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Discussion Starter #1
hi what sort of whp are most stage 1 400hp gtr putting out?. my shed with stage1 mods made 373hp and 312hp atw my std injectors were at 96% probally running a bit rich. anyway i thought my car was a bit short of power

but ive noticed a quite a few gtr having 400hp atf but having less power than my car at the wheels. i take it this is just down to different dynos either that i have more efficient 4wd system some how
 

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Discussion Starter #3
decat hks exhaust. apexi ecu and filters. boost controller set 0.9 bar but spikes to 1 bar at about 6000
 

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your only halfway stage1 as I can see it.

Your missing downpipe, intercooler and a remap (pref with aftermarket ECU), and maybe a intank uprated fuelpump.

And the difference in hp could be the use of different dyno's or mostlikely a different way of calculating loss in hp from flywheel to wheel hp.
 

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Discussion Starter #5
the standard intercooler is meant to be good for about 600hp so should be fine for stage 1 the apexi ecu is a aftermarket ecu that i got remaped on the dyno and im pretty sure the downpipes arent standard
 

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Sounds like your doing it right. Its at the wheels that matters mate! Ive noticed that dyno results vary a bit. Some people falsify the results by uping the air temp measurements, to make the dyno read out compensate the hp.
Ive gone for a set of nismo 550cc injectors and a fuel pump. Just stops the injectors maxing.
 

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373 does sound about right with those mods but as has been said before thats probably not full stage 1 .
And although what exactly constitutes stage 1 mods is not set in stone anywhere very few people would leave the intercooler out of neccessary mods for 400bhp.

Even if it the std intercooler is good for 600 bhp is its certainly nor ideal . Equally the injectors and std fuel pump are probably pretty much maxed out at your figure.

It is proven that the rb engines work better when you upgrade the components before you need them especially as its rather expensive to do this afterwards.

so injectors and fuel pump with intercooler should be on your list (IMHO)

.
 

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Discussion Starter #9 (Edited)
i dont really see the point in changing the intercooler if it doing its job fine just now. im planning on buying bigger injectors and fuel pump next and maybe some hks 2510 or similar

ive seen some cars at stage1 loose over a 100hp:chuckle: through the transmission losses which doesent sound right. my car only lost 61hp through the transmission
 

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Personally i wouldnt change it either mate. 600+cc injectors and fuel pump is the way to go. Mine made about 490hp at 1.2bar with the same mods on N1 turbo's.
 

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std intercooler is good for 450hp, the R34 GT-R is up for max 550hp.
Still would give you a decent amount of extra hp if you upgraded it.

You would need a full remap if you change injectors / intercooler btw.
 

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Approx 80hp in transmission losses, although there are lots of variants in the calculation.
If that's correct, I've made 400bhp with nothing more than cat back exhaust, front pipe, pods + stock ceramic shitter 34R turbos.

Untuned and no boost control other than what the factory had in place (-minus restrictors, ~1 bar)
 

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Figures vary from dyno to dyno and sometimes from day to day

The most accurate is measuring it is at the hubs as this is a true fig and more importantly (IMO) thats the power that counts

As I understand when flywheel bhp is measured it is then recaculated to wheel bhp by measuring the transmissions rolling resistance on no power . Then the atw figure is calculated using that reading .
For example when my stagea was dynod on surrey rolling road they seemed to subtract a bit over 100 from their flywheel figure but abbey only added 75 onto their hub figure . when they did a power run recently.
The torgue figures were also quite a bit different abbey 445 SRR 425 @4500 rpm

Also when using rollers you assume no wheel slip which isnt always the case - my stgaea certainly jumped about a fair bit even though strapped down prettty well..

)
 

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Discussion Starter #14
whp is measured on the rolling road. then the power losses through the transmission are worked out using a coastdown test and then the flywheel hp can be worked out or exagerated!
 

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Fair enough that but whp readings are much more accurate if you use a dynapac type dyno taking the readings direct from the hubs as theres NO slip.
 

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400 fly is around 330 at the wheels.

with your mods and the right man mapping you should see 400fly pretty easy.I had mine running 435 fly with stock injectors and pump before so mayby your car is running abit rich if your near maxing at your current power.

who mapped your car?
 

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Discussion Starter #19 (Edited)
i got the car mapped at wallace performance Aberdeen i think the guys are better with evos than gtrs. im pretty sure my car is running a bit rich at higher revs. 330hp atw sounds a bit more realistic for 400hp at the flywheel. ive seen some guys claiming 400+hp from about 306 whp
 
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