9m Racing 4.0 litre engine test
05-20-2009, 08:34 PM
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9m Racing 4.0 litre engine test
I figured that the real petrol heads here would enjoy looking at this movie of my 4.0 litre 9m Racing engine on the dyno a week last Saturday.
http://www.youtube.com/watch?v=8VmS_xI04eY
The tests were carried out as part of the final year project of our resident work-experience student, Jack, who is doing a Motorsport Engineering degree at Derby University. The purpose of the exercise was to quantify the benefit from relocating the fuel injectors overhead of the intake tract as opposed to the conventional side location and from varying the height of the injector. Sure, we know that overhead injection is nothing new, but it's an idea I have been contemplating for some time and besides, it's always good to prove things to yourself under your own test conditions.
Interestingly the 4.0 litre engine has now been in my car since 2006 & was only removed for an upgrade in August 2007 when we fitted the new 9m high lift cam package, so the bottom end has now won two Speed Championships, placed 2nd overall in the third year and has just set a new record (& fastest tin top) at the last sprint event at Anglesey in it's fourth season, so it's not exactly had an easy life (as a recent leak down test will testify). The bad news is that it's a little down on torque from where it started out from, the good news is that it still makes great power. On the test we tried two injector heights before refitting the injectors in the throttle bodies (you can see the location in the video from the dummy injectors we fitted to seal the holes up) and repeating the test under the same conditions.
The results will follow as I'm posting this from my home Mac desktop and the dyno graph is on my laptop.
http://www.youtube.com/watch?v=8VmS_xI04eY
The tests were carried out as part of the final year project of our resident work-experience student, Jack, who is doing a Motorsport Engineering degree at Derby University. The purpose of the exercise was to quantify the benefit from relocating the fuel injectors overhead of the intake tract as opposed to the conventional side location and from varying the height of the injector. Sure, we know that overhead injection is nothing new, but it's an idea I have been contemplating for some time and besides, it's always good to prove things to yourself under your own test conditions.
Interestingly the 4.0 litre engine has now been in my car since 2006 & was only removed for an upgrade in August 2007 when we fitted the new 9m high lift cam package, so the bottom end has now won two Speed Championships, placed 2nd overall in the third year and has just set a new record (& fastest tin top) at the last sprint event at Anglesey in it's fourth season, so it's not exactly had an easy life (as a recent leak down test will testify). The bad news is that it's a little down on torque from where it started out from, the good news is that it still makes great power. On the test we tried two injector heights before refitting the injectors in the throttle bodies (you can see the location in the video from the dummy injectors we fitted to seal the holes up) and repeating the test under the same conditions.
The results will follow as I'm posting this from my home Mac desktop and the dyno graph is on my laptop.
05-20-2009, 08:56 PM
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And here are the results as promised.
For the baseline we tuned the Motec fuel curve at 100% throttle with the injector in the lower of the two overhead heights, aiming for a flat LA = 0.88 from 3000 to 8000rpm which we pretty much achieved. We logged the mixture on the pull using the Motec to achieve this, which is amazing in it's own right when you see the fuel standoff clouding out of the trumpet during the run. The second test raised the injector, the third test had the injectors back in the usual side location. We did not retune for the other runs as we wanted to use the log of the new lambda readings to indicate the change of mixture that the cylinder is running with the different injector positions.
No surprise that the best power was recorded by the overhead injector in the lowest location at a very respectable 456.4hp, in second place was the raised location at 453.1hp and in third place is the side location at 451hp.
For the baseline we tuned the Motec fuel curve at 100% throttle with the injector in the lower of the two overhead heights, aiming for a flat LA = 0.88 from 3000 to 8000rpm which we pretty much achieved. We logged the mixture on the pull using the Motec to achieve this, which is amazing in it's own right when you see the fuel standoff clouding out of the trumpet during the run. The second test raised the injector, the third test had the injectors back in the usual side location. We did not retune for the other runs as we wanted to use the log of the new lambda readings to indicate the change of mixture that the cylinder is running with the different injector positions.
No surprise that the best power was recorded by the overhead injector in the lowest location at a very respectable 456.4hp, in second place was the raised location at 453.1hp and in third place is the side location at 451hp.
05-20-2009, 10:46 PM
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Were these crankshaft numbers or at the driven wheels? In any event, very impressive.
Andrew
05-21-2009, 05:54 AM
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Andrew,
The dyno measures the rear wheel power, then measures transmission & tyre losses on the coast down, adds one to the other at each point in the graph before correcting the result for atmospheric conditions to DIN standard by using it's internal weather station. The result you see here is hence DIN flywheel power. That said, dyno's vary significantly and no chassis dyno can ever give you a 100% accurate measurement of fwhp, so you must always compare the result with other cars of similar power tested on the same conditions in order to make valid comparisons. The best standard 996GT3RS on this dyno made 408hp.
The dyno measures the rear wheel power, then measures transmission & tyre losses on the coast down, adds one to the other at each point in the graph before correcting the result for atmospheric conditions to DIN standard by using it's internal weather station. The result you see here is hence DIN flywheel power. That said, dyno's vary significantly and no chassis dyno can ever give you a 100% accurate measurement of fwhp, so you must always compare the result with other cars of similar power tested on the same conditions in order to make valid comparisons. The best standard 996GT3RS on this dyno made 408hp.
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05-21-2009, 09:28 AM
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It's all relative, in truth I'm pleased with the result as injector position accounted for > 1% increase in power which is pretty significant when you're already running the engine at 114bhp/litre. The actual exhaust mixture (lambda) change interested me more because it proved that with an optimised injector location the engine would run more efficiently, but I'm keeping that data to myself.
I remember talking to the F1 development boys when we designed the heads and they were more used to searching for gains in the order of 0.1% - in fact the one time a team member found a whole 1% the entire engine development team celebrated down at the pub!
