom made bell-mouth mild steel dump from a good exhaust shop. Should not cast you too much.

Its not the afr's that kill the engine ................... it doesn't matter if you have a "richer tune" if it detonate's it will do more damage with rich tune than a lean tune.

Maybe your solution is to fit a better dump pipe then check / retune or not fit the dump and get a safer tune ?

I am not suggesting your tuner did not tune it safe but if you don't want to blow another cheap shit rb25 then get it detuned.

Its not the afr's that kill the engine ................... it doesn't matter if you have a "richer tune" if it detonate's it will do more damage with rich tune than a lean tune.

Maybe your solution is to fit a better dump pipe then check / retune or not fit the dump and get a safer tune ?

I am not suggesting your tuner did not tune it safe but if you don't want to blow another cheap shit rb25 then get it detuned.

That's right, but a lean tune creates more heat, more boost creates more heat, this setup has both. What can promote detonation? You guessed it..................HEAT.

May be alright on the dyno, but on the track and under the car's own load, detonation may occur. I would consider that top end tune unsafe for a "built engine" let alone a std one. Holding 19psi to red-line ain't doing it any favours too.

Just a second thought though :(

-If the dump is restrictive doesn't that slow down the exhaust gasses, so shouldn't the turbo be creating less boost than expected or at least dropping off dramatically?

- Just thinking whether the car may have another issue :)

Personally i would give this event a miss, knowing my car is not running properly. Can you afford possibly blowing another rb25? Is this event that important to risk all?

Just saw you sig, so obviously this Winton day is important to you.

Having my car at DECA, on my 30th B'day was important to me too, but that didn't happen; knowing now that my car is 100% ready and working perfectly is more important. There will be other events and other B'days, hell i was glad i didn't have it, as i would have had to drive it back the next morning :(

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

    • I had absolutely no symptoms whatsoever that anything was wrong.... I'm very happy it was all spotto'd and re-bled and re-torqued and aligned though. Will be picking it up tomorrow and undoubtedly be like "Oh, that clunk is gone" "Oh, the car really wants to drive straight" "Oh, that pedal feels better" "Oh, it feels like I've gained 25hp" "Oh, the handbrake works now" It should have been a sign that the new Project Mu shoes had 3mm of pad depth on them out of the box, and the OEM ones from 25 years ago that we took out also had 3mm of pad depth, implying the issue was not, and never was the shoes, but we put that down to it not being adjusted correctly. It wasn't, but it wasn't even adjustable at all given one side was boned and the T Junction of the cables was on a 45 degree angle, the non-working side being the one on the massive angle. Obviously when I had adjusted it and reset it and re-tensioned it I had either got it stuck or something along those lines. Oh well. Live and learn and absolutely could have been catastrophically worse so I'm rationalizing it as a win, kinda. I also got the chance to measure the distance between rear rim and the suspension arm/shocks and found a 30mm rubber block only just doesn't fit there. Which is great to know before ordering wheels, when I assumed 30mm was easy. The man with the Porsche adapters has rims that use 23.9mm of that space, so it's safe to assume I have between 23.9 and 29.9mm of space there to play with on the inside. The wheels looked pretty stupidly pokey with the 20mm spacers on the rear, only for me to find that the studs come out another 12mm and the wheel doesn't actually sit flush with the hub because you're supposed to cut your original studs. The wheels do have cutouts that kinda accomodate it, but not fully. So my 20mm spacer was anywhere between 25mm and 35mm. ~25mm and send it will determine on where the wheels sit with the spacers on. When I put the pads in for the track day I will mess around with spacers (with wheels that do not clear studs properly when mounted to spacers) and do more math, for the last time, for the 7th time.
    • Lucky pick up Best to find these things before something horrible happened to the yoke flange thingies I would hate to think what would happen if it dropped the tailshaft  Hopefully the holes are not flogged out in the yokes and it was just the bolts that got munted  As for the hand brake.....ouch, look like the disc got rather hot, and I assume smokey, I recall when I had a front caliper seize on the Commodore, there was lots of smoke and the disc was glowing cherry red when I was able to eventually stop and have a look, and stopping a big heavy car, going down a big hill with some rather high RPM down shifts and some hand brake action is something that makes you think hard about life
    • One of the things that never seemed right was the handbrake. Put in some nice new Project Mu shoes. We figured the rears were out, so why not. We're right there. My handbrake never worked well anyway. Well, this is them, 15km later. 67fdcf94-9763-4522-97a4-8f04b2ad0826.mp4 Keen eyes would note the difference in this picture too:   And this picture: Also, this was my Tailshaft bolts: 4ad3c7dd-51d0-4577-8e72-ba8bc82f6e87.mp4 It turns out my suspicions that one side of the handbrake cable was stretched all along were pretty accurate, as was my intuition that I didn't want to drop the tailshaft to swap them on jack stands and wasn't entirely sure about bolt torque. I have since bought the handbrake cables which have gone in. I'm very glad that I went to my mechanic friend who owns an alignment machine to get an alignment before the track day, because his eyes spotted these various levels of "WHAT THE f**k IS GOING ON HERE?". Turns out the alignment wasn't that bad, considering we changed the adjustable castor arms out for un-adjustable castor arms, and messed with the heights. Car drove pretty good with one side of the handbrake stuck on, unbleedable rear brakes, alignment screwy, and the tailshaft about to go flying and generally being a death trap waiting to happen! (I did have covid) (I maintain I adjusted the handbrake correctly, but movement caused shennanigans and/or I dislodged the spring on the problem side somewhat, or god knows what). G R E G G E D
    • Very interesting, im not sure how all those complications fit in to running a haltech instead of a stock ecu but I'm starting to think I'm a bit out of my league.
    • I just put 2 and 2 together. This is a Neo converted R32. The Neo ECU (in concert with the R34's AC controller) runs the AC quite differently to how the R32 ECU and AC controller do it. If you just drop it all in, it won't work. There is some tricky wiring required, including changing to the pressure switch that the Neo controllers want to see. I don't know what it is, because mine was done by a guru. It was a year or so after I did that transplant before he worked out what needed to be done.
×
×
  • Create New...