Hi
The throttle bodies or TB,S are butterflies, commonly called inlet manifold.
When it comes to empower the engine, it is essential to have good TB,S, but, how differentiate good from the not so good.
Starting from the premise that, as more air enters a cylinder greater proportion of gasoline can be injected, always get more power.
The power does not come out of the air, but this is not true entirely, as soon explain.
One inlet manifold of 4 butterflies, give more power that one inlet manifold of 1 butterfly, but sometimes, you get the same power, but less torque and despite what people think, not there is much differentiates of fuel consumption if we get the same power between 1 and 4 butterflies.
In the market there are several types of TB,S, but I focus on two mark, Jenvey and PTP.
Both TB,S of Jenvey as PTP have advantages and disadvantages.
The advantage of PTP is in the diameter of the mouths 45/38mm and disadvantage are weight, price and the system of mixture of air and fuel.
The TB,S of PTP, has the accommodations for the injectors too near to the inlet port and lack of regulatory needles.
This produces a mixture of air/fuel that is not as good.
It would be better for injectors were more away of the inlet port.
The Jenvey have all the advantages that are disadvantage in the PTP and the disadvantage, is the advantage of PTP about Jenvey, as the mouths of admission are 34/42mm.
But this can be solved very easily, simply lead to the TB,S of Jenvey to machinist and open your rear mouth back to 38mm.
But what happens with the front mouth?
For the mouth front we have two solutions, one is open the mouth front to 45mm and the other is to put spacers.
The spacers are no more than a extensions for TB,S that are placed on the front and can make the diameter is rear 42mm and in front of 45mm, bringing our TB,S of Jenvey would now have 38/45mm the same that original PTP, but with an added advantage.
The advantage is that the greater length of TB,S, so that we obtain greater torque.
This gives us a clear picture that there will also be some who seek trumpets to be as long as possible, but there is a limit to the length of the total group formed by the TB,S, spacers and trumpets.
Each tuner has his own formula for the length and often a well-kept secret.
I want to say that these two TB, S are very good, but I prefer the Jenvey by explained above.
The injectors must satisfy two essential missions, obtain the best fuel flow and the flow adequate.
With a good ECU, is possible establish us the flow and should be a job well done and whenever possible in the rolling road.
The flow stems from two factors, needle injectors and pressure fuel regulator.
We regulate the pressure is possible to change from the fuel regulator, but the flow thing will be to choose better the injectors.
A greater number of needle injectors, the flow is better and with better spray, as more homogeneous is the mix, more power and torque.
With a excess pressure in the fuel flow, we lose power, so that it will drown the engine, albeit little and not notes.
For rover K series a good injectors are blue of 4 needles, which first appeared in the MG ZR and the MG TF.
These injectors are not the best, but are easy to find and not too expensive.
The airbox plays an essential work that is getting the most cold air in the inlet manifold.
How air is more cold, get more power for two things, a greater number of molecules O2, and many more fit into the cylinder.
The airbox must have the diameter of the inlet mouth of suited to the specifications of the piston head and TBS, mainly.
If it is too small, not enter the air sufficient to meet the demand of 4 butterflies in full operation and will stop earning power.
A good trick is to use a blanket thermal protection around the airbox, so that isolating of the hot air of engine.
The thermal blanket does not give us more power, but to prevent the lose when the engine this to the optimum working temperature.
Regards