My car is a 1991 chevy camaro z28 305 tpi. What would be the best thing to add power, being turbo or supercharger. Where could I find these setups or parts to build one.

 

well, thats a very broad question. ill touch bases with what you do have. 305 tpi. 305s are not the best base for building lots of power, but you can make the 305 work for up to about 7-10 psi for cheap. I know there is lots to consider with those numbers, but keeping the motor stock and just throwing a supercharger or turbo onto the motor. I dont think you could get much more power and be reliable with the stock engine running over 10 psi. But all of this is dependent on what your goals are.

 

I second whitroc's thoughts, and I think the minimal uprades to your motor should be valve springs with a timing chain. The turbo should make for a faster car, and be more adjustable depending on the sizing/goals. The supercharger is easier, and probably cheaper too. I think it's more up to you which of those descriptions fit you better.

 

fast, thats an ineresting point you brought up regarding valve springs. He would want to got with a heavier rated spring correct? I have an interest in this also because I'm building another engine to mate to either a D1SC or F1A this spring.

 

The stock springs are probably worn anyway, and boost doesn't makes things any better. I figure if you do area times psi gives the extra lbs. needed in the springs. The area of the intake valve is roughly 3sq.in., so multiplied by whatever psi gives the extra needed spring pressure. On 10psi of boost, the springs should have about 30lbs more seat pressure and at least that at lift. I don't think I've really heard anyone else talk about this, but it just seems like common sense to me.

 

It all comes down to what you want. do you like the spool up of a turbo? the blow-off valve making its musical release? or do you like the wind up of a roots blower? Or the idle note of a centrafugle (spelling) blower? maybe a little nos Any of these power adders can make enough power for anything you may want to do with your car. its all about your preferance at this point. let us know what you want as far as power goes and you'll have one hot thread of people loading you up with info and opinions.

 

I would prefer to go with a supercharger. I like the torque. Not a fan of turbos. If i get a roots will i have to change the car to a carb?

 

The PSI above the valve is the same as below the valve when the valve goes to close. That is the important part.
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I had no idea. my turbo setup will make 8 PSI at 2500 RPM all the way to redline. Read up on forced induction and then decide.
What are you better at........tuning EFI or carb? Pick the one you understand.

 

double post

 

This info came from CraneCams and will help you in spec'ing the valve springs as junk and fast already mentioned. This makes ALOT of sense once you read it:

Selecting the proper valve spring for any performance engine is important; but it is critical to proper operation of supercharged engines. Consider the fact that when the engine is in a "boosted" condition, the supercharger (or turbocharger) is trying to blow the intake valve open. The boost pressure actually reduces the intake valve spring seat pressure. This is extremely critical on engines with hydraulic lash adjustment. Proper seat pressure (working through the rocker arm and pushrod) is necessary to keep the hydraulic lifter plunger centered in the lifter body to prevent "pump-up." If an engine has 2.25" dia. intake valves, there is 4 sq. inches of backside valve area. Now add 12 (psi) of boost pressure, and you have reduced your effective seat pressure by 48 lbs. (12 lbs/sq.in. X 4 sq. in.). If you started out with 120 lbs. of seat pressure (static), you now have 72 lbs. of operational seat pressure. There is no way that 72 lbs. of pressure is going to control a 2.25" valve!



For street use, the answer is to select a tall, mild-rate spring that assembles at a high seat pressure, yet keeps the open pressure reasonable over the nose of the cam to assure long cam life. (For example; a great spring on a Big Block Chevrolet with a hydraulic roller and a supercharger is our #96879 spring, which will provide 169 lbs. at 1.880" seat and 432 lbs. at 1.280" open with a .600" net lift cam.) Exhaust valve seat pressure does not need to be raised significantly on supercharged engines. Racing applications with solid lash adjustment do not experience lifter "pump-up,â€� but still need the high seat pressure to prevent the valve from bouncing on return to the seat against the boost pressure. Consult our easy to use valve spring pressure chart at the back of our Valve Spring and Retainer catalog.Â

 

CraneCams is correct but they neglect the other stuff going on.

1) start of intake stroke: with a turbo there is a 1.5x or greater EBP to intake boost so the valve is trying to be held more closed than boost trying to open it. Note: with a SC this doesn't apply and therefore stronger intake spring would be necessary.
2) during intake stroke and at end of intake stroke both intake boost and cyl boost are equal.
3) during compression stroke the intake valve is pushed closed more than intake pressure
4) during power stroke the intake valve is pushed closed more than intake pressure
5) during exhaust stroke with turbo there is more exhaust pressure than intake holding the intake valve closed. Note: with a SC this doesn't apply and therefore stronger intake spring would be necessary.

Could be wrong......could by right........that is how I see it.

 

It would be better just to build the 305 into something better and more reliable.

 

Thats all true but what you have to think about is it's all happening at the same time in a V8. Since the lobes on the crank are 90 degrees apart, there are always 2 cylinders involved in one of those phases. Plus when you think about the fact that the motor will see 5500-6000 rpm minimum thats how you get the issue of valve float. I don't understand it fully myself but I know it occurs under highboost or rpm conditions cause the valves actually bounce off the seat in some cases. Also the solution isn't always a heavy spring but sometimes reducing the weight of the valve and spring combo by using titanium retainers and such can yield a better albeit more expensive solution. The best solution is a blower specific cam and spring set with the appropriate seat pressure for the desired boost level. The best way to figure that all out is find a local speed shop or somebody with lost of experience you can sit down and talk to and figure out exactly what you need.