rb20det and front mounts

[GTeatR]

to the guys with rb20dets and front mounts, do you notice a lot of lag with aftermarket front mounts? there is quite a bit of piping from the cooler outlet to the manifold and was wondering what the throttle response is like?

[Roy]

No differnce, if anything felt punchier

[Sydneykid]

Hi guys, here is one I prepared earlier using an example of 4 intercooler setups and pipework we have actually used;

1. R33 GTST Standard Intercooler and standard R32 GTST pipework

150 rwkw = 27 lbs of air per min @ 13 litres of i/c & pipework

2. Supra Intercooler and matching 63mm pipework

180 rwkw = 30 lbs of air per min @ 15 litres of i/c & pipework

3. Standard GTR GTR and 63/75mm pipework

250 rwkw = 40 lbs of air per min @ 21 litres of i/c & pipework

4. Greddy 600 X 300 X 115 and 80 mm pipework

400 rwkw = 60 lbs of air per min @ 28 litres of i/c & pipework

If you look at the numbers you can see that the rate of air flow and the volume of I/C and pipework have a fixed relationship (27 = 13 , 30 = 15 , 40 = 21 , 60 = 28). This is not an accident, I designed it that way. The reason is I wanted to keep the throttle response as close what it was when the car had 150 rwkw, because I though that was very nice response.

The theory I followed was, the more power the engine produces the more air it needs. Thus if I keep the increase in the volume of air inside the inlet system in the same proportion as the power increase, then the throttle response should stay the same. This is based on the engine using the air in the same time frame.

So when people say they fitted a FMIC and have not noticed any less throttle response, my response would be, that is what I would expect. As long as they went from 150 rwkw to 180 rwkw. On the other hand, if there was no power increase then it would be simply physically impossible for there to be no decrease in throttle response.

The problem of poor throttle response arrises when you have a 220 rwkw engine with a 28 litre inlet system. This is something I see way to often.

Hope that makes some sense:cheers:

[GTeatR]

so if i'm making around 200 odd kwatw, would a gtr i/c be ok? or will i lose throttle response?

[Sydneykid]

so if i'm making around 200 odd kwatw, would a gtr i/c be ok? or will i lose throttle response?

Stick to 63 mm pipework for the feed from the turbo to the intercooler and 75mm from the intercooler to the throttle body. Then apply the 120 degree bend at the throttle body design of pipework. You will end up around 19 litres which will give the appropriate airflow versus inlet volume ratio for 200 rwkw:cheers: