12v VR6 turbo

[raj_vr6 6]

Hi guys,

 

I have a 12v 2.9 forged engine in place. Looking for the right turbo to get me around 500hp.

 

So far I have shortlisted these turbos:

• GTX3076R
• GT3582R
• GTX3582R

 

Leaning towards a GTX3582R at the moment. Any one out there running any of these turbos on their VR6's that can help me make up my mind?

[RBPE 198]

Garrett have changed their sales so it's all compressor side and buy what turbine side you want for it, GTX will obviously be more money than GT with the changes, so first point is budget! If you can GTX over GTR or GTW then may as well.

 

All will get you there, spool will depend on turbine side a/r, usual for road is probably about 0.82, some go for 0.63a/r but they give good low down but can choke a bit up top, prob better for a 400hp set up or so. Couple hundred rpm's difference on the GT30 turbine over 35 using same a/r good around the 500+hp mark which is what you are aiming for, should be slower wheel speeds too. 

 

So, a GTX3076R will give you a little better spool, arguably a bit better for daily driving, GTX3582R will give you lower wheel speed/stress, also bit more potential as you get the boost bug for 500+, what I would go for. It's all Gen II stuff now too - I also wouldn't mind testing out their GTW journal bearing ones to see what they are like compared with the old T series or PT Turbo's they're aimed at.

 

http://www.atpturbo.com/mm5/merchant.mvc?Screen=CTGY&Store_Code=tp&Category_Code=GG2

 

http://www.atpturbo.com/info/garrettgtw.html

[raj_vr6 6]

21 minutes ago, RBPE said:

Garrett have changed their sales so it's all compressor side and buy what turbine side you want for it, GTX will obviously be more money than GT with the changes, so first point is budget! If you can GTX over GTR or GTW then may as well.

 

All will get you there, spool will depend on turbine side a/r, usual for road is probably about 0.82, some go for 0.63a/r but they give good low down but can choke a bit up top, prob better for a 400hp set up or so. Couple hundred rpm's difference on the GT30 turbine over 35 using same a/r good around the 500+hp mark which is what you are aiming for, should be slower wheel speeds too. 

 

So, a GTX3076R will give you a little better spool, arguably a bit better for daily driving, GTX3582R will give you lower wheel speed/stress, also bit more potential as you get the boost bug for 500+, what I would go for. It's all Gen II stuff now too - I also wouldn't mind testing out their GTW journal bearing ones to see what they are like compared with the old T series or PT Turbo's they're aimed at.

 

http://www.atpturbo.com/mm5/merchant.mvc?Screen=CTGY&Store_Code=tp&Category_Code=GG2

 

http://www.atpturbo.com/info/garrettgtw.html

 

Appreciate the detailed response sir. 

 

Just to throw a spanner in the works, I have just now got off the phone to a Garrett supplier and he recommends the Garrett GTX3576R for good low end torque. Apparently the GTX3582R is all top end which is not practical for a daily / street car. He also mentioned putting a smaller housing such as 0.68 to get faster spool will only do more bad than good on a GTX35.

 

[RBPE 198]

I'd say that set up is more for 4 cylinder engines really.

The VR's produce a lot of heat on the second bank due to the design, take a bit of compensation tuning, as such, although the heat can help with higher gas speeds, it can also obviously be a bane (we all know cold, dense air makes power, heat destroys components etc). 

That set up uses the larger GT35 side turbine, so it is set up for decent gas flow at the expense of speed over a 30, so it should make this hot gas a bit cooler then as the flow would be slower, kind of what we want, but then it is somewhat strangulated with the small a/r to give it better low end manners, but this in turn speed's up the gas we've just wanted to slow down!

This turbine set up can have it's benefit's and it can operate a bit differently over the same a/r on a 30 as can be seen here;

 

 

 

It just seems like it's one for the 4 cylinders in that respect, these VR's have decent flow with the extra 2 cylinders plus we've not even mentioned things like running higher compression ratio's with greater efficiency/less heat/knock (off boost driving characteristics for day to day) and so on.

 

On the compressor side; a quick bit of maths like on Garrett's website, means that a potent 100% VE 2.9 running 7000rpm would be pushing about 15psi to hit 500hp. In reality it's more like 17-20psi. So let's plot that on the compressor graphs;

 

 

As you can see, the 35 sized compressor wheel is pretty much perfect for these in terms of compressor efficiency, it also keeps the wheel speed lower at desired hp/flow targets.

 

It is a bit of a tricky question to answer, tuning is always a balancing act really, but most get a bar of boost at mid 3000rpm's on a 35 0.82 and are very happy, will also do 500+hp with ease. I can see the point of a 35/76 hybrid but it seems like a 550hp turbo for 4 cylinders, enough flow for decent top end, but strangled to keep low end happy. There's lot's more to tuning as well like compression ratio, timing and of course efficiency. We've also not mentioned the size of orifices T3 v T4 etc which have an effect on gas speed.

 

P.S. If you have the money and want a bit better road manners, a properly made twin-scroll exhaust manifold slaving the gasses correctly, using a GT35R with the 0.78a/r twin scroll housing on a T3 would be a nice one I reckon. But most are happy with a potent cast log 0.82 35r for less!

Edited December 21, 2016 by RBPE

[Hotskillet 0]

I don't mean to hijack the thread but in be same boat. I'm rebuilding my old VR6T from and old Turbonetics 60-1 T4. My goals are 600WHP. Can you plug in the numbers and see if the GTX35 can do the job and where will boost come in?  

 

Im on a built 2.9, JE 9:1 pistons, forged rods, ARP bolts top and bottom end. I'm also looking to update the standalone from a DTA P8pro.  Don't say Lugronic who picks and chooses their customers.

Edited January 16, 2017 by Hotskillet

[RBPE 198]

You need to guess rpm limits and VE and what have you, Garrett's tuning threads tell you how to do it. You also can't really guess on spool accurately without looking into what others run similar to you, efficiency of set up, ecu tune/cam timing, turbine housing etc can all make a big difference. You can guess but use Garrett's info.

 

At a quick guess on these anything around 600hp crank or wheel even, would be looking at top end limits of top pump fuel, 98/99 RON here so a couple of bar maybe a bit more or less depending on efficiency, so go to the 60lbs/min y axis on the GTX35/40 or whatever compressor wheel, plot 3 bar on the x axis (1 bar ambient pressure + 2 bar boost), look at wheel speed and efficiency - efficient set up less boost (2.7) or opposite (3.2bar psia on x) to see guesstimates. You can go off the usual "double the torque figure for a bar of boost" but it's not very accurate, too many efficiency aspects to consider!

 

Spool though, in my experience and with lot's of factors to consider;

0.63ar roughly low 3krpm's for decent spool not best at top end >400/450hp, 0.82ar mid 3krpms for a bar of boost >500/550hp, big hp chasers/turbo's look at mid 4krpm's for 20psi+ - again though, lot's of factors to consider!

 

Rough estimates though!

[Hotskillet 0]

Thanks for the response and assistance. I think your X-horizontal, and Y-vertical references are unversed by understand what you're saying.

 

I'll to get into the Garrett calculator but based on your input, the smallest I should go is a GTX35/82 but the GTX35/84RS edges out in efficiently, wheel speed and potential growing room but not much after 60lb/min

 

 

Edited January 19, 2017 by Hotskillet

[RBPE 198]

On 19/01/2017 at 3:22 AM, Hotskillet said:

Thanks for the response and assistance. I think your X-horizontal, and Y-vertical references are unversed by understand what you're saying.

 

I'll to get into the Garrett calculator but based on your input, the smallest I should go is a GTX35/82 but the GTX35/84RS edges out in efficiently, wheel speed and potential growing room but not much after 60lb/min

 

 

 

I'm itching to use a GTX3584, I'd say yes for a 600whp set up - go for around 1a/r at 600 - it's all kind of changing at Garrett to keep up with the Jones' though, all the Gen 2 and buy comp/turbine seperately - you can dig out the odd old GT35R from some - sort of a transitional phase and Brexit here for prices, lucky in the US for those things!

 

Yeah - got the axis mixed up though I think? I type quickly - x axis lbs/min times 10 for rough hp rating, 1 on vertical is ambient (outside) pressure so 1.5 is a half bar boost etc - Garrett's guide gives you rough equations, I'd type them up if I was computer literate to do the lines!