Independent Scientific Confirmation

Well, I've taken someone else out in the Birkin for a scientific assessment of the performance in a comparitive situation vis a vie the performance. And the verdict is it's faster than most. Which is good, 'cause I was worried.

OK, so it's not exactly scientific, but it's nice to have someone tell you that, depsite the dyno report which showed the output was the same as theirs, the reality is somewhat different.

In other news - the lean cylinder is back, and is colouring up the exhaust once more, so there's some work to do looking at the injector. In addition, if you take the air filter off, you can see the spark flash actually in the intake, which isn't good.

So I had better not overdo it - running the cylinder lean means its heating up unevenly, which can lead to cracking and detonation if I'm not careful. So until this is resolved, I'll be driving more conservatively....

I did fill it up with petrol the other day, and someone was taking photos while I was paying. They either liked the car, or were sending the photos off to the police to report me under the anti-hoon laws ;-)

Back from the Tuna

So, after all the hype and hyperbole of this blog, saying how my car will be super powerful and go really fast, it finally went onto a dyno. Expecting a call with a figure of 'Gee mate, it's bloody great. Rips 230bhp off at the flywheel, and tore the dyno out of the floor', I was a little non-plussed to get something a little different.

The comment from the tuner was that, overall, it seemed a little disappointing. He kept saying things like it felt that there was a restriction somewhere - perhaps the throttle bodies are too small (they're 48's, so no). Perhaps the standard cams aren't up to much (oh, wait, they're 220bhp raceline cams, not standard). Perhaps the cam timing is off (nope, done by a guy who builds motorcycle engines - finer tolerances on a Ducatti than a Ford lump). So really no idea as to why it pulled the figures it did.

So, to be blunt, the dyno showed a paltry 106kw at the rear wheels. This translates to around 180bhp from the engine. Given all the fruit that's been thrown at it, there's either a serious problem with the engine, or a problem with the dyno.

As it turns out, it may be the dyno. One of the other Birkins just went in with a stage-3 CNC milled high compression head, cylinders bored out plus forged pistons and rods, which should have sent the power skyrocketing. Instead, they showed a 5kw loss. The guy at the shop also said his RX-7 seemed to have lost 20bhp somewhere, and a few other cars are showing lower than expected results, so my guess is that something has gone a little wonky with the dyno. Mind you, being at least 40bhp down is a little more than just a small issue. But I'd rather believe that than believe I just spent that much money on an engine that does just 25% above the standard Ford Focus.

The ultimate test will be on how it now drives. The tuner has worked the power and torque curves to be nice and smooth, so as long as the whole lot just moves up a few inches on the page, then it should all be fine.

I'll either challenge some of the other Birkins to a drag race (under controlled conditions with trained professional drivers, of course), or use my new toy, the Performance Box from Racelogic, which has a power estimation calculation based on weight and 0-100 times. Obviously the calculator is a little hit and miss (lots of driver, tyre and other factors), but if with my poor driving and cooked tyres it tells me I have anything like 180bhp, I'll know its much higher ;-)

Or, I'll drive it for 6 months and think it's great, then someone clever will say 'hang on, this looks wrong', make a tweak, and uncover another 40bhp for me. That would be nice.

So, not ready to scrap the whole thing just yet. But would have liked a little bit more certainty around what it is I've actually got.