Jump to content
SAU Community

Recommended Posts

Hi, I hope the following post will make sense, as I’m quite disturbed to write.

Recently I did a turbo swap on my RB20. I put a RB25 turbo which was in good condition. From what other ppl said, the RB25 turbo makes 10 – 20 rwkw more than the stock one.

I just had a few runs with my mate, laser with mazda-familia engine, and he was beating me more than before the turbo swap.

He ran a 14.1 at the creek and he is a consistent driver, so all the times are within 1 sec. Before the turbo swap he would be beating me 1 – 2 car lengths but this time he got me 3 – 4 car lengths. His setup hasn’t changed at all.

My car is R32 – auto with only a pod and RB25 turbo. It’s running 9 psi.

I didn’t put the car on the dyno before the conversion so the only means of comparing the power output is against his car, and so far it doesn’t look good. I was hoping to at least even out with him, with the new turbo setup.

Also, I got a 0 – 100 km/h option on my turbo timer and even that is showing I’m about 1 sec slower than before.

I'm almost tempted to put the old turbo back on and go for a power run on the dyno.

Does anyone have any ideas why would my car go slower than before and how to fix it?

Please HELP!!!

you are only running fairly low boost.. the point at which the rb25 turbo hits its efficiency range on the rb20 may be different to the stock turbo, so that could be the situation.

Have you had it tuned since the upgrade? its not going to give an instant 10-20rwkw just by sticking it on, without the appropriate tune.

Thanx for the replies guys

predator:

i haven't had it tuned yet, i'm waiting till my new exhaust goes in.

i was under impression that i should get more power from the turbo upgrade even on stock boost but maybe i was wrong. I hope it's just that and not some other problem.

Jay95R33:

I’m running the rb20 actuator, so 9 psi. I don’t have the boost controller yet but getting one.

meggala:

I did try to run him rolling start as well but he was still pulling away. Quite different from the stock turbo, coz then he would have an advantage at the start, up to 100 km/h where our speeds would be about the same and I’d start catchin up, but now he gets ahead at the start and stays there, maybe even keeps pulling away. Very annoying.

does anyone else have any ideas?

ppl who have done this conversion, what were your results on stock boost with rb25 turbo compared to the stock boost with rb20 turbo and on the increased boost with both?

I've had a VG30 on my RB20t and even though it made more power in the top end general street use was much slower than the boosted RB20t turbo.

First gear with the vg30det sucked arse. It felt like it was soo hard to make it make some decent boost.

I've been in a blokes car who was running a RB25 turbo. He pumped in around 13-14psi.

My 164rwkw RB20DET felt like it had a stronger mid range and accelerated quicker, BUT it wouldn't keep pulling past 7000rpm like the the rb25det turbo would.

I wasn't happy with the mid range from the rb25t turbo on the rb20det so I decided to scrap the whole idea of spending $$ on a turbo for the rb20det. Hence the build up of my rb30det.

The rb20det with the stocker turbo running 16psi would get me to 100km/h in a shade over 5secs with a real clean launch. A bad launch would typically be in the mid to high 5sec range.

The VG30 turbo only lasted 3 days before I pulled it off and put back the rb20t turbo.

Its the power to peak power that accelerates the car not the peak power. :D

You will find with the setup you have now the rb20t turbo gave you more average power over the usable RPM than what the rb25t turbo does.

Keep pumping boost in to it until it fuel cuts then back it off a little. :D

BUT make sure you have an aftermarket fuel pump, you wouldn't want the stocker leaning out.

Then throw it on a dyno for a power run (~$40) and make sure the AFR's are not leaning out. If so just back boost off a little :)

Also... you may have some restriction in the exhaust somewhere as my rb20t only ever made 8-9psi with the stock exhaust and stock fist sized cat convertor.

As soon as I had the exhaust fitted boost raised to 10.9psi.

Do yourself a favour and get a 3 inch exhaust from the dump or including dump. You cant expect the turbo to be working at its best if it cant breath properly. 9psi did nothing for me with the rb25 turbo. It really starts to howl once over 11psi.

Before you start winding the boost up though, get your AF ratios checked on the dyno.

Doc

I have a rb25 turbo on my r32 and make 180-190rwkw depending on the day. I also have hks super dragger zorst, dump, chip remap, pod, fmic, blitz sbc iD. I run 14psi.

It is a bit laggier than the stocker obviously and the power delivery is different, its more progressive than all at once like the stocker. Pulls much harder up top than the stocker did.

Thanx guys on the replies.

I'm planning to get the exhaust done this weekend - turbo back and then on the dyno, to be safe before i boost it up.

Can anyone recommend any exhaust shops in sydney, preferably west but not essential.

Also, dyno places?

Thanx.

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 know why it happened and I’m embarrassed to say but I was testing the polarity of one of the led bulb to see which side was positive with a 12v battery and that’s when it decided to fry hoping I didn’t damage anything else
    • I came here to note that is a zener diode too base on the info there. Based on that, I'd also be suspicious that replacing it, and it's likely to do the same. A lot of use cases will see it used as either voltage protection, or to create a cheap but relatively stable fixed voltage supply. That would mean it has seen more voltage than it should, and has gone into voltage melt down. If there is something else in the circuit dumping out higher than it should voltages, that needs to be found too. It's quite likely they're trying to use the Zener to limit the voltage that is hitting through to the transistor beside it, so what ever goes to the zener is likely a signal, and they're using the transistor in that circuit to amplify it. Especially as it seems they've also got a capacitor across the zener. Looks like there is meant to be something "noisy" to that zener, and what ever it was, had a melt down. Looking at that picture, it also looks like there's some solder joints that really need redoing, and it might be worth having the whole board properly inspected.  Unfortunately, without being able to stick a multimeter on it, and start tracing it all out, I'm pretty much at a loss now to help. I don't even believe I have a climate control board from an R33 around here to pull apart and see if any of the circuit appears similar to give some ideas.
    • Nah - but you won't find anything on dismantling the seats in any such thing anyway.
    • Could be. Could also be that they sit around broken more. To be fair, you almost never see one driving around. I see more R chassis GTRs than the Renault ones.
    • Yeah. Nah. This is why I said My bold for my double emphasis. We're not talking about cars tuned to the edge of det here. We're talking about normal cars. Flame propagation speed and the amount of energy required to ignite the fuel are not significant factors when running at 1500-4000 rpm, and medium to light loads, like nearly every car on the road (except twin cab utes which are driven at 6k and 100% load all the time). There is no shortage of ignition energy available in any petrol engine. If there was, we'd all be in deep shit. The calorific value, on a volume basis, is significantly different, between 98 and 91, and that turns up immediately in consumption numbers. You can see the signal easily if you control for the other variables well enough, and/or collect enough stats. As to not seeing any benefit - we had a couple of EF and EL Falcons in the company fleet back in the late 90s and early 2000s. The EEC IV ECU in those things was particularly good at adding in timing as soon as knock headroom improved, which typically came from putting in some 95 or 98. The responsiveness and power improved noticeably, and the fuel consumption dropped considerably, just from going to 95. Less delta from there to 98 - almost not noticeable, compared to the big differences seen between 91 and 95. Way back in the day, when supermarkets first started selling fuel from their own stations, I did thousands of km in FNQ in a small Toyota. I can't remember if it was a Starlet or an early Yaris. Anyway - the supermarket servos were bringing in cheap fuel from Indonesia, and the other servos were still using locally refined gear. The fuel consumption was typically at least 5%, often as much as 8% worse on the Indo shit, presumably because they had a lot more oxygenated component in the brew, and were probably barely meeting the octane spec. Around the same time or maybe a bit later (like 25 years ago), I could tell the difference between Shell 98 and BP 98, and typically preferred to only use Shell then because the Skyline ran so much better on it. Years later I found the realtionship between them had swapped, as a consequence of yet more refinery closures. So I've only used BP 98 since. Although, I must say that I could not fault the odd tank of United 98 that I've run. It's probably the same stuff. It is also very important to remember that these findings are often dependent on region. With most of the refineries in Oz now dead, there's less variability in local stuff, and he majority of our fuels are not even refined here any more anyway. It probably depends more on which SE Asian refinery is currently cheapest to operate.
×
×
  • Create New...