My DJ on a Rolling Road.

[syncrosimon]

Decided to have my syncro's 2.1 DJ tuned on a rolling road by TSR Performance in Bridgewater, Somerset.

http://www.tsr-performance.com/pages/rollroad.asp

She spent 2hrs on the dyno, and ended up with the timing at 9 degs, and other settings as shown below. This cost £80, and included about 6 power runs to try different settings.

The strange thing was that only the timing made any difference, and 9 degs was all she could take before pre detonation took hold.

The operator was very familiar with the mkII Golf injection system which is identical, and was very pleased with how smooth the torque and power curves were.

http://s199.photobucket.com/albums/aa28 ... V00119.flv

[IMG:640:480]http://i199.photobucket.com/albums/aa28 ... C00122.jpg[/img]

[IMG1536]http://i199.photobucket.com/albums/aa28 ... 050495.jpg[/img]

[IMG1536]http://i199.photobucket.com/albums/aa28 ... 050496.jpg[/img]

The max power achieved at 10degs, but with detonation gave a power figure of 110.6BHP. This was backed off till a sustained full throttle run was achieved and 105BHP.

The two top lines on the graph are torque (orange) and BHP (red). The steps on the torque curve correspond to the ECU increasing fuel, with revs, giving level amounts of torque till fuelling is increased. The blip in the power at 80BHP 3700rpm is where maximum fuelling is achieved, and torque flattens off, power increase is achieved by revs only after that point. This is shown by the blue line at the bottom flattening off at that time.

The operator Tom did not touch any of the idle stabilisation stuff, and did all tuning as is. He stated that at idle there is a set amount of fuel introduced into the engine by the injectors, and the CO mix screw only plays with air, which if you richen the mixture there is a point where it does not burn due to inefficiencies, and if you weaken the screw it will actually show a increase in emissions.

The blue line also shows the gear changes. Note the oil temp of 87degs, after 2 hours of stationary running.

[Ian Hulley]

85mph .... is that a Syncro transmission thing or the engine itself ? .... cos I know our 2wd 5 speed DJ with lpg/DG carb does that (by Tomtom) without pushing it that much.

Ian.

[syncrosimon]

Obviously the rev limit is at 5400 rpm, not 4900 rpm, so the theoretical top speed is higher than that, 4900 and 85mph represents max power, not max speed. The engine is making full power at that speed anyway, and the video clip shows the engine bouncing off the rev limiter at 5300rpm and still produced the same power. On this particular run the operator chose only to rev it to 4900rpm, as there was no point going any higher.
Dont forget it is only driving rollers!!!

[Simon Baxter]

Engine in good fettle too with those readings, just a tad on the rich side but better that than lean.
Interesting to see, thanks for posting.

[Aidan]

Speed is a 16" syncro with 5.43 fd thing, don't compare with 2wd, nice post Simon.

[Syncro G]

An interesting post! Was it on a 4 wheel dyno or a 2 wheel one? Would be interesting to see how much extra transmision drag the front axle makes.

[syncrosimon]

She was in 2wd. The rolling road had an adjustable wheelbase, so could have run it in 4wd. The blue line is something like power versus friction, you can see that it flattens off at the same time that torque flattens, as after max torque the engine only makes more power by increasing revs, not through increased fuelling, and on this bus the frictional losses of the transmission and a theoretical wind resistance go up at a slightly increased rate than the power.

This is why torque is so important, it is the power of the moment, and not by a multiplication of engine speed.

Unless you can increase fuelling, you are not going to increase torque.

It also shows that actually the fuel injection system is very good. The tuning boys said that they prefer it everytime to carbs, and that the digifant system rarely gives them problems. They have a little man in a shed that they keep for re building AFM's. Worth remembering.

[Ye Olde Syncrospares]

yours is digijet not digifant,were you using posh petrol for this as it would be interesting to see what it makes on 95 with timing altered,cj.

[syncrosimon]

I can never remember between digifant and dijijet, let alone spell them. I did mean dijijet though, that TSR were refering to. I suppose it either works or it doesnt. This one works mainly due to CJ's fine selection of spare parts.

[jason k]

were those figs on super or regualar unleaded??

[syncrosimon]

I try and always run her on V-Power 98 Unleaded. It is the most advanced fuel you can buy, and should keep all the internals nice and clean. There is a Shell garage in Taunton that is close to Sainsburys Superstore and sells the stuff at a very competitive price. I believe it is good for 1 extra mpg.