How Much Boost Should I Run

[Briggs]

hey guys,

after a new clutch, followed closely by new turbo's, am now looking to get some reliable power out of the car. it was apparently running 15 psi and getting 310rwkw with some pretty basic upgrades (i never saw the dyno sheet so have no proof here, could just be talk).

Upgrades:

JJR cam gears

HKS GT-SS turbos

HKS Exhaust from turbo back

HKS step 1 cams

Hi-Flow Cat

Apexi power fc

Twin Apexi power intake with k&n filters

Blitz Boost controller

54mm aluminium radiator

Gearbox gears all cut and cryo strengthened

I have fitted a jim berry full monty clutch that he asures me will easily handle the power, and replaced the turbo's with their garret counterparts (the -9's), i will be using the HKS actuators from the stuffed ones. also on the way are some 600cc injectors and a pair of z32 AFM's. so my question is,

how much boost can i run without causing significant damage to the engine or running gear?

what sort of power figures should i expect?

cheers in advance guys,

Briggs

Edited June 14, 2011 by Briggs

[DVS JEZ]

Around 300kw should be safe for a while. If u push more u run the risk of reducing engine life and reliability even more with stock internals

[R31Nismoid]

+1 to the above. 300-320rwkw would be a nice safe limit.

You'll make that power on around 18psi or there abouts.

[SargeRX8]

Why? Simon with the kando is making 500hp stock motor, with rpm 8000 red line and still going strong. If you can keep egt down and detonation, it should last long

[R31Nismoid]

Willing to take that risk with your motor dude?

Simon knows it will die, infact I'm sure he's even said himself he is surprised its still together - impressive as it may be (and indeed it is impressive, taking nothing away from it), longevity is important to some people and not talking 2 years. Some people want motors to last 4yrs+

Have a look @ some of the RB25s that are starting to pop now @ 300-320rwkw or so. They've been fine for 2-3 years - some are STILL fine... Yet some are giving up the ghost. It's that "some" that is always the ole gamble.

There is no hard and fast rule unfortunately. The only 'rule' so to speak that really exists is this:

If you cannot afford the rebuild or replacement motor - Don't chase the power.

[Briggs]

thanks guys, as i'll be using it all the time, i might just stick with about 300kw (i'm asuming you meant at the rears, not all 4???), fast enough for now. in terms of strengthening the motor for more power, if i was to spend say 5k, ignoring that i'd need bigger turbos, would that be enough for say 450kw? or would i need bigger injectors, fuel reg, pump, etc, etc, and the list goes on? am considering selling the bike if there are significant gains to be had.

thanks for the feedback guys, lots of help

Briggs

Edited June 14, 2011 by Briggs

[R31Nismoid]

The list goes on, 5k won't get you far at all, double it and you might start getting closer

[SargeRX8]

What is it that kills the motor? There are many factors but I would think the main ones are heat and detonation as well as maintenance.

Running an ethanol fuel blend will bring down temps and increase power. Having 300rwkw won't kill the motor, its more how its used. My brothers rotor has 700hp and that is going for a rebuild now, after 6 years.

[zebra]

What is it that kills the motor? There are many factors but I would think the main ones are heat and detonation as well as maintenance.

Having 300rwkw won't kill the motor, its more how its used.

Yes it will

Factory pistons can only handle so much combustion pressure, same with rods, bearings etc. these motors are nearly 20 year old and most will have over 200,000ks so getting near rebuild time at factory power levels, and well past it when they are making double the factory power.

Sure you could build a 1000hp rb25DE run it once on the dyno for a number and then never go past 3000rpm ever again and it will last quite a while.

But what is the point in that?

[SargeRX8]

You know you have the power when you need it. There is a difference in use between a 1000hp and a 400hp car. A 400hp car, depending on the driver, will not be driven like a 1000hp car. A 1000hp car is driven with the intentions of being put down the track day in day out as long as it will last.

My old line had 320hp never had an issue with it and I drove the car like its just a normal car. Just because you have a skyline does not mean every second you're driving you need to race, hit limiter, full boost etc.

That is the misconception. You've got a car with potential to go fast, doesn't necessarily mean you have to go fast all the time. Its like a cop with a gun; just because he has it, does not mean he has to put it to use. The difference then is giving the gun to a criminal, who will just be pointing and shooting all the time.

Basically what I'm getting at is your car can make the power and how long it last is not in the car, its in the driver. 300rwkw can last you years with some moderate driving.

I'm speaking on my perspective. I don't know what he intends to do with the car but if I had 300rwkw I'd still drive the car like it was a stocker and every now and then open her up just for the thrill. That's just me.