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Author Topic: What BHP to expect....?  (Read 8053 times)

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Entwood

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Re: What BHP to expect....?
« Reply #45 on: 13 March 2014, 10:55:41 »

hopefully to clear this up a bit....

all the fuel pressure regulator does is to suppkly a constant amount of fuel pressure across the injectors. This means that when the ecu opens the injectors for, say, 15ms, then it results in a known quantity of fuel supplied.

increasing the pressure supply to the injectors increases the fuel supplied - its as simple as that. But you can't expect this to be a better or more precise fuel map - its just the same map with more fuel in it everywhere up the rev range.


On the one hand, you could "luck out" and get more fuel at your maximum power speed which will indeed give you more power, but its far from assured. its more likely that you will overfuell everywhere in the rev range, leading to a whole host of other issues.

As an example, I have a Rover VVC engine, which a previous owner had blown up and substituted the 160HP version insteaad of the 143HP original one. He did, however, keep the 143HP fuel injectors "because they're higher flow ones and will give more power". Now, despite giving only 4% more fuel, the car never passed an MOT again because it was running far too rich. Needless to say, I substituted the correct injectoirs for the engine and retro-fitted the correct ecu and it now runs perfectly

I would agree with all of that on an older non-lambda injected engine, or the omega when cold and in "open loop" .. however, with a lambda control giving closed loop operation the lambda sensors will detect the higher fuel injected in that "say 15ms" and will then, via the ECU, reduce the injector time to "say 11ms" to give the same fuel as before, and the only way of knowing that would be to look at the fuel trims, which would show the ECU "trimming" the fuel ... which is EXACTLY what it was designed to do under closed loop conditions ...
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05omegav6

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Re: What BHP to expect....?
« Reply #46 on: 13 March 2014, 11:52:45 »

The 3.2 has a highr pressure regulator as the engine demands more fuel.

Not convinced that is the case guiven that the injector durations never get anywhere near 100%, I suspect its more to improve the spray pattern
3.2 fuel rail/manifold/injectors are identical to the 2.6, but with a 3.8 bar fpr instead of a 3.5 bar one :-\
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Kevin Wood

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Re: What BHP to expect....?
« Reply #47 on: 13 March 2014, 12:04:25 »

Ahh, the "bonfire" theory of engine tuning again!..  ::)

"More fuel = more power".....Nope!
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05omegav6

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Re: What BHP to expect....?
« Reply #48 on: 13 March 2014, 12:09:21 »

Ahh, the "bonfire" theory of engine tuning again!..  ::)

"More fuel = more power".....Nope!
;D
It also needs a suitable increase of intake air, and an equivalent increase in exhaust space from our previous discussion on the subject... not to mention remapping to properly manage the whole process... :y
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Marks DTM Calib

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Re: What BHP to expect....?
« Reply #49 on: 13 March 2014, 13:03:48 »

The 3.2 has a highr pressure regulator as the engine demands more fuel.

Not convinced that is the case guiven that the injector durations never get anywhere near 100%, I suspect its more to improve the spray pattern
3.2 fuel rail/manifold/injectors are identical to the 2.6, but with a 3.8 bar fpr instead of a 3.5 bar one :-\

2.6 has the 3.8 bar reg as well  :y
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05omegav6

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Re: What BHP to expect....?
« Reply #50 on: 13 March 2014, 13:28:43 »

So the only differences between the 2.6 and. 3.2 are...

Ecu map
600cc
Different MAF sensor
 :-\
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Kevin Wood

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Re: What BHP to expect....?
« Reply #51 on: 13 March 2014, 13:29:26 »

So the only differences between the 2.6 and. 3.2 are...

Ecu map
600cc
Different MAF sensor
 :-\

 :y
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05omegav6

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Re: What BHP to expect....?
« Reply #52 on: 13 March 2014, 13:32:41 »

Ok, so the ecu map allows for the extra air demand...
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TheBoy

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Re: What BHP to expect....?
« Reply #53 on: 13 March 2014, 22:55:18 »

hopefully to clear this up a bit....

all the fuel pressure regulator does is to suppkly a constant amount of fuel pressure across the injectors. This means that when the ecu opens the injectors for, say, 15ms, then it results in a known quantity of fuel supplied.

increasing the pressure supply to the injectors increases the fuel supplied - its as simple as that. But you can't expect this to be a better or more precise fuel map - its just the same map with more fuel in it everywhere up the rev range.


On the one hand, you could "luck out" and get more fuel at your maximum power speed which will indeed give you more power, but its far from assured. its more likely that you will overfuell everywhere in the rev range, leading to a whole host of other issues.

As an example, I have a Rover VVC engine, which a previous owner had blown up and substituted the 160HP version insteaad of the 143HP original one. He did, however, keep the 143HP fuel injectors "because they're higher flow ones and will give more power". Now, despite giving only 4% more fuel, the car never passed an MOT again because it was running far too rich. Needless to say, I substituted the correct injectoirs for the engine and retro-fitted the correct ecu and it now runs perfectly

I would agree with all of that on an older non-lambda injected engine, or the omega when cold and in "open loop" .. however, with a lambda control giving closed loop operation the lambda sensors will detect the higher fuel injected in that "say 15ms" and will then, via the ECU, reduce the injector time to "say 11ms" to give the same fuel as before, and the only way of knowing that would be to look at the fuel trims, which would show the ECU "trimming" the fuel ... which is EXACTLY what it was designed to do under closed loop conditions ...
At WOT, it will be open loop. However, I reckon by the time its done a few miles, the trims will be in such a mess, its unlikely to run that great.

However, initially after fitting, it may give a small boost until the trims move.


OP - when going back to standard FPR, reset trims, else you may end up running lean, which I'm sure you know is very bad.

There are a few on here who know their onions, and its worth listening, taking on board what they say. Obviously, if beyond that you still wish to poke and hope, then at least you are doing in in the knowledge of the gains/pitfalls :)
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Kevin Wood

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Re: What BHP to expect....?
« Reply #54 on: 13 March 2014, 23:27:17 »

However, initially after fitting, it may give a small boost until the trims move.

Even that assumes the standard map errs on the lean side. In my experience OEM maps tend to be richer than ideal anyway, as that's the "safe" side to be on. ;)
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2woody

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Re: What BHP to expect....?
« Reply #55 on: 16 March 2014, 22:00:56 »

re injector trim.

yes Entwood, I'd expect that the system could self-adapt thru the injector trims, but nowhere enough to make the difference between base engine specs.

the furthest that the system could go might be 2% fuelling, whereas th e is going to need at least 10 to 15% fuelling to match his power expectation
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cd 2.2

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Re: What BHP to expect....?
« Reply #56 on: 17 March 2014, 01:35:30 »

I don't know if this is off topic for this thread as it talks allot about Fuel pressures etc.

In my experience, when tuning an engine, the best thing to do firstly is to allow the engine to breath more easily ... by this I mean to allow air and fuel mix in at a better rate and allow exhaust to flow more freely (obviously there are limitations connected with back pressures in the exhaust side, but I won't go into that)! In my experience MOST of the power restriction will be within the inlet manifold / Throttle Body .... In my honest opinion don't bother with a stupid cone filter or similar, Just fit a K&N or similar panel filter as the standard air intake isn't too bad!

As far as Fuel Pressure Regulator's are concerned, I think the jury is out as to whether or not you will see any gain ... You may see a sharper throttle response when linked with an uprated throttle body but it seems allot of length to go to for maybe <4bhp and decrease in Mpg's!
The other things I would look into is extensive head works, More aggressive cams, Full gas flow and port polish, Uprated Valves (they can get very expensive) and some degree of skim to increase the compression (but you may have to consider uprating your pistons / con rods and crankshaft including all bearings)!

Above all just remember to get the breathing balance correct Before you consider just dumping more fuel into the engine ... more gains can be had elsewhere and the ECU's fitted are very restrictive (maybe fitting an Omex or similar would benefit) and I believe if you want Omex ecu unit fitted, you would have to figure out a way to run it in tandom with the standard system and convert to a cable throttle to see the best increase in power!

Hope that helps towards your quest for power
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Kevin Wood

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Re: What BHP to expect....?
« Reply #57 on: 17 March 2014, 09:16:54 »

My opinion - in days gone by you might have found an engine where the throttle body or some other ancillary component was the weakest link.

These days, engine designers have access to much better simulation tools and testing facilities. In addition, emissions requirements force them to keep gas flow velocities high through the throttle, manifolds and ports, so they will tend to design an engine at a particular power output and you'll find everything is sized to top out at about the same  level of tune.

This means, IMHO, to get anything significant out of a naturally aspirated engine, you might as well start again with cams, ported head, maybe larger valves, etc. By that time, you might as well replace the engine management with one you can map properly yourself.

The days of bolt on accessories that will give you power increases are gone (they were only really there in marketing BS). You might gain a bit by remapping with a slightly less conservative ignition map and a tweak at the fuelling at WOT but the cost is likely to make it pointless unless you have an older ECU that can be chipped.

The exception to this is the odd engine, such as the 2.5/2.6, where the engine was probably detuned by fitting quite mild cams to position it in the market, and forced induction engines, of course, where the rules are radically different.

Changing parameters such as injector flow rate and fuel pressure on an original equipment management system just throws away all the work that was put in by the manufacturer to refine the system. You'll just end up with something that does everything badly, IMHO.
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TheBoy

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Re: What BHP to expect....?
« Reply #58 on: 17 March 2014, 18:08:06 »

My opinion - in days gone by you might have found an engine where the throttle body or some other ancillary component was the weakest link.

These days, engine designers have access to much better simulation tools and testing facilities. In addition, emissions requirements force them to keep gas flow velocities high through the throttle, manifolds and ports, so they will tend to design an engine at a particular power output and you'll find everything is sized to top out at about the same  level of tune.

This means, IMHO, to get anything significant out of a naturally aspirated engine, you might as well start again with cams, ported head, maybe larger valves, etc. By that time, you might as well replace the engine management with one you can map properly yourself.

The days of bolt on accessories that will give you power increases are gone (they were only really there in marketing BS). You might gain a bit by remapping with a slightly less conservative ignition map and a tweak at the fuelling at WOT but the cost is likely to make it pointless unless you have an older ECU that can be chipped.

The exception to this is the odd engine, such as the 2.5/2.6, where the engine was probably detuned by fitting quite mild cams to position it in the market, and forced induction engines, of course, where the rules are radically different.

Changing parameters such as injector flow rate and fuel pressure on an original equipment management system just throws away all the work that was put in by the manufacturer to refine the system. You'll just end up with something that does everything badly, IMHO.
Yeah, but the bloke down the pub told me his mother's dog's uncle's mate's sister's boyfriend put in a "tuning chip", easy to fit, as it only had 2 wires going to the CTS, and it gave him 50 bhp more, then he fitted an aftermarket turbo from ebay that just needed a 12v, 1a supply, and it gave him more power than a Veyron. Its well wicked, init.
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05omegav6

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Re: What BHP to expect....?
« Reply #59 on: 17 March 2014, 18:23:52 »

Ay boyakasha...
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