Leg@cy

iTrader: (2)

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........

turboDean

iTrader: (4)

To have power higher in the rev range on a 2.5 you really need a bigger turbo IMHO.

Leg@cy

iTrader: (2)

Thanks Dean

I also should have stated, Constructive comments only

bighead

iTrader: (1)

upgrade yr heads and valvetrain , forge piston and conrod
also has it been mapped properly after the conversion ??

Biggs

iTrader: (14)

I'd go with what bighead say's, the rev limit is really restricted by your heads

Leg@cy

iTrader: (2)

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

bighead

iTrader: (1)

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

banny sti

iTrader: (68)

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

StickyMicky

samco inlet pipe?

Leg@cy

iTrader: (2)

And I WAS fancying a 321t

mhhhhhh

Leg@cy

iTrader: (2)

I must add......

When I said the power 'cuts' - it's Not a rev limit or fuel cut.....

It just runs outta PUFF......big time...

Phil

dynamix

iTrader: (3)

Bigger Turbo

My FP Green on my 2.5 revs to 7500 (forged rods/pistons etc) but the power up top is very strong indeed.

Jay m A

iTrader: (2)

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?

dynamix

iTrader: (3)

is yours on a 2 litre though ?

Jay m A

iTrader: (2)

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.

Leg@cy

iTrader: (2)

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)

Leg@cy

iTrader: (2)

Dean,

do you have 'standard' heads on yours i.e. not ported etc ?

What rpm have you taken it to ?

StickyMicky

not all the time, from previous experiance

Jay m A

iTrader: (2)

<---- View my scooby, I have STIv3 heads too.

My car has its boost tapering to the redline, your car is probably mapped similar?

Leg@cy

iTrader: (2)

D'oh !! I see

Preetty similar !

Just took a look at my graphs and yes, mine does actually taper slightly...





as you can see

Jay m A

iTrader: (2)

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

jd5217

Think you hit the nail on the head above, I am sure your mapper will get the most out of the car.

John Stevenson

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

jd5217

The Simtek is MAP based

StickyMicky

already tried suggesting that a few times in the thread but nobody is listening, but thanks for offering to send me 20p

Leg@cy

iTrader: (2)

I am listening....... !!

I am Listening to all comments suggestions....

Thank you....

Leg@cy

iTrader: (2)

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......

Leg@cy

iTrader: (2)

This was probably 'one of the better runs' and no doubt during mapping, the limitations were understood, hence why there was no need to take it past 5500 as it had peaked.......... sadly

Cheers

jd5217

gt30 hybrid next??

Leg@cy

iTrader: (2)

we shall see..........

need to do some overtime first ..........