SAABsPORTUGAL
Oficina => Motor / Escape / Admissão => Tópico iniciado por: contribuinte em 22 de Março de 2013, 21:19
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Boas pessoal,
Eu encontri isto na net, já alguem exprimentou algo assim?
Possivelmente só o Carlos Tavares é que teria corrones...
B234i Camshafts
After looking at some cam specs posted by Nick Taliafferro recently, and noting his 15 or so hp improvement switching to the B234R cams, I noticed that the B234i cams (from the naturally aspirated 2.3L) are particularly aggressive.
I also happen to have a piece of software called "Desktop Dyno" ... which allows me to put in exactly the cam specs that Nick listed and get fairly accurate results. Unfortunately the program does not account for turbocharged engines.
Generally to simulate a 4 cyllinder turbo Saab engine on that program I just use the stock Bore and Stroke from Saab, then multiply the number of cyllinders by the pressure ratio between intake and ambient. For the Viggen this makes it equivalent to 8 cyllinders. The Viggen also suffers from a boost taper towards redline, however this is partially accounted for because when you make it an 8 cyllinder engine, you double the frictional losses. As it turns out those two things seem to cancel out nicely. Just guesstimating at the setup, and putting in the stock cam specs got me to within 5 hp of my actual dyno results, and within 10 lb ft of torque. All suprisinging, at exactly the right rpm.
Next, because changing cams can affect turbo cars differently than Naturally aspirated V8's, I tried putting in the cams that Nick put into his Viggen and looking at the results. They were also nearly spot on, lending about a 15 horsepower increase in the higher revs, with a very slight decrease down low. Excellent ...
Then I put in the naturally aspirated cam specs and gained about another 17 horses. Doesn't seem like a lot ... but that's over 30 additional horsepower from stock! The affect was similar on the T7 2.0 (B205R) which also netted about 30 extra ponies up top. However the older 2.3 and 2.0 are likely only to see about 10-15 horsepower.
Before everyone runs out to buy cams though, there are some things to comsider.
Firstly ... if you have a T5 car, the adaptability of the speed density fueling system to account for the increase in volumetric efficiency is limited. But if it makes you feel better, T5 cars already have cams that are pretty aggresive, so it won't be a huge difference.
Secondly ... T7 cars should be able to adapt, the MAF sensor should register the changes and the partial speed density system will adapt to the new cams. However you will be pushing the stock injectors, and it would be wise to buy an uprated Fuel Pressure Regulator. The T7 computer will adapt to this as well, so you won't run overly rich, but you will have some extra margin to make sure you don't run lean either.
Thirdly ... it's hard to say how this would affect gas mileage. Since the VE is lower at cruising RPM it should in theory go up. A lower VE simulates a smaller engine. But things like valve overlap also affect gas mileage. The Naturally Aspirated cams have less than the T7 2.3 cams, but more than the T5 cams. One could assume the mileage would be somewhere between those two.
Now it's just a matter of testing this out. And of course, finding a place that sells B234i camshafts. Oh and btw, as far as performance upgrades go in relation to your warranty, this one would be nearly impossible for the dealer, or anyone else, to spot. A very stealthy mod. Sleeper town ...
Agora toca a desmonar... :|@
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Sim. Já tinha lido sobre isso e sobre as molas de válvulas dos Volvos....
Mas penso que existam cams com melhores aberturas, como as da maptun...
Contudo as opiniões são unânimes, a diferença nos b234 não são grandes.
Abraço
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Até te posso adiantar mais :P
O b234i têm exactamente os mesmos tempos de abertura que as cams dos restantes 9000... excepto no b202 turbo com catalisador que difere o tempo de admissão:
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Para visualizar hiperligações por favor faça LogIn)
Portanto... para 9000... não adianta, só para t7´s :D
Abraço
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Sim, pela explicação descrita é isso mesmo. Todos nós sabemos que os componentes dos 9000 são melhores que os Pseudo GMs :P
Abraço