Che exhaust power figures... +6 bhp! (now with sound clips)

[ChrisGB]

Hi to All

Had Engine Advantages (Witham, Essex) fit the Che single exit exhaust today. Fitting was good with everything lining up well. Tailpipe looks a little close to the lower edge of the bumper but does not touch. I need to keep an eye on heat damage there I think. Finish of the welding and pipework is very good. I also had them do before and after dyno testing to keep things objective. Results:



Noise wise, the exhaust sounds deeper and louder than standard, but is not obtrusively so. It is possible to creep discreetly around in traffic. When the throttle is open, the noise is much more "purposeful" than from the stock system but never downright loud. I would say a well judged balance of sporty and everyday useable.

EDIT:

 m http://www.cbuckle.pwp.blueyonder.co.uk ... evving.wav m

 m http://www.cbuckle.pwp.blueyonder.co.uk ... evving.wav m

Well 6.4bhp for an exhaust was way better than I was expecting  s8) s8)  The difference is echoed by the butt dyno that confirms the graphs nicely. Happy days  s:D s:D  

Hope this helps anyone considering this exhaust. Many thanks to Che for excellent and fast service.

Manifold next.

Chris

[Anonymous]

I think a Che full system is on the cards for me now!  s8) s8)  

Extra performance and cheap, cant go wrong really  s:D s:D

[evileye_wrx]

I've noticed a definite increase in oomph with my Che Exhaust on. Butt Dyno only I'm afraid altho I plan to get it done once I have the rest of the exhaust system fitted. Seems to pick up a little earlier than before through the gears and does sound that touch more aggressive than the TTE before it.

Chris, now what you need is to add a downpipe, probably an H&S would be best, and probably a unichip to bring it all together. Now I wonder where you might be able to pick those up from?   s:roll: :roll: s:roll:    s:wink: :wink: s:wink:  

And Andy, I really think you chould consider a TTE exhaust, just to finish off the look on your '2. Again, couldn't think where that might be available, cheap AND local???   s:evil: :evil: s:evil:  

Phil

[ChrisGB]

Chris, now what you need is to add a downpipe, probably an H&S would be best, and probably a unichip to bring it all together. Now I wonder where you might be able to pick those up from?   s:roll: :roll: s:roll:    s:wink: :wink: s:wink:  

Phil

Stop it you are killing my bank manager  s:twisted: :twisted: s:twisted:  

I need to do the manifold next. I still have the stock manifold and beloved precats in place. I was not even going to get an exhaust until I looked into replacing the manifold on the group buy that is on at the moment and saw these. So next stop manifold (due March). I dont think I will see any significant power gain from that, but we shall see.

From there, the route gets expensive. Removal of the main cat will yield more power, but only if I add a further expense of Unichip and hours of rolling road. Che does a downpipe, spookily enough. I then have the hassle of removing the pipe and refitting the cat to pass MOTs which I really cannot be bothered with. A sport cat may be a nice halfway house.

Still not sure if a Unichip or similar will be needed with the 4 > 2 > 1 manifold. I can see why it is essential with the 4 > 1 as this fundamentally alters the way the system scavenges, but 4 > 2 > 1 is still essentially the same as stock setup.

We shall see what happens with the manifold swap, then work it out from there.

Chris

[evileye_wrx]

Unichip will increase your BHP whether its mapped or not. The Che system isn't so different that re-mapping would be essential. You'll just improve BHP more by re-mapping. The reasons for this are beyond my limited knowledge of engine management but the chip makes it extra vroomy.

If stock = 139bhp, then unichip may = 145bhp, so mapped unichip would = 150bhp

These are examples not actual amounts, but you see what I mean?

The fact that I am selling one... no two... unichips at present has absolutely nothing to do with it.

Phil

[ChrisGB]

Unichip will increase your BHP whether its mapped or not. The Che system isn't so different that re-mapping would be essential. You'll just improve BHP more by re-mapping. The reasons for this are beyond my limited knowledge of engine management but the chip makes it extra vroomy.

If stock = 139bhp, then unichip may = 145bhp, so mapped unichip would = 150bhp

These are examples not actual amounts, but you see what I mean?

The fact that I am selling one... no two... unichips at present has absolutely nothing to do with it.

Phil

Hi Phil

If only it worked that way. Usually, power gains are not just add up to total. It is obvious that the standard exhaust system was limiting power in this case. This means that the niether the precats or main cat were the limiting factor. Looking at a cutaway of the stock exhaust (it is a horror story in there) it would be reasonble to expect that a decent exhaust would make a difference.

Next thing to consider is how removal of the precats will effect things. There will quite possibly be a little more torque and power to come from precat removal. As they were not the limiting factor to begin with, probably a small 1-3 bhp. Now the main cat is known to restrict overall power, but the engine is set up to work against this, so removing it may well mean that the unichip is needed to change the valve overlap. This will yield further breathing gains, possibly getting one up to 152bhp if FG Robs car is indicative.

However, the earlier thread where I asked about a full Che system contained some excerpts from a recent rolling road day. On these, cars with the Che manifold made more power than cars without it but running the Unichip. These cars made 146 & 147bhp.

From this, I think that the unichip is only going to offer serious gains if I do go sports cat. The stock header or Che manifold will then become the limiting factor. Power could possibly peak around 147 - 152bhp. To go past this, I will need a 4 > 1 manifold. Here I lose mid range flexibility (and with 131 lb/ft running through the mid now, that will impact on drivability).

Another way to go is fit the Che manifold and Unichip, then program fuelling to swell the midrange some more. However, the engine does not feel like it is underfuelling in the midrange, so I doubt there is a huge amount of gain to be had there from the setup I am looking to use.

Last thing to consider, and it is important to me, is that the car gets used for long journeys and days out all over the UK over summer. Should I decat, the price I will pay in increased noise may prove too high. I am already prepared for an increase in noise with the precats out, but taking out the main cat will quite possibly be too noisy to live with on the motorway.

Looking at all this, I feel that I would be best to aim for a decent midrange and good drivability, get the precats out (via the Che header) and enjoy the car for the summer, putting the money saved towards decent restaurants. By the time I have the Che header on, I will have spent the grand total of £390 to get to hopefully 147bhp.

The next meaningful gain from this is going to cost me a Unichip + harness (£400) Sports cat pipe (£400+) 4 > 1 manifold (£500) RR time (£400) and on a good day I may see 155 - 160 bhp with more noise and less drivabiltiy. £1700 for a less useable road car seems like a bad idea from here. If I find there is much to be had in torque from going Unichip, I will get one, but on the evidence so far, this is again an area where diminishing returns rules the day.

Next mod for me will be breastplate I think. I need to get under the car and measure up. I have in mind a triangulated web plate made from a skeleton of 12mm thich 6082T6 ally with pocketed hose clip area and bolt holes. If I make one, I can of course make more. Trouble is that I am time poor in the exteme this month and next.

Chris

[Anonymous]

Unichip will give you more power than any exhaust will, and is better value for money to boot. The best thing about the Unichip is not the amount of power it makes, but the difference in the torque delivery on any car, modified or not. It's foolish to go chasing the odd BHP here or there on headers and intakes and exhausts etc when by far the best option for all-round driveability is the Unichip.


*EDIT* I'm not sure why you think the Unichip will actually decrease everyday driveability: Have you driven a UC'd car? The difference over a stock one is like night and day.

[Liz]

When I had my UC mapped on my previous '2 it was on the rolling road for about 45 mins - certainly not hours like you have said especially if you take it to Millways who know what they are doing with it.  

I can't personally see how you can notice 6BHP in the butt dyno, you need to have a go in a UC car before you dismiss it.

Mine previous '2 had an H & S - main cat still in place and gutted precats - the sound of it is legendary - ask those on here who heard it, it wasn't intrusive at all.

[ChrisGB]

Unichip will give you more power than any exhaust will, and is better value for money to boot. The best thing about the Unichip is not the amount of power it makes, but the difference in the torque delivery on any car, modified or not. It's foolish to go chasing the odd BHP here or there on headers and intakes and exhausts etc when by far the best option for all-round driveability is the Unichip.

The Unichip on the rolling road day cars actually did not make as much power as non unichip cars with Che manifolds and aftermarket exhausts. Torque, similarly was not spectacular either, with one exception where the owner in another thread reckons they recorded the 144lb/ft wrong anyway. I have done a bit of reprogramming over the years and there may well be more torque to come from the setup, so the unichip could / will be under consideration once the other bit (manifold) is in place but not before.

*EDIT* I'm not sure why you think the Unichip will actually decrease everyday driveability: Have you driven a UC'd car? The difference over a stock one is like night and day.

I dont think the Unichip would reduce the drivability in itself, but to yield the maximum power from this engine, one would need a 4 > 1 manifold and sport or decat. Now it is well known and through my own experience also that a 4 > 1 manifold allows more peak torque and power higher up the rev range at the expense of torque in the mid band and it is this path I do not want to follow because it is expensive and potentially noisy.

I would be interested to see how the car would work out with Che header / exhaust and Unichip. It will cost me a lot to find out, but reckon SH value should be OK if I dont feel much benefit.

Chris

[ChrisGB]

When I had my UC mapped on my previous '2 it was on the rolling road for about 45 mins - certainly not hours like you have said especially if you take it to Millways who know what they are doing with it.

Hmmm. I have had custom mapping done a few times. On cars with variable inlet tract volume and fuelling mods, it took around 3 hours for a custom map. For a turbo car, RR time was around 4 hours. The '2 has variable valve timing and the Che header / exhaust combination is a bit of an unknown to the prospective mapping company, so I would be wary of getting it nailed in 45 mins.

I can't personally see how you can notice 6BHP in the butt dyno, you need to have a go in a UC car before you dismiss it.

I find the difference quite easy to detect. Maybe I am pretty well attuned to the small differences as I have been tweaking and tuning stuff for years, often with the RR only at the end of the process.

Mine previous '2 had an H & S - main cat still in place and gutted precats - the sound of it is legendary - ask those on here who heard it, it wasn't intrusive at all.

Keeping the main cat is most likely the way I will go. How much power / torque did your N/A car with gutted precats, Unichip and H&S make?

Something that does spring to mind, an old trick of the engine remapper, (and manufacturers) is to make the TPS torque requests higher at part throttle openings giving the impression of more torque / better response. Only the dyno or a perceptive driver sees the truth in this case. My Fabia is custom remapped and the torque request curve was made more linear. The upshot of it is that some who drove it reckoned it felt less urgent than the standard car. Truth dawned on them when they could not stay with it (in similarly output rated remapped cars). The linear throttle response is not  impressive to drive, but does allow good control of traction and the power is still there. Looking at the dyno numbers from the rolling road day, none of the Unichip cars with the main cat present was making any more torque than I have now. As everyone keeps telling me they make a huge difference, is it just the throttle linearity that is different? Personally, I like the throttle to be linear as it means I can go harder in the wet. I really need to either try one or drive a '2 with one fitted.

More expense I feel this way comes  s:roll: :roll: s:roll:  

Chris

[rtbiscuit]

chris was it you who wanted a ride out in mine once i had the che header on, cos its on now, and i'm currently on half term if that helps.

[ChrisGB]

chris was it you who wanted a ride out in mine once i had the che header on, cos its on now, and i'm currently on half term if that helps.

Yes it was. I am not about until Friday night now (lovely business trip up to Leeds) but would like to meet up sometime Friday or Saturday evening if you can make it. No worries if you cant as I am having the Che manifold anyway.

Chris

[rtbiscuit]

get in contact closer to the weekend, could possibly do friday or sat,

sunday will be getting ready to go back to school

[Anonymous]

I dont think the Unichip would reduce the drivability in itself, but to yield the maximum power from this engine, one would need a 4 > 1 manifold and sport or decat. Now it is well known and through my own experience also that a 4 > 1 manifold allows more peak torque and power higher up the rev range at the expense of torque in the mid band and it is this path I do not want to follow because it is expensive and potentially noisy.

No, to yield maximum power on one of these engines you need either a turbo or a supercharger. Anything else is only ever going to give mild games, and chasing HP on an N/A engine is much like weeing into the wind, except without the warm feeling.

Hmmm. I have had custom mapping done a few times. On cars with variable inlet tract volume and fuelling mods, it took around 3 hours for a custom map. For a turbo car, RR time was around 4 hours. The '2 has variable valve timing and the Che header / exhaust combination is a bit of an unknown to the prospective mapping company, so I would be wary of getting it nailed in 45 mins.

Utter tosh. A tuner is a tuner is a tuner more or less, as changing fuelling/ignition/airflow is the same for any engine. Tuning an N/A car is far easier than tuning a turbo too, especially when you consider that you've got a far narrower power range to play with (and thus less to go wrong). LeeUK had a PPE manifold/downpipe/H&S exhaust when he had his Unichip tuned, and that was as much of an unknown propect as a simple TRD-copy manifold and single exit exhaust is. His result was outstanding in his car, coming in at 160bhp IIRC, and by far most of that gain was in mid-range torque: Third gear was something else, and I have yet to experience anything like it in a '2 without a turbo on.

I've also had the pleasure of following Chris when we both had almost identical setups (Markiii pipe, TTE exhaust but I had a TRD air filter as well) with the main exception being the Unichip that he has: He absolutely pissed all over me, and that was my first real-life view of what a UC can do. Lee's car was the same, but that was on track where you're giving it full beans all the time.



To be perfectly honest (and this is going to sound a bit harsh, but I'm only offering it as advice as I learnt the hard way) you're going totally the wrong direction with this car IMHO. It's never going to be a world record beater unless you boost it, and it's never going to be silly noisy unless you run a straight-through pipe with no silencer or cat either. It is what it is, and that's a fun car that's nothing short of awesome through the twisties. Save your money on chasing that last little bit of horsepower, and get some lowering springs if you don't have them already, some decent bracing (Corky's and TRD front strut or similar), short shift and a lightweight flywheel, and then get the Unichip. With the mechanical mods you'll make the most out of the car and what it's strengths are, and with the Unichip you'll get the most out of the engine.

For the record, I had a Markiii pipe, TRD filter, TTE exhaust and the flywheel on my car when it hit the dyno. Result? 155bhp. On the same day, Mark did his car that (at the time) was basically the same, except he had the H&S exhaust. He had around 4bhp less IIRC (please correct me if I'm wrong Mark!). Now given that the TTE exhaust gives no power increase apparently, and the intake mods are basic to say the least, I'll let you decide which made the most difference to the power of the car.

[Tem]

Now it is well known and through my own experience also that a 4 > 1 manifold allows more peak torque and power higher up the rev range at the expense of torque in the mid band

Are you sure?  s;) s;)

Here's a dyno of the PPE 4 > 1 manifold with catless downpipe:
 m http://www.ppeengineering.com/assets/im ... dpdyno.JPG m

The power/torque stays the same at one spot after 4k, but other than that you get more everywhere and less nowhere.

You can get even more with PFC and get rid of that "flat spot" too.  s;) s;)

[Liz]

I am trying to dig out my plot from Millways, however, this report by Grant (GSB) a well respected member of this forum, whom I went with to Millways.It is a superb write up of the benefits of Unichip to this car.  From my experience it changed the cars driveability, pickup as Grant says in the higher gears is excellent - not as good as a Turbo of course - but still great...have a read.

I've now had a day or so to mull over the changes that the Unichip has brought up, and more importantly, I've had a chance to compare the car in pre and post unichip mode... The difference is quite simply staggering...

The final peak power figure Millway extracted from my car was 156bhp, running on 97 Ron Esso Super.  The peak figure doesnt tell the whole story though, in fact it doesn't even come close... Peak power is all very well for grabbing headlines, but its the rest of the rev range thats surprised me...

I've been analysing the dyno plot (I dont have a scanner so I cant post it here yet, but point for point its so close to Martin's pre turbo dyno plot its uncanny. So by all means refer there unil I get my camera and take a photo of it.), and one thing has become very apparant, both on paper and on the road... The car pulls like a train from astonishingly low revs.

This is most telling by the fact that when I got the car (I swapped from a 5 speed '01) I had to train myself to drop two gears rather than one and grab 4th to pick up some proper speed on motorways. Dropping to 5th didnt seem to have any marked effect. On the way home from millway, I not only found that car was comfortable cruising at about 10mph faster than normal, but I wasnt having to drop gears at all. 6th gear has become a proper usable cog, wheras before I had no use for it rather than economy. Economy isnt the reason I bought this car, and before now I'd rather have had the slicker shifting 5 speed.

Analysing the plot, the reason why has become apparant. Toyota quote the peak torque of this engine as 125 ft/lbs. Thats the absolute max, with most of the rev range being less than that, although the 1ZZ is comendable in that it maintains the vast majority of that 125 ft/lbs for a large portion of the rev range. With the Unichip, the engine now knocks out much more torque than Toyotas quoted maximum throughout almost the entire rev-range! In fact the only time it dips below 125lb/ft is at about 6000 rpm, when the torque curve makes its usual decline. Better than that, it maintains just under 140 ft/lbs from 2000 all the way through to 5000 rpm, with a peak of about 142 ft/lbs at around 4000 to 4200rpm... Thats about a 20% gain!

This inflated torque band, rather than the headline 156bhp, is what makes itself felt in normal driving and enables faster acceleration, and easier overtaking. It throws you back in your seat that much harder, and really feels like the engine is doing some serious work. It also sounds better, like the engine really wants to get on with the job in hand, Its a pretty nice soundtrack...

Of course most people think bhp is the be-all and end-all of performance, but the Unichip seems to deliver there as well. The power curve has moved up and left, meaning theres more power coming earlier in the rev range. So much so that the usual peak power of 138bhp now comes up at a relatively lowly 5500rpm, but this is just a short stop on the way up the power band, which now achieves its peak at 6300rpm, some 800 rpms later.

So, overall, I'd have to agree with Martin, who's mantra over the last couple of years is very true... For ages he's been telling us how good the Unichip is and by and large we as members of MR2ROC have steadfastly ignored him, plumping for CAI's and dual exhausts... But the cold hard facts are these;
The unichip is quite simply, the best value for money modification you can get.
 In terms of performance per £, it's leagues ahead of everything else you can possibly do to this car. Forget Cold Air Intakes, they dont work, they just sound nice. Exhaust systems like the H&S or the TTE? Very worthwhile mods, but in terms of bhp per £ spent, they're only 20% as effective as the Unichip, if that.  I really cant say it any plainer...

Still not convinced?  Have a read of this whole thread:

 m http://www.mr2roc.org/phpBB2/viewtopic. ... sc&start=0 m

Obviously its up to you, however, I just wanted you to see the write ups on it.  If I hadn't of gone Turbo I would of gone UC again for sure.

[ChrisGB]

Many thanks for the replies folks. Where to start?

Well the Unichip is obviously working well for many people. The dyno day results seem to be 2:1 average torque to good torque (the 144lb/ft is credible), but it would seem that in general more people got good results from the Unichip than bad or zero. So apart from unichip, anything else similar that anyone would recommend? Looks like mapping device of some sort will be on my shortlist. Am I correct in believing that 140+lb/ft and 150+bhp are acheivable with the main cat in place? Only reservation is the fact that much of the increase is ingition timing.

The breathing mods. I was going to just remove the precats. Then I saw the Che header group buy and the rolling road results. The things that struck me were that the cars running Che header and aftermarket exhausts seemed to go well for NA. I did not like the way the stock exhaust sounded and did not want a twin exit pipe system (weight gain). Fabricators could collectively not make what I wanted at a reasonable cost, so the Che exhaust was worth a punt. Worked out well IMO. The more I think about it, the more I want to retian the main cat, so 4>1 is not really an option. I think the torque improvement on a 4>1 mentioned by Tem is a result of the decat improving things more than the 4>1 costs in the mid range.

As most of the cost of removing precats is labour anyway, I thought a move to the lighter Che header would make good sense.

Airbox and filter, no real gains to be had over stock apart from inlet elbow which is done.

So engine wise, the car is never going to be as quick as even my Fabia. I did not buy it for that, I bought it for the handling ( when deciding what car to buy I had more than one 400bhp car on the shortlist). So what else to do?

The underfloor brace I will make myself. I am probably going for a light rigid skeletal plate from 12 or 18mm 6082T6 plate, pocketed for clips and bolts. Just need time to get underneath and measure up. I will see what this does for handling before investing anywhere else. FTBrace may well be on the cards, need to see how the front and rear being more properly connected works out first.

The prospect of going lower may not suit me. My favourite environment for an entertaining tharsh is the B road. They are challenging and seldom speed trapped! The are also very uneven and bumpy. Here I would worry that shorter, harder springs would mean less compliance and wheel travel combined with harder work for the dampers. Possibly counter productive for my preferred driving environment?

All food for thought really. Unichip or similar would be last engine mod once precats have gone. I am really not into chasing down the power, would not have bought it if that was my aim. Chassis bracing seems like a good idea. I dont want to lose progression and as I drive hard in confined spaces, I need to retain the cars natural understeer to a degree even though I found it a bind on the track.

Again thanks for the replies. All really good food for thought.

Chris

[markiii]

I'd get an emanage over a unichip

cheaper and in addition to ignitiion you can control teh fuel

[GSB]

Unichip controls fuelling too, but not quite to the degree that the likes of eManage or AFC allow. Of course, if you're just tuning your car once, and staying NA, the extra complexity isnt really required... A unichip will suit all but the most dedicated tweakers needs. The extra flexibility and computing power of other chips is really only required if you wish to drastically change the way your engine operates. i.e. stroking/boring, forded induction, or radically different fuelling, intake and exhaust arrangements. The margins in the stock ECU program simply cannot cope with such changes.

In answer to Chris' post above I have the following observations to make.

Ignition timing is key to power. If you are using more fuel, and expecting to get more power out of it, you will need to light it at a different point in the 4 stroke cycle. Petrol burns fast, but it still takes a set amount of time to fully combust a set amount of fuel. In an engine doing 6000 rpm, with each piston firing 50 times every second, you have to ignite it early to achieve a full burn of the mixture and maximise the force on the piston during its power stroke. Ideally you want to achieve peak pressure in the cylinder when the piston is about 20degrees past TDC, at the point where the geometry of the the piston, rod and crank are best positioned to turn that pressure into useful mechanical force. To do that you have to light it early, sometimes when the piston is perhaps only just half way up on its compression stroke. Light it to late and the energy is wasted. Light it to early and you can have the flame front trying to run the engine backwards. Put simply you have to change the igntion timing to effectively burn more fuel, and burning more fuel equals more power... If you are unwilling to change the key parameters of your engines operation, then you will not realise its full potential. Exhausts and intakes and all these other things are all very well, but in the end they are just garnish, its the clunky lumps under the bonnet that make it go, and thats where you need to spend your time and effort.

For reference, the figures quoted by liz above on my car were achieved running on Tesco Super Unleaded on a stock engine. The only mods were a decatted manifold, an H&S silencer, and a markiii inlet.

With regard to weight gain, my twin exit H&S wieghs (IIRC) 7lbs less than the stock single exit pipe.

Never-ever compare an MR2 to a skoda again... People have been banned from ROC for less.  Behave yourself... s:shock: :shock: s:shock:    s:wink: :wink: s:wink:  

If you are a dedicated and even partially skilled driver, the you will find that chassis reinforcements help, rather than hinder. As any suspension designer will tell you, suspension works best if all four corners are rigidly tied together, as it allows the springs and dampers to do the job of keeping the tyres on the ground, rather than have for springs tied to another, bigger, and undamped spring in the form of a flexible chassis. Even with all the bracing in the world, the cars natural tendency to understeer can be retained, or tuned out with careful use of trye pressures and suspension geometry. The benefits are there to be had, and with no downside that I have ever experienced in 6 years of driving mk3's.

Lowering a car has a bad reputation due to every spotty max power reading scrote adopting it to make his shopping car look "In-Der-Vidge-Yool  -  Innit..."  Yes they are clueless tossers, but it doesn't mean lowering is a bad thing. Unlike neons, lambo door conversions, or ridiculous carbon wings...

The benefits are plain to see. A lower chassis means a lower roll centre, which means less body roll for a given speed and corner, and therefore more stable suspension geometry, and a more stable contact patch on your tyres. This is good. A set like the TTE springs only take 30mm of the ride height, leaving enough to deal with all but the most alpine of speed humps. If the roads you drive on are that bumpy that a lowered MR2 would become a liability, you really need to consider something more suitable, like a Land Rover...

[Anonymous]

Wow this thread is getting bigger, so it's time to show what I've got coming on Friday  s:D s:D  



One full blown 304ss equal length, knifed /profiled collector, custom manifold. It's still needs cleaning but that's it plus it's got a ss heat shield.

So after Saturday my car will have the following:

Zero Manifold
SP de-cat down pipe
Blueflame custom exhaust
K&N panel filter
Markiii pipe.

After all this I'll get it re-dyno'd to see what happens with the performance, then I'm going to have a Power FC fitted, I'm working on the basis I've gone this far so what the heck. Then eventually a new fly wheel and clutch.

Rob

[markiii]

sweet, dare we ask how much?

[ChrisGB]

Unichip controls fuelling too, but not quite to the degree that the likes of eManage or AFC allow. Of course, if you're just tuning your car once, and staying NA, the extra complexity isnt really required... A unichip will suit all but the most dedicated tweakers needs. The extra flexibility and computing power of other chips is really only required if you wish to drastically change the way your engine operates. i.e. stroking/boring, forded induction, or radically different fuelling, intake and exhaust arrangements. The margins in the stock ECU program simply cannot cope with such changes.

If emanage is cheaper, any reason not to use it instead of unichip? (that is if I dont succumb to the offer made by a fellow member here)

In answer to Chris' post above I have the following observations to make.

Ignition timing is key to power. If you are using more fuel, and expecting to get more power out of it, you will need to light it at a different point in the 4 stroke cycle. Petrol burns fast, but it still takes a set amount of time to fully combust a set amount of fuel. In an engine doing 6000 rpm, with each piston firing 50 times every second, you have to ignite it early to achieve a full burn of the mixture and maximise the force on the piston during its power stroke. Ideally you want to achieve peak pressure in the cylinder when the piston is about 20degrees past TDC, at the point where the geometry of the the piston, rod and crank are best positioned to turn that pressure into useful mechanical force. To do that you have to light it early, sometimes when the piston is perhaps only just half way up on its compression stroke. Light it to late and the energy is wasted. Light it to early and you can have the flame front trying to run the engine backwards. Put simply you have to change the igntion timing to effectively burn more fuel, and burning more fuel equals more power... If you are unwilling to change the key parameters of your engines operation, then you will not realise its full potential. Exhausts and intakes and all these other things are all very well, but in the end they are just garnish, its the clunky lumps under the bonnet that make it go, and thats where you need to spend your time and effort.

I fully understand the way the tuning of an engine works (perhaps I should mention I spent 12 years in automotive R&D in engine management, everything from single point injection for Fiestas to F1 teams, all of them, came through our doors and tuned bike and car engines for hobby and profit when fuel injection was the new black). My reservation about the mapping is borne from this experience. People staing 45 mins for a map reinforces this feeling of uncertainty. I know little of these afterarket controllers and how they program up, but back in the day, you had an excel spreadsheet with columns of figures for air mass index (itself a product of temp and flow), throttle position, engine speed and for this a matching entry for fuel input and ignition advance. Throw in variable valve timing and it all gets pretty complicated. to optimise. I can only imagine modern software has "macros" that allow proportionate block changes to be entered?

When I read that the wizardry is done with agressive advance settings, this concerned me a little. If one were to optimise for say V-Power, then pick up a batch of duff 95ron stuff, would there be enough room for error? Would the car, like so many marginally remapped cars, run rough on it? Of course if it is already ballpark right and the programmer is just tweaking up a parameter across a range, then I can see how it would be done quickly. In view of the fact that the cars advance is set by its own anti knock sensor to some extent, the programmers might be pushing close to the edge. The stock car never feels lean, but I reckon it could stand more fuelling under full load to its benefit.

For reference, the figures quoted by liz above on my car were achieved running on Tesco Super Unleaded on a stock engine. The only mods were a decatted manifold, an H&S silencer, and a markiii inlet.

This is good to know.

With regard to weight gain, my twin exit H&S wieghs (IIRC) 7lbs less than the stock single exit pipe.

It could weigh 5 or 6 lbls les still with one pipe  s:wink: :wink: s:wink:  

Never-ever compare an MR2 to a skoda again... People have been banned from ROC for less.  Behave yourself... s:shock: :shock: s:shock:    s:wink: :wink: s:wink:  

I do it daily. The Fabia remap was done in 4.5 hours. Torque request linearity was improved for better modulation of engine power, along with changes in the slopes of fuel vs boost vs revs to give less boost and less lag low down but higher boost and power higher up. Injection timing was optimised to smooth out said power gains. With 190bhp and 280 lb/ft going through the front wheels, an easy to modulate throttle is essential. Moreover 50mpg today between Chelmsford and Castleford at comfortably above NSL wherever possible shows the mappers art. Diesel. There I said it. I have sworn on the forum   s:oops: :oops: s:oops:  

you are a dedicated and even partially skilled driver, the you will find that chassis reinforcements help, rather than hinder. As any suspension designer will tell you, suspension works best if all four corners are rigidly tied together, as it allows the springs and dampers to do the job of keeping the tyres on the ground, rather than have for springs tied to another, bigger, and undamped spring in the form of a flexible chassis. Even with all the bracing in the world, the cars natural tendency to understeer can be retained, or tuned out with careful use of trye pressures and suspension geometry. The benefits are there to be had, and with no downside that I have ever experienced in 6 years of driving mk3's.

Again well aware of the theory. Will stiffen the mid brace up first then decide how to go next. The front strut brace seems probable, but I want it light. I was amazed at how much carrying 5Kg in the front bin made to the feel of the car, so itwill be a case of try it and see. Better is not always preferable. I really like the way the car behaves generally and dont want to lose its core caracter, so one mod at a time. The car does need bracing for sure though.

Lowering a car has a bad reputation due to every spotty max power reading scrote adopting it to make his shopping car look "In-Der-Vidge-Yool  -  Innit..."  Yes they are clueless tossers, but it doesn't mean lowering is a bad thing. Unlike neons, lambo door conversions, or ridiculous carbon wings...

Uh ohh... better take the demon super speed bodykit off then, I spend hundreds on those neons and the rear wing wont fit im my garage once it is off. The weight of the sound system and bodykit saved me buying lowering springs. Innit.

The benefits are plain to see. A lower chassis means a lower roll centre, which means less body roll for a given speed and corner, and therefore more stable suspension geometry, and a more stable contact patch on your tyres. This is good. A set like the TTE springs only take 30mm of the ride height, leaving enough to deal with all but the most alpine of speed humps. If the roads you drive on are that bumpy that a lowered MR2 would become a liability, you really need to consider something more suitable, like a Land Rover...

Lowering and I assume stiffening will marginally lower the roll centre. It will not neccesarily mean a more stable contact patch for the tyres though. 30mm in itself wont make much odds to roll, the stiffening will though. Roll has desirable effects too. Progression past the limit is often bettr in a softer set up car. What I want o avoid is a car that is beautifully tied down but difficult to drive at the limit. Also, lower means less travel, so car can be more inclined to hop on yumps and bumps. Pitch will also be reduced, but pitch s also useful in enhancing weight shift. I have had cars set up properly lower than stock. You can ultimately go faster on reasonable surfaces, but often at the expense of driver involvement. I really love the MR2s interactivity and would need a good long drive in a lowered car before comitting to lowering my car.

Thanks again for the input. Lots of mods is not what I had in mind for the '2. getting  more go from the engine without bankrupting myself will be nice. Will look closely at Unichip and Emanage.

On bumpier corners, there is plainly a lack of rigidity that allows the movement at the front end to upset the rear. A bit of bracing here and there ought to help with that. There is much available, but it is weight on, so need to be selective about what I do.

Any further mods will be on a try it in somone elses car first basis.


 EDIT: Back on topic, still think the Che exhaust was a good decision.
Chris

[ChrisGB]

Wow this thread is getting bigger, so it's time to show what I've got coming on Friday  s:D s:D  



One full blown 304ss equal length, knifed /profiled collector, custom manifold. It's still needs cleaning but that's it plus it's got a ss heat shield.

So after Saturday my car will have the following:

Zero Manifold
SP de-cat down pipe
Blueflame custom exhaust
K&N panel filter
Markiii pipe.

After all this I'll get it re-dyno'd to see what happens with the performance, then I'm going to have a Power FC fitted, I'm working on the basis I've gone this far so what the heck. Then eventually a new fly wheel and clutch.

Rob

Hmm that does look very nice!

Chris

[Anonymous]

sweet, dare we ask how much?

Hi Mark

Price £450 plus VAT - as per original quote, that includes the shield as well. I'll post pic's when it's fitted.

Rob

[spit]

Thanks for the preview on the shield Rob. Sexeh!   s:wink: :wink: s:wink: