HKS Turbo's vs Garrett Turbo's...

[Merli]

If the result is mixed, GTSS's better at low rpm and 2530's better at high rpm, then we can argue about which is better forever and not get a result.   I would argue average power over the rpm range used is as good a method as any.  So if you want to do a comparison then let's do it, here is my submission based on Mark's result, since it is published on this forum.

So in my opinion if GTSS's make 249 rwkw average between 4,250 rpm and 7,250 rpm then they are better than 2530's for all round use.

Okay, that sounds like a fair way of comparing them, except I'd want to compare them from 2000-8000rpm, not 4250-7250rpm.

Why would you start the comparison after the GT2530s have spooled up? That will negate the GT-SS's advantage in the lower revs and skew the results in favour of GT2530s... Hardly fair.

BTW, I have no idea what these GT-SS turbos will make... I'm as interested and clueless as everyone else I'm just hoping that they'll spool up faster than the GT2530s and still make 300kw @ all four peak power... If it can do that I'll be over the moon

[Merli]

Hi Merli, you asked "if I am able to bring the turbos on 500rpm earlier than stock with my GT-SS turbos, would that be better for street than GT2530s in your opinion?"

Yes, if the GTSS's make more power than the standard turbos EVERYWHERE, then they are better than the standard turbos.  But in order to be better than 2530's they have to make more power EVERYWHERE than the 2530's.

I said that if the GT-SS were able to come on boost earlier than the GT2530s, would they be better for STREET, not for circuit racing...

So I'm not sure why you want to compare power EVERYWHERE?

On the street 99.5% of the time I'm between 1500rpm and 4000rpm.

So surely for this STREET comparison we'd be wanting to compare the area under the curve for that rev range...

If we were doing a CIRCUIT comparison we'd want to compare the area under 4000-8000rpm

If we were doing a STREET AND CIRCUIT comparison, we'd want to compare the ENTIRE rev range... Correct?

So keeping in mind that I NEVER said that GT-SS would be better for street/circuit, but only said that if they are able to spool faster than GT2530s, they would be better for STREET, do you really think my statements are that wild and shocking?

Over to you.

[DoughBoy]

Check this out: http://www.phoenixs.co.jp/bigsite/ranking/...r-18_2600a.html

It's a chart of Phoenix's Power and cars they have tuned. This one is for low mounts. Interesting to see the range of turbos that they have used.

[Sydneykid]

Hi guys, fantastic, a bit of friendly debate going on here, I like threads that have differing opinions. I will try and respond one by one..............

Hi Dougboy, the last T88-34D we had made 80 rwkw at 4,250 rpm on a 2.6 litre RB26. As a result there is no way the average from 4,250 rpm to 7,250 rpm gets anywhere near 249 rwkw.

Hi Merli, on the street, like you, I use all the rpm range. I might only use the last 500 in the rpm range for 1% of the time, but that 1% is very important to me. That's the reason I own a Skyline.

When I am using from idle to say 2,000 rpm, I don't need more than 20 or 30 rwkw at full throttle. I don't see the point of having 40 rwkw at full throttle when I only need 20 rwkw to keep up with the traffic. All that is going to happen is I am going to use less throttle opening. So on the 20 rwkw car I use 20% throttle and on the 40 rwkw I use 10%. I see no advantage in that. Fuel economy is irrelevant, if the engines are tuned properly and efficiency is equal, then both will use around the same amount of fuel to make 20 rwkw.

If I was only interested in idle to 2,000 rpm performance then I would own a Viper, not a Skyline. When I think about it, that's actually not correct, with maximum torque from 0 rpm, an electric motor would be better.

The reason I chose 4,250 rpm to 7,250 rpm for my average was because the 3,000 rpm difference is what the standard gear ratios cause the engine to loose on the upchange. I didn't go to 8,000 rpm because I thought saving 10% (750 rpm) was reasonable. For your comparison you can choose any rpm range you like, as long as it is 3,000 rpm wide. Otherwise any average power comparison does not account for maximum acceleration, which is what you would want at 100% throttle opening. If you don't want maximum acceleration then you wouldn't be using a 100% throttle opening anyway. So the comparison would be meaningless.

In conclusion, I don't think we want to get in response here. I have no doubt that given tuning and other systems equality, a smaller turbo will always have better response than a larger turbo. But I have found that turbos are far from the only thing that affects response. Things like compression ratio, camshafts, camshaft timing, ignition timing, porting, manifolds, throttle bodies all have arguably a more import role than turbos in regard to response.

Hope that adds a little more to an interesting thread.

[Roy]

Something GTR owners may be able to help clear up with me. The 300rwkw figures typically seen by guys on the forum with 2530s, PFC, split dumps etc, are these figures still using std exhaust manifolds?

What sort of additional power if any can these setups make if used with aftermarket exhaust manifolds?

Im looking at the price and weight of two smaller turbos and there appropriate piping vs one larger series of turbo. Looking at response balanced with power, i would think a single would compete with the 2530 setups and be cheaper and lighter. Is my thinking floored, it must be noone seems to do it.

What are the engineering reasons for using twins on an inline engine (not marketing "TWIN TURBO POWER stickers") I can understand the lower centre of gravity argument, and the desire to use generic parts from the one manufacturer, ie housings/centres for the T25/28 turbos...but why is there so much aftermarket support for turbo setups that support the same power that a bigger single can provide?

What are the exprience/thoughts with say a T67 vs twin T517s or a GT3040 vs 2530s, some others may have better examples.

[Sydneykid]

Hi Roy, I honestly can't answer your question. We have one car with twin 2530's, one with twin N1's and one with a big Garrett single. Each one has a different reason for its particular turbo choice.

The car with the N1's has them because they are a "standard" Nissan part, so it can race in Production car racing.

The car with the big single Garrett has it because, for 650 bhp out of 3.1 litres, it was way cheaper than a pair of suitable singles. Plus it is in a GTST which had one AFM and an RB20DET Power FC. Running twins would have meant even more expenditure than the turbos themselves. BTW it is mounted low and rearwards like a R31 GTSR, better for weight distribution than a high forward mount.

The car with 2530's has them because I reckon they are the best all round turbos for a combination road and track GTR with 2.6 litres. I had 2530's on it originally, which we were talked into taking off and using 2540's, in a quest for more power. The max power was 25 rwkw higher but the average was crap and the lag terrible, so I took them off and put another set of 2530's on.

I think there is way more involved than just which is better, single or twins. So, to keep it simple, I have a few rules of thumb;

1. If its a GTST, then a single is the go for a combo road and track car

2. If its an RB20 or 25 with standard internals, then I use a ball bearing hi flow

3. With modified internals it's a Garrett GT30

4. With 3.1 litre modified internals it's a GT35 or larger

5. If it's a combo road and track GTR, then twins are the go

6. With 2530's for 2.6 litre GTR's

7. Garrett GT25's for 3.1 litre GTR's (there is an argument for GTRS's here as well).

As you can see from the above, I never use plain bearing turbos. So I can't comment on their comparisons.

Moving on to standard cast manifolds for twins or aftermarket stainless. If you are going bigger in core size then 25/28 series and using external wastegate/wastegates, then you really have to go high mount. There is simply not enough room for everything mounted low. So the question really becomes whether or not to change the standard manifolds for similar (low) mounted stainless ones. I can honestly say I have never seen any major difference, that I can confidently point at and say the stainless manifolds are much better.

Note; This is not the case with a single turbo, stainless, tuned length, mandrel bent manifold, there are certainly gains to be had from them.

The car with the 2530's uses them, but not because of any perceived power advantage, but because I could easily wrap them and lower the engine bay temperature. I would have had to have the cast ones ceramic coated inside and out to achieve the same result. That would have cost more than making the manifolds, so we made the manifolds.

None of that really answered Roys' questions, but it is the reasoning for why we do it the way we do.

[GTR-Ben]

Ok there seems to be some good ideas for turbos in here.. and I am feeling rather stumped.

RB30DET with stock bottem end and RB26DETT head.

Have a manifold with a T04 flange, high mount.

I want good usable power. I have someone with a T78 and a T67. These both have the T04 flange and are in a good price range for me. I think the T78 may be too large.. but I am not sure what power I will get at what boost pressure etc..

I could also go for an older T04 of some flavour but I think the Trust turbos will preform better.

Also need a suitable ex wastegate.

What are your recommendations for me oh wise turbo gurus?

[Roy]

So, to keep it simple,  I have a few rules of thumb;

4. With 3.1 litre modified internals it's a GT35 or larger

7. Garrett GT25's for 3.1 litre GTR's (there is an argument for GTRS's here as well).

Yeh i appreciate there are many different ways of going about the mods process, but about the only big singles you see are T78/88s (ie really big turbos), never Garret based singles like GT30/35 (Or K27 from KKK etc).

So am i right in assuming these engines (4 & 7 above) have similar peak power outputs???? Are the characteristics of the engine any different, i would think better lower torque in a GTR would be desirable due to the increased weight.

Its just an interesting trend i have noticed with RB26 setups.

Oh GTR-Ben the T67 i have seen had a 3 bolt flange like the TD06/05 range, not the 4 bolt split pluse housing like the T78/88.

[Merli]

True about the response point... A smaller turbo will almost always be more responsive than a larger turbo. Hence why I think that the GT-SS's will be better street-oriented turbos than the GT2530s...

Anyway, I'm just speculating here and pulling this purely out of my ass, so I'm going to stop until they are installed and I have a dyno sheet to show you guys...

[Elithrar]

A hard question to answer, probably, but what kind of rwkW would I 'max-out' at with a R34 GT-t turbo on an RB20DET with basic exhaust and intake modifications, a PowerFC, cam gears and ~1bar of boost (using stock internals)?

Also, with the same modifications, what Garrett turbo would I need to reach 200rwkW's? The HKS GT-SS goes for about $2500 (RRP), and is rated at about 300hp (depending on what site you go to), and would seem to suit my needs.

[Roy]

True about the response point... A smaller turbo will almost always be more responsive than a larger turbo. Hence why I think that the GT-SS's will be better street-oriented turbos than the GT2530s...

Anyway, I'm just speculating here and pulling this purely out of my ass, so I'm going to stop until they are installed and I have a dyno sheet to show you guys...

Its good to see someone trying a different setup:)

I know the GTSS are a newer turbo then the 2530, are visibly smaller and have a lower hp rating, but are the trims, pitch of blades, number of blades different to previous HKS offerings, or have they just been mixed and matched with previous offerings for different results.

If say the compressor uses an entirely new wheel, then the results may be a real surprise, that Phoenix Power table raised my eyebrows

[jezzrrr]

Guys,

... ineteresting stuff, the debate re 2530's vs GTSS's is a good one, the thing is that in OZ GTR owners (who are into street/track driving) dont seem to have "swung" to the GTSS's in the way the Japs have.

THe Japs appear now to be using almost excusively (at least the road cars with moderate track work) the GTSS's. The following thread is instructive in this regard. It from Pheonix tuning house Japan, who are quite a reputable mob over there and almost all of their customers low mount cars use GTSS's.

http://www.phoenixs.co.jp/bigsite/home.html

In fact none of their customers incuded in their power graph use 2530's. I cant read Japanese but it appears that figures as high as 579 PS@wheels is able to be had from GTSS's which, I would have thought, outs them into (or at least close to) the league of the 2530's.

I also have a friend who is "well in the know" using GTSS's on an R33 GTR with standard internals getting 421 RWHP at about 1.3 bar which leaves alot of room for improvement.

In addition (if I havent bored everyone yet) the HKS Jap web site rates GTSS's at the same power level as the 2530's.

I will be interested to see Merli's ressults.

I said that if the GT-SS were able to come on boost earlier than the GT2530s, would they be better for STREET, not for circuit racing...

So I'm not sure why you want to compare power EVERYWHERE?

On the street 99.5% of the time I'm between 1500rpm and 4000rpm.

So surely for this STREET comparison we'd be wanting to compare the area under the curve for that rev range...

If we were doing a CIRCUIT comparison we'd want to compare the area under 4000-8000rpm

If we were doing a STREET AND CIRCUIT comparison, we'd want to compare the ENTIRE rev range... Correct?

So keeping in mind that I NEVER said that GT-SS would be better for street/circuit, but only said that if they are able to spool faster than GT2530s, they would be better for STREET, do you really think my statements are that wild and shocking?

Over to you.

[GTR-Ben]

Oh GTR-Ben the T67 i have seen had a 3 bolt flange like the TD06/05 range, not the 4 bolt split pluse housing like the T78/88.

This is the T67 I was thinking of using.. maybe an older model, not sure.

You can see it has a 4 Bolt t04 flange.

This is it compared to a T78.

Any ideas?

[Sydneykid]

Hi Elithar, if the engine is in good condition and the tuning is good, there is no reason why the RB20 won't make the same max power as an RB25 with the same mods, condition and tuning. So almost 200 rwkw is entirely possible. Average horsepower is of course a different question entirely, the RB25 is after all 25% larger.

Hi jezzrrr, let me use my sceptical bone here, what if the only reason the HKS supported workshops are using GTSS's is because it's "new" and there is money to be made. What would be the point of pushing 2530's? They are "old" news and everyone knows that "newer" must be better.

Looking at the GTSS power claims, 579 rwps, that's around 310 rwkw. I have seen 330 rwkw out of a pair of 2530's locally in Shoot Out mode on a Dyno Dynamics. But the extra 20 rwkw is not the point, it's how it gets there that is important. Somewhere around I have seen the dimensions of GTSS's and they looked remarkably similar to 2510's. The HKS ratings are;

GTSS 300 ps

2510 310 ps

2530 320 ps

2535 340 ps

2540 350 ps

2540R 370 ps

2835 380 ps

HKS rate the GTSS lower than a 2510, and I have driven a GTR with 2510's and it was awesome up to 7,000 rpm then it went flat line. It felt like it had some boost just above idle rpm, which is totally alien in a GTR, where the real pleasure for me comes from giving them a rev. The guy who owned it loved it like that as he just stepped out of a grunter 6 litre Commondoor. If HKS (and Garrett) had found a combination of compressor and turbine that gives a GTSS the bottom end of a 2510 with a slightly better top end, then for some people that would be perfect. But I keep going back to the fact that HKS don't rate them with the same max power as a 2510, therefore they themselves are saying GTSS's have a lower top end than 2510's.

So, like many others, I await Merli's results with great interest.

[Roy]

This is the T67 I was thinking of using.. maybe an older model, not sure.

You can see it has a 4 Bolt t04 flange.

This is it compared to a T78.

Any ideas?

Well im thinking the T67 you have pictures isnt a Trust turbo, more likely a Turbonetics turbo. The exhaust housing doesnt have the usual round turbine outlet with 3 bolt flange for dump pipe, and the compressor cover looks nothing like the Trust T67 covers i have seen, including the blue nameplate like you see on the T78.

From the Turbonetics site...i couldnt find anything on the T67 at a glance other then the fact it has ben superceded, im sure a more thorough search will reveal more...

The 68-1 Performance Turbocharger

TURBONETICS is pleased to introduce the 68-1 as an upgraded replacement for the original Series 67 “Super-turbo”. Externally identical to the Series 67, the new 68-1 combines a new generation compressor with even higher flow and efficiency, with all of the rugged attributes of the 67, including the “Tuff-Turbo” configuration. See compressor map on page 18 for flow rates. (Add PN 10680 for polished compressor hsg.)

[jezzrrr]

Hi Elithar, if the engine is in good condition and the tuning is good, there is no reason why the RB20 won't make the same max power as an RB25 with the same mods, condition and tuning.  So almost 200 rwkw is entirely possible.   Average horsepower is of course a different question entirely, the RB25 is after all 25% larger.

Hi jezzrrr, let me use my sceptical bone here, what if the only reason the HKS supported workshops are using GTSS's is because it's "new" and there is money to be made.   What would be the point of pushing 2530's?  They are "old" news and everyone knows that "newer" must be better.

Looking at the GTSS power claims, 579 rwps, that's around 310 rwkw.  I have seen 330 rwkw out of a pair of 2530's locally in Shoot Out mode on a Dyno Dynamics.  But the extra 20 rwkw is not the point, it's how it gets there that is important.  Somewhere around I have seen the dimensions of GTSS's and they looked remarkably similar to 2510's.  The HKS ratings are;  

GTSS 300 ps

2510 310 ps

2530 320 ps

2535 340 ps

2540 350 ps

2540R 370 ps

2835 380 ps  

HKS rate the GTSS lower than a 2510, and I have driven a GTR with 2510's and it was awesome up to 7,000 rpm then it went flat line.  It felt like it had some boost just above  idle rpm, which is totally alien in a GTR, where the real pleasure for me comes from giving them a rev.  The guy who owned it loved it like that as he just stepped out of a grunter 6 litre Commondoor.  If HKS (and Garrett) had found a combination of compressor and turbine that gives a GTSS the bottom end of a 2510 with a slightly better top end, then for some people that would be perfect.  But I keep going back to the fact that HKS don't rate them with the same max power as a 2510, therefore they themselves are saying GTSS's have a lower top end than 2510's.

So, like many others, I await Merli's results with great interest.

I see your point BUT you must be looking at the HKS Oz web site in arriving at those figures - see HKS japan: http://www.hks-power.co.jp/

They rate the GTSS (in bold below) as having the same power output as the 2530:

MODEL 付属制御装置 1機での

対応出力(PS)

GT-SS HKS製強化

アクチュエーター 320

コンプレッサーホイール

トリム 入口径(mm) 外径(mm)

60 46.6 60.1

コンプレッサーハウジング

入口径(mm) 出口径(mm) A/R

専用 専用 0.60

タービンホイール

トリム 外径(mm) 出口径(mm)

76 53.8 47.0

エキゾーストハウジング

入口フランジ 出口フランジ A/R

GT25 S/V GT25専用 0.64

I wrote to HKS Australia and they responded saying their web site was wrong and the Jap one was correct.

[Steve]

Looking at the GTSS power claims, 579 rwps, that's around 310 rwkw?

Sydneykid perhaps its closer to 425rwkw? that skeptical bone is playing tricks I think.

[Merli]

Actually HKS have revised their power rating for the GT-SS turbos.

In my 2002-2003 Goodsmaster (when GT-SS/RS were first announced), the GT-SS was rated at 280ps, but now it has been revised to 320ps (same as GT2530s)...

Yes, I'm just as confused as you are :looney:

[Merli]

Steve... Those power figures on the Phoenix Power site are engine hp figures, not wheel hp.

[Elithrar]

Hi Elithar, if the engine is in good condition and the tuning is good, there is no reason why the RB20 won't make the same max power as an RB25 with the same mods, condition and tuning. So almost 200 rwkw is entirely possible. Average horsepower is of course a different question entirely, the RB25 is after all 25% larger.

I'm a little confused; would ~200rwkW be possible on the R34 GT-t turbo? I know it is possible on the GT-SS, but I'd rather save money and use it for other mods.