Duratec in detail

[KingK_series]

I must confess, I did not measure how perpendicular the bell-housing mounting surface was to the crank, but have just done that on the engine that has come out. It was within .015 mm so well within the spec for the clutch (0.05 mm) and I am happy Ford can achieve the level of alignment required. Concentricity is more difficult to measure but it is doweled, and I guess for that reason. My comment about the clutch being firm was the spring pressure - the smaller diameter of the clutch (compared to OE) means higher spring pressures are required (albeit mitigated to some extent by two plates).

- Again from personal; experience actually using and driving with these clutches ....I've driven Quartermasters with their very stiffest spring, and the spring below, and Superclutches with the spring Tony Tewson specs for Caterhams on a 184mm twin plate, -

-when the engine was square there was no real difference in clutch feel over a stock K series clutch, certainly not after a few hours driving it.

When the thing was all akimber, it felt heavy, until it spun, then of course an Elephant wouldn't have budged it - you should have seen 4 big lads with long crowbars trying and failing to pull the box off - hence having to cut the bellhousing

finally - if the sump is doweled - I think your chances of a block machined somewhere by Ford [Germany, Belgiium?] are highly unlikely to be square with a sump machined by whoever SBD uses?

I'd bet a pint on it, in fact -

[philthy]

I don't really see how your posts are contributing anything to david other than doubt about his build, if anything it reads like scaremongering.

The smaller twin plate is gauranteed to be heavier than the standard item that came out so feeling really firm shouldnt give any cause for concern.

After all this is a home build, and one of the best I have read for that matter with regard to attention to detail.
Looking forward to reading about the results.

[KingK_series]

I don't really see how your posts are contributing anything to david other than doubt about his build, if anything it reads like scaremongering.

The smaller twin plate is gauranteed to be heavier than the standard item that came out so feeling really firm shouldnt give any cause for concern.

After all this is a home build, and one of the best I have read for that matter with regard to attention to detail.
Looking forward to reading about the results.

not in the slightest


- there is nothing worse , more frustrating or such a waste of money, as having problems with a piece of kit that you have no experience of - as I did when someone bought a Superclutch and asked me to fit it to their engine. Such was my interest I showed it to 4 others who followed suit and bought them - all 5 caused horrendous problems for months - 5 totally undrivable Lotus's that I really struggled with for my.... inexperience with this type of clutch and totally useless support from Tony Tewson [Superclutch]

the above is the result of grief, tears, frustration and a fortune in wasted money to get them to work as they should - beautifully, and there's a big difference between sort of working and working.... as I said 'as they should'.

- For instance the clutch that spun on the mainshaft ran - awkwardly with a heavy clutch for about a year before the owner of that car turned up at a very expensive track day to have the box/clutch totally seize/jam/fubar up in the very entrance of Silverstone race track - had to be trailered back.



so with all due respect, unless you have one of these clutches, have run it, you have raced it faultlessly and understand exactly what is required to make them run faultlessly, you will forgive me if I think your post is way off point.

[David]

I've just spent a couple of day trawling the Caterham forums and speaking to people who have used these clutches in Caterhams. A fairly consistent response - they are reliable in a Caterham, both Vauxhall and Duratec, but not ideal for road use. They do have a heavy feel and a sharp bite, the only issues seem to be related to shock loading in the drive train, particularly with the diff mountings (and there is a mod for this).

I take on board your comments Simon, but this whole project does has a high risk element to it. There are many things that can (and probably will) go wrong and I see the real challenges of this project as just beginning. I will deal with the issues one by one - the first is the real risk that this engine will not survive the dyno, so the clutch durability is a little further down the road at the moment.

[KingK_series]

I've just spent a couple of day trawling the Caterham forums and speaking to people who have used these clutches in Caterhams. A fairly consistent response - they are reliable in a Caterham, both Vauxhall and Duratec, but not ideal for road use. They do have a heavy feel and a sharp bite, the only issues seem to be related to shock loading in the drive train, particularly with the diff mountings (and there is a mod for this).

I take on board your comments Simon, but this whole project does has a high risk element to it. There are many things that can (and probably will) go wrong and I see the real challenges of this project as just beginning. I will deal with the issues one by one - the first is the real risk that this engine will not survive the dyno, so the clutch durability is a little further down the road at the moment.

- hah

Getting an engine to survive a full professional race season let alone the dyno is the easy bit in my books


fyi, the clutch that spun was awkward as a road car, then it fubared a track day and the box, since it went back with all the know how I sweated blood and tears to learn its a pussy of a perfect road clutch, as well as track - the only difference from a sprung pressed steel clutch is that it rattles when out - because there are no retaining springs


I suspect its the same rate of spring as in your Caterham [std Tony Tewson spec], but now its square it is no heavier than OEM.


It was before - obviously because it was binding -

[Gourlay83]

Thanks for taking the time for posting this up, i've reading with interest during my lunch breaks and looks great.
It's Just a shame I won't have a car to join you on the track days etc. Maybe have something by summer.

Best of luck with the dyno.
Alan

[David]

Yesterday was spent on the rolling road running-in and putting together a safe map to allow some track time. The running-in was an alternating pattern between various stages of throttle and full vacuum (closed throttle). The idea (I'm told) is to allow the rings to be pushed out followed by all the debris being sucked out. This went on for about an hours or so as we watched and listened for any thing out of the ordinary. The operator wore a stethoscope bolted to the knock sensor bolt just to give us early warning of any issues. The Supertech pistons, apparently, were heard slapping about a bit - typical of the short skirt design, but it ran smoothly with less vibration than the predecessor.



Once this was completed, we moved on to mapping. The objective at this stage was not to get a headline BHP figure, but to get something safe to build a bit of track time. We therefore set a rev limit of 7600 RPM and mapped with an eye on the budget. The detailed tweaking is still to come, but we did a few power runs at the end which gave 226BHP at the wheels - which was better than I expected.



What did become clear is that the cams are really intended for high RPM. It really came alive at 6000 RPM and, in the words of the operator, 'about to go ballistic' when the rev limiter cut in. I know the 4:1 exhaust is not ideal for low torque and also the Cosworth barrels have limitations too, so this was good news and spot on what Simon at Ultimate had predicted.

http://www.youtube.com/watch?v=fU6U_N9_mPc

There was an induction noise at around 3000 rpm that sounds horrible, but is probably the large overlap on the cams. All in all a good day

[Dominic]

[robin]

The horrible noise is probably some sort of standing wave in the air intake path, being excited by the cam overlap like you say ... does it correspond to the torque dip you see in the 2,750-3,750 range? Anyway with those cams, 3,000 RPM is only useful for putting it on/off the trailer

I assume the tiny dip in torque at the end is him coming off the throttle? Or does it signal the beginning of the end of the power band? Anyway it looks like you'll have a band of 2,000 RPM if you stick to a 8,000 RPM limit ... does your gearing match that?

I do like that torque curve though - proper track-only setup

Cheers,
Robin

[David]

I assume the tiny dip in torque at the end is him coming off the throttle? Or does it signal the beginning of the end of the power band? Anyway it looks like you'll have a band of 2,000 RPM if you stick to a 8,000 RPM limit ... does your gearing match that?

I do like that torque curve though - proper track-only setup

Cheers,
Robin

I think there is some processing going on to 'smooth' the graph which is a bit misleading. When looking at the raw data, it was a straight line to the limiter and we think it will continue to go up for quite a while. I didn't understand all the data, but apparently the fueling was still increasing at the limiter, indicating that it was breathing well and not reached its optimum flow rate. Interesting what you say about the dips - I think there are standing waves and harmonics causing problems. It was difficult to get the fueling right in parts - almost like it was spitting it out at times. I think I need to do some research on trumpet length. (known to be a problem with the Cosworth roller barrels which were designed to fit the space under the CSR bonnet).

I have got a shorter diff that I had hoped to fit to take advantage of a higher revving engine. But I might rethink that if the power band is small. Here's it compared to the old engine (blue) - as you can see, swings and roundabouts. I suspect it'll be quicker but harder to drive.



It's definitely a track only car now - I failed miserably to drive on to the trailer after the RR

[robin]

LOL

To make it go you'll need more revs or a pretty short box or both Shorten the diff if top speed is too fast to be of use on typical tracks you compete on.

If the torque curve is flat at 160 lbft out to 9,000 RPM (and assuming the engine will take it) you'll have 260BHP at the wheels.

[edit: looking back you were aiming for 8,250-ish RPM, so you should end up with 240-ish at the wheels which is almost bang on what you said on page 1 - good effort!]

Cheers,
Robin

[robin]

Re: intake stuff, you will probably find it works just fine on part throttle in the 2-4K range - realistically this engine is going to spend its track time at 6K and beyond; you only need the lower RPM stuff for shuffling the car on and off the circuit - though you would like it not to stall! Plenty of clutch slip and 6K RPM to pull away should be ideal

Cheers,
Robin

[David]

I've spent a little time getting my head round the map we ended up with. There are a couple of features (yellow highlight) that are where something quite dramatic happens. As one is almost exactly twice the RPM of the other, I think it is fair to assume this is a resonance of either the exhaust or induction. My guess (and it is only a guess) is that this is induction as it coincides with the noise we heard and is related to throttle opening too. I need to read up and research the theory and work out what the best lengths are.

[Stu160]

Could be something to do with tuned lengths etc. dont know anything about it, but did read an article in a mag once

Stu

[robin]

Is that the ignition advance map?