Duratec in detail

[robin]

Nice Looking forward to next rolling road data ...

Cheers,
Robin

[Dominic]

That looks suitably meaty!

[Scottish Scrutineer]

I presume there's a cat in the can?


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Renny

[David]

I presume there's a cat in the can?


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Renny

Yes - I've even got them to put a wee hole in the collector for you to stick a mirror in and look . I'll try and get some pictures of the insides too as some stage.

http://www.btbexhausts.co.uk/products/F ... -05/11.htm

[Scottish Scrutineer]

I presume there's a cat in the can?


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Renny

Yes - I've even got them to put a wee hole in the collector for you to stick a mirror in and look . I'll try and get some pictures of the insides too as some stage.

http://www.btbexhausts.co.uk/products/F ... -05/11.htm

You spoil us David



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Renny

[David]

Mostly when I hit a problem I try and think it through, come up with a plan, and, when my solution doesn't work, start again . But the torque curve was different - the solution had lots of £££ in front of it. I couldn't afford to get this one wrong. I was essentially prototyping the exhaust for this package, so was a little apprehensive but, every now and then, things comes together. BTB beautifully packaged the exact exhaust dimensions and delivered on time, Ulitimate's exhaust spec was spot, and Northampton Motorsport did their stuff on the rolling road.




I am still digesting the data and will comment more later, but at last got a torque curve, and some BHP figures, that put a smile on my face. . In many ways the figure are an embarrassment as I'll need to ballast up for the SLS - and there may be gearbox and diff issues too, but we will deal with that as and when we need to. Looking forward to Saturday and driving it for the first time

[mckeann]

Great result. Is that the same RR as before for a direct comparison???

[Shug]

Sorely tempted to take a run across to KH on Saturday just to see that in action now... Great result

[David]

Great result. Is that the same RR as before for a direct comparison???

No, it's Northampton Motorsport which is a 'single' roller and the other was Russ at HQ - so direct comparison is with the usual provisos. With no disrespect to HQ, the Northampton set up is designed for light RWD race cars and was more integrated to the ECU data so probably the more accurate.

[David]

The R400 running up on the single roller of Northampton Motorsport . . .



With a little bit of time to absorb the chaos of the last two days, I can see a close to this project on the horizon.

The figures I am getting are now of the high side of what was predicted and talking to the 'team' Ultimate, BTB, and Northampton Motorsport, it has become clearer that there is an awful lot of luck in how things work out. If you maximise each system on their own, there's no guarantee that they'll all work together. If there is a secret, it seems to be the way induction, exhaust interact with each other. But contrary to what you might think, you don't particularly want them to work together. In fact you can use them to draw any torque curve you want. In my case, the exhaust was made to to 'rock' the torque curve towards the lower RPM while the roller barrels are trying to 'rock' it the other way. The net result was to flatten it over a larger RPM range which gives a more useful power band. Earlier in the project I thought the roller barrels would need replaced with something longer, but it turns out that the ram tuning cuts in just at the right point to extend the power band. Seems Cosworth may have got this one right



I made this graphic that compares the wheel HP at the various stages of tune the car has been in. Firstly theses are from different dyno so don't take them too literally, but they do give an idea of how things have changed. The new engine has exceeded previous power graphs at all speeds above 3000 rpm. It is a bit bumpy in places but is essentially straight. The BTB exhaust has done to two things - its bigger diameter has released more power, and the 4-2-1 design has pulled the the torque up at 6000 RPM and below (secondaries). Theoretically, the roller barrels are in tune around 7500 to 8500 rpm, and you can see evidence of this with the second hump towards peak power. There's still another 1000 RPM still to explore, but it is likely that the exhaust may not work so well there. . . . . now I could just make a 4-1 exhaust with shorter primaries . . . . .

[David]

OK, it time for an update as the project seems to be coming to a natural end with driving the car for the first time.

Watch on YouTube

Although the weather conditions were appalling, it was an excellent test of the car's drive-ability which had been my main worry about the upgrade. In fact, it seemed better behaved than the old engine. . The Clutch was fine too, maybe a little off or on, but I quickly got used to it.

As the trackday was halted after these laps, I went to HQ Garage to do the SLS yesterday power check with with Russ.

Watch on YouTube

It gave a wheel HP of 240.2 HP (on a later run not shown in the graph below) which was within a 1 BHP of Northhampton Motorsport figure (in the region of 270-280 BHP at the flywheel). But more importantly, it allowed a direct comparison of pre (red) and post (Blue) exhaust upgrade. I am please with the power, particularly as there's still another 1000 RPM to explore, but it is a little off target for the SLS class B upper limit of 375 WHP/tonne (it came to 386WHP/tonne). I'll either go up to Class A, or put some ballast in.



The exhaust works well and effectively solved the torque delivery issues - easily the single most important component in the upgrade. Also, as it was not cheap, it was a great relief that I made the right call in terms of what was wrong after the initial dyno work.

I've learnt a huge amount doing this - maybe not in putting it together, but certainly in the concepts of tuning and what it really works in the real world. The process of manipulating the torque curve hadn't really be fully appreciated by me at the start. The process of using exhaust primaries, secondaries, and induction length all tuned to different RPMs to make a flat torque curve just makes so much more sense now.

Things I would do differently: I wouldn't have bought a new engine, but would have upgraded the old one. Maybe, kept the old flywheel and clutch. Taken more time to research things. But that's about it.

[Sanjøy]

Great job.

[Scottish Scrutineer]

Good figures and curves David. Looking forward to seeing it in a couple of weeks


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Renny

[KingK_series]

David

I have taken the liberty of posting your flywheel figures on dyno plot, I aoplogise in advance for any inaccuracies - its very difficult doing it without a sheet of numbers - however it makes a useful comparison with my old 2006 BTCC engine since they make identical numbers to all intents and purposes.

http://www.dyno-plot.co.uk/dyno/dynoplo ... /index.htm

= with the proviso, you have more lift [0.5mm], bigger valves [1.5mm] individual throttle bodies and a dry sump, the dry sump alone should be worth 10bhp and 10lbft, mine was obviously on a plenum and a single 60mm throttle body - same as Ford OEM I believe?

- so what is there to learn? - well you are well down on lower torque even with a less revvy engine, and have two distinct spikes in the lower rev range. Looking at your graph I can tell you your exhaust collectors are wrong and if they were corrected you'd pull up your torque curve and lose the dips, secondly you are running out of steam at 7900rpm...that I cannot understand, though your induction is way too short - for best torque and I suspect for top end too. how are the TBs fed with air? a pic of the engine installed would answer a lot here - please?

The guys at Northampton are great, but they are not right to say tuning the exhaust rocks the curve, that will happen if everything is not working together but a tuned exhaust, and induction with 36mm valve and 12.5mm lift should see you well clear of 300bhp and 200lbft of torque - and lift and smooth the bottom end.

would love to see installed pics

[David]

Thanks for the feedback Simon. I find it quite flattering that it stands up so well to a BTCC engine - my experience is limited at this level and budget is certainly not in the BTCC league. Given unlimited funds, I would be quite happy to play around with exhaust lengths, but the fact of the matter is that they are as good as I'm likely to get in a one-off attempt.

I have always intended this to be a three stage project - engine, exhaust, and induction. I still need to improve the induction - but that won't be this year as the roller barrels are working well enough. The roller barrels are 45mm but the Duratec really needs 48+mm to get above 280BHP. The engine is also soft limited to 8000 rpm so I think there is more to come.

The dip you refer to has been the subject of some discussion, and we feel it is induction. At low RPM the roller barrels struggle with velocity past the injectors and fueling is particularly tricky. Torque actually increases as the barrel closes and we think it this is because velocity past the injector increases due to the geometry of the roller barrel (their shape is like a funnel). The standard fix for this is to move the injector out of the head and further up the induction path (which will be part of the induction upgrade).