# tuning advice



## KevrevsGTR (Jan 2, 2009)

Currently running apexi pfc (maf version) walbro 255 pump,rc engineering 550cc injectors stock turbos and mafs and usual full exhaust and decat & hks induction on my r33 gtr.Currently 1.1 bar but maxed turbos and almost mafs!. So have now accquired r34 turbos and z32 mafs for next upgrade.
Couple of questions:- 
1.what hp can pump and injectors handle?
2.what power can the turbos handle with steel internals / hybrid ie larger wheels?

Reasons asking im after circa 500 hp atf or more if poss.tuner advises 1.2bar so what kinda power would that give?

cheers


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## pupsi (Aug 29, 2006)

Your injectors will be maxed out. You need at least 600cc injectors.


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## SkylineUSA (Jun 29, 2001)

If I am doing the math right.

Jump the fuel pressure up to 75psi, it will take those 550 to the 620 range, and that is with a boost pressure of 1.3 bar, which will cover your 500hp figure.


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## ru' (Feb 18, 2007)

Any reason for going for R34 turbos rather than steelies?

And I thought injector cc roughly equaled bhp (fly), meaning your 550s should be okay for 500 atf?


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## SkylineUSA (Jun 29, 2001)

I thought it was atw, so with that being said. I agree with ru'


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## ru' (Feb 18, 2007)

Yay!


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## Pontio (Jun 4, 2009)

if your turbo's are steel internal then you have a similar set up to me just that i have maf'less f con and runnig 1.35 bar with 420 @ hubs
My injectors are 720cc but from what your asking of yours i think they will be fine. i only got mine because tr had them going cheap.

Forgot to mention you will more then likely need splitfires or something along those lines..


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## SkylineUSA (Jun 29, 2001)

Splitfires, waste of money at that level.


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## Pontio (Jun 4, 2009)

SkylineUSA said:


> Splitfires, waste of money at that level.


only speaking of my own experience and some stories i have heard from a couple of others. my splitfires didnt handle more then [email protected] wich is prob low 400's at fly..
also you will need some colder plugs more then likely.


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## SkylineUSA (Jun 29, 2001)

It is not really the power level, its more about boost level. He said 1.2, so I was going off of that. 

You can always tighten your spark gap to get the same result, instead of blowing money on the splitfires. Like you said, it all comes down to what you have experienced.


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## kismetcapitan (Nov 25, 2005)

if plugs aren't firing at 1.2 bars, it's the plugs, not the coilpacks.

Adding more fuel pressure will indeed turn those into 620cc injectors, but there is a huge caveat, depending on your fuel pump. Let's just say that a small misunderstanding of the added pressure/more injector flow rule, cost me over two grand in multiple broken fuel pumps and one blown engine (15 grand to rebuild).

That being said, I think it'd be hard to max out 550cc injectors with stock/N1 sized turbos. I maxed out stock injectors on stock turbos, but it took 1.4 bars to do it. MAFs were a must to upgrade though; I think I was getting 5115mV maxed at only 1.25 bars.


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## SkylineUSA (Jun 29, 2001)

1.4:bowdown1:


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## SkylineUSA (Jun 29, 2001)

kismetcapitan said:


> if plugs aren't firing at 1.2 bars, it's the plugs, not the coilpacks.
> 
> Adding more fuel pressure will indeed turn those into 620cc injectors, but there is a huge caveat, depending on your fuel pump. Let's just say that a small misunderstanding of the added pressure/more injector flow rule, cost me over two grand in multiple broken fuel pumps and one blown engine (15 grand to rebuild).
> 
> ...


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