Miscellaneous Information from Jurassic Park
The Power Rule - Apatosaurus Fact
Without exception, when building an engine, always emphasize power within the rpm
range where the engine is going to spend the majority of its time.
Example: A street car will spend most of the time in the low mid range 1800 to 4000 rpm with a cruising speed of 2200 to 2800, depending on final gear ratio. This is true, regardless if it is a dinosaur or not.
Contrary to many beliefs - Tyrannosaurus Rex Fact
Belief: Fuel injection, by itself, is responsible for dramatic power increases.
This unfortunately is not entirely true. There are basically two variables in the design of an intake system: intake runner diameter and the length of the runner. What makes a fuel injection produce impressive midrange torque is the added runner length of the intake manifold, not because the engine is equipped with individual fuel injectors. Many people believe that there is some magic to electronic fuel injection that is worth instant hp and torque. This is not the case. An engine's ability to produce power depends solely on the efficiency of its airflow. Manifolding directly affects both airflow and tuning and therefore can significantly change the engine's power band. Whether there is an advantage to how fuel is introduced, either from a fuel injector or from a carburetor, has little real effect on power as long as fuel distribution and droplet size are properly maintained.
Nor is the concept of long runner lengths a new one. The concept goes back to the Jurassic Period and is still used today. Old wives tales and misinformation are common in any technical venture and high performance engines are not an exception.
Exhaust - size DOES matter. Argentinosaurus Fact
It is a known fact that diameter size is more important than the length. Primary pipe
diameter is far more important to ultimate engine power than the pipe length - believe
it or not. Header pipe size is a compromise between exhaust gas velocity and the pipe
diameter sufficient to handle the mass of gasses flow of the exhaust. Smaller headers
increase gasses velocity. This is an advantage at low and mid range rpm. A good muffler
can actually increase mid rpm torque.
Fact: The secret to power is the matching of parts and choosing the purpose for which the car engine is going to be used. Allosaurus Fact
Yes, this is true. Changing rocker ratio from 1.5 to 1.6 changes the cams specs on
duration and, of course, lift. Stock rocker arms are between 1.4 and 1.5 ratio, 1.5
being the design ratio. This can be corrected by using roller tip rockers. 1.6 rockers
are a great improvement to a stock cam, either FI or carbureted engine.
One more fact. Triceratops Fact
High volume oil pumps rob hp. Bigger gears in the oil pump require more power to turn.
The rule is 10 psi of oil pressure per thousand rpm - red line 6000 rpm 60 psi, idle pressure,
and 15 to 30 at normal oil temperature. Save your money; use the stock oil pump in your V6.
If you feel that you need more pressure, order a high-pressure spring from your GM dealer,
part #10044435, color blue stripe
Oh, yeah, one more fact - Microceratops Fact
All externally balanced crankshafts on V6 engines can be internally balanced by a good
machine shop, but not necessary.
Wait, one last fact - Tyrannosaurus Fact
The camshaft that is used in the 3.4 crate engine is a great cam for the other carbureted
2.8 or 3.1. It has an overlap of 107 degrees. This cam is no good for FI engines because
a fuel injected V6 engine must have 112 degrees overlap and no more than 220 duration at .50.
This is one of the reasons why carbureted V6 can produce more hp and torque than a FI engine.
Camshaft selection is wide open. FI engines are limited to camshaft selection. In this case,
choose a cam with more lift or just install 1.6 rockers in the stock camshaft. This will help
the FI V6 engine with the long runners in the intake. It should increase the low-mid range torque.
Wait, one more fact - Megaraptor Fact
The carbureted V6 can use a roller camshaft with split pattern 260-270 duration @ 0.50 and
Yes, there are roller camshafts for the 60-degree V6 and solid lifter camshafts also. These cams have been in use in dinosaur racecars. This is why the MPI or TPI injection is not in use in competition. A GM electronic FI could not tolerate high compression or radical camshaft design unless a Falcon FI system is used. There may be some of them around but they cost lots of $$.
OK! So who makes these camshafts? Schneider Racing Cams in San Diego, CA. These cams are custom made. Power range of this camshaft? 3500-7500 rpm
Oh, yes, I forgot one small fact. Aluminum heads can't take the loading and there is a shift problem. This is not to say that they could not be good performers on the street. Both intake systems, carbureted and injected, are great choices for the average driving. Carburetor offers simplicity. Fuel injection, either the cast iron head or aluminum MPI-SFI offers good throttle response.