Hks2835pros Or Gt3040r

[ECR033]

I know that some may think this has been done to death, but hear me out first

Basically, I'd like to get some opinions on the 2 above mentioned turbos (i.e HKS2835ProS & GCG GT3040R) relative to each other. I was pretty much set to go ahead with the GT3040R on my RB25DET, but after several conversations I've had with a few different people this week, I'm now totally undecided again...

To give some backround, I currently have the following mods:

PFC, EBC, FMIC, 3" turbo back exhaust w/ hi flow cat, K&N panel filter & HD Clutch

I've also purchased the following parts in anticipation of my turbo upgrade and have them ready to go on the car:

Nismo 555cc fuel injectors, Bosch 040 fuel pump, Z32 AFM & HKS Adj Ex Cam Gear (not essential, but thought I'd might as well give it a go).

If I purchase the 2835ProS (w/0.87 turbine housing) from Nengun, i'm looking at around $2900 (incl 3% duty + gst).

If I purchase the 3040R (w/0.83 turbine housing) from GCG, i'm looking at $1710 (w/SAU discount) + $990 for a manifold + $585 for ext wastegate. Total $3285.

I'm assuming that I'll need to get oil and water lines etc made up regardless of which turbo I go for. I also assume that I'll need to get both the intercooler and exhaust piping plumbed up to the new turbo as well.

As for a goal, I'd be happy with 275rwkw at this stage, but would possibly like to potentially reach 300rwkw if I upgrade cams and/or do some internal work further down the track. I'm also optimistically chasing an 11 sec 1/4mile (on drag radials) and would also eventually like to do some track work at some stage (once I do the necessary suspension/brake mods and oil cooler etc).

Basically, my questions are:

Is the 2835 capable of safely producing the 275-300rwkw that I'm after? And if so, how much boost will I need to run? If not, what is a realistic power output for this turbo and my given mods?

Is the additional response of the 2835 more of a benefit than the larger potential top end of the 3040R? If so, when can i expect the 2835 to come on boost?

Considering the additional costs for manifold/wastegate etc on the 3040R, is the 2835 better bang for buck? Or is the higher power potential of the 3040R worth the extra money?

Overall, given my goals and intended use for the car, which turbo is the more suitable choice?

And last but not least,

Is there any other options that I should consider (keeping in mind that I don't want to spend anymore than my current options)???

I understand that most of these questions are opinion based, but that's exactly the information that I'm after. I've done a some searching on the forums and have got fair bit of information for both turbo's, but nothing in a comparitive sense, so I'm keen to hear of people's opinions.

Any advice is appreciated. Thanks

Apologies for the long post...

[czy18e]

I cant comment on the hks turbo but a gcg 3040 are not as laggy as some people make out.(4000rpm isnt too laggy for me)

And even if you optioned the 3040 with a .63 rear it should make the power with a fraction less lag again.

[paulr33]

i think thats pretty much the nail on the head. do you want some more lag and some more beefy top end or you do u want a tiny bit more lag and some great midrange but not as much top end (again probably only 40rwkw top end max), just slightly less. i think for a quick streeter 2835 is probably max you'd goto. the .64 a/r should make it come on nice and quick whereas the .84 will make it come on more progessively.

i think when comparing to stock turbo once you upgrade everything other than the stock turbo you find the car comes on like a bitch on heat and absolutely screams to full power as the a/r on the stocker is perfect for the capacitiy. as soon as you throw on a bigger .84 a/r then you get much more lag. i couldnt live with boost coming on at 4500rpm hell no. i absoletely love the stocker screaming at 2700rpm theres not many cars that can keep up with a fully worked up ecr33 with stock turbo but has had everything else upgraded. the powerfc and 3" dump, hiflow cat, cooler etc really make the combo the perfect streetable. (again without breaking the sound barrier)

i reckon the 2835 would be the limits of the "nice streeter" configuration.

i think you get to a point where you migrate from quick streeter to a really nice 1/4 mile and then loose some of the nice streeter zest that you once had.

i guess thats why the hiflow was so good and respected. comes on like the stocker tiny bit bigger exhaust wheel/opening and it flows more so you get best of both worlds.

have you spoken to gcg to see if they can do a garret equiv of hks 2835 just not in those exact words. there would have to a be garrett equiv just as good, only not hks brand

[r33_racer]

GCG have ya oil and water kits too, designed for 3040 for rb25. something like 300 bux i think.

[discopotato03]

ECR033 it sounds like you're turbocharging an NA RB25 with its higher (10:1 ?) CR .

IF so it becomes more sensitive to back pressure (heat + reversion) so a turbo biased toward low exhaust restriction becomes critical for it not to detonate to death .

In this case the GT3040R is bad because the compressor (82mm GT40) is a bit big for its 60mm GT30 turbine - sort of biased wrong way round .

Arguably the GT 2835 Pro S missed out on a bit of turbine efficiency with its cropped turbine , there is a similar version offered by Garrett called the GT3071R which uses an unmolested 60mm GT30 turbine cartridge no 700177-23 .

The thing I don't know is how well the cropped turbine works with HKS's purpose made exhaust housing . Its a bit lame when used with Garretts GT28 .86 ARR housing which I believe is overbored beyond the 54mm it was designed for . I think the HKS Pro S style housings are based on the GT30 or 60mm turbine dimensions and cope ok with the cropped 57mm turbine .

I would be costing the real GT3071R with plain .50 ARR comp housing (T04E) , and one of the two available HKS Pro S GT30 housings from their 3037 Pro S in .68 or 87 . Don't forget the cost of the waste gate actuator as well .

The 2835 Pro S is at least designed to be a bolt on and comes with the actuator . Someone on this board recently got one though with the .68ARR turbine housing and posted some pics so do a search .

Cheers A .

[ECR033]

czy18e,

I agree, I don't think the 3040R with the .83 rear is overly laggy. I've spoken with gcg and apparantly I can expect to start seeing boost around 3500rpm. Obviously, I'd expect the 2835 to come on boost earlier though, I'd just like to know how much earlier it would start making boost.

Also, I won't be going down the path of getting the 3040R with the .63 rear as I've heard they come on boost like a rocket, so traction would be a real issue even on a very good suspension/tyre setup.

paul,

I think you've accurately described my dilemma! To answer your question, I want good response, mid range and top end

In reality, it's just a shame that you can't have all 3 components, but I'd like to get the best compromise on these components without sacrificing too much of either of them.

I don't know if I'm pushing the limits by wanting a streetable car that also does a decent 1/4mile and track work. I did originally contemplate the hi-flow for those very reasons, but in the end I didn't want to only go half way with the turbo upgrade so to speak as I know that I'll probably be looking for more than the 240-250rwkw that it could produce.

disco,

Nope, not turbocharging an NA - just upgrading the std turbo on my R33 RB25DET

So you would recommend the 3071R as the better of the 2 options I've already mentioned? Or was that only in the case that I was turbo charging an NA rb25 due to the higher CR?

I've had another look on the GCG website and they've got the 3071R, with the 0.7 comp housing and 1.06 turb housing. Do you think I'd be better off with this combo, or should I see if it's possible to put together a 3071R with a 0.50 comp housing and say a .87 turbing housing? If so, when could I expect to start seeing boost on this combo? I'm assuming that it shouldn't have any problems making the 275rwkw I'm after...

[ECR033]

One more thing...

I noticed that the 3071R has a T25 flange as opposed to a T3. I know this probably sounds stupid, but is it just a matter of getting an adapter plate made up to fit to it, or is there more to it?

[discopotato03]

There are different versions of the GT3071R , 3 from Garrett and I believe 3 from HKS .

Basically they are all GT30 turbine based and use one of the three available trims of the GT35 compressor . The Turbines are mostly 60mm (GT30) and the compressors 71mm (GT35) hence the name GT3071 , the R means rolling element ball bearings .

The main issue with this series is the exhaust housing because it locks you into a mounting flange size ie T3 or T25/28 . It also forces you to choose integral or external waste gate . The single turbo RB exhaust manifold is T3 flange and unmodified assumes you'll use an integral gate turbo . HKS has tried to make it easy (if expensive) by selling the GT Pro S turbos (2835's and 3037's) with a T3 flange integral gate housing . I think we can assume the two available Pro S ARR sizes (.68 , .87) are aimed at RB20's and RB25's respectively .

The confusion exists because at some stage Garrett decided to crop the 60 (59.9) mm turbine down to 56.6mm in order to fit it inside the GT28 (T25/28) flange exhaust housing . The in between hybrid or cropped turbine does not work very efficiently with the GT28 housing but allows for a simple bolt up solution for manifolds with the T25/28 flange (eg CA18DET , SR20DET) similar or same exhaust outlet too . Garrett calls their GT3071R with the cropped turbine and GT 28 housing "GT3071R wastegated" . They do 2 versions of it .

1) Turbo no 700382-0003 with hybrid turbine 84 trim and .64 AAR GT28 housing .

2) Turbo no 700382-0020 with hybrid turbine 90 trim and .86 AAR GT28 housing .

They also do a version with the full sized GT30 turbine requiring a GT30 turbine housing . You can buy HKS's Pro S exhaust housings separatly and turn this last one into something that bolts to your T3 flanged manifold with the integral gate . The HKS GT 3037 Pro S turbo uses a 60mm GT30 turbine and its this housing that will fit the propper full turbine sized GT3071R (cartridge or CHRA no 700177-0023) .

This may not be the cheapest or easiest option but from an engineering point of view it gives the best chance of success in this series .

For a similar but slightly greater result you could always try the 52 trim version of the HKS GT 3037 with the Pro S exhaust housing but I'm not sure if HKS market that particular option , someone in the US may be able to mix and match for you .

Adapting a T3 to T28 flange is always the last option and a definite compromise .

Cheers A .

[RS500]

the GT3071R (with larger 60mm GT30R turbine wheel) is available with a T3 flanged exhaust housing to suit external w/gate. Given this, there is no need for an adapater plate or even an aftermarket exhaust manifold. just weld up a flange for the external on the factory manifold and you're swet ;-)

this turbo with an A/R .82 would be your ideal combo for a quick street car with good response.

Edited September 10, 2005 by RS500

[RS500]

a bit more in detail but you beat me to it disco ;-)

[discopotato03]

Fair enough , I just like the Pro S housings because their a bolt on and could look vaguely std - sort of self contained . For me external gates are a bit much for the road but I'm a bit conservative and look to simple answers where possible .

Cheers A .

[RS500]

Fair enough , I just like the Pro S housings because their a bolt on and could look vaguely std - sort of self contained . For me external gates are a bit much for the road but I'm a bit conservative and look to simple answers where possible .

Cheers  A .

<{POST_SNAPBACK}>

you're cool dude.

actually the HKS Pro S exhaust housings are also a cost effective solution and allow for easier fitment and as u say, also give the standard look.

[ImpulR33R]

I have the 2835 pro Spec S on my Car and its awesome. not laggy at all. I am currently running 15 psi and making 250rwkw. I have the same mods as you are planning to run. to really make this turbo boogey it needs a to run at about 18-20 psi and then you will make the 275rwkw. but then run the risk of destroying pistons. my 250rwkw is crazy, and find it hard to get traction through 1st and 2nd. If i were you go for the 2835 and run 15psi and be satisfied with 250rwkw. its nuts and not laggy at all.

[gtst25]

I have the 2835 pro Spec S on my Car and its awesome.  not laggy at all.  I am currently running 15 psi and making 250rwkw.  I have the same mods as you are planning to run.  to really make this turbo boogey it needs a to run at about 18-20 psi and then you will make the 275rwkw.  but then run the risk of destroying pistons.  my 250rwkw is crazy, and find it hard to get traction through 1st and 2nd.  If i were you go for the 2835 and run 15psi and be satisfied with 250rwkw.  its nuts and not laggy at all.

<{POST_SNAPBACK}>

Hi there,

Nice results - I've just bought the kit myself - getting the exhaust housing ceramic coated now and will be fitting in December - really looking foreward to it. About the only thing I need now is an oil catch can - you must be running one??

Have you got the 2835 with the .68A/r exhaust housing?

Also do you know of anyone on here that's wound the boost up to 18-20psi without decompressing?

Sorry for all the Q's - there doesn't seem to be many people here running 2835's

Cheers.

[jezzerrr]

I have the 2835 pro Spec S on my Car and its awesome.  not laggy at all.  I am currently running 15 psi and making 250rwkw.  I have the same mods as you are planning to run.  to really make this turbo boogey it needs a to run at about 18-20 psi and then you will make the 275rwkw.  but then run the risk of destroying pistons.  my 250rwkw is crazy, and find it hard to get traction through 1st and 2nd.  If i were you go for the 2835 and run 15psi and be satisfied with 250rwkw.  its nuts and not laggy at all.

<{POST_SNAPBACK}>

That sounds just like the kind of power i eventually want! What did the whole shooting match end up costing you? mine is basically bone stock bar the zorst and pod filter.

[ECR033]

I have the 2835 pro Spec S on my Car and its awesome.  not laggy at all.  I am currently running 15 psi and making 250rwkw.  I have the same mods as you are planning to run.  to really make this turbo boogey it needs a to run at about 18-20 psi and then you will make the 275rwkw.  but then run the risk of destroying pistons.  my 250rwkw is crazy, and find it hard to get traction through 1st and 2nd.  If i were you go for the 2835 and run 15psi and be satisfied with 250rwkw.  its nuts and not laggy at all.

<{POST_SNAPBACK}>

Nice result mate.

I'd also like to know which size turbine housing you're using (i.e .68 or .87)?

If possible, could you also post up a copy of your dyno run?

Thanks for the info disco & RS500. It's been a great help, although I'm still slightly confused on what to do!

[TommO]

Nice result mate.

I'd also like to know which size turbine housing you're using (i.e .68 or .87)?

If possible, could you also post up a copy of your dyno run?

Thanks for the info disco & RS500. It's been a great help, although I'm still slightly confused on what to do!

<{POST_SNAPBACK}>

I found a copy of ImpulR33R's dyno sheet in his for sale thread:

I've been watching this thread with interest.

Cheers,

Tommo.

Edited September 10, 2005 by TommO

[ImpulR33R]

no, i'm not running an oil catch can. I had one on my car when i was running a 2530 at 15 psi and after about 3 months i checked it and it had nothing in it. not even dirty.

yeah i got the .64 exhaust housing.

i havent heard of anyone running above 15psi, but you probably shouldnt unless you have forgies.

edited-

the above was at 15 psi and the adjustable actutor isnt set properly, with extra time, playing with the actuator 250rwkw would be fairly easy.

Edited September 11, 2005 by ImpulR33R

[Al]

At first i wasn't going to post this, as you stated that you wanted to reach 300rwkw, but felt that i should after reading the recent posts.

I am currently in the process of modifying my rb25, roller bearing, hi-flow turbo, by replacing the ext. housing with one off a VG30 turbo (slightly larger than the std. rb25 ext. housing). I am also installing a pair of Tomei PonCams and porting the head. I have read and received various PM's from forum members that have used the same combo, minus the porting, and have acheived approx. 270rwkw with the same response of a std hi-flow. I have already instucted my mechanic/tunner to keep the tune safe and not push the eng, as it still runs the std. bottom end. So i will limit the power and be VERY happy at about 260rwkw. (Note: i believe 270-280rwkw is acheived using 18psi)

The best thing about this combo is that it still looks std. Apart from the fuel pressure reg (but still does not stick out like a sore thumb) and the straight swap 550cc inj, the whole package looks factory.

Hopefully this hasn't confused you more in your decision, but if others are looking at 250-280rwkw than i beleive this combo will be best choice while still appearing std. Remember "stealth" is your friend

[porschephile]

My friend has an R33 Gtst w/ a HKS gt2835 Pro S. It's a stock motor, stock cam, etc and only has a metal headgasket (1.2mm I believe). With a PFC it was tuned conservatively to 378rwhp @ 18psi (on a Dynojet), which is about 282rwkw. This was with an extremely crappy manual boost controller that wouldn't hold more than ~.8bar above 4500rpm. From what I understand, the 2835 pro S is most efficient around 20-24psi. I'm judging that there is at least 30-40+rwkw still there with a little more boost and proper electronic boost controller to hold the boost. I'll see if I can get ahold of the dyno chart and post it.