rolling road results of a tweaked S4...a realistic expectation

[sailorbob]

From what I've seen there's nothing in the 'mild' chips that's going to cause engine damage; the standard overly rich fueling and adaptive learning stop things going awry. They do leave something to be desired in terms of VE and spark tables but upping the boost for more performance is after all what Lotus did with the S4S and S300

[dodge1979]

Derek, indeed boost was increased, but also they ran bigger turbos, bigger valves..so gains were made through physical mechanical differences too...whereas my point is probably most obvious as an example of an SE running a 'red race6' chip...if thats what its called..which I would not say is made specifically with those mechanics in mind....the lust for big power figures without going through the basics fron start to finish first to gain benefits..

[sailorbob]

Boost was increased on the GT3 too

[brian.harper@netassoc.net]

Darren,

 

I found your writeup very informative, and detailed.  I am doing similar updates to my S4.  I do have a few questions, and comments to share.  I am also looking for better efficency, not just brake hp, in that I want to retain the fuel economy, and hopefully increase that with my updates.

 

Why did you feel a fuel system upgrade was necessary given the target hp.  Is the factory system not capabile of supporting 300hp?

 

What type of injectors did you use, and why were the primary injectors increased in size?  I worked closely with John Welch on selecting new injectors, and (at his recomendation)  I stuck with stock size on the primarys at 390, and went to 270 from 190 on the secondaries, since I am also going the stock s4s mark v chip with the additional boost.  I went with his rc engineering injectors, which reportably have a superior spray pattern compared to the stock rochester injectors, and were hand matched.  The better dispsersion from the spray pattern is also reported to deliver better fuel economy, and I have read too many posts regarding rochester failure modes when reaching this age, going lean or rich, take your pick.  So my motivation was to not only install 'better' injectors, but to also have a better known quantity of what the injectors are doing, a maintenance upgrade per say.  A lean or rich old injector going unnoticed could create more problems for the engine than I care to think about, or pay for in the near future.

 

What was actually done 'tuning' wise past adjusting the spring pressure on the blowoff valve (I expect that is why it quit leaking) and adjusting the fuel regulator, due to changing from the stock system.  I would consider the various hose leaks more of a needed repair and needing attention than 'tuning'.

 

I do have a de cat and k&n filter on the way from esprit performance.

 

I am surprised you also did not go to the green dot cam pulleys, considering the amout of trouble you have already gone to.  They should provide better off turbo response on the bottom end (as in free torque), and I expect some overall performance gain.  By going to the green dot's, you are returning the cams to their designed proper mop of 104 degrees.  The intake cam has a red dot 110 degree pulley, the exhaust pulley is a blue dot at 100 degrees (which reportedly is actually a 97 degree pulley).  Those give the intake a 6 degree retard, and the exhaust a 7 degree retard.  I would futher speculate the green dots running the cams where they are supposed to be could also increase fuel economy.  Even if you do not upgrade both pulleys, swaping the aux pulley (which is a 104) with the intake pulley would be desired, at zero cost.  Most that have converted also report a much deeper throaty exhaust note verses the stock sewing machine sound, and I am good with that. 

 

Thanks for sharing your experiences!

 

Brian

Edited January 31, 2013 by bharper

[lotusesprit1]

Darren,

 

Yes the leak does sound a bit like a supercharger.  I will fit a blanking plug on the dump valve and try to chase the leak down.

 

Espritmon looks like a good program. My ECU Chip ID from the program is 278A the car is an 89 SE, I looked on line but could not find a reference to what the chip is. Does any one know what that is? The previous owner did mention he chipped it but was vague as to what with.

 

Have you compared your HP and Torque readings with those given by Espritmon? 

 

Paul

[sanj]

Your chip is either one of Marcus' or one of Andy Whittaker's, but they all used the same 278A ID, so not much help there.

[dodge1979]

Well firstly appologies in the delay in getting to respond on the comments given above, Ive been a little busy! Ill go through them as they appear in order, so firstly, Brian!

 

In terms of the fuel system, Id like to say that at no point during my intial build etc did I have a target BHP. Horses are not the most important figure to me, and as such I merly wanted to improve as stated previously. The fuel system was updated because the injectors, whilst obviously working on the standard car, were old. As I was doing everything in depth, I wanted to replace them with new ones primarily, then having researched and spoken to other members of the forum the recomended injectors from Five-o in the USA were selected. These were chosen because of the improved spray pattern and performance over standard and as I wanted new injectors, were at a good price compared to buying standard. I was also satisfied that wherever my build took me in terms of improvements, these would handle and perform without the need to change them again. The fuel pump was changed for an uprated unit purely because the original one was getting old and a new unit that exceeds demand is never a bad thing. So my fuel upgrades were along similar lines that you have thought too.

 

Tuning wise, as we know the ECU cannot be tuned. The only thing capable is the chip to be exchanged. The fuel pressure regulator was fitted and adjusted, because running the different injectors means that the fuel being actually let into the inlet charge would have changed, even fractionally. The need to have control over this becomes more essential when you start changing several things. For example, when the decat was fitted recently, the dyno showed a change in lamba readings which required adjustment on the fuel pressure to control the fuelling a little better to compensate for the engine running leaner with no cat..Also the adjustable pressure requlator was fitted because the original fixed unit was old..and therefore how reliable and how accurate it was could not really be relied upon...so another change to cover all eventualities..

 

The word 'Tuning' is a general term..if you start changing induction/exhaust flow/fuel flow etc that is tuning. Bolting parts on that change the way things run is as much tuning as pluging a laptop in to program an ECU or changing carb needles to suit the engine..provided that everything changed is checked, adjusted where required and tested to show it is running to the best of its ability.

 

Yes, the boost leaks discovered are repair orientated, but as I stressed before, everything was built with new items as per the factory manual. The point of talking about them is to raise awareness that even new, perfectly fitted items are not always good and can require further work to ensure that they perform to the best level possible along with everything else...so its important to be aware of these things..the rolling road allowed me to discover the faults and correct them without guess work..which is the whole point really!

 

Now when you fit your decat and K&N filter, what do you think will happen? Youll run a little lean in the fuelling. which will need compensating for by adjusting the fuelling, which cant be altered in the ECU, but the amount of fuel forced through the injectors under pressure can be altered by altering the pressure in the fuel..even though the length of time they stay open is a fixed variable. That is a very important and useful tuning step which will enable you to get the most out of your work..

 

Lastly Brian you mention the pullys. Yes originally I considered this on my first build. However at the time I didnt have different pullys to make the change easy, green dot or fully adjustable. However, when my engine comes back out in April for its service, this is something I am seriously considering doing as the small benefits will no doubt compliment the other improvements made.

 

Now then Paul! Espritmon BHP and Torque readings....well to put it politely ..what a load of rubbish. They are pure fantasy and unless you want a laugh I wouldnt even press the button...its a fantastically usefull tool for diagnosing faults and seeing realtime running on some items, but the performance figures are to be ignored. It has no way of correctly calculating them let alone collecting the data required. No offence to the chap who wrote it, we are all very gratefull!

 

As for the chips used...Ive said it before...not a fan. Its not an accurate and always safe way for tuning your engine. Id rather use the standard Lotus chips and improve the physical restrictions in the mechanics to make a very smooth useable car moreso...

[brian.harper@netassoc.net]

Darren,

 

Thanks for your reply.  I agree with most things said, except adjusting the fuel pressure given the larger primary and secondary injectors.  Where I get lost in that, is the fuel pressure should be set to a given value required by the factory.  Making a fuel pressure adjustment on the dyno as a short term tune will probably not stay effective due to the self tuning of the ecu, at least on how I understand how things work between the engine and the ecu. 

 

Most, after making a change in tuning, injectors, whatever, disconnect the battery for a short period to clear the ecu's self learned tuning data.  After doing this reset, it is said to take about 30 minutes of driving around for the ecu to relearn the new values for the given setup you are running. So, after 30 minutes of driving around, the ecu will have a fairly accurate idea of how much fuel needs to be injected to maintain a correct air/fuel ratio, while looking at things like manifold pressure, air density, throttle body position sensor, and probably half a dozen other sensors I am leaving out.

 

So, given the rich condition of your engine, in this case the oversized primary injectors, the ecu should shorten the pulse width to pull the a/f ratio back to a correct value.  If the ecu has not been power cycled, it will adjust much more slowly, as I understand it that it is then averaging in the new value with the existing learned values.

 

I am new to the steven's cars, having just purchased my S4 in December, so my limited understanding of what's actually going on could be causing me to throw out personal opinions that seem logical to me that are lacking in depth of knowledge.  But the fuel pressure deal, even though it may have been required to cut back the richness of the primary injectors, seems to me to either be covering short term the larger size of the primarys, or that the ecu was not cleared to allow the ecu to relearn the settings needed for the new injectors.  I have been around g cars since the 70's, when I purchased my first S1.  Things are indeed quite different in todays environment verses needed a few jets and a screwdriver to tune a S1.  Or using a lid from a coke to adjust the points on the side of the road (or a thin dime).

 

So, where I am probably all wet, it fuel pressure would seem to me to be a fixed value to the diff control regulator, and the control regulator needs to track boost pressure and adjust the final pressure to what is required the given boost.  If the fuel pressure is lower than factory to compensate for the primary's low end flow, is there enough pressure there to supply the injectors properly toward their maximum pulse widths?

 

Obviously the dyno sheets show very smooth power progression, and would seem to indicate you have a very good overall tune on your engine at this time.  So little of what is bothering me seem to really matter, unless the tune starts to go away as the ecu updates its tables.  But given that its adjustements are basically looking for correct a/f ratios, perhaps that will not mess with you unless the primarys just still put out too much fuel at the shorter end of their pulse width operating areas.

 

Hopefully my idiot side will catch up with my rational side, there is certainly nothing wrong with your tuning, it appears to be in my head.

 

Brian

[CHANGES]

Hi Brian,

Sorry to but in on Darren's thread. But with regards to fuel pressure regulator the two points made by Darren are evident from my experience, 1) The standard units are long in the tooth and starting to fail and become inaccurate for the job they do, I have seen several falling apart when stripped.. This can give all sorts of fuel tuning issues that are not major, but confuse the ECU and make the engine not as smooth as it should be.. By just replacing it for that reason is worth it... or fit new / service standard unit to be safe.

2) when fitting new larger better quality injectors, you move outside the the ECU programmed data. It still believes it has standard injectors and will constantly adjust on that basis. The only way you can bring the larger injectors more in line with what the ECU is thinking is to vary the pressure,

This is in main because the ECU is not quick enough and the operating band not wide enough to react for the larger injectors particularly at lower RPM.  

There is a limit to how much bigger you can go with the primary injectors before it becomes impossible to control.  The secondary's are there to fill the hole at the upper RPM as the primaries can not be big enough to supply the top RPM fuel needed and the ECU operating band wide enough. 

When you start doing changes you upset the standard equilibrium so this needs addressing. Any changes even an exhaust system will make a difference, but there is only so much compensation the ECU can cater for, its a great little unit but limited.

When you go outside the ECU range more changes are needed to bring the mods back under control of the ECU, this is what Darren is referring too. 

It is also very important to note that the data to confirm it is all under control is only available from dyno testing. So many people do mods and end up with major issues due to their tuning parameters being wrong and they never had them checked.

Just because it feels quick does not make it correct..A lean running engine will feel quick but fail just as quick ..!!!!! 

Hope this answers some of your questions.

Dave.

Edited February 18, 2013 by CHANGES

[dodge1979]

Many thanks for the reply Dave, that pretty much sums it up!

[Vulcan Grey]

Agree on the failing fuel pressure regulators and pumps too.  I've received a bunch of emails thanking me for mentioning that a new BOSCH fuel pump fixed my boost cut and lean condition, because the same fixed their issues as well.  My issue became apparent immediately after I switched to the #2 chip.  Did not have any issue with the stock SE chip, but then the S4s MK5 chip showed a deficiency in the pump's ability to supply enough fuel under boost.  And this was with new BOSCH injectors (stock sizes), an new pressure regulator, and a fairly recent replacement of the pump (though used from an '91 X180-R). 

 

I also discovered that the pulsation damper that is installed above the fuel pump is definitely a source of pressure loss in the fuel system.  It can drop pressure during boost, and it can be a cause of pressure loss when the car is off, making it more difficult to start later.  I highly recommend it is removed and replaced with fuel submersible hose.

[dodge1979]

Thats something I did as a precaution when I replaced the pump too..

[dodge1979]

Just bringing this back into the current as people are struggling to find the thread..

[Jacques]

Very good read. Now I just need to find a propper Dyno and operating people.

 

What could be interesting to see is what a banana manifold like for example the one from alunox would do to NM and Hp, now that other mods and finetuning are done, so that engine is reliable and well running (to rule out these as possible error.sources).

 

Cheers,

Jacques.

[dodge1979]

Well im booked back on the dyno in july to do just that. Ive had so much going on since last year ive not been able to test the alunox manifold since I fitted it a year ago. With the documented dyno runs ive done with various changes it will show its potential should all these things be done correctly and optimized. Obviously ill be posting up the results at the end of july. Apart from daves 412 thread no one else has dyno run the manifold. Its potential is known on daves engine but for us mere mortals it will prove an interesting test to see its actual gains.

On another more serious note I will be refraining from testing bananas on my esprit. They just dont flow the exhaust gases well