[rogue5861]

Well here goes.
I'm new to turbo vehicles, an my patrol being the only diesel I've owned I have a few questions regarding increasing power of the great little motor Nissan made for us. I owned an r31 rb30e 5 speed skyline, that had guts but would drink the juice, is why I purchased the rd28t over the 3ltr.

I have just ordered an egr plate which should remove some of the turbo "lag" that is there. I not expecting 0-100 in under 10s, just wanting to push a few more ponys out of the motor without masses of cash. I know I can add exhaust an snorkel an push a fair bit more, just don't have that sorta cash ready to spend yet.

Boost- How to increase with stock setup?
Boost gauge- Do I need one, if so where do I hook it up to in the engine bay?
Wastegate- What is it an what does it do?
BOV- Don't need the flutter, but I read stock one limited to 10psi, yes no an how to improve?

I'm pretty clever in working things out, just can't find much info on the gq 2.8t an increased performance. The patrol is a daily driver an a weekend get away as well. I won't be towing big loads so I'm not even thinking about the td42, just want to increase it a little bit for added comfort.

 

[rogue5861]

Well apparently I've worked out most of what I had asked. Spoken to a couple turbo heads an have explained most it.

Just wonder what the go is with the BOV. Why and what purpose do it serve? Would one with a flutter improve performance?

What boost gauge is of decent quality an not with a fortune, don't need a 5" gauge. Would prefer a smaller one I can put at the bottom of a pillar.

Cheers Rick.

 

[Roo72]

Your Diesel has no throttle (butterfly)...so it wont create the "flutter" noise you hear on petrol cars as you lift off the accelerator when on boost. The flutter is the residual boost trying to open the throttle against the return spring. The reason "throttled" intake systems use blow off valves is to vent the residual boost so it doesn't over pressurise the intake which causes the "flutter" but more importantly the pressure build up slows the compressor creating lag.
I think you have confused wastegates and Blow off valves(BOV) although some diesels have a BOV to prevent overboost.
The wastegate on your turbo would be set at a certain psi of intake pressure and when reached it will open and allow exhaust gases to bypass the turbo impeller limiting boost.
your other questions...
Boost- How to increase with stock setup?
a bleed valve will fool the wastegate into allowing more boost...BUT..and its a big but... you need to be careful. My 2.8 GU had a new head on it due to the previous owner playing with more boost.$4k later and he learnt an expensive lesson.
Boost gauge- Do I need one, if so where do I hook it up to in the engine bay?
I had an Autometer mechanical guage, it was ok but there are plenty of them out there including electric type ones which don't require a thin tube to be run from the engine bay to the guage to read intake boost pressure. some cheap units on ebay look pretty flash.

First thing to do to make it perform better is get rid of the stock exhaust and dump pipe...if it still has it... there are a few 2.8's on here running 3" systems with and without muffler for a worthy increase in driveability. the Search function is your best bet.

Cheers, Roo.

 

[rogue5861]

I've looked into exhaust an dump pipe. $1000 from beaudesert, 2 3/4 is apparently all that is needed. Coming into christmas time unfortunately don't have that just laying around. I think on the radiator end of the inlet manifold is the stock bov, doesnt look like it does anything tho lol. Read somewhere that not only is the wastegate psi limited to 10 so is the bov.

Turned up fuel a just under 1/4 of a turn an now is pushing alot harder then it was, just really increases fuel at higher rpm thus still letting it power through. Seems alot smoother from idle to 3500 rpm. Alot less lag. Apparently from factory they run very conservative on fuel.

Not planning on pushing boost up high or anything stupid, just gonna get it to 12 psi an leave it at that. Otherwise I will be asking for trouble without exhaust an intercooler. Even then its not a street car, just wanted a little bit more grunt.

So boost gauge then boost controller. Not gonna pay someone to tune it until zorst an ic goes on. Same thing as taking at diesel to a specialized diesel mechanics. Why pay him for a simple oil change?

Mounting a boost gauge to bottom of "A" pillar, are there pods that are pillar mountable suited to the GQ?

Cheers Rick

 

[rogue5861]

RD28T GQ Patrol soon to be converted. - Page 3 - Bio Fuels Forums

Post 25 has a picture of the BOV. Like it is said in this thread. Nissan shouldnt of called it a BOV, but yet a intake relief value.

So if anything to do with BOV, it should be taken out and blocked off. Dont need to increase PSI through there at all as the Wastegate is what will limit the PSI.

Learn something new every day.
Loving the little RD28T, fantastic motor.

 

[8MadDog8]

Im pretty sure most of this stuff has been covered before, so you could search for it easily enough.

What i did to get some more grunt out of the little engine:

Blocked off EGR

Fitted boost gauge (so you can actually see what the engine is getting)

Fitted beaudesert straight through exhaust (made a good improvement)

Fitted pyro gauge (to keep and eye on temps when upping the fuel)

Fitted boost controller (just a small manual one)

Removed the relief valve on the intake manifold and blocked it up

Increased fuel and therefore increased boost

Set boost to 13psi (personal preference)

Increased the fuel until it was running how i like and exhaust temps werent getting to high

Then after a while i added the intercooler and upped the fuel a bit more while keeping an eye on temps


And now im a lot more happy with the performance compared with how i got it

 

[rogue5861]

Did a search an couldn't find a whole lot of info on the gq rd28t, is why I made the post. There is no "bible" for the motor as you would know.

Upping fuel- does fuel economy go down by an awful lot when you have done exhaust an intercooler? What's your economy like now with what you have done. I seem to get about 700kms at stock.

Exhaust will come, just not sure when. Seems the biggest bang for buck.

Rick

 

[Goldtrol]

This is more for 8maddog8.

I have the 2.8 obviously and have already fitted the 3" straight through exhaust and blocked off the EGR. So I've taken alot of notice of this thread and have just ordered a boost gauge and boost controller from eBay (good quality stuff, the gauge is VDO and the controller is turbotech) and was wondering if you had some pics of your setup???

I've noticed that the factory set up has a line from the turbo outlet then a T piece, one going to the waste gate and the other to the boost compensator on the fuel pump and that's it. I'm wondering how you plumbed your gauge and controller in??

Also if you knew the thread of the bolt you replaced the manifold pressure relief valve with that'd save me stuffing around trying to get the right one.

Cheers

 

[lewie]

With mine i put another T piece up near the boost compensator and then ran the line into the cab for the boost guage. And then with the boost controller you will need some longer air line because the piece between the T piece at turbo outlet and the wastegate is quite small.

Extend that line so that you can mount the boost controller somewhere accessable and have the controller in line with that T piece and the wastegate.

 

[DeansyGQ]

Here's a few pics of mine if it helps anyone.

Cheers

 

[Goldtrol]

I farkin love this forum!!!!

Just what I was after lads, cheers. Only question I have is do I want the gauge AND the line going to the boost compensator after the boost controller???? Or either or??? Obviously the waste gate should be. That way the gauge and fuel pump know what the new pressure is??? Never done any "ricer" work before and wanna make sure.

Thanks again boys, more than helpfully as usual!!!

 

[Azotek]

Stock boost pressure on RD28T is 0,9bar(around 13psi?).
Relief valve on intake manifold is set to 1-1,1bar(15-16psi).

 

[lortapQG]

relief valve is there to stop you damaging things if wastegate fails/malfunctions and overboost occurs,

why would you remove it and block it off? (especially if above post is correct (15-16psi))

could understand if you were running 15 or more psi otherwise relief valve would activate only allowing (once again going off above post) 13psi.
i thought it was more like 10psi but any way figures are only for example

also the egr
"the exhaust gas recirculation (EGR)valve, when open,recirculates exhaust gases back through the inlet manifold to lower the combustion temperatures inside the engine."
question is, when is it open, and how often, does blocking this really give much difference? also if it does what its meant to do, engine temps would suffer, wouldn't they?
(understand how it opens and what it is controlled by just not when exactly)

 

[Matty T]

10psi is all it runs, gets to 14 and the relief valve vents (put a turbotech on the WRONG way around and had the turbo "free boosting" once, fixed that pretty quickly).

exhausts can be made up cheaper, doesnt need to be too fancy but kept up high. If you can find someone good at welding, get some 3" pipe, a flexi joint and a few flanges and im sure a system could be made up for around the 500 mark easily

 

[rogue5861]

How would piping hot exhaust into intake cause it to combust at lower temperatures?

Maybe I don't understand the egr as much as I thought. Thought it raised the temp/pressure on the exhaust, is why people say not to block egr before getting a pyro. Mine seems to be holding up. No increased internal temperatures and seems to hold revs a little bit higher between gears. As I'm not running exhaust or intake mods I will not be able to test it to it's full extent. When building a td42t people do not install egr's. They hinder performance if at all doing anything.

Egr was a shot at lowering emissions, but did no do the diesels any better for performance. I believe they have now removed them from the production line because of this reason.

Back pressure is essential, is why people don't put on 5" exhausts. More pressure on turbo exhaust side would cause it to drag more oxygen as is spinning turbines faster?

Like I said I'm no expert. Just a man looking at increasing the power safely on my patrol.

 

[lortapQG]

yeah i don't know ay, i just quoted that from the gregorys manual, the benefit i thought it had was by removing the egr it allows ALL the exhaust gases to pass by the turbo rather then AN amount of it getting plumbed back through the egr valve into the manifold meaning better exhaust flow causing turbo to spool up a little faster.
also by my understanding blocking the EGR actually can make the engine run cleaner as well??

perhaps someone with better knowledge could shed some light??

i actually thought the egr was for pollution, plumbing exhaust air into the manifold to help engine get to optimum temperature faster as engines produce more emissions at cold operating temperatures, according to the gregorys manual that is not entirely correct unless im reading it wrong, it states there:

the exhaust gas recirculation (EGR) valve, when open,recirculates exhaust gases back through the inlet manifold to lower the combustion temperatures inside the engine.
the lower combustion temperatures result in a reduction in an exhaust pollutant known as oxides of nitrogen (NOx).
The preheat system and the EGR valve share the same control unit. the signals received from the coolant temperature sensor , engine revolution sensor and the throttle position sensor determine the time and amount the EGR valve opens.
Two vacuum switching valves (VSV's) allows vacuum to open the EGR. Vacuum is supplied by the vacuum pump on the back of the alternator or on the top of the rocker cover , depending on the model.
The valves are opened electrically by an internal solenoid, energized by the control unit. When the control unit earths terminals 3 and 4, the EGR valve is fully opened. If the control unit earths terminal 3 only, the EGR valve is opened half way. When the control unit does not earth the VSVs, the EGR valve is closed.

that's verbatim from the workshop manual.

biggest one i would question is blocking the relief valve as 8MadDog8 suggested i cant see any reason for doing this unless running boost higher then its "relief" setting which someone else stated as being like 15-16psi, 8MadDog8 states running his at 13psi negating the need to remove an item intended to save your engine from EXPENSIVE repairs, unless and please correct me if im wrong, the actual setting for the relief valve is 13psi??

 

[rogue5861]

From what I've read/heard the egr helps with cruising. "The Ferret" has a good write up about it in his post. Egr is a joke, mine is blocked been like that for a week. Not sure wether it has lowered smoke at all, had to turn my fuel back to stock coz it was puffing (that was before I put shim in). Shim didn't seem to help or hinder it.

I reckon I read relief valve let's out at 10psi. Don't quote me coz I cant remember where I read it. But doesn't match what others have said. I think both wategate an relief are set to 10 psi. I will test it when I hook up a boost gauge, in theory if I boost it up should let out at either 10 or 13.

Might be a couple weeks or even a month before I do that.

Rick

 

[Goldtrol]

Well I'll confirm it for everyone Tuesday night, my boost gauge will be in and I will fit it without the controller.

If I only get 10psi then we know that the relief valve has to go. If not then 13psi it is as that's what's looking safe.

Can't wait to get it boosting a bit harder, will make the drive from Perth to Cairns via Melbourne a bit easier

Will have it booked into A1 fuel injection for a tune before I leave too

 

[rogue5861]

Have you blocked egr off? Im guessing that would vent some of the pressure off the turbo back into intake. (Maybe)

Would be good to hear what yours is running stock and what it will boost too before the relief valve will let out.

Cant wait for the results =)

 

[RTD13]

Hi fella's
on mine the relief vents at 15 psi, I recently fitted a gauge and boost controller, before I was getting no more than 9 psi with stock exhaust, then fitted controller and running at at 13 psi, when I was playing with the controller it boosted up to 15 then I definitely heard the relief go off and it dropped the boost, seems to be a good fail safe to stop over boosting