Large Turbo With Small Housing Vs Small Turbo With Large Housing

[R34NRG]

im not sure if this has been covered properly but i wanted to ask the gurus what differences would be noticed when you compare eg (gt30 1.00 housing vs gt32 .63 housing)

came about this question wen asking myself if i would later be upgrading to a T04z.

any help appreciated

[paulr33]

how much money do you have?? jesus

running a large style turbo with a small housing can make it nose over and become peaky early

it can also cap its flow and make a lightswitch style setup - but you need to drive the larger compressor

running a small style turbo with a large housing gives you drive of good top end and plently of peak power

and because the compressor drive isnt a big donkey style t88 compressor it can be driven fairly easily

which usually results in quicker response, faster transistion and linear style OEM operation

ie: good average power / linear oem turbo curve etc instead of lag lag lag lag power

[R34NRG]

how much money do you have?? jesus

running a large style turbo with a small housing can make it nose over and become peaky early

it can also cap its flow and make a lightswitch style setup - but you need to drive the larger compressor

running a small style turbo with a large housing gives you drive of good top end and plently of peak power

and because the compressor drive isnt a big donkey style t88 compressor it can be driven fairly easily

which usually results in quicker response, faster transistion and linear style OEM operation

ie: good average power / linear oem turbo curve etc instead of lag lag lag lag power

hrmmmm last thing i want is a lightswitch setup......being rwd n all.

but then again im not fussed to much on peak power, more focused on usable power.....i guess theres a fine line before u cross into the other.

reading so much about 3.0L and its hype on low down toque and its ability to spool turbos faster......i guess if that is the case, running a bigger housing wouldnt be to bad......

i guess i should 1st see how the gt3540 goes and base it on that......

btw paul, unfortunately i dont have enough money to buy a gtr, which is why its going into makn the gtt better.....at least try newai......

[R34NRG]

hrmmmm last thing i want is a lightswitch setup......being rwd n all.

but then again im not fussed to much on peak power, more focused on usable power.....i guess theres a fine line before u cross into the other.

reading so much about 3.0L and its hype on low down toque and its ability to spool turbos faster......i guess if that is the case, running a bigger housing wouldnt be to bad......

i guess i should 1st see how the gt3540 goes and base it on that......

btw paul, unfortunately i dont have enough money to buy a gtr, which is why its going into makn the gtt better.....at least try newai......

i really hope the neo 25/30 combo is good......

[The Mafia]

so many make the mistake of picking a turbo before they pick their power target.

Pick a power target, and THEN ask what turbo would be good for it.

Any other way is a hopeless way of doing it.

Edited March 22, 2008 by The Mafia

[paulr33]

please tell me youve spent some money on handling

[BHDave]

I tend to think there's a lot more to picking a turbo these days.

What do you want it to do? dyno queen, drift hack or something in between?

I tend to lean towards the smaller end of the garrett range. There just seem to be a lot of guys putting 3076's and bigger on otherwise stock engines and being slapped with a response penalty and not making the most of the turbo. I don't see the point of that. I'd say even a 3540 is too big for an otherwise stock engine.

I don't know if you have a built engine btw. You may be able to make the most of a 3540.

The 3076 comment isn't directed at you either mafia, you seem to be 1 of the few who is willing to really lean on your setup. When are you going to cam it?

[discopotato03]

The real propeller heads used to say that a large A/R turbine housing on a modest turbine was better than the other way around . The reason mentioned was that the expansion ratio was higher across the smaller turbines blades in a large housing than with a larger turbine and smaller housing .

You could take a leaf out of Nissans book with the Neo RB25 and use a slightly larger A/R turbine housing and have the response evened up with the more sophisticated VCT .

Personally I'd have the head off/ported/larger exhaust valves and Poncams in before contemplating large turbochargers .

The better you can make it breathe the easier it is to make power with modest pressure - in inlet / exhaust / fuel rail .

IMO going any larger than a GT30 series turbo is too much for any 90+% road only driven RB25 . In large housing form a GT3076R/GT3037 can support ~ 540 Hp and the HKS spec GT3082R 50T a bit more again . This is snapping on the heels of what many get out of GT3582R's on basically std engines , the overall power delivery would be better with the improved engine and 30 series turbo I'd think .

Cheers A .

[R34NRG]

so many make the mistake of picking a turbo before they pick their power target.

Pick a power target, and THEN ask what turbo would be good for it.

Any other way is a hopeless way of doing it.

i think picking a purpose, rather then a power target makes more sense, but i get wat u mean.

i was aiming for around the 350+ area, alot less if it was the standard 25, but since being a 3.0 i would hope that the increase in power wouldnt result in a big lag.

please tell me youve spent some money on handling

only sway bars and new bushes..........i believe the standard nissan spings/shocks are perfect for going fact in a straight line. altyhough i still need to lower the car.....

I tend to think there's a lot more to picking a turbo these days.

What do you want it to do? dyno queen, drift hack or something in between?

I tend to lean towards the smaller end of the garrett range. There just seem to be a lot of guys putting 3076's and bigger on otherwise stock engines and being slapped with a response penalty and not making the most of the turbo. I don't see the point of that. I'd say even a 3540 is too big for an otherwise stock engine.

I don't know if you have a built engine btw. You may be able to make the most of a 3540.

the engine is forged and is stroked to 3.0L, so everything youve said pretty much is good advice but properly just a extra size bigger on all the turbo sizes u mentioned.

The real propeller heads used to say that a large A/R turbine housing on a modest turbine was better than the other way around . The reason mentioned was that the expansion ratio was higher across the smaller turbines blades in a large housing than with a larger turbine and smaller housing .

You could take a leaf out of Nissans book with the Neo RB25 and use a slightly larger A/R turbine housing and have the response evened up with the more sophisticated VCT .

Personally I'd have the head off/ported/larger exhaust valves and Poncams in before contemplating large turbochargers .

The better you can make it breathe the easier it is to make power with modest pressure - in inlet / exhaust / fuel rail .

IMO going any larger than a GT30 series turbo is too much for any 90+% road only driven RB25 . In large housing form a GT3076R/GT3037 can support ~ 540 Hp and the HKS spec GT3082R 50T a bit more again . This is snapping on the heels of what many get out of GT3582R's on basically std engines , the overall power delivery would be better with the improved engine and 30 series turbo I'd think .

Cheers A .

ive read alot about turbo selections on the 25 but my dilemma is exactly how well a 3.0L would compare with the same turbo ect ect. im still yet to cam my setup, but depending on how it runs without it......i may do it at a later stage......

should be gettn the car back in about a week or so (but we all know things happen) ill keep u guys posted. in the mean time more discussion would be great =]

[Al]

The GT3540 should be more than sufficient to make 350rwkw, as it's rated at 700hp, same as a T04Z. Hopefully you have purchased the 0.83A/R split-pulse housing, to maintain some response.

With the right supporting components, you should make the power easily.

- cams

- GReddy plenum

- Larger t/b

- Split-pulse top mount manifold (split pulse is more responsive)

- Injectors

- etc

[R34NRG]

.

Edited March 23, 2008 by R34NRG

[R34NRG]

The GT3540 should be more than sufficient to make 350rwkw, as it's rated at 700hp, same as a T04Z. Hopefully you have purchased the 0.83A/R split-pulse housing, to maintain some response.

With the right supporting components, you should make the power easily.

- cams

- GReddy plenum

- Larger t/b

- Split-pulse top mount manifold (split pulse is more responsive)

- Injectors

- etc

i defiently did get the .82 housing

plazmaman plenum

72mm tb

6boost manifold

800cc injectors

but i am still running the standard cams....

how much better are these split pulse designs

[discopotato03]

Compressor wise the GT3076R can make the wind for 375-400 Kw easily enough but you have to size the turbine housing to suit the engine capacity .

Cubes here uses a GT3076R IW with a 0.82 A/R housing on an RB25DE based RB30DET and it starts early from memory . If you were to use the largest available 1.06 A/R housing it would start a bit later and make the power more easily through less exhaust restriction .

From Garretts turbine flow maps for the GT3076R the flow rates in corrected lbs/min are as follows - approximately .

0.63 A/R - 20.5 lbs/min .

0.82 A/R - 23.5 lbs/min .

1.06 A/R - 26.5 lbs/min .

Food for thought , cheers A .

[R33GOD]

how much power can the 3076r with the .63a/r make?

and the 3071r with the same .63a/r?

[Al]

i defiently did get the .82 housing

plazmaman plenum

72mm tb

6boost manifold

800cc injectors

but i am still running the standard cams....

how much better are these split pulse designs

Good work.

For the money you have already spent i would complete the picture and invest in a set of Type B (may be called stage 2) Tomei Poncams. Direct bolt in, no fuss, and gives great advantages over std cams. I think they are about $800 landed.

Both the turbo and manifold have to be split pulse designed to work. I think it's about 500rpm more responsive than the std snails, if not a little more. Just helps bring on the bigger turbos a little quicker.

[Dale FZ1]

how much power can the 3076r with the .63a/r make?

and the 3071r with the same .63a/r?

The two blokes to ask this question of would be

The Mafia - 3076

BHDave - 3071

edit: not intending to lead this thread off-topic so apologies to R34NRG. In that respect, I would say if comparing same/similar housing running a different/larger rotor eg. GT30 vs GT35 you would have higher mass flow capacity from the GT35 because the exducer size and corresponding hole in the rear end of the housing is larger. It would become a bit of a juggling act if going up from (say) GT30 0.82 to GT35 0.63 and probably counter productive.

I think Al is onto a reasonable proposition with considering a TO4Z in split pulse though, especially at the power rating either that or a GT35 is capable of supporting.

Edited March 24, 2008 by Dale FZ1

[The Mafia]

I managed a 314rwkw run, on the 0.63 rear on the 3037 (3076) but that was ringing its neck. Was only on 18psi boost too.

But bare in mind that is with water methanol injection.

Curve looked like a V8's.

[joeyjoejoejuniorshabadoo]

i love and hate when discopotato03 posts....

teh 11ty numberz hurtz teh eyes....

i'm from the school of going for the most response... how often can you actually USE 350rwkw?

its not like a daily is going to be redlining 4th terribly often

Edited March 24, 2008 by joeyjoejoejuniorshabadoo

[discopotato03]

Yes Mafia's answer was the one I was waiting for . So 314 Kw on not stratospheric boost in the smallest of the three propper GT30 turbine housings . Depending on how you like to work the numbers in potato theory the larger housing supports between 1/5 and 1/4 extra gas flow which is a huge change to the world the engine see's .

More numbers for the numerically agrivated .

0.63 GT30 = ~ 20.5 lbs/min ......... 0.63 GT35 = ~ 23 lbs/min .

0.82 GT30 = ~ 23.5 lbs/min ......... 0.82 GT35 = ~ 27 lbs/min .

1.06 GT30 = ~ 26.5 lbs/min ......... 1.06 GT35 = ~ 32 lbs/min .

From these approximate numbers you can see that for the sameish flow rate the GT30 turbine needs the next A/R size up to be about the same as a GT35R turbine and housing combination .

The point I am trying to make is that if the GT3076R's compressor can move more than enough air to meet your goal and its turbine with the 1.06 A/R turbine housing can handle almost as much gas flow as a GT35 turbine in its 0.82 A/R housing do you really need to go any larger ?

Your call but I reckon the GT3582R is getting a little big for what you're doing and T04Z's are really a ball bearing large frame dinosaur . HKS housings make a big difference to the Z turbo but you pay dearly for them .

Over to you , cheers A .