What restricts a 2.5 revving past 5500rpm ?
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What restricts a 2.5 revving past 5500rpm ?
Had my conversion for a while now and the power has always tended to tail off pretty sharpish after 5500rpm.....
(Don't get me wrong....... there's POWER there !! - it just tends to fade earlier than i'd like, sometimes)
i've recently had tubular manifold and the inlet raised...... so would have thought the breathing was sorted..... which I thought could be an issue.... coupled with a 3" exhaust..
It is due to be remapped.... but I wanted to understand from the masses !!
What are your findings on the matter?
I've more recently seen people quoting theirs revs to 8k........
I don't want that.... but to have the freedom to take it over 6k, would be nice...
I have v3 heads.....
If you need further details to help diagnose, please feel free as I have NO idea when it comes to engines and would like to understand .....
I was thinking (in my infinite wisdom) that the Heads may not have been ported to suit/allow it......... thats as far as my knowledge takes me...
MANY Thanks !!
sorry:
2.5
AF20g
I thought i had everything else to complement it........
(Don't get me wrong....... there's POWER there !! - it just tends to fade earlier than i'd like, sometimes)
i've recently had tubular manifold and the inlet raised...... so would have thought the breathing was sorted..... which I thought could be an issue.... coupled with a 3" exhaust..
It is due to be remapped.... but I wanted to understand from the masses !!
What are your findings on the matter?
I've more recently seen people quoting theirs revs to 8k........
I don't want that.... but to have the freedom to take it over 6k, would be nice...
I have v3 heads.....
If you need further details to help diagnose, please feel free as I have NO idea when it comes to engines and would like to understand .....
I was thinking (in my infinite wisdom) that the Heads may not have been ported to suit/allow it......... thats as far as my knowledge takes me...
MANY Thanks !!
sorry:
2.5
AF20g
I thought i had everything else to complement it........
Last edited by Leg@cy; 27 May 2008 at 08:33 PM.
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It has V3 heads... which i understood were supposed to be good...... but I suppose it is no substitute for custom components
also forged pistons.....
It's been mapped by a 3 people now and the power band still cuts at 5500 rpm
thanks
also forged pistons.....
It's been mapped by a 3 people now and the power band still cuts at 5500 rpm
thanks
#7
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get the heads ported , uprate the valves and springs with supertech ones that will raise the rev limite on yr engine , the forge internals are so you can run 350+ bhp
also if you have an aftermarket ecu (motec, simtec etc etc )that can set the rev limite on yr engine by yr mapper
also if you have an aftermarket ecu (motec, simtec etc etc )that can set the rev limite on yr engine by yr mapper
Last edited by bighead; 27 May 2008 at 12:58 AM.
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#8
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It is the size of the turbo that dictates how long it makes boost and where the power tails off in the rev range. Per stroke the 2.5 engine is producing more exhaust gasses, meaning the turbo will spool a lot sooner than a 2ltr but the trade off is the power tailiing off earlier.
Dont waste your money on the heads get yourself a drive in a MD321T equipped 2.5 car and you will see what I mean, as this makes power a lot further than 5.5k and will allow you to rev the car to 8k should you wish.
Banny
Dont waste your money on the heads get yourself a drive in a MD321T equipped 2.5 car and you will see what I mean, as this makes power a lot further than 5.5k and will allow you to rev the car to 8k should you wish.
Banny
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I don't understand a AFP20g running out of puff at 5k5, mine doesn't and I've got a near identical setup to yours.
What boost are you seeing through the rev range? And what boost did you want to see?
Have you checked your inlet pipework? Are you sure its not collapsing / leaking as the airflow increases?
What boost are you seeing through the rev range? And what boost did you want to see?
Have you checked your inlet pipework? Are you sure its not collapsing / leaking as the airflow increases?
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Nope, pretty much identical to the OP
1.45 bar to 5k5, 1.3 at 6k5, 1.25 at 7k. Never been on the dyno, but the power is there, and its there for a while. When I had a 16g on it it fell away at 5k5 very quickly.
In fact comong home from Zen after the remap the most significant difference I noted was that the power keeps on going to 7k, so I think the OP should look elswhere rather than at the turbo.
1.45 bar to 5k5, 1.3 at 6k5, 1.25 at 7k. Never been on the dyno, but the power is there, and its there for a while. When I had a 16g on it it fell away at 5k5 very quickly.
In fact comong home from Zen after the remap the most significant difference I noted was that the power keeps on going to 7k, so I think the OP should look elswhere rather than at the turbo.
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I don't understand a AFP20g running out of puff at 5k5, mine doesn't and I've got a near identical setup to yours.
What boost are you seeing through the rev range? And what boost did you want to see?
Have you checked your inlet pipework? Are you sure its not collapsing / leaking as the airflow increases?
What boost are you seeing through the rev range? And what boost did you want to see?
Have you checked your inlet pipework? Are you sure its not collapsing / leaking as the airflow increases?
It is/was set at 1.4BAR and was seeing this and holding from just over 3k to 5k
I had an issue where the inlet pipe was collapsing, but that was last year and was fixed.... the pipe collapsing has different characteristics... i.e.Boost guage going to minus figures....
The car is at the Tuners at the moment, they have alot of experience and i'm sure they'll get the most out of it...
I'll await the official findings.......... and am sure that all leaks have been tested for as the inlet pipe work is all new
Jay, what heads are you using ? are they standard?
Cheers guys !!
(I'm learning slowly)
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Yes but they've pulled the run at 5600, why did they do that? If it was because the operator saw the torque / power dropping abruptly at 5500 as the graph suggests then there probably is a problem somewhere, its not typical of a 20g on a 2.5
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Your inlet pipe to the turbo might be sucking shut. I've experienced this myself. Is the car MAF or MAP based for load ?
I'll bet 20p against anyone that want to take the bet that's what's happening
I'll bet 20p against anyone that want to take the bet that's what's happening
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already tried suggesting that a few times in the thread but nobody is listening, but thanks for offering to send me 20p
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Some more information......
I've received some further information that may or may not help or confuse the matter.
At 5500 rpm it looses over 100 hp
It also jumps UP by about .2/.3 BAR
Pipe(s) collapsing and leaks have been checked and monitored......
I've received some further information that may or may not help or confuse the matter.
At 5500 rpm it looses over 100 hp
It also jumps UP by about .2/.3 BAR
Pipe(s) collapsing and leaks have been checked and monitored......
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Cheers