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Discussion Starter · #1 ·
I find this really strange. When my car was tuned before the rebuild it made 265rwhp & 364nm of torque at between 0.5 & 0.6 bars of boost. After the rebuild & having shimmed the wastegate by 4mm, the car is apparently boosting to 0.8bars (11.5psi), but is making only 276rwhp & 366nm :confused: I was told something about roller ratios on the dyno...???
Are these power figures about right? I have to say though, the car does feel smoother & quicker, but I am dissapointed with the figures. Another question is that, based on the fact that I have an aftermarket management system I was told the car has to be remapped every time I increase boost. Is this true? I wanted to connect a bleed off valve to increase boost, but i was told that I could not do this. One last bit of confusion, i was told that I cant go any further with these injectors, at this power, they are maxed!!!! But this is contrary to all my research.
 

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Well, was this done on the same dyno, or a different dyno? Different dyno's will give different numbers and readings. And what injectors do you have?
 

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Discussion Starter · #3 ·
Well, was this done on the same dyno, or a different dyno? Different dyno's will give different numbers and readings. And what injectors do you have?
Same dyno. My motor is completely stock, with stock injectors. All I have is a 3" exhaust, larger intercooler with all the relevant plumbing, including DV, a Gotech MFI management & just before the last dyno, a rebuild, minus pistons & rods & a 4mm shim on the wastegate.
 

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There are a lot of variables here. It's possible that timing is different (i.e. pulling more retard on 2nd dyno run) that would affects hp. Did you put in fresh gas since the rebuild? Old gas on a dyno is a no no. Also, suggest to find out its A/F ratios during dyno runs using a wide band.
 

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Things like motor and coolant temperature and then outdoor temperature and barometer can all lead to a difference. You would think 4 psi would result in a nice bump in power though...
 

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Discussion Starter · #6 ·
Things like motor and coolant temperature and then outdoor temperature and barometer can all lead to a difference. You would think 4 psi would result in a nice bump in power though...
Thats what I figured. I was hoping to reach at least 290rwhp, considering the initial rwhp, & the bump up in boost. I would have been ecstatic had I reached 300. Do the figures I have seem reasonable though, or is it on the lowish side considering the boost level?
 

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Discussion Starter · #7 ·
There are a lot of variables here. It's possible that timing is different (i.e. pulling more retard on 2nd dyno run) that would affects hp. Did you put in fresh gas since the rebuild? Old gas on a dyno is a no no. Also, suggest to find out its A/F ratios during dyno runs using a wide band.
Now that you mention it, I think that he did mention that he had retarded the timing.....I think...........
 

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Do you have a wideband hooked up?

You may be able to get a little more out of those injectors but you MUSt have a wideband to monitor your a/f....

If you start adding fuel while tuning and keep getting A/f over I would say 11.5 or so then your injectors/pump are probably maxed-hell, you can get a nice set of 550's pretty reasonable--better too much than too little--that would be my next upgrade unless you're gonna up the fuel pressure a crap load temporarily
 

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Discussion Starter · #9 ·
Do you have a wideband hooked up?

You may be able to get a little more out of those injectors but you MUSt have a wideband to monitor your a/f....

If you start adding fuel while tuning and keep getting A/f over I would say 11.5 or so then your injectors/pump are probably maxed-hell, you can get a nice set of 550's pretty reasonable--better too much than too little--that would be my next upgrade unless you're gonna up the fuel pressure a crap load temporarily
No, no wideband. As you mentioned, 11.5 is about where I am & according to the tuner the injectors ARE maxed. I have absolutely no intention of doing anything to this car that would result in a failure of any component, attributed to pushing it beyond it's reliable limitations. My next step would be 750cc injectors (I have aftermarket management), Walbro fuel pump & 57 trim upgrade.

On a side note, I spoke to the tuner, & the timing has not been retarded...
 

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"According to the tuner?"

Here's my .02/worth....get a wideband installed like yesterday-dont trust a tuner-trust the gauge-otherwise you are playing russian roulette.
Go with the 550's-I know u have standlaone but with a 57trim upgrade why would you need 750cc injectors? Are you running a crazy amount of boost?

I just recommend going in stages, getting it working, then moving on to the next level....those 550's will handle 450hp maybe more...
 

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Discussion Starter · #11 ·
"According to the tuner?"

Here's my .02/worth....get a wideband installed like yesterday-dont trust a tuner-trust the gauge-otherwise you are playing russian roulette.
Go with the 550's-I know u have standlaone but with a 57trim upgrade why would you need 750cc injectors? Are you running a crazy amount of boost?

I just recommend going in stages, getting it working, then moving on to the next level....those 550's will handle 450hp maybe more...
I will look at wideband...as soon as I can afford it, not really something popular locally though. The only reason I am looking at 750cc's is because I have every intention of going bigger turbo, forged internals, etc, at a later stage. I would prefer buying bigger injectors now, rather than having to sell 550's at a later stage & losing money on them.
 
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