The fuel mixture will no longer be correct. Higher duration and lift cams are the main modification for increasing power. Most of the same power increasing methods from above can also be applied to turbo engines. Engine Displacement For street use, you want as many cubic inches as you can get. Avoid matching for efficiencies of under 65% at full power and operation near the surge line also. Bigger turbos don't necessarily mean quicker times.
Eventually, the main bearing caps cracked from the power output but this was caught before major damage occurred. These are a bad idea at high boost pressures. Don't expect gains of over 10% with these mods on most engines. The stock hp is rated at 70 at 6000 rpm. Stock turbos are usually sized for mid range torque and are undersized even for stock top end power. Stock intercoolers with a few exceptions are total crap when used for performance applications.
With properly matched components and an efficient intercooler, one rarely needs to exceed 15 psi on the street. Because turbo engines usually have lower compression ratios than atmo engines, they do not take kindly to hot cams on the street. To get these characteristics, most street engines have relatively moderate camshaft timing, small turbos, small diameter intake ports with long runners and usually cast pistons. Valves were enlarged from 41 to 44. Turbos need to be properly matched for the application and primary intended usage. Always go for as many cubes as you can if you have a choice of engines.
Some people really know what they are doing and some don't. This is probably the biggest question related to successful mods and the most often ignored. Engines which are heavily cammed may not begin to produce substantial gains until above 4500 rpm and you are paying for this 95% of the time while being able to enjoy that top end only 5% of the time. You can make the same power with less boost or more power with the same boost. It either can't produce the pressure or volume needed or will burn out quickly due to the massive increase in current draw. Most of these were designed by guesswork rather than by actual turbo experience.Next
Of course, top end power should be better. Since engine life will plummet once you exceed this type of output, it is not a viable option for most people to be rebuilding an engine every 10,000 miles. If the ports and runners are enlarged greatly, low speed torque will suffer considerably. Many high compression street engines must have their timing severely retarded to avoid detonation which reduces the power right back to stock levels. . Let's examine the differences in the 2 different worlds: Street A good street engine should have a smooth idle, have lots of low end torque, a wide powerband, long life and good fuel economy.Next
Nitrous oxide injection is used quite extensively in drag racing for a substantial power gain. The more duration and valve overlap a cam has generally, the worse the low end torque, fuel economy and idle will be. The factory redline is there for a reason. Check out some of the cars on our project page prepared at Racetech if you don't believe this. I'm sorry for not being able to update for so long, but from now on, you can expect frequent updates! The difference in power is minimal going from say 9 to 10. If you need more power, you need a larger engine usually.Next
We see more problems and complaints with people fitting race type cams in street type engines. Expecting your 18 second car to do 13 seconds while retaining good idle and fuel economy when modified is unrealistic most of the time. Read the other tech articles relating to combustion and fuel for a better understanding. The camshaft selected was the same cam we used on our race atmo 2T engines with. These have poor turbo response and a super narrow powerband. The effective powerband was 5000 up.Next
Most settings can be saved to a file so you can easily load them anytime. This is not usually a great mod for street use as everything must be just right as far as fuel and nitrous flow goes and of course the major disadvantage is that the tank runs dry after only a few minutes of use and must be refilled. You don't normally use pliers to turn a screw in. If your stock fuel pressure is 45 psi, you will need 180 psi to double your fuel flow. At some point, the stock injectors and possibly fuel pump will not supply enough fuel. Install a properly matched core from Spearco. Some companies offer rising rate fuel pressure regulators with their turbo kits to allow increased injector flow rate over stock pressure.Next
This mod brings the displacement out to 1702cc and drops the compression ratio from 8. To achieve higher power, ports are opened up for increased flow at high rpm and camshaft timing and lifts are increased, both of which kill off low rpm torque, power, fuel economy and that smooth idle. Valve guides were shortened and bronze bushed for increased flow and heat dissipation. In any case, running 20 psi on the street is relatively meaningless. Don't raise the compression ratio too high! On the externals; A custom, equal length header was made using 1. When adding large amounts of nitrous, engine components may have to be upgraded to withstand the higher pressures involved. Redline was limited to 7700 rpm mainly for valvetrain longevity although hp was still increasing at this point.Next