Jump to content
SAU Community

Recommended Posts

I got an RB20 with a GT25R, so I know about lag aswell...

you say it kicks in bout 3500 and full boost bout 5000.. sounds very similar to my car. I'm not sure you have done anything wrong, it may just be down to the fact that the turbine is abit small for the compressor to be responsive.

I bought a SII RB25 turbo to put onto my car, as I'd prefer abit less power with more response (i'm into drifting, so it makes sense to have more usable power..

Although in saying all this, The GT25R I have would be a ripper turbo for a drag GTS-t or even better on an RB25. The turbo you have will probably make buttloads of power aswell, although only in the top end.

  • Replies 52
  • Created
  • Last Reply

Top Posters In This Topic

Top Posters In This Topic

Posted Images

Thanks for the input dude, I did check whe I hooked it up but may be something to look at (plus I can get to it while it is in there). I am also going to check for boost leaks because I have a feeling that may have something to do with it...

Cheers,

Todd

Check the actuator is not the problem, being too long and holding the wastegate open.

Did you check that before you put the turbo on? I had a GCG on my 2.5 and it was as laggy as you describe, turned out the wastegate was being held open. Fixed that up, now nice and responsive.

lag is fun anyway.

Not as fun as a responsive turbo!

I hate not being able to stab it in third and get thrown back!!

I hate not being able to put my foot down in second coming out of a corner and get the back end out!!!

I hate lag!!!! :(

Unless there is something wrong that I can fix, its coming out!

BTW: the turbo has a fast ticking noise down low (even when revving while stationary) and then once it hits boost, it has a real high pitched whur/scream - almost sounds electronic)

I am just putting this down to larger wheels, larger turbo... Any suggestions?

I am going to take it to some mates that know their stuff and see what they think...

Edited by CATKICKER
BTW: the turbo has a fast ticking noise down low (even when revving while stationary) and then once it hits boost, it has a real high pitched whur/scream - almost sounds electronic)

I am just putting this down to larger wheels, larger turbo... Any suggestions?

I am going to take it to some mates that know their stuff and see what they think...

Id say you turbo is worn out, that screaming noise when it comes on boost ids most probably the compressor wheel rubbing against the comp cover (not good).

I d check it out for shaft play.

Have just had another look at it tonight.

The wastegate is definatly closing all the way (I can hear in when I pull the actuator arm manually).

When revving it in the garage, the ticking sound (only way I can think to describe it, kinda sounds like a big 308 - almost sounds like it is running rough, but it isn't).

I am pretty sure it is going to be the gasket between the manifold and the turbo leaking somehow as that is where the sound seems to be coming from (stuck a bit of tube to my ear and then around the turbo area to get a presise area where it was)... I tried to tighten it but really wasn't able to get any more out of the bolts.

I think I will run it past one of the performance mechanics down here and see what they think! Not looking forward to having to take it off again but will have no choice if that is the case. Might take it out and sell it to get something a little less laggy.

Can anyone tell me what the symtoms of a leaking turbo gasket are? sound I am guessing but what else? Will I be losing responce / power? Cough a little when streching out?

Thanks for all the suggestions and comments guys, it all helps and is much appreciated!

Todd

Edited by CATKICKER

my issue will have the following symptoms

- semi silent turbo on idle

- on slight slight throttle, there will be a rattle in the dump pipe/turbo area

- once 0psi+ is reached, the rattle (its like, small bearings in a can being rattled) goes away.

The noises you describe sound like a manifold to turbo gasket leak..... you did change it right when you changed the turbo??

I think your paying the price of buying something without knowing the specs.

You can see that the turbine housing has been milled out a silly amount to fit that exhaust wheel in there.

I wouldnt be surprised if it came off an RB30

I believe it came off an RB25 and was then hiflowed... Yeah, I noticed that the exhaust wheel was pretty friggin big!! Can't believe they fit it in!

Will be nice to see how it goes if it indeed is the gasket.

I will get a pro opinion and update.

Is there a best place to get the gasket? How much should I expect to pay? (Standard t3 I am guessing?)

Hmmm, the turbo looks a little like my one i have waiting to go on my RB20. Reading your restults of your new turbo have got me worried about my new one, i really want to avoid too much lag as my car is a daily driver.

Here are some pics of my "hybrid" turbo, its a HT18 front off a RX7 series 4/5 with a rb20 rear housing on the back and the RX7 steel wheel that has been machined into the rear housing. Most people here would agree my turbo would probably have the same response as yours catkicker. Ill might sell mine now, anyone want a fresh'ly rebuilt turbo :ermm: i couldnt handle full boost by 5000rpm

DSC00096.jpg

DSC00097.jpg

Edited by Ceffy_SA

Obviously I don't know that much about turbos however the compressor housing is a lot smaller... still could be laggy though. I am getting used to mine now and have booked it in for a checkup tomorrow to find the problem (have been told it sounds like the gasket as expected!)

Not any good for drifting or stop and start but top end power is huge! Probably give it a bit just for the love and see if I get sick of it...

Well... I took it to the mechanics today and had then run their eye over it. They told me that the turbo was too big for the car (as I already knew) and that there was a leak between the manifold and the turbo.

Ah hah... there we go!

soooo, I got pissed off with it on the way home so decided to cut a little sik!

I pulled it apart again and unbolted the turbo from the manifold (2hrs). I then found that the bottem left had pooed itself and there was nothing there, so I grabbed my gasket silicone and dropped it like it was hot!

Result, well at this stage I do not have anything to go on other than driving it from the garage to the cold outside (because I wanted to let the goop cure) however there was no leaking.

I will take it to work tomorrow and give it some stick on the way home and update... Fingers crossed!!

Well... I took it to the mechanics today and had then run their eye over it. They told me that the turbo was too big for the car (as I already knew) and that there was a leak between the manifold and the turbo.

Ah hah... there we go!

soooo, I got pissed off with it on the way home so decided to cut a little sik!

I pulled it apart again and unbolted the turbo from the manifold (2hrs). I then found that the bottem left had pooed itself and there was nothing there, so I grabbed my gasket silicone and dropped it like it was hot!

Result, well at this stage I do not have anything to go on other than driving it from the garage to the cold outside (because I wanted to let the goop cure) however there was no leaking.

I will take it to work tomorrow and give it some stick on the way home and update... Fingers crossed!!

Will be good to see how it goes now, hopefully you will have reduced turbo lag

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

    • As discussed in the previous post, the bushes in the 110 needed replacing. I took this opportunity to replace the castor bushes, the front lower control arm, lower the car and get the alignment dialled in with new tyres. I took it down to Alignment Motorsports on the GC to get this work done and also get more out of the Shockworks as I felt like I wasn't getting the full use out of them.  To cut a very long story short, it ended up being the case the passenger side castor arm wouldn't accept the brand new bush as the sleeve had worn badly enough to the point you could push the new bush in by hand and completely through. Trying a pair of TRD bushes didn't fix the issue either (I had originally gone with Hardrace bushes). We needed to urgently source another castor arm, and thankfully this was sourced and the guys at the shop worked on my car until 7pm on a Saturday to get everything done. The car rides a lot nicer now with the suspension dialled in properly. Lowered the car a little as well to suit the lower profile front tyres, and just bring the car down generally. Eternally thankful for the guys down at the shop to get the car sorted, we both pulled big favours from our contacts to get it done on the Saturday.  Also plugged in the new Stedi foglights into the S15, and even from a quick test in the garage I'm keen to see how they look out on the road. I had some concerns about the length of the LED body and whether it'd fit in the foglight housing but it's fine.  I've got a small window coming up next month where I'll likely get a little paint work done on the 110 to remove the rear wing, add a boot wing and roof wing, get the side skirt fixed up and colour match the little panel on the tail lights so that I can install some badges that I've kept in storage. I'm also tempted to put in a new pair of headlights on the 110.  Until then, here's some more pictures from Easter this year. 
    • I would put a fuel pressure gauge between the filter and the fuel rail, see if it's maintaining good fuel pressure at idle going up to the point when it stalls. Do you see any strange behavior in commanded fuel leading up to the point when it stalls? You might have to start going through the service manual and doing a long list of sensor tests if it's not the fuel system for whatever reason.
    • Hi,  Just joined the forum so I could share my "fix" of this problem. Might be of use to someone. Had the same hunting at idle issue on my V36 with VQ35HR engine after swapping the engine because the original one got overheated.  While changing the engine I made the mistake of cleaning the throttle bodies and tried all the tricks i could find to do a throttle relearn with no luck. Gave in and took it to a shop and they couldn't sort it. Then took it to my local Nissan dealership and they couldn't get it to idle properly. They said I'd need to replace the throttle bodies and the ecu probably costing more than the car is worth. So I had the idea of replacing the carbon I cleaned out with a thin layer of super glue and it's back to normal idle now. Bit rough but saved the car from the wreckers 🤣
    • After my last update, I went ahead with cleaning and restoring the entire fuel system. This included removing the tank and cleaning it with the Beyond Balistics solution, power washing it multiple times, drying it thoroughly, rinsing with IPA, drying again with heat gun and compressed air. Also, cleaning out the lines, fuel rail, and replacing the fuel pump with an OEM-style one. During the cleaning process, I replaced several hoses - including the breather hose on the fuel tank, which turned out to be the cause of the earlier fuel leak. This is what the old fuel filter looked like: Fuel tank before cleaning: Dirty Fuel Tank.mp4   Fuel tank after cleaning (some staining remains): Clean Fuel Tank.mp4 Both the OEM 270cc and new DeatschWerks 550cc injectors were cleaned professionally by a shop. Before reassembling everything, I tested the fuel flow by running the pump output into a container at the fuel filter location - flow looked good. I then fitted the new fuel filter and reassembled the rest of the system. Fuel Flow Test.mp4 Test 1 - 550cc injectors Ran the new fuel pump with its supplied diagonal strainer (different from OEM’s flat strainer) and my 550cc injectors using the same resized-injector map I had successfully used before. At first, it idled roughly and stalled when I applied throttle. Checked the spark plugs and found that they were fouled with carbon (likely from the earlier overly rich running when the injectors were clogged). After cleaning the plugs, the car started fine. However, it would only idle for 30–60 seconds before stalling, and while driving it would feel like a “fuel cut” after a few seconds - though it wouldn’t fully stall. Test 2 – Strainer swap Suspecting the diagonal strainer might not be reaching the tank bottom, I swapped it for the original flat strainer and filled the tank with ~45L of fuel. The issue persisted exactly the same. Test 3 – OEM injectors To eliminate tuning variables, I reinstalled the OEM 270cc injectors and reverted to the original map. Cleaned the spark plugs again just in-case. The stalling and “fuel cut” still remained.   At this stage, I suspect an intermittent power or connection fault at the fuel pump hanger, caused during the cleaning process. This has led me to look into getting Frenchy’s fuel hanger and replacing the unit entirely. TL;DR: Cleaned and restored the fuel system (tank, lines, rail, pump). Tested 550cc injectors with the same resized-injector map as before, but the car stalls at idle and experiences what feels like “fuel cut” after a few seconds of driving. Swapped back to OEM injectors with original map to rule out tuning, but the issue persists. Now suspecting an intermittent power or connection fault at the fuel pump hanger, possibly cause by the cleaning process.  
×
×
  • Create New...