Turbo sizing and recommendations for a unopened 3.0

I don't see much talk about turbo sizing on here, it seems most just go with whatever a pre-built kit provides.

I'm trying to get a idea of what I want to use, I was thinking about a Borg Warner S300 based Turbo. I've used these on rotaries in the past and they've been fast spooling turbo's.

Here are the specs, let me know what you think.

T4 flange
Modular center/backwall
.313 dia. shaft
Compressor has 4" inlet x 3" outlet
1.0 divided turbine w/4" outlet
Small "Q" trim turbine 76mm x 68mm
Compressor is 61mm x 84mm rated 82% @ 18psi 64#/min.

FYI, my engine is unopened and I don't plan on opening it so I'd say 450 whp is the max for me.

Thanks guys!

The turbo that comes with my kit is an excellent match to the NSX motor and cost effective too.

Pm me for info.

450 Hp is pushing it on a stock motor. Are your goals street
or track? 400 RWHP is more than enough for most and you
reduce the chance of problems. A smaller turbo may spool
faster and bump your torque curve down low but adds more
stress overall.

kookoo4nsx said:

450 Hp is pushing it on a stock motor. Are your goals street
or track? 400 RWHP is more than enough for most and you
reduce the chance of problems. A smaller turbo may spool
faster and bump your torque curve down low but adds more
stress overall.

Click to expand...

Yeah, I'm only wanting 400 whp. I just threw out the 450 whp number to show I don't want or need a large turbo.

So, it seems everyone is playing secret squirrel when it comes to giving out information on their turbo's. What gives?

EAC said:

So, it seems everyone is playing secret squirrel when it comes to giving out information on their turbo's. What gives?

Click to expand...

It's a thing called proprietary information.
If this companies have done lots of R&D to come up with sizes and types of parts that work well together then why should they feel obligated to 'give' that information away for free? They should be compensated(i.e. buy their products) for the effort they have already put forth making sure that everything works correctly and efficiently.
Would you like it if someone came to your job and asked you to do work for them and then not pay you for it ? You see where I'm going.

92NSX said:

It's a thing called proprietary information.
If this companies have done lots of R&D to come up with sizes and types of parts that work well together then why should they feel obligated to 'give' that information away for free? They should be compensated(i.e. buy their products) for the effort they have already put forth making sure that everything works correctly and efficiently.
Would you like it if someone came to your job and asked you to do work for them and then not pay you for it ? You see where I'm going.

Click to expand...

I've never heard of a company that sold turbo kits but refused to say which turbo it came with.

I'm not asking for something for free, hell; it's just a turbo. I've been in the turbo game for many years. He'll, we're talking about throwing together a low boost 400 hp setup, not a 3,000 hp 10.5 outlaw car. I just don't see the competition to warrant the secrecy..

EAC said:

I've never heard of a company that sold turbo kits but refused to say which turbo it came with.

I'm not asking for something for free, hell; it's just a turbo. I've been in the turbo game for many years. He'll, we're talking about throwing together a low boost 400 hp setup, not a 3,000 hp 10.5 outlaw car. I just don't see the competition to warrant the secrecy..

Click to expand...

Can we get your budget?

The amount your willing to spend is going to play a big part here. If you wanted the best, then just get a GTX35/82R and be done with it. It will even SPANK angus's secret turbo. BUT, angus's turbo puts out REALLY good numbers for its price......in-fact, probably the BEST numbers for the price, so if your looking for things to be more cost effective than I would PM angus and order a turbo through him.

Some may suggest the new 83mm EFR turbo from borg warner, but those turbo's only shine from higher pressure ratio's when compared to its garrett competitor...so the GTX will be the better guy in that one.

If you were to look at the HTA 35R, I would say DON'T. No compressor maps published so its just a shot in the dark as to what that turbo can really do and how efficient its wheel design is compared to the new GTX line, and many would say that now that garrett has release the new 11 blade GTX wheels it would be a crap shoot as to if the HTA35R could even keep up with the new GTX series......now if you looked at the HTA 35/86R......not a very tested turbo, but I would say its going to put out about 5% more than a regular gtx35R, but with that larger 86mm wheel its going to be 5% more laggy so then you have to ask yourself, if your really going there....why not just step up to the 40R.......but that is ridiculous for the power your looking to make.

In-fact just ignore that whole idea of even looking at the 35/86R from FP, and got with either the angus turbo if on a budget, or the GTX35R as the BEST OPTION but also the MOST EXPENSIVE.

Gotta pay to play.

JR

Flexer said:

Can we get your budget?

The amount your willing to spend is going to play a big part here. If you wanted the best, then just get a GTX35/82R and be done with it. It will even SPANK angus's secret turbo. BUT, angus's turbo puts out REALLY good numbers for its price......in-fact, probably the BEST numbers for the price, so if your looking for things to be more cost effective than I would PM angus and order a turbo through him.

Some may suggest the new 83mm EFR turbo from borg warner, but those turbo's only shine from higher pressure ratio's when compared to its garrett competitor...so the GTX will be the better guy in that one.

If you were to look at the HTA 35R, I would say DON'T. No compressor maps published so its just a shot in the dark as to what that turbo can really do and how efficient its wheel design is compared to the new GTX line, and many would say that now that garrett has release the new 11 blade GTX wheels it would be a crap shoot as to if the HTA35R could even keep up with the new GTX series......now if you looked at the HTA 35/86R......not a very tested turbo, but I would say its going to put out about 5% more than a regular gtx35R, but with that larger 86mm wheel its going to be 5% more laggy so then you have to ask yourself, if your really going there....why not just step up to the 40R.......but that is ridiculous for the power your looking to make.

In-fact just ignore that whole idea of even looking at the 35/86R from FP, and got with either the angus turbo if on a budget, or the GTX35R as the BEST OPTION but also the MOST EXPENSIVE.

Gotta pay to play.

JR

Click to expand...

The 40r can barely make 700whp but spools up like your typical 67mm billet wheeled unit capable of 900+whp. I've never liked this turbocharger, and if you look at garrett's compressor maps the gt3582r can outflow the 40r. All the new 62mm billet wheeled units(gtx3582r, hta3586, & precision 6262) spool up as fast as the 40r or faster and can make 750-800+whp. Although a better choice than a gt4088r even those seem like overkill for meager 400-450whp goals.

Kookoo touched on a great subject a smaller turbo is often pushed harder to meet the same power goals because the turbos dont flow as much air as a larger turbo at the same boost level. When pushed harder the midrange torque increases while the top end wont see as much of an increase in torque.

I rarely use these but i have a couple comp maps here to illustrate what im trying to say, keep in mind these arent using exact numbers but just gives you an idea on why a turbocharger that can make 400whp might not work well on an NSX:

I am assuming a 15% driveline loss of power to get 400whp so 475hp at the crank for the calculations which requires ~47 lb/min of air. i also used 130 degree intake air temps which i think would be on the higher end of what you can expect, and a 98% VE. Shown below is a compressor map for a gt3076r with a few select points. the Red line shows the air requirements of the NSX engine at 10psi(i was conservative i think the NSX can easily reach 400whp at ~8psi with a quality setup), and the green line shows the engines air requirements at 12.5psi(the minimum boost required to make 400whp on this turbocharger per the comp map). As you can see on the red line at 10psi and 8000rpm the turbocharger cant supply enough air to meet the NSX's engine demand. This means you will see torque drop off and you wont be able to make 400whp at 10psi. In an attempt to make 400whp one would try to increase the boost to lets say 12.5psi and try to attain 400whp. Unfortunately when boost is increased airflow through the entire engine increases. So when looking at the green line you can see at 3000rpm and 5000rpm the engine is now getting more air(lb/min) which means more torque and more stress on the motor to achieve the power we want. With our new found boost we will achieve our goal of 400whp at ~7400rpm and torque will then start to drop and our HP will likely maintain 400whp because the turbocharger cant supply any more air. It would seem the gt3076r might be too small for this particular application.



Now looking at the new GTX 3076r this looks like it will meet our goals of 400whp without having to push a higher boost level, it should supply the necessary 47lb/min required for the NSX engine at 10psi. Unfortunately when you want to achieve greater power from this unit it might not be the ideal turbocharger though because it wont be able to feed the 3.0L engine in the upper rpms. This would likely be the fastest spooling turbocharger you can use without putting additional stress on the motor to acheive 400whp.


IMO what might be the most well rounded turbo for the NSX on applications form 400-600whp seems to be the gt3582r. It seems to be able to feed the engine all the way to 8000rpm and beyond



just some food for thought.

Great reply. Just a few corrections:

You say the GT35/82R out flows its larger GT40R? What compressor maps you looking at? If its the new GTX35R FINE, but the old 35R doesn't out flow the GT40/88R, and hell no to the GT40/94R.

And lets be even clearer before you make that comment, the GTX35R flows EQUAL to the GT40/94R until pressure ratio's really get up there and then the GTX35R goes down, so I don't get your comment of a 35R outflowing a 40R.

The rest of your advice is spot on and I think the GTX76R would be a great turbo for the 400 whp but it is going to choke up top, and with the huge torque it will make at low RPM's its going to be loosing traction all over the place. Make the car hard to drive I would think.

Go with the GTX35R and its still going to spool super fast, but the main benifit is he can hit the 400 whp number with less boost, and less heat. It will be alot less strain on the motor because of less boost, less heat, and it will keep his torque numbers down at low RPM where most engine damage occurs.

Post up the old 35R and 40/88R compressor maps if you would like to look at them together to see the 35R in no way shape or form flows what a 40R does.

JR

Flexer said:

Great reply. Just a few corrections:

You say the GT35/82R out flows its larger GT40R? What compressor maps you looking at? If its the new GTX35R FINE, but the old 35R doesn't out flow the GT40/88R, and hell no to the GT40/94R.

And lets be even clearer before you make that comment, the GTX35R flows EQUAL to the GT40/94R until pressure ratio's really get up there and then the GTX35R goes down, so I don't get your comment of a 35R outflowing a 40R.

The rest of your advice is spot on and I think the GTX76R would be a great turbo for the 400 whp but it is going to choke up top, and with the huge torque it will make at low RPM's its going to be loosing traction all over the place. Make the car hard to drive I would think.

Go with the GTX35R and its still going to spool super fast, but the main benifit is he can hit the 400 whp number with less boost, and less heat. It will be alot less strain on the motor because of less boost, less heat, and it will keep his torque numbers down at low RPM where most engine damage occurs.

Post up the old 35R and 40/88R compressor maps if you would like to look at them together to see the 35R in no way shape or form flows what a 40R does.

JR

Click to expand...

The whole point of my post is that you wont have to push these turbochargers(with the exception of the gt3076r) in the midrange to make the power levels you want. This means you will have around the same torque at say 4000rpm as you will at 6000-8000rpm. It will of course fluctuate as the VE of the motor changes through RPMS, and as you pass through the most efficient points of the turbocharger, this will happen on a larger turbo as well. It wont be a huge spike in the midrange though because you won't need to push a higher boost level to reach your goals. If you were breaking traction at 6000rpm though, you will break it at 4000rpm now yes.

About the 35r vs 40r i never noticed this until just now so i was skeptical at first as well. As you can see they are very close in the lower boost levels, and then the 35r starts to shine once above 2.5bar. I think the compressor map for the 4088r isnt as complete as the 35r and might show some more left at higher boost levels, but it would be hard to argue they arent almost on top of each other. Obviously the 4094r outflows both by a considerable amount i wasnt talking about that one.

EAC said:

I don't see much talk about turbo sizing on here, it seems most just go with whatever a pre-built kit provides.

I'm trying to get a idea of what I want to use, I was thinking about a Borg Warner S300 based Turbo. I've used these on rotaries in the past and they've been fast spooling turbo's.

Here are the specs, let me know what you think.

T4 flange
Modular center/backwall
.313 dia. shaft
Compressor has 4" inlet x 3" outlet
1.0 divided turbine w/4" outlet
Small "Q" trim turbine 76mm x 68mm
Compressor is 61mm x 84mm rated 82% @ 18psi 64#/min.

FYI, my engine is unopened and I don't plan on opening it so I'd say 450 whp is the max for me.

Thanks guys!

Click to expand...

I'm not sure which turbo that 61mm is, most of the borgs have 62mm inducers not 61mm, but I dont know borg warner turbos very well. I'm a garrett guy myself but the borg warner s362 would be a great choice compared to a gt35r. If you want to run between 400whp and 600whp this turbo should fit the bill.

This thread has gone pretty wild..
It's going to sound like a cliche, but it will only come down to the OP, Where does he wants the power at?
Me, because it will be a track car I don't want my power to come too early, so a 35R it's out of the question for me, I used a couple HTA's(35) on my dsm and the power was very abusive even when it was only a four cylinder With a low compression engine!!
I can imagine what it would do on a six cylinder car with such a hight compression engine on a track cennario.

The 40r should be more mid/top end power, even at such low psi.

To the OP I would say, get your turbo ball-parked and go from there, linear power where you want it, it's just a housing change away.


-MSR

if you just want 400hp, get this...

http://www.scienceofspeed.com/produ...roducts/NSX/ScienceofSpeed/twin_turbo_system/

Timpo said:

if you just want 400hp, get this...

http://www.scienceofspeed.com/produ...roducts/NSX/ScienceofSpeed/twin_turbo_system/

Click to expand...

I'm sorry... but that is the worst exhaust collector I have ever seen in my life...

The OP is looking for advice.. I hope he gets it from a knowledgable source.

Regards

92NSX said:

It's a thing called proprietary information.
If this companies have done lots of R&D to come up with sizes and types of parts that work well together then why should they feel obligated to 'give' that information away for free? They should be compensated(i.e. buy their products) for the effort they have already put forth making sure that everything works correctly and efficiently.
Would you like it if someone came to your job and asked you to do work for them and then not pay you for it ? You see where I'm going.

Click to expand...

I think its valid question to ask. I don't know how "propriety" that questions really is. Ive spoken to three turbo experts and each of them openly told me what size turbo they plan on using. Its not like I asked in order to sneak behind their back and DIY at home. lets face it, forced induction is basic in principal but hard to perfect. When I eventually buy my turbo system there is no way in hell I am going to do it myself. But like EAC I like to ask them what turbo they use in their installation and why. Mostly because I want to know what I am getting for my 15K!

Some people like the larger turbos, some people like them small... some like one turbo and one a twin system. If I am going to spend this kind of money I think I have the right to ask around to see what the best setup is so that my 15K gets me EXACTLY what I want. Based on feedback from current NSX owners you can gauge what system to buy, and what turbo to ask for... not to steal all their hard work!

I got to tell you, Cody at Lovefab and Chris at SOS are very open about everything, and I like that. But its interesting that they both attack FI in totally different ways. Cody is a large single turbo, 58-68mm or so (if memory serves) and Chris said a pair of 25's would do the trick. So of course I want to ask around... maybe I want to pay a little extra for 28's, or 31's or whatever.

FYI - I am just beginning my quest for info, and LOVE how open the NSX community is. The rest of your guys who are giving us so much data is absolutely the reason why I love my online NSX family. You guys have helped me so much already, in fact, I don't think I would have ever enjoyed ownership nearly as much without the open and free communication.

Oh, and by the way, before I go with SOS or Lovefab, you bet that I want all of your opinoins. Its not like we are racing for pink slips LOL

J

captainjman said:

I think its valid question to ask. I don't know how "propriety" that questions really is. Ive spoken to three turbo experts and each of them openly told me what size turbo they plan on using. Its not like I asked in order to sneak behind their back and DIY at home. lets face it, forced induction is basic in principal but hard to perfect. When I eventually buy my turbo system there is no way in hell I am going to do it myself. But like EAC I like to ask them what turbo they use in their installation and why. Mostly because I want to know what I am getting for my 15K!

Some people like the larger turbos, some people like them small... some like one turbo and one a twin system. If I am going to spend this kind of money I think I have the right to ask around to see what the best setup is so that my 15K gets me EXACTLY what I want. Based on feedback from current NSX owners you can gauge what system to buy, and what turbo to ask for... not to steal all their hard work!

I got to tell you, Cody at Lovefab and Chris at SOS are very open about everything, and I like that. But its interesting that they both attack FI in totally different ways. Cody is a large single turbo, 58-68mm or so (if memory serves) and Chris said a pair of 25's would do the trick. So of course I want to ask around... maybe I want to pay a little extra for 28's, or 31's or whatever.

FYI - I am just beginning my quest for info, and LOVE how open the NSX community is. The rest of your guys who are giving us so much data is absolutely the reason why I love my online NSX family. You guys have helped me so much already, in fact, I don't think I would have ever enjoyed ownership nearly as much without the open and free communication.

Oh, and by the way, before I go with SOS or Lovefab, you bet that I want all of your opinoins. Its not like we are racing for pink slips LOL

J

Click to expand...

One of the reasons SOS went with a x2 turbo is that allowed them to provide something different, which was the ability to keep your factory cats and any aftermarket exhaust. As well, it doesn't run an external dump tube and you can sub in bypass valves instead BOVs. This is the most "OEM" type setup for the NSX. I'm sure Chris could have done a single turbo but I'm sure he was hearing from guys like me that they want something OEM-ish, quiet and unobtrusive. I would last 1/2 hr with a BOV psssshhhh before it would drive me crazy.

I had to read it twice, too much information. The more I know, the more don't know about what to get for FI or NA. I guess that's a good thing because most of the pleasure goes into the process of looking for the right parts for my car.

+1 Captainjman. Eventually, it comes down to the research owners do to obtain the right parts for their needs according to their budget. Turbo sizes are the last secret vendors should worry about.

This is the first time I heard about making power too soon is bad. (Sorry if I am misinterpreting Flexer) You guys are saying a high flat torque through out RPM is bad because it put too much stress on the motor in low RPMs, and it also makes it hard to control because of traction?

I thought if both turbo makes 400whp, the one with a higher torque number through out would be faster. And isn't minimal lag and power everywhere instead only at high RPMs is what people have been trying to achieve? I am confuse.

Also, as J said, while we are at it, SOS or Lovefab?:biggrin: Ross, why do you think the exhaust collector is not ideal. Though, I know SOS design this with OEM-ish goal in mind so I know there are compromises but just want to know what they are compare to the Lovefab.

Hugo

CL65 Captain said:

it doesn't run an external dump tube and you can sub in bypass valves instead BOVs. I would last 1/2 hr with a BOV psssshhhh before it would drive me crazy.

Click to expand...

Just wanted to comment on your noise concerns, any system (including mine) could easily be tailored to your needs by recirculating the BOV and the wastegate, I have alreay done this for a couple customers.

I could pretty easily make a car with my kit as quiet as stock...

angus said:

Just wanted to comment on your noise concerns, any system (including mine) could easily be tailored to your needs by recirculating the BOV and the wastegate, I have alreay done this for a couple customers.

I could pretty easily make a car with my kit as quiet as stock...

Click to expand...

ANGUS - tell us about your system!!

I currently have a GT35R on my stock nsx, I'm not quite making 400hp (8psi) but close. in my honest opinion this is an excellent choice for a street driven nsx.
I'm impressed with how responsive it is. It may drop off in the Higher rpms but who needs that on a street car.

I'm currently upgrading to TO4Z specs but I plan to be more of a track car than street car.

HGL1668 said:

I had to read it twice, too much information. The more I know, the more don't know about what to get for FI or NA. I guess that's a good thing because most of the pleasure goes into the process of looking for the right parts for my car.

+1 Captainjman. Eventually, it comes down to the research owners do to obtain the right parts for their needs according to their budget. Turbo sizes are the last secret vendors should worry about.

This is the first time I heard about making power too soon is bad. (Sorry if I am misinterpreting Flexer) You guys are saying a high flat torque through out RPM is bad because it put too much stress on the motor in low RPMs, and it also makes it hard to control because of traction?

I thought if both turbo makes 400whp, the one with a higher torque number through out would be faster. And isn't minimal lag and power everywhere instead only at high RPMs is what people have been trying to achieve? I am confuse.

Also, as J said, while we are at it, SOS or Lovefab?:biggrin: Ross, why do you think the exhaust collector is not ideal. Though, I know SOS design this with OEM-ish goal in mind so I know there are compromises but just want to know what they are compare to the Lovefab.

Hugo

Click to expand...

Hugo,


A turbo manifold... just like a y-pipe or even a header.. collect's exhaust gases. The goal is to collect them evenly and without turbulence.

Turbo's are sensitive ... they want "predictability"... the easier the air enters the turbo.. the more response the turbine will have.

If you look how the 3 exhaust pipes "run into each other rather than flow with each other... you can start to understand this theory.

Looking at other manifolds done correctly would be your next step... I'll use another NSX fabricators products to explain... since his turbo kit uses a y-pipe and remote turbo... which isn’t "un-oem” at all considering Porsches have remote turbos too...

Love fab manifolds...

Sr20DET



RB25DET or RB26DET - very impressive Cody (if you read this)... those Rb manifolds look top notch




here are a few from full-race










And then… Look at every turbo manifold AFI Turbo makes on these two pages... none of them have exhaust gases collect in the "run into each other" fashion.

The SOS kit was made to fit... not made to maximize efficiency.. at $100 per horsepower gained... I just don’t know why more people are asking... why




My $.02

Ross,

Does the exhaust tubing need to be equal length from the exhaust port to the collector? Or would it need to be different length relative to the firing sequence so that it optimize the exhaust pulses (which travel more a less like a series of tennis balls down a tube) pushing and pulling each other as it makes its way towards the exhaust for greater and unobstructed velocities?

Ummm!!!
I miss it a big deal, I used to run them on my other car.

-MSR

MetalSpikeRacing said:

Ummm!!!
I miss it a big deal, I used to run them on my other car.

-MSR

Click to expand...

I have the privilage of working with many Full-Race and AFI-Turbo fabricators...

Full-Race and AFI are only 3 miles from my shop...

Here is our K20 Turbo Manifold... rotating the air prior to the turbine wheel also has been proven to increase response.

BATMANs said:

Ross,

Does the exhaust tubing need to be equal length from the exhaust port to the collector? Or would it need to be different length relative to the firing sequence so that it optimize the exhaust pulses (which travel more a less like a series of tennis balls down a tube) pushing and pulling each other as it makes its way towards the exhaust for greater and unobstructed velocities?

Click to expand...

Equal length is the goal... and equal length is more of a factor with turbo than NA

Manipulating firing order comes into play with twin-scroll turbos... the theory is that the first cylinder to fire is directed to the inside of the turbine wheel... with the second cylinder directed to the outside of the turbine wheel.

This is why they say twin scroll's spool faster.

Regards