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Originally Posted by dragger Thanks for the prompt reply v-16,and thank you once again for exlpaining fellow member's the problem's with availability of close ratio gear box's and the cost factor,besides all this the entire close ratio gear box has to be designed keeping in mind your current engine setup which is a very tedeaous task and a lot of r&d required there,v-16 the idea to phase the piston's is pretty interesting,but what about the NA high-lift cam,turbo's dont work well with that,i believe turbo cams have an exactly opposite grind as compared to the NA cams,would always like to learn more,cheers,happy revvin..! |
Whilst modifying one has to firstly see, the usage of that modification. Cars to be used as daily drives are to be modified in a different way than cars with a track use in mind. The basic problem is that a lot of new enthusiasts are advised by a lot of people who are quite ignorant with little or no knowledge or bookish knowledge about what to do.
Is the car going to be used as a Daily drive or as a Track/Race car?
You cant race in a car prepared for street and vice versa. A Daily drive should have a wide power band (good low and mid end mostly), strong reliable build that lasts, smooth idle and should above all offer good return in kms to a litre of fuel.
The cams used in these cars IMHO should not exceed the profile of 285. Any higher it will idle wildly and have pathetic bottom end power with the resultant power band becoming so narrow that the car becomes a burden and a pain to drive as a daily drive in normal traffic conditions, what a daily drive will be doing most of the time. The problem starts when ill guided people fit cams of 300 profiles on their daily drives and then complain that the car has no bottom end power. Also such a car is extremely irritating to tune, assuming its fuel injected. Rev above 4500rmp and watch that very car change its characteristics and drastically too. But how many daily drives spend more than a few minutes of their every day lives above revs of 4500??
Smaller turbos may be used provided they are run with stock internals.
On a race engine one has to get optimum power, so ports are opened up for increased flow at high rpm and camshaft timing and lifts are increased. This set up results in
dull delivery of power in low rpms, (this is where a close ratio gear box comes into usage and are fitted to minimize the rpm drop when shifting from one gear to another. Close Ratio boxes are generally fitted only on race prepared engines (I said generally) and are again a pain to drive in normal trafic as it requires constant shifting), wilder unstable idling (if one can call it idling at all) and of course increased fuel bills. Engine parts are changed with stronger engine internals and if running turbo, then the turbos are of a big to huge variety.
Coming to Turbos:
Many of the above problems are repeated in turbo installations too. Going in for larger than required turbos will result in low end power loss unless matched with the engine and the proper intercooler not to mention poor reliability of the engine when using an improper setup.
I dont exactly agree with your turbo cam theory. (What is a Turbo Cam?)
Turbo engines, as already discussed, usually, have lower compression ratios Top end gains will be offset by loss in the lower powerband and also considerable turbo lag. For a Turbo engine, stock cams are recommended for daily drives if your engine is a four valve type. Don't waste your money on the Turbo Cams (again what are they?). There are far to many factors in deciding what cam to go for a turbo charged engine (again this is mainly for race engines so we should not be discussing here, only for general information) some of which are Boost level, Backpressure, RPM range, Intended Horsepower, A/R of turbo, head flow, cubic inches, location of turbo, heat shielding the turbo and plumbing, Matching Intercooler,...etc. All of these factors are extremely important in determining the cam that best suits your needs. There is no rule of thumb with a turbo cam.
PHEW!!
Hope it has been informative. Gurus; Psycho, Viper, Karan if hes on the forum and other gurus if ive not mentioned them (sorry) please feel free to correct if i'm wrong.