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Question about the boost for a stock GTS-t

Guilty

By Guilty,
in Engines & Forced Induction

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Guilty Proficient

Guilty

Posted
Posted

Hi, i currently have a stockish r33 gts-t and am running the standard boost of 7 psi. I have an exhaust, pod as my only mod. Ummm well my question is, i was looking to buy a fmic and a avcr boost controller within the nxt few months and i am just wondering, which mod should come first?

I heard that putting on a aftermarket fmic, i may actually lose boost if i dont have a boost controller so does that mean i should purchase the boost controller before i get my fmic?

And also what is the maximum amount of boost i can run on a stockish gts-t?

im thinking around 13psi? to 0.85 bar?

Also lastly, there is nothing wrong with boostin up my car even tho my cars quite stockish, like it wont harm the car in anyway because of the added boost to the stockish engine?

Sorry for the longish post but i hope i can get some answers.

Thanks.

Cheers

GuiLty

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cameron Mentor

cameron

Posted
Posted

its got good kilometers on it.

The RB25 has a fault with the intake manifold and if you run too much boost piston number 6 tends to starve and leans out. which casues it to go bang... but this general happens as the car is coming up to the 100k mark & has had a hard previous life. in your case your car is still fairly new an i would once you get the boost controller (avc-r) fitted put it on a dyno and play around with the boost and monitor the a/f ratios. if they start to lean out turn boost down etc: but i would say 10 - 12 psi is safe.

rev210 Grand Master

rev210

Posted
Posted

Hi,

Keep the factory intercooler for now.

1)It is not going to stop you running low 13's on the factory cooler.My old gtst ran low 13's with one. The old car was one of the quicker factory turbo'd gtst's around and ran little 205 tyres too.

2)It won't restrict you to only 10psi of boost. The fragile turbine is what you want to be carefull of, it might not last long over 12psi of boost so keep it to 12 or less.

Before shelling out for the fmic consider you won't need it really till you get a bigger turbo in. The extra pipework and cooler size 'may' reduce the engine response even though the power 'might' increase.

the AVCR is an expensive controller ,the blitz units are a little better and cheaper too.A bleeder valve will do the job too.

The pod filter needs a cold air partition otherwise your sucking hot engine bay air. The factory airbox is a better setup than what you have right now, so fix that. Unique autosports sell a partition box kit from memory or you can make one.

JasonO Enthusiast

JasonO

Posted
Posted
its got good kilometers on it.

The RB25 has a fault with the intake manifold and if you run too much boost piston number 6 tends to starve and leans out. which casues it to go bang... but this general happens as the car is coming up to the 100k mark & has had a hard previous life.

Cameron,

Surely if it's starved of air, then it'll run rich.

I've never heard of this problem on the RB25DET, certainly on the RB26 the end cylinder (Nº6) gets more air than the others, leading to this being the first cylinder to fail due to det. On the RB25 the plenum feeds over the top of Nº's 3&4 which would suggest that these two would be susceptible to det more so than the others.

Got any more info on this, on the RB25DET ?

JasonO Enthusiast

JasonO

Posted
Posted

Hi Rev, been a while :)

Guilty,

The stock IC is good for 300bhp and 0.9bar, the stock turbo is only good for about .85bar and running beyond this will be risky.

The intresting thing is that increasing boost beyond .8bar on the stock IC / turbo will not result in an increase in peak power (low down torque will increase though) as the IC is saturated (can't cope with the volume of air) and the turbo is operating out of it's efficiency zone resulting in a rather hot intake charge and subsequently more of that nasty det at high rpm.

This is from experience gained on a dyno, using all sorts of measurements and dataloging everything as we went, Intake Air temp, Turbo outlet temp, IC outlet temp, etc. etc.

Keep the stock cooler unless you intend to fit a bigger turbo ;)

JasonO Enthusiast

JasonO

Posted
Posted
The RB25 has a fault with the intake manifold...........
Consider we have proof x2 i meant that it starved of fuel... to much air thats what happens when you run too much boost because the standard fuel pump injectors carnt keep up....

i'll post some pics

That's not an intake manifold problem Cameron, that's fueling and not relevant to the boost levels we're suggesting here.

The stock 370cc injectors can cope well and easy with .95bar, with the right regulator, pump and mapping. :)

cameron Mentor

cameron

Posted
Posted

i know it may be different to with his car but we ran 12 psi throught an avc-r and melted piston number 6 as you'll see in these next pics their are 2 different Rb25's here. the reason i said run lower boost is because an avc-r runs propper boost really hard unlike a bleed valve which doesn't hold it as good... about the fault its not really a really common one but its the design of it thats why with the Rb26 they change to the plenum style intake.

cameron Mentor

cameron

Posted
Posted

The first 2 pics, that R33 gtst RB25 we found out that i had a R34 gtt turbo which has a plastic front wheel an it had a steel exhaust wheel. being plastic it sucks a lot harder which causes bigger air flow. thats part of the reason piston number 6 melted. and the last 3 photos that R33 rb25det had a highflow standard turbo which was able to flow more air which caused piston number 6 to go bang due to running too much boost... (both these have avc-r's)

JasonO Enthusiast

JasonO

Posted
Posted

Ooooh, Ugly :throwup:

Yep, Nº6 killed by det. Still not convinced of the plenum being to blame though.

I recall of some discussion (about the RB26) along the lines of Nº6 failing becasue it is the warmest, with little (no) cooling airflow actually managing to reach it all the way back in the bay against the firewall.

Did them engines in the pics die on the dyno or on the road ?

rev210 Grand Master

rev210

Posted
Posted

cameron,

That pistons ringlands are rooted thanks to poor tuning not 12psi of boost (you can see the marks caused by pinging). I've run 12psi and 150hp shot of nitrous on a standard Rb25det and all my pistons ringlands were 'as new' when I pulled it down.And the bleeder valve held 12psi no problems.

cameron Mentor

cameron

Posted
Posted

Road... soon as it melted it start running like hairy goat burr bup blup burr.... couldnt bring it on boost had to stay under 2500rpm...

it leans out and gets to hot... its the design of the plenum because of the way it seperates the air from the throttle body unlike a greddy plenum were it has seperate butterflys for each cylinder.... simpily number 6 runs the hottest as you said and because its at the back it doesnt really start working intill high up in the Rpm rang which is when its really hot... the standard plenum is not the full blame but is part of the problem... as well as detination/leaning out.. not anough fuel etc:

cameron Mentor

cameron

Posted
Posted

poor tuning ? with the standard ecu ?

put it this way, the rb25 in the frist 2 pics we had that car dynoed and at 12psi it was 12:1 -14:1 a/f ratios but at 14psi it was 30:1 leaning out big time. that was on bleede valve and then we just hooked up the avc-r and took it for a strap and it was running 11 - 12psi exact boost on boost guage and the avc-r. when we had the bleede valve hooked up full boost was at 5000rpm an when we put the avc-r in it was full boost at 3000 all way to redline. which caused it to over heat etc...

cameron Mentor

cameron

Posted
Posted
cameron,

That pistons ringlands are rooted thanks to poor tuning not 12psi of boost (you can see the marks caused by pinging). I've run 12psi and 150hp shot of nitrous on a standard Rb25det and all my pistons ringlands were 'as new' when I pulled it down.And the bleeder valve held 12psi no problems.

The nos would of cooled the engine down heaps which would have stoped it from getting to hot... an melting pistons etc:

also the photos were its broken the rings my brother brought that car with it like that already and we didnt know intill it went bang.

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