It seems to be the be-all and end-all of the engine and modifying it can, we are told, yield huge gains. 8v are supposed to get better gains but is it worth the apparently vast cost of doing a 16v head?
Depends really. If you want a project then you can make gains by tidying up the head. Like matching the head to the manifold, smoothing off any casting clag, radiusing the join between castings and machined faces. Then there's triple angle or radius valve seats.
You'll no doubt make it run sweeter and add a few percent.
For more then you'd need years of flowbench and dyno testing ro really make it.
But 16v heads are expensive compared with 8v ones, so in the grand scheme it's touchy as to whether it's worth it.
I can only speak for modifying the head when running tb's - definitely made a big difference to airflow above 4-5k rpm.
as a DIY job it's excellent value for money - but I don't know whether spending 400 quid+ and keeping the standard induction gives you good bhp per pound - it'll get you extra power for sure - but it's one of those things that on it's own won't make a tremendous difference imho - once you start adding things though it may pay off - the whole being greater than the sums of the parts an all that...
do you use a flow bench when modding? If not how do you get all the ports matched?
I've been considering making a very basic flow bench, the idea not being to determine absolute flows, but just getting the flows all the same.
I dunno, some double sided sticky tape, blue tack and an old vacume cleaner. Anyone got one they prepared earlier?
bascially a little device which you hold against the intakes, which reads off the airflow against a scale - done @ idle or low rpm, as well as balancing the throttles, it technically should compensate for small variations in intake effiency too - only thing is you can't do high rpm where weird intake effects take place, so won't be able to pick up things a flow bench could.
hell I'm so cool anyway that my headwork was perfectly matched on all four
you'd only have to dismantle it all if you attacked the head like a numpty with crowbar - I did a lot of head work and there was no imbalance @ idle (well at least the throttles all looked to be open the same amount after balancing )
Gary, damn youre good, fancy giving me a lobotomy with your Dremmel?
Yep, thats the problem with Syncomometers, you cant use them on high load, and really its at high airflows that any differences are going to show up. In the most basic form I can think of the equivalent is that drag is a square of speed; so if you double your speed you quadruple your drag. Hence if you're measuring a 0.5% error in cylider to cylinder variation on your syncro at no load conditions at normal operating (see: denting the floor with the pedal) the error is......errrrr....bigger.
**** I should stop going for those Friday Lunches, specially on Tuesday and Wednesday.
I could lobotomize with the dangerous tool of your choice.. nearly done it a few times to myself..
did you know #2719 :
the original lobotomization was actually a railway worker in the US a century ago - a charge went off and sent a rail spike through his head at an angle - he lived on for quite a few years (albeit with some personality changes). For years afterwards surgeons copied the wound on mental patients before they discovered the 'proper' way to do it - the guys skull (plus the actual spike which got him) is in a museum somewhere..