Highest boost on stock turbo?

[krzysiu]

HOw much money would you have to spend to get a car with a stock turbo to 225 KW without changing the turbo. I just say that is stupid and a waste of money. My car doesnt run at its full potential cuz i can run 1.2 bar boost (HKS Turbocharger) comfortably and it pulls 250 at the wheelz. I just need to but a boost controller and the mechanic said that he can push my boost to 1.6 bars. and what mods do i have? not many. HKS turbo, HKS huge front mount intercooler, Bosch Fuel Pump. HKS POD FILTER and of course a 4.5 inch exaust + more. I think it would cost more money to get a sotck turbo to run as my car does. Its just not worth it and u r luckyt that u havent cracked the turbo. Laterz

[Sydneykid]

Hi krzysiu, I posted this elsewhere, but I think it answers your question.

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Hi guys, a lot of people look at the other upgrades (cams, porting, manifold etc), on a turbo car, as a way of increasing the maximum power at one particular rpm point. That's not what I do it for, I actually use these other items to increase the average power over the used rpm range. I also use them to reduce the amount of boost I run to achieve the same maximum power, this increases the responsiveness of the engine as well.

A comparison;

1. I have an RB engine that needs 1.6 bar to achieve 600 bhp with standard cams, ports, lowered compression ratio (thick head gasket) and a combined dump. It has 360 bhp average power (4,000 rpm to 7,500 rpm).

2. The same RB engine that only needs 1.3 bar to achieve 600 bhp with 264 cams, ported, manifolds matched, standard compression ratio and a split dump. It has 440 bhp average power (4,000 rpm to 7,500 rpm).

Some people would say that I wasted my money on the cams, porting, split dump etc since I still only have 600 bhp. I would of course reply yes, but I have a 22% increase in average power, so the car will be substantially faster. Plus the response will be also dramatically improved by the enhanced breathing, with better off boost performance and faster to build boost.

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So by simply sticking a bigger turbo on, you may well be increasing the max power at one RPM point, good for bragging (or dyno heros) but not much good for actually going fast. The magazines are full of cars with big max power claims, but stick them on the track and they fall short. Why? Because, generally, they have poor average power and/or lousy suspension and poorly chosen tyres. It's all part of the package

Hope that adds to this interesting thread.

[Sydneykid]

Hi krzysiu, I posted this elsewhere, but I think it answers your question.

----------------------------------------------------------------------------------------

Hi guys, a lot of people look at the other upgrades (cams, porting, manifold etc), on a turbo car, as a way of increasing the maximum power at one particular rpm point. That's not what I do it for, I actually use these other items to increase the average power over the used rpm range. I also use them to reduce the amount of boost I run to achieve the same maximum power, this increases the responsiveness of the engine as well.

A comparison;

1. I have an RB engine that needs 1.6 bar to achieve 600 bhp with standard cams, ports, lowered compression ratio (thick head gasket) and a combined dump. It has 360 bhp average power (4,000 rpm to 7,500 rpm).

2. The same RB engine that only needs 1.3 bar to achieve 600 bhp with 264 cams, ported, manifolds matched, standard compression ratio and a split dump. It has 440 bhp average power (4,000 rpm to 7,500 rpm).

Some people would say that I wasted my money on the cams, porting, split dump etc since I still only have 600 bhp. I would of course reply yes, but I have a 22% increase in average power, so the car will be substantially faster. Plus the response will be also dramatically improved by the enhanced breathing, with better off boost performance and faster to build boost.

---------------------------------------------------------------------------

So by simply sticking a bigger turbo on, you may well be increasing the max power at one RPM point, good for bragging (or dyno heros) but not much good for actually going fast.  The magazines are full of cars with big max power claims, but stick them on the track and they fall short.  Why?  Because, generally, they have poor average power and/or lousy suspension and poorly chosen tyres.  It's all part of the package.

Hope that adds to this interesting thread.

[Gizmo73]

Hi Gizmo, 9 to 10 psi on the standard turbo and intercooler and 11 to 12 psi on the standard turbo with a GTR intercooler. On the road, should be no problems as the heat build up isn't extreme. But on the circuit, 4 or 5 hard laps will still be a problem.

 

 Hope that helps some more.

Hey SK...

Thought i would drag up this thread since there has been some more talk circling around the stock turbo and boost settings..

With your quote above, it seems pretty straight forward - and it also seems that most people seem to run no more than about 12psi on stock turbo backing up the argument...

However, with some recent comments circling (some by yourself) - im most confused, as now i believe you are saying that 10psi is the most you would run..

http://www.skylinesaustralia.com/forums/sh...stock+turbo+r33

Im just interested in the reasoning, as im getting my car boost levels altered to 12psi, and the conflicting reports are confusing...

Mods are..

Ext Cam Gear

Full Exhaust - including cat back (HKS super-dragger), hi flow cat and dump pipe (ceramic coated)

GTR intercooler with piping (120 degree bend from plenum)

rb20 actuator + bleed valve (to be installed) to get the 12psi (...maybe - depending on the comments !!)

pod filter with CAI partition

iridium sparkies gapped to .8mm

power fc and hand controller

the relevant whiteline handling thingys..

Car is a daily driver, doing mixture of freeway and city driving. Sees the drags about once every 4 months...

Possibly im confused in regards to having an larger intercooler or not (hence less boost the turbo has to generate to acheive the same restriction at the engine)

This is NOT a dig at you SK, just would like to get some clarification prior to my car going in on Thursday..

[fresh]

i have found on my stock edu'd r33 that anything over 10 pounds feels quite a lot slower.....is this normal, i got FMIC, full 3" exhaust but the car feels faster and definitely runs smoother on 10 psi compared to 12-13psi, getting a PFC installed soon which will hopefully make 12 psi and reasonable amount to run, but i was running 12-13 psi on stocko cooler, and yeah engine didn't like it at all

[Zoix]

this is good, I'd like to also know what electronic boost controllers you use, not which is best, but what you recommend.

[R31Nismoid]

The turbo is best at 10psi, running 11-12 you are really not making any huge gain so there is no real point taking it that far. 10psi and you'll be a happy camper for a long time

But SK was making a point of for short bursts he beleives you can use 11-12, but for anything less that a one-off squirt then its 10psi.

Where SK said 10psi, that post was made with a hard driving stretch of road in mind i beleive, which would have similar conditions to that of a few laps of a track.

hope that gets you the clarification you need.

-ash

[gatty]

my mate runs about 12 PSI - misses like a bitch

he has a fuel cut defender also - FMIC and that about it..

goes ok for a auto

[RB30-POWER]

I read so many people with missing cars and having to gap the plugs down.

If you have to gap them down, you must have a faulty ignition system i would say.

It does seem to be common that the coils crap themselves.

I thought SK said once before, that if you run more boost than factory setting, the ecu goes into "Rich and Retard Mode" and you have to advance the base timing up to 20deg btdc to counteract the ecu retarding the ignition. Or was that just Series 1 cars?

The other thing, where does the factory turbo run out of its efficiency range? No need to boost beyond this point as the extra heat will counteract the extra boost pressure.

[Sydneykid]

i have found on my stock edu'd r33 that anything over 10 pounds feels quite a lot slower.....is this normal, i got FMIC, full 3" exhaust but the car feels faster and definitely runs smoother on 10 psi compared to 12-13psi, getting a PFC installed soon which will hopefully make 12 psi and reasonable amount to run, but i was running 12-13 psi on stocko cooler, and yeah engine didn't like it at all

The standard ecu does not like the additional airflow, it adds a bit of fuel and retards the ignition timing. So you end up with less. Once the Power FC is in you will find a big difference in both max and average power.

[Sydneykid]

Hi Gizmo and other readers; this is not a simple subject, there are lots of factors involved. That's why there are lots of opinions and plenty of different experiences. There are two things that cause the ceramic to part company with the shaft and find a home in the cat. The first is boost, or more correctly turning torque. The turbine (propelled by the exhaust gases) is trying the turn the compressor (resisted by the boost). The higher the boost the more torque is exerted on the shaft. The second is heat, the ceramic in the turbine is very good at resisting heat, but even ceramic has a limit. Noting that heat is not instantaneous, there is a build up over time (minutes not hours).

I will have a go at writing out the factors;

1. The boost at the turbo and at the inlet valve are different. A good intercooler may only have 1 to 2 psi drop at (for example) under 1 bar. On the other hand I have seen 10 psi drop on a not so good intercooler at 1.5 bar. These increases in resistance are not linear, the resistance is OK up to a point (airflow) then it goes ballistic. For example 10 psi (boost at the inlet valve) might have 2 psi resistance (12 psi at the turbo) and 12 psi might have 6 psi resistance (18 psi at the turbo).

The standard intercooler makes running more than 12 psi pretty much a waste of time. You don't really get any more power, some people like the bragging rights though ("my car runs more boost than yours"). It adds heat to the inlet air that lowers the engine's efficiency and also adds heat to the exhaust. Running 2 boost gauges, one at the turbo and one after the throttle body, the former will tell you what the turning torque really is.

2. The standard ECU makes running more than 10 psi a bit of a waste of time. Once the airflow gets up the ECU goes rich and retard (R&R) and the car actually makes less power. Note the word "airflow", boost is irrelevant. Always remember that boost is simply a measure of restriction to airflow.

With a GTST intercooler and small exhaust I have seen R&R at 12 psi. With a GTR intercooler and a large exhaust I have seen it at 10 psi. Why? Because the airflow is higher at 10 psi since the intercooler and exhaust have removed the restriction.

3. ECU tune is very, very important to the whole equation. When the airflow gets up, the standard ECU is mapped to run the engine rich (way before it gets into R&R). Using a piggy back (SAFC, EManage, FCon etc) means you can lean the engine off and make more power and get rid of the flat spots. Using a full computer replacement (Power FC, Wolf, Motec, Autronic etc) gives a lot more tuning flexibility and none of the tuning compromises that you have to do with a piggy back.

But (there is always a BUT), the leaning off (and maybe ignition timing optimisation) adds heat to the exhaust. Rich mixtures tend to cool the turbine, it is one of the reasons for the R&R strategy.

4. The sole object in increasing boost is to make more power. In my case that's average power, not necessarily max power. If the engine makes more power at 10 psi, then I don't run it at 12 psi.

The tuning conundrum, you can decrease the boost and lean off the mixtures, advance the ignition timing and make more power. On the other hand, you can increase the boost, richen up the mixtures, retard the ignition timing and make more power. This is were a good tuner (not me) makes all the difference.

So the factors break down as;

turning torque (TT) + heat (H) + Time (T)= ceramic in cat (CIC).

In order to work out TT (boost if you like) you have to know the values for H and T. I don't think there is much doubt that 4-5 minutes on the circuit can cause CIC, there are enough examples to give substance to that hypothesis. What I have seen a few times lately is the effect of similar amounts of time with hard running on the street. Recently I used the example of the run up Mooney Mooney that caused CIC. H is easily measured with an exhaust gas temperature gauge (EGT), so if you have one you can "back off" when the temps get too high, thus avoiding CIC.

There are therefore 3 answers;

Run whatever boost you like for as long as you want, keeping in mind to tune the car for the highest power output. Have 2 boost gauges and carefully watch the boost at the turbo, also run an EGT gauge and back off when the temp gets too high.

OR

Run 12 psi, but don’t run hard for long.

OR

Run 10 psi and feel relatively safe that you won’t get CIC.

Hope that makes some sense:cheers:

[Gizmo73]

Hey SK and Ash....

Great info - thanks so much for the responses.

Seems like there are many factors to be decided when tuning for higher boost..

Two immediate questions come to mind..

1) Based on what you have stated, would it also make sense that the boost delivery could also (adversely) affect the heat of the turbo - ie higher rated wastegate actuator as compared to bleed valve or ebc ??

2) Is there a psi at the turbo in which the stock s1 turbo would definetly CIC ??

Based on my current circumstance (and mods), im geting the power fc tuned tomorrow (reputable tuner) and trying to decide whether i want/need 10psi or 12psi...

Possibly i need to chat with the tunersome more..

[RB30-POWER]

Thats a great response SK.

Im sure alot of people appreciate you taking the time to explain things in detail such as you do.

Atleast if this thread topic comes up again, we can just link here, instead of the whole thing again.

[Cillham]

great info ta

It been said that the 33 turbo on a rb20 can be boosted slightly higher and still be safe as 10psi on a rb25. Is this true?

[JCMarshall_Law]

What are peoples opinion on hard track running of a R33 with stock boost (constant 7psi by solenoid grounding)?

Any idea on how long it would take for a CIC event?

[RB30-POWER]

7psi would be fine all day everyday i would reckon...

Nissan would have put a small margin in there for safety.

When they develop and test the engines, they probally have tests that run an engine at WOT for many many hours for durability testing. If it was going to fail only a tiny bit above spec they wouldn't risk it, in regards to possible warranty claims.

My understanding is that you could run more boost on the R33 turbo, because the 2L isn't using as much volume as air as the 2.5 would.

A 2Litre with rb25 turbo on 14psi, might be supplying the same air as and rb25 would use but only on 10psi.

If that makes sense....

Im sure SK would have a better answer though

[Duncan]

What are peoples opinion on hard track running of a R33 with stock boost (constant 7psi by solenoid grounding)?

Any idea on how long it would take for a CIC event?

well, I can share my experience, 3 years, 12-15 track days per year. 10psi. No CIC event.

SK terms a new term!

[Sarkis]

I'm running 12PSI on my R33 GTS-T with Stock Intercooler/Turbo.

[Robo's]

I ran 13psi with stock cooler and afterwards FMIC for over a year. If your not going to race it around the track this should be fine as most 95% of skylines drivers dont circuit race. This also included about 20 1/4 races. So it was driven as "most" skylines drivers would drive or probably harder.

Using less boost and it was dyno proven, peak power didnt decrease a hell of alot, but the midrange torque was much more impressive with stronger boost. Also, stock coolers dont like long amounts thrashings so be careful there.

[JCMarshall_Law]

Duncan

well, I can share my experience, 3 years, 12-15 track days per year. 10psi. No CIC event.

Was that in a R33 GTST?