Rb26 Turbo Comparision Graph (from Latest Hpi Mag)

[paulr33]

manifold

turbo housing(s)

dump pipe

front pipe

cat

exhaust

making any of these larger or taking away restriction is likely to yield more power. ie a dyno run with the gtss and the front pipes dropped unbolted is likely to make a bit more power as theres no back pressure from the cat being there

[shanef]

I assume that re-profiling the exhaust/inlet ports would be another way of getting more air into the engine.

Another would be to remove casting dags/imperfections in the head and bottom end giving better flowing characteristics

[Guest Mashrock]

Whats the major way to reduce restriction so you can flow more air, run less boost and get more power? I understand that if you remove restirction the engine can breath easier so it doesn't need as much pressure to force the same amount of air into it. I'd guess CAMS are the first/biggest difference? What else can you do? ... sorry if this is a dumb question, i really don't know.

a shit load of money to be spend on just the head alone, biggest valves possible and all supporting springs etc, lots of porting, lots of metal comming out of the head, cams that match up well with your turbo's.

and at the end of that i beleive a good porting job can cost you upwards of 5k? perhaps even more.

[Sydneykid]

Whats the major way to reduce restriction so you can flow more air, run less boost and get more power? I understand that if you remove restirction the engine can breath easier so it doesn't need as much pressure to force the same amount of air into it. I'd guess CAMS are the first/biggest difference? What else can you do? ... sorry if this is a dumb question, i really don't know.

The intercooler and its pipework are restrictions.

The inlet manifold including the plenum can be a restriction

The throttle body/bodies can be a restriction

Inlet and exhaust ports in the cylinder head are restrictions

Camshaft timing and lift are obvious restrictions

Valves are a restriction

Valve seats can cause turbulence, another restriction

The exhaust manifold is a restriction

The turbine itself is a restriction

The wastegate is a restriction

The dump, engine pipe, cat and cat back exhaust are restrictions

Remove the restrictions and the boost goes down, the airflow goes up and so does the power. If all of the components are matched to the airflow (necessary for the power target) then the efficiency will also be at its highest, which means better response.

The trick is knowing which of the items is going to be a major restriction for your particular power target on your engine and then removing them. The old school thinking on turbocharged engines used to be “who cares about that stuff, just turn up the boost”. But the late 80’s F1, the turbo Group A era, WRC's and, to a lesser extent, Indy cars have all killed of that thinking.

Cheers

[Sydneykid]

i beleive a good porting job can cost you upwards of 5k? perhaps even more.

Shoot, remind me never to go anywhere near your machine shop.

I have never spent more than $1K on an RB engine's ports, and that was for 1100 bhp plus.

cheers

[Guest Mashrock]

Shoot, remind me never to go anywhere near your machine shop.

I have never spent more than $1K on an RB engine's ports, and that was for 1100 bhp plus.

cheers

p.s. i have no idea!

but i did mean the whole head. not just a bit of rub and tickle

Edited June 19, 2006 by Mashrock

[Sydneykid]

i did mean the whole head. not just a bit of rub and tickle

So did I

cheers

[SLY33]

ok so what you guys are saying is that if i dont plan to run avgas and push the turbo to its absolute limits then the garret will be just as good as the hks to4?

True a lot was spent on a nice bottom end and someone said just finish it off with HKS turbo, but thats the problem, the bottom end ate majority of the funds! and i still need cooler, zaust, injectors, plus a host of other stuff! At first it was a spare no expense operation, but now its scrimp and save time or we will never finish it off So saving a couple of grand on the whole turbo kit sounds good at the moment!

Ive always been an HKS over garret person, but recent garret results are turning me... The figures some guys are putting out with garret stuff are very impressive.

[mazgtr]

The dump, engine pipe, cat and cat back exhaust are restrictions

Remove the restrictions and the boost goes down

Cheers

Why then when you fit a larger higher flowing aftermarket exhaust to a stock turbo car does the boost pressure rise? Or a less restrictive Intercooler can also see the car making more PSI without any other adjustment.

My old Mazda GTR used to run 14PSI stock. With a 3inch exhaust and aftermarket Intercooler boost rose to 18PSi....

I know that most Intercoolers are measured on their ability not to allow pressure drop across the face of their core, i:e your feeding it 14PSI but its seeing 2-3PSI of pressure drop across its core due to restriction. A better flowing Intercooler would then see less restriction and a rise in PSI wouldnt it?

I know power and PSI are not linked, just because you run 2.0Bar doesnt mean your going to make more power than a better setup car with 1.5Bar. Power is based on air-flow, the more air and fuel you can stuff into an engine and the quicker you can get it out is what effects power. The less restriction in the system, the more power you will make at lower PSI, but reducing the restrictions doesn't reduce boost pressure by itself.

Also, even after you reduce every possible restriction within reason, you can still run high boost pressures to make power. If you took 2 GTR's one with a Garret and one with HKS turbo, for arguments sake lets say the HKS is more efficient at higher boost levels, then once both cars were removed of all possible restrictions that could be expected, the owners of said cars would start to wind up the wick on their turbo's to make the most of their "restriction free-er" setups. This is where a turbo that performs better at higher boost levels will make more power (provided its still within its efficiency curve) I dont know what HKS or Garret quote as their peak PSI, in know that most HKS turbo's are in the real meat of their power curve up to and approaching 2.0Bar.

At the end of the day, once you do remove restrictions, you then would start to look at larger more powerfull turbo's and higher boost levels.

I think you said in an earlier post "if someone says to me im running 2.0Bar, i say then you havent removed all the restrictions" Just look at Top fuel dragsters in the NHRA where money is no object and engines and support systems are just about the best power producers in motorsport, with power figures approaching 5000BHP. Where most races are decided by 1000th of seconds, every last BHP is gold, thus the engines/heads/cams/valves are all patiently labour intensivley poured over in the search for the higher possible flow, and yet these dragsters still run 40PSI. The most efficient way to make power is reduce restriction, but once thats been achieved then the most efficient power producing turbo is necessary, and when chaseing big power figures you need big turbo's, and big turbo's are usually most efficient at higher PSI levels than lesser turbo's. Simply if the cars on the dyno and your continueing to see power gains as you increase the PSI without sending inlet temps sky rocketing then the turbo's still being efficient and producing mor epower than heat, where-as a lesser developed turbo might start to trail off at similar boost levels.

Personally im neither a Garret or HKS person....

Cheers. Matt

[DoughBoy]

Shoot, remind me never to go anywhere near your machine shop.

I have never spent more than $1K on an RB engine's ports, and that was for 1100 bhp plus.

cheers

What engine is that, I've seen you mention it a few times now. The amount of RB's making over 1K hp in Aus can be counted on one tasmanian hand, yet this combination hasn't been mentioned? Esp since it's a "drag motor", the amount of high powered RB's racing are pretty well known.

[paulr33]

stock car

7psi

stock exhaust

fit larger exhaust

boost rises to say 9psi

and you make 10rwkw more

if you dropped the psi back to 7psi you would probably still make a bit more power. as you take away restrictions, the engine can flow more air easily, thus reducing the restriction, which in turn flows more air

[paulr33]

and on the same token its much better to make a given power level on the lowest boost possible. it will be much better to drive, less laggy and have a good throttle response, and youll likely have decent compresison.

if you need to run 2.2bar to make some good power its likely to be a laggy pos off boost and be a real crapstick to drive

[CruiseLiner]

Also, even after you reduce every possible restriction within reason, you can still run high boost pressures to make power. If you took 2 GTR's one with a Garret and one with HKS turbo, for arguments sake lets say the HKS is more efficient at higher boost levels, then once both cars were removed of all possible restrictions that could be expected, the owners of said cars would start to wind up the wick on their turbo's to make the most of their "restriction free-er" setups. This is where a turbo that performs better at higher boost levels will make more power (provided its still within its efficiency curve) I dont know what HKS or Garret quote as their peak PSI, in know that most HKS turbo's are in the real meat of their power curve up to and approaching 2.0Bar.

At the end of the day, once you do remove restrictions, you then would start to look at larger more powerfull turbo's and higher boost levels.

I think you said in an earlier post "if someone says to me im running 2.0Bar, i say then you havent removed all the restrictions" Just look at Top fuel dragsters in the NHRA where money is no object and engines and support systems are just about the best power producers in motorsport, with power figures approaching 5000BHP. Where most races are decided by 1000th of seconds, every last BHP is gold, thus the engines/heads/cams/valves are all patiently labour intensivley poured over in the search for the higher possible flow, and yet these dragsters still run 40PSI. The most efficient way to make power is reduce restriction, but once thats been achieved then the most efficient power producing turbo is necessary, and when chaseing big power figures you need big turbo's, and big turbo's are usually most efficient at higher PSI levels than lesser turbo's. Simply if the cars on the dyno and your continueing to see power gains as you increase the PSI without sending inlet temps sky rocketing then the turbo's still being efficient and producing mor epower than heat, where-as a lesser developed turbo might start to trail off at similar boost levels.

Personally im neither a Garret or HKS person....

Cheers. Matt

exactly my point, once u get rid of the restrictions like all these 2.8L hks stroker engines, etc and u want more power they are still all using over 25psi to create big numbers so in the end if u want the most from the setup u are gonna have to wind the wick up and push the turbo to its limit if the rest of the engine can handle it, so how can i make my hks t04z make its maximum power potential on like 20psi? surely running 28psi on the exact same setup will gain better results wouldnt it if the turbo can handle it?

pretty basic question but i personally would like to run 20psi and make 670rwhp+ rather than run 28-30psi if possible, i got full porting done and big big cams setup, and all the other usual goodies (trust manifold, bigger exhuast, big wastegate, etc etc) so where do i go from here to help? would changing to bigger valves and bigger throttle bodies then affect response on the same setup?

sorry if its unclear what im saying but its the best way to put it into words.

and also Ash i havent personally seen any hks vs garrett at 2 bar plus but going by every other garrett vs hks turbos, the garretts just dont produce much more power from 25-26psi onwards. also your point on going from 16psi to 25psi and making a huge difference is right, but try winding it from 25psi upto 28-30psi and see if u make any more power at all????

thanks and im only saying my opinion so no offence meant to anyone.

P.S. this has turned into a nice little imformative thread, keep the info/ideas coming

Brad

Edited June 19, 2006 by CruiseLiner

[Sydneykid]

What engine is that, I've seen you mention it a few times now. The amount of RB's making over 1K hp in Aus can be counted on one tasmanian hand, yet this combination hasn't been mentioned? Esp since it's a "drag motor", the amount of high powered RB's racing are pretty well known.

Hi Chris, we did 2 at the same time early last year, one is in 240SX in Florida (9.3 at 150 mph) and the other is going into an R32GTS4 in the UK. We are also doing one for a Canadian at the moment. Not enough racing here I gues for the guys to justify the costs. Sports Compact is so big in the US, they race every couple of weeks.

cheers

[R31Nismoid]

so how can i make my hks t04z make its maximum power potential on like 20psi? surely running 28psi on the exact same setup will gain better results wouldnt it if the turbo can handle it?

More capacity.

More you have, more air your eating.

Not saying it will reduce. But you see the big V8's running 7psi in a TT scenario and they are munching out the most stupid numbers, because thier 7psi is the equivalent to a lot more on a smaller motor

Again, its where the turbo falls into the efficiency ranges and stuff on the comp map

[Sydneykid]

exactly my point, once u get rid of the restrictions like all these 2.8L hks stroker engines, etc and u want more power they are still all using over 25psi to create big numbers so in the end if u want the most from the setup u are gonna have to wind the wick up and push the turbo to its limit if the rest of the engine can handle it, so how can i make my hks t04z make its maximum power potential on like 20psi? surely running 28psi on the exact same setup will gain better results wouldnt it if the turbo can handle it?

pretty basic question but i personally would like to run 20psi and make 670rwhp+ rather than run 28-30psi if possible, i got full porting done and big big cams setup, and all the other usual goodies (trust manifold, bigger exhuast, big wastegate, etc etc) so where do i go from here to help? would changing to bigger valves and bigger throttle bodies then affect response on the same setup?

sorry if its unclear what im saying but its the best way to put it into words.

and also Ash i havent personally seen any hks vs garrett at 2 bar plus but going by every other garrett vs hks turbos, the garretts just dont produce much more power from 25-26psi onwards. also your point on going from 16psi to 25psi and making a huge difference is right, but try winding it from 25psi upto 28-30psi and see if u make any more power at all????

thanks and im only saying my opinion so no offence meant to anyone.

P.S. this has turned into a nice little imformative thread, keep the info/ideas coming

Brad

Hi Brad, it's all a bit circular, you end up back where you started from.

So you run ever higher boost

You need to lower the compression ratio

And retard the ignition timing

Plus add a larger intercooler to scrub the increased temperature

To avoid the detonation

And that loses power

So you add some more boost

Then you have to run jungle juice

Which not many people can afford to do on the road

So you turn the boost back down

Now you have a low compression engine

With retarded ignition timing

And a monster intercooler

Running lower boost than the turbo is efficient at

That's both unresponsive and laggy

Except when it is running the 1/4

Then it's a weapon

But would it be better with a bigger turbo?

For less turbine restriction

So it makes the same power

At lower boost

So you don't need to lower the compression ratio

And retard the ignition timing

Back where you started from, except you have just raised the rpm threshold.

cheers

Edited June 19, 2006 by Sydneykid

[R31Nismoid]

and also Ash i havent personally seen any hks vs garrett at 2 bar plus but going by every other garrett vs hks turbos, the garretts just dont produce much more power from 25-26psi onwards. also your point on going from 16psi to 25psi and making a huge difference is right, but try winding it from 25psi upto 28-30psi and see if u make any more power at all????

Yeah i see what your saying, but if you look @ the comp map, any turbo can be worked out when its gonna stop being useful, and where it starts to be.

I was on track to make more power, and it didnt seem to let off. We just didnt have ignition, and i didnt have the funds to pursue it any further.

You cant argue where the turbo is and is not efficient. It can all be worked out reasonably well... although i think the maps for HKS turbos are hard to find... if at all???

I doubt the wheels HKS used are the big difference here.

And i doubt even further that the "higher boost on a HKS turbo" argument comes ultimately down to housing designs in the HKS range.

I still think there is no major difference and its just a case of myth busters

If there is a difference, it will be due to the slight varyation of the wheels and housings which is what makes things go around. But IMO its not a massive difference.

As for 25psi onwards from a Garrett, there are countless cars on this forum, and aboard that are using a lot more than that through their Garrett turbos for power over 500rwkw

Leewah's is a great example that comes to mind as with many others

[paulr33]

of course this could be settled at a pub with a beer and a pencil and a calculator if HKS released their compressor maps.

[BOOSTD]

Have you had the car on another dyno. I have now seen a few results from Advan that perhaps flatter the car.It has rana quick time at a good mph, and Advan obviously punch out nice cars, only i suspect their dyno reads higher then some

Advan didn't build it, I did. I also tuned it. The horse power calc for my weight (1620kg) at 120Mph came to 355kw and that was on higher boost. so ADVAN's dyno may actually be alittle happy. Peter mentioned the other day that it had been re-calibrated and now reads lower.

[CruiseLiner]

Yeah i see what your saying, but if you look @ the comp map, any turbo can be worked out when its gonna stop being useful, and where it starts to be.

I was on track to make more power, and it didnt seem to let off. We just didnt have ignition, and i didnt have the funds to pursue it any further.

You cant argue where the turbo is and is not efficient. It can all be worked out reasonably well... although i think the maps for HKS turbos are hard to find... if at all???

I doubt the wheels HKS used are the big difference here.

And i doubt even further that the "higher boost on a HKS turbo" argument comes ultimately down to housing designs in the HKS range.

I still think there is no major difference and its just a case of myth busters

If there is a difference, it will be due to the slight varyation of the wheels and housings which is what makes things go around. But IMO its not a massive difference.

As for 25psi onwards from a Garrett, there are countless cars on this forum, and aboard that are using a lot more than that through their Garrett turbos for power over 500rwkw

Leewah's is a great example that comes to mind as with many others

good info Ash i dont think the hks will make a huuugeee difference but when u want to push it to the max i'd personally rather the better of the 2 products to get that big more without having to jump upto a gt42 or something laggy as hell. if someone happens to lend me a garret t04z for a few dyno pulls i wouldnt mind comparing my hks t04z to a garret t04z on the exact same engine setup, they both bolt on to same manifold type, but then the cooler piping inlet is 2 and 3/4 inches on the HKS and only 2.5" on the garrett so then i'd have to change the cooler piping (or maybe i could just use a silicone reducer). plus the exhuast flange on the HKS one is a v-band and im not sure whether garrett use a v-band also?