06-12-2012, 04:27 PM
From what I've heard, and don't quote me on this. The cam profiles were specced by someone who made nice bi-turbo (sequential and parallel) HDi DW10 drag-cars in another Euro country... and he specced them for his 220bhp+ car, for drag-race use.
Now, "assuming" cough wink cough, that what Piper is selling you is the same as those cams, then it's a good bet that they won't do ANYTHING at all for you until you are running 220bhp worth of airflow and find the standard cams limiting.
Pete ran his 205bhp VNT car without a cam change, and I've seen cars from 150-185bhp without a cam, so I'm really not sure why you'd want a cam unless you just want to spin the roulette wheel and take a gamble on it not actually costing you power/torque or driveability.
I've not done the calculations on the cam, not even sure what the spec is, but most FI cams on any half modern car (like the HDi is) will flow easily for double their standard config (referenced from many books/sources on FI tuning)... thus since the DW10 cam is used at 90-110bhp standard, it's reasonable to say we start to run into problems at 180-220bhp... which is exactly where a certain drag-race user of the DW10 specced his cams for, about 200-220bhp!
So, my 2p. Avoid. If you hit 185bhp and then fit a cam and suddenly find you have 195bhp, then great. But I don't think you will.
I think you *start* to need one after about 200bhp, and from there on in a change will start to benefit you at the high end power outputs... but again that is only a high output. What's it like at idle? Sub 2000rpm? Everyday driving rpm's?
Save your money for something with proven gains, or bigger brakes
Dave
Now, "assuming" cough wink cough, that what Piper is selling you is the same as those cams, then it's a good bet that they won't do ANYTHING at all for you until you are running 220bhp worth of airflow and find the standard cams limiting.
Pete ran his 205bhp VNT car without a cam change, and I've seen cars from 150-185bhp without a cam, so I'm really not sure why you'd want a cam unless you just want to spin the roulette wheel and take a gamble on it not actually costing you power/torque or driveability.
I've not done the calculations on the cam, not even sure what the spec is, but most FI cams on any half modern car (like the HDi is) will flow easily for double their standard config (referenced from many books/sources on FI tuning)... thus since the DW10 cam is used at 90-110bhp standard, it's reasonable to say we start to run into problems at 180-220bhp... which is exactly where a certain drag-race user of the DW10 specced his cams for, about 200-220bhp!
So, my 2p. Avoid. If you hit 185bhp and then fit a cam and suddenly find you have 195bhp, then great. But I don't think you will.
I think you *start* to need one after about 200bhp, and from there on in a change will start to benefit you at the high end power outputs... but again that is only a high output. What's it like at idle? Sub 2000rpm? Everyday driving rpm's?
Save your money for something with proven gains, or bigger brakes
Dave