Jump to content
SAU Community

Want more KW out of my RB20DET

HR31GT

By HR31GT,
in Engines & Forced Induction

 Share

Recommended Posts

HR31GT Contributor

HR31GT

Posted
Posted

I have HR31 Pasage gt serIII, with eccs rb20det, auto, 3", big fmic, 2.5" cooler piping,hks air pod, just recently installed a boost controller and upped it to .9bar, and its a bit laggy but it hits at 3000rpm. Looking to get more go(especcially more torque and bottom end_as funny as that sounds) out of it and thinking of either getting my ecu remapped, put an rb25det turbo, or fmac. And also as I live in brisbane it would be good to know any workshops that dynotune and have much experience with rb20's any help would be appreciated. Any ideas guys as i'm sure we all go through same stages........

Link to comment
https://www.sau.com.au/forums/topic/29275-want-more-kw-out-of-my-rb20det/
Share on other sites
Cubes Grand Master

Cubes

Posted
Posted

HR31GT,

So you have the older RB20DET. From memory it has a 248duration inlet cam which gives slightly more top end but causes the bottom end to be gutless. The R32 RB20DET has a 240duration inletcam and a 240duration exhaust cam, I guess this is why the new R32 RB20DET apparently has a little more poke down low and in the mid.

You could try fiddling with a set of R32 cams in it.

Some time ago a few people fiddled with R32 RB20DET NA cams. The only difference is that the inlet cam is a 232 duration which gives more bottom end and slightly more mid range. The car will be faster on the road even though it may pull a few kw's from the peak power figure.

If I were keeping my RB20DET I would slap a 232duration R32 RB20DE cam in to it and leave the exhaust cam the way it is or if I had the money to spend $400 or so on an exhaust cam I would go the 256 duration just to open up the top end a little more. Slap on a RB25DET turbo and pump 17psi in to it.

The only problem with the RB20DET's is lag when you want to make big power, some times even though you end up making more peak power the street speed will be slower.

HR31GT Contributor

HR31GT

Posted
  • Author
Posted

It does have eccs silver top rb20det in it,,,,,,,also i just been rising the boost and it seems to have a boost cut at around 0.8bar, is that normal....unless i unhook the factory bleed valve it wont go over 0.8bar, but if i unhook it starts to idle lower and it dont seem to be right.....any answers on that???

Cubes Grand Master

Cubes

Posted
Posted

nope its not normal to have a boost cut at .8bar unless you are running the non-silver top RB20DET ECU?!?!? Not sure on that one though.

My boost cut is up around 18psi.. It vary's with the day. On a warmish normal day it is around 18psi where as on a cold night if you wind out third or fourth depending how cold it is she will boost cut on 16psi. Damn scary when it does as you think you have broken some thing.

I've bumped my boost up to first 16psi and now i've gone to 17psi which pulls rather hard until around 5500rpm where boost starts to drop to 12.5psi.

I'm also running around 22degree's timing which makes a big difference to power delivery.

Unless your AFM is playing funny buggers causing the boost cut.

I'm not sure what it is with mine but every now and again it appears that boost rises and as it does the power delivery is not smooth. The power feels like it dips then picks up again. If I pull over and remove the AFM plug wiggle it around then plug it back in again all is normal?!?!

MM2death Grand Master

MM2death

Posted
Posted
My boost cut is up around 18psi.. It vary's with the day. On a warmish normal day it is around 18psi where as on a cold night if you wind out third or fourth depending how cold it is she will boost cut on 16psi. Damn scary when it does as you think you have broken some thing.

My 32 is exactly the same.

Scott

WazR32GTSt Grand Master

WazR32GTSt

Posted
Posted
HR31GT,

So you have the older RB20DET. From memory it has a 248duration inlet cam which gives slightly more top end but causes the bottom end to be gutless. The R32 RB20DET has a 240duration inletcam and a 240duration exhaust cam, I guess this is why the new R32 RB20DET apparently has a little more poke down low and in the mid.

You could try fiddling with a set of R32 cams in it.

Some time ago a few people fiddled with R32 RB20DET NA cams. The only difference is that the inlet cam is a 232 duration which gives more bottom end and slightly more mid range. The car will be faster on the road even though it may pull a few kw's from the peak power figure.

If I were keeping my RB20DET I would slap a 232duration R32 RB20DE cam in to it and leave the exhaust cam the way it is or if I had the money to spend $400 or so on an exhaust cam I would go the 256 duration just to open up the top end a little more. Slap on a RB25DET turbo and pump 17psi in to it.

The only problem with the RB20DET's is lag when you want to make big power, some times even though you end up making more peak power the street speed will be slower.

pumping 17psi into the rb25 turbo with its ceramic exhaust wheel is asking for trouble... they are only good at 14psi or below so keep that in mind

Cubes Grand Master

Cubes

Posted
Posted

What is the killer of the ceramic exhaust wheel?

Overspeed is no. 1 and then excessive heat/detonation.

When you increase the engine RPM the engine requires more airflow. As the engine RPM increases so does the turbo's shaft speed in order to keep up with airflow demand. An RB20 consumes less air than a RB25 so for a set boost pressure the turbo spins slower on the RB20 than it does the RB25. In turn this gives you a little more head room to run more boost and possibly match the air flow to make as much power as the turbo did on the RB25.

The other problem that blows the ceramic exhaust turbine is excessive heat. This is caused by running around a track flat out. I've heard of ceramic turbo's blowing with simply 12psi in this instance.

The japs have been doing it for some time now. 1.1-1.2bar on stock turbo's.

I initially had mine tuned at 15psi then I bumped it up to 16psi. For the last year i've been running 17psi. Although that 17psi is only up to 5500rpm where boost starts to drop down.

It also comes down to the turbo its self. Some times you get a good one some times you get a crappy one.

I've had the car for over 2 years now and racked up 60,000km's with the turbo pumping 1.1-1.2bar for a majority of the time.

When a car detonates it can also blow your turbo as its possible for a bit of spark plug to break off and smash in to the exhaust wheel. It all comes down to tuning and ensuring there is enough fuel around to keep things cool.

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
 Share
Go to topic listing


  • Similar Content

  • Latest Posts

    • MissMintyR33
      R33 persistent issues. P/steering and lag/misfire

      By MissMintyR33 · Posted

      I thought that might be the case, thats what I'll start saving for. Thanks for the info 
    • jtha7
      Strange issue RB25DET wont start

      By jtha7 · Posted

      Ps i found the below forum and it seems to be the same scenario Im dealing with. Going to check my ECU coolant temp wire tomorrow    From NICOclub forum: s1 RB25det flooding at start up Thu Apr 11, 2013 7:23 am I am completely lost on this. Car ran perfectly fine when I parked it at the end of the year. I took the engine out and painted the engine bay, and put a fuel cell with an inline walbro 255 instead of the in tank unit I had last year. After reinstalling everything, the engine floods when the fuel pump primes. if i pull the fuel pump fuse it'll start, and as soon as I put the fuse back in it starts running ridiculously rich. I checked the tps voltage, and its fine. Cleaned the maf as it had some dust from sitting on a shelf all winter, fuel pressure is correct while running, but wont fire until there is less than 5psi in the lines. The fuel lines are run correctly. I have found a few threads with the same problem but no actual explanation of what fixed it, the threads just ended. Any help would be appreciated. Rb25det s1 walbro255 fuel pump nismo fpr holset hx35 turbo fmic 3" exhaust freddy intake manifold q45tb q45 maf   Re: s1 RB25det flooding at start up Fri Apr 12, 2013 5:07 am No, I didn't. I found the problem though. There was a break in one of the ecu coolant temp sensor wires. Once it was repaired it fired right up with no problems. I would have never thought a non working coolant temp sensor would have caused such an issue.
    • jtha7
      Strange issue RB25DET wont start

      By jtha7 · Posted

      Hi sorry late reply I didnt get a chance to take any pics (my mechanics on the other side of the city) but the plugs were fouled from being too rich. I noticed the MAF wasn't genuine, so I replaced it with a genuine green label unit. I also swapped in a different ignitor, but the issue remains. I've narrowed it down a bit now: - If I unplug and reconnect the fuel lines and install fresh spark plugs, the car starts right up and runs perfectly. Took it around the block with no issues - As soon as I shut it off and try to restart, it won't start again - Fuel pressure while cranking is steady around 40 psi, injectors have good spray, return line is clear, and the FPR vacuum is working. It just seems like it's getting flooded after the first start I unplugged coolant sensors to see if its related to ECU flooding but that didnt make a difference. Im thinking its related to this because this issue only started happening after fixing coolant leaks and replacing the bottom part of the stock manifolds coolant pipe. My mechanic took off the inlet to get to get to do these repairs. My mechanics actually just an old mate who's retired now so ill be taking it to a different mechanic who i know has exp with RBs to see if they find anything. If you have any ideas please send em lll give it a try. Ive tried other things like swapping the injectors, fuel rail, different fuel pressure regs, different ignitor, spark plugs, comp test and MAF but the same issue persists.
    • GTSBoy
      Freddy Plenum vs Genuine options RB25

      By GTSBoy · Posted

      My return flow is custom and puts the return behind the reo, instead of at the bottom. All my core is in the air flow, rather than losing some of it up behind the reo. I realise that the core really acts more as a spiky heatsink than as a constant rate heat exchanger, and that therefore size is important.... but mine fits everything I needed and wanted without having to cut anything, and that's worth something too. And there won't be a hot patch of core up behind the reo after every hit, releasing heat back into the intake air.
    • Murray_Calavera
      R33 persistent issues. P/steering and lag/misfire

      By Murray_Calavera · Posted

      There is a really fun solution to this problem, buy a Haltech (or ECU of your choice) and put the MAF in the bin.  I'm assuming your going to want more power in future, so you'll need to get the ECU at some stage. I'd put the new MAF money towards the new ECU. 
×
×
  • Create New...