a quick catch up before this thread gets burst wide open again!
paulo, pm sent, speak soon
rodger, johnboy, al, kev, i'll be ringing you all over the next day or so to have a chit chat,
if i'm omitted to contact anyone ragards this work, my apologies, i've not been very forum active recently, sadly none alfa issues have been keeping me away!
right, as i said, the thread may burst open again soon, i should say the design debate really, not the thread itself, as i've recently been contracted to build an equal length stock layout for a very nice spec 33 race car.
the car is already running this style of manifold, and whilst most of the design should be good, (designed and built by a Cossie F1 engineer) i believe some lengths need changing quite a bit to suit the particular motor and user, and those planned new lengths sit very nicely with what i've learnt other very succesful boxer tuners are using to some extent.
one thing that seems to be recurring, is that the massive majority of the flat four race fraternity, do not use a crossover manifold.
i personally suspect that this is for a number of reasons, which is not an extensive list of negatives for the snake pit shape, i do have faith in the crossover design if applied correctly, but all the factors should be considered when chosing shouldn't they.
Choice - or rather the lack of
back in the day, Ansa were amongst the very small number of exhaust manufacturers who went anywhere near the boxer engined stuff, and certainly their design, although flawed by todays standards, certainly has the potential to work considerably better than stock pipes. But as less and less people continued to keep producing manifold for a shrinking market, Ansa were virtually the only choice left.
Seduction - the fondness of memories,
and the likely success of the Ansa brand, continues to seduce us into belief in their product, which as we've found, is good, but not perfect, and not impossible to improve on.
Pricing - for once Ansa seemed cheap!
knowing now just how much some people have had to pay to get an improved manifold of any design, layout, or even effectiveness, its no wonder folk kept buying and searching for an Ansa again, and subsequently the CSC version
Performance - ahh, the big one!
yep, the crossover works, no doubt about it, and i wouldn't recommend against one. the different scavenge and flow characteristics are notable over stock systems. but the stock shape idea shouldn't be written off just yet.
Ground Clearance - hmmm!
the achiles heel of the crossover design. theres no avoiding it, it is a scarifice if you want the crossover layout, as Al will testify, on lowered cars, its a struggle, so that is likely to be another reason why in mopre recent times, i've learnt that so many of those campaigning a flat four motored race car just haven't entertained the notion of even trying a crossover layout.
What Now? - (Ot Oh!)
well, like i said, the debate is still open, the jury is still out.
the only way to prove the out and out king of pipes in terms of sheer performance gains, is of course to back to back dyno the same car, same day, two different manifolds, BUT, i still believe that both exhaust layouts can improve on stock, so i don't believe that that should be the main or single consideration when chosing.
i believe that the two different designs both work, but depending on the motor itself and the state of tune, it appears that some of the guys who have gone the furthest with the flat four engine tuning, have found that an equal length stock layout has supported those mods very well indeed, and for that reason alone it deserves this thread time and some R and D.
one thing is certain, with the race cars i'm going to build manifolds for shortly, and the lesson learnt along the way, we could be a lot closer to answering the debate and choice quandry for a lot of people, soon...