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Rb20 Gt35 Dyno Graph Boost Curve ?

joe blo

By joe blo,
in Engines & Forced Induction

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Roy Grand Master

Roy

Posted
Posted

Look, provided the foundation of what your trying to work with is sound (manifold works, gate is decent...your exhaust doesnt have a collapsed muffler or cat etc) then I say forget these knockers.

I get it... :) MY 310rwkws RB20 hammered. When I put the TD06 on it in 2002 everyone knocked me saying they are crap etc. Fark em...I did it anyway and loved the 11 years of enjoyment it has given me :)

So...do it....you obviously dont mind lag for the fun hit of power....but I like you cant see why that turbo isnt working miles better. Based on what a TD06H-25G does on an RB20 (similar but a tad smaller then GT35) I would say you should be able to get 20psi by 5,300-5,500rpm. Rev the thing to 8,500 and its still a pretty good power band

On a turbine as big as the GT35 I think you can go down to a 0.63-0.72. I woudl try to get it in the 0.6X range but dont know whats available. People will say its restrictive etc but remember you are only using 2L to spin it.

If you have the chance then throw E85 at it. It just dumbs everything down and you can just throw ignition and boost at it reliably until you are happy. Make sure you have cam gears, and dont mess with the inlet manifold or cams. Leave them std

Easiest thing to do is drop the exhaust on the dyno and just run the dump pipe. Remove and blank the wastegate with a blanking plate and give it a few dyno pulls increasing the revs 500rpm at a time. Run it to 4,000rpm and see what the boost curve looks like. Then 4,500rpm, etc etc. You will get an idea of what theboost curve is without worrying about whether the exhaust is a restriction, wastegate creeping etc.

LOL, the GT35 will be lazxy so easily able to control it without a gate and not fear overboosting the engine. I would also put a cheap pressure gauge on the pre intercooler and post intercooler. You have not mentioned the cooler you are running and can easily be the cause of a few psi going walk about etc. If you are fault finding its is very possible a number of small things compound the main problem. When you have a GT35 on an RB20 its only going to exacerbate the small problems.

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Roy Grand Master

Roy

Posted
Posted

I will add , plenty of other setups will work better and make for a quicker car...but I have never had the fastest car etc but I tell you what just about everyone who drives my car loves it (when it has functioning, matched brake setups on it :) ) So, I think it can work better than it is and shoudlnt be too expensive to get the most out of it. If you dont mind popping the engine then just keep it, because hwen sorted you are going to have a 350rwkws setup and I am not sure how long std RB20s last at that power with those revs and boost. LOL, I can vouch for 22psi, 8,800rpm and 310rwks :)

BlueRB240 Collaborator

BlueRB240

Posted
Posted

That turbo might not be a real GT35. I run a Precision SC61 (yestertech turbo close to the same size as the GT35 back in the day) turbo on my 20 with the .63 housing and stage 5 exhaust wheel. I see full boost @ 5500. 308rwks @ 18psi on my local pump gas and 323 @ 18psi with meth injection at the same boost.

Roy how often do you rev your motor out to 8800? I want to rev mine higher but I'm way too scared it's going to kill the oil pump past 8000 :(. I have to gear to make more power up top too.

Roy Grand Master

Roy

Posted
Posted

That turbo might not be a real GT35. I run a Precision SC61 (yestertech turbo close to the same size as the GT35 back in the day) turbo on my 20 with the .63 housing and stage 5 exhaust wheel. I see full boost @ 5500. 308rwks @ 18psi on my local pump gas and 323 @ 18psi with meth injection at the same boost.

Roy how often do you rev your motor out to 8800? I want to rev mine higher but I'm way too scared it's going to kill the oil pump past 8000 :(. I have to gear to make more power up top too.

Well in first and 2nd gear often. I used to wring its neck to make sure it fell back into the meat of the power band for the next gear. So 3rd used to get 7,800 or so....4th about the same...i just shifted based on the shape of my power curve.

So my rule of thumb was revs + boost + power kills engines. So I woudl just take whichever two options I needed on a given day. For instance Winton I use to take boost and power and dropped the rev limit to under 8,000rpm. At Sandown I would drop the boost to about 18psi and take the revs to get the thing out of the slow corners.

If you truly want the engien to hang together then I think as long as your tune is good and you are running 18psi then 8,000rpm is not a concern for the motor if you are under 300rwkws. Depending on what you are trying to achieve beyond that I guess its all a balancing act

LOL...this was 9,600rpm in 3rd gear on a motorkhana run through some witches hats :) But the engine had a leaky head gasket so I upped the pain threshold I was putting on that engine :)

IMG_4054.JPG

Roy Grand Master

Roy

Posted
Posted

Do you have gauges or oil pressure, water and oil temp? I never used to let that stuff get hot. As long you know your oil pressure is good then I was always comfortable leaning on it. LOL, then I removed my dash logger and operated on the ignorance is bliss theory. Hey, it worked too. What killed my engine was sittinng in day to day peak hour traffic when a coolant hose under the inlet manifold got a split and dumped all the coolant in traffic and overheated. Fixed and drove it for another 6 or so months but the head gasket was making it miss at idle etc.

Point being....as long as you are being sensible about the abuse, keeping an eye on things....just enjoy it :) A $2 coolant line in traffic can kill it pretty quick.

I say a GT35 setup could be a fun thing. The more I think about it though I think E85 woudl help wonders with regards to controlling any inclination the engine may have to detonation when you start running decent ignition and boost. They need ignition to get them going

joe blo Experienced

joe blo

Posted
  • Author
Posted (edited)

its in a 2wd hilux ute so its pretty beefy.

had a mate watching the gauges this afternoon. said it hit 15 psi about 120kmh in 3rd. dunno but. he said he hasn't seen it go over 15 psi which is possible going off dyno sheet as the last psi's come real slowly and run out of road before can get there. see max revs in 2nd but prob not enuff load to get full boost with the way it is. whatever is possibly wrong or not wrong. or maybe the boost has been turned down since dyno on one setting of the boost switch

will check it myself at drags Wednesday if its on

Edited by joe blo
BlueRB240 Collaborator

BlueRB240

Posted
Posted

Do you have gauges or oil pressure, water and oil temp? I never used to let that stuff get hot. As long you know your oil pressure is good then I was always comfortable leaning on it. LOL, then I removed my dash logger and operated on the ignorance is bliss theory. Hey, it worked too. What killed my engine was sittinng in day to day peak hour traffic when a coolant hose under the inlet manifold got a split and dumped all the coolant in traffic and overheated. Fixed and drove it for another 6 or so months but the head gasket was making it miss at idle etc.

I do have water temp and oil temp, The Oil temp isn't hooked up tho and trying to find the 1st gen Defi oil pressure is a pain in the rear at the moment. I did suffer from busted coolant hoses under the intake manfiold too lol.

XKLABA Grand Master

XKLABA

Posted
Posted

There's no way you are having boost creep with only the power output it is delivering and that savage lag. I'm guessing the wastegate never ever closes. Ever.

This turbo only belongs on an RB20 when feed by a supercharger.

FYP :D

What exhaust have you got in this thing ?

Actually what are your supporting mods ?

Turbos need to be able to breath in and out so any restriction in or out will make the turbo lazy, even more so when the turbo is to big for the engine it is put on

Boost creep is when the turbo hits full boost then keeps climbing, usually cause by to small of a wastegate or incorrectly setup boost controller

Wastegate creep is when the wastegate flap starts to open to early and make turbo lazy to come on boost, usually caused by to soft of a wastegate spring or incorrectly setup boost controller

joe blo Experienced

joe blo

Posted
  • Author
Posted (edited)

It's got 3 inch exhaust with some small cannon muffler on the end of it. There's at least a cat frame in it.

Surge tank. 044. Ecu. Injectors. Think 100mm intercooler with 3 inch pipe both sides and a plenum that we all love for bit if extra lag apparently.

What did the plasma man plenum cost you in lag Roy mate?

Think wastegate is some blue china thing. Thought it was turbo smart originally but put camera down there and took photo and had no brand on it from what I could see

Edited by joe blo

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