Hi, I have searched but have not found any final argument for my question.

I have a S4 GXL NA with intake cold air filter, TB mod, emissions removed, free exhaust (just two pipes 40cm long) and I am swapping S5 UIM with VDI. It is for autocross racing.

I have already set the 6port opening electronically to 3800rpm and I have read that if I have worked into intake and exhaust 6port opening time can be raised and VDI rpm lowered and I am wondering if the could be opened at the same point without a huge loss in mid range power. I haven´t got any dyno near my city for testing it with everything closed, then 6port then everything opened..

Does anyone have the three graphs? Do you know if 6port and VDI can be opened at the same rpm with great mid range?

Thanks a lot

 

have a look:

https://www.rx7club.com/showthread.p...light=roen+vdi

 

Thanks theory, I had also seen that one, but there are people that says 6port and VDI opening both at 4200 rpm kills power until 5000 rpm..

By the other way I haven´t found the dyno "crossed" graphs

Thanks for the reply

 

I just finished this swap a few days ago. I opened my 6pi at 4250(RTek), and open my vdi at ~4800-5000(Summit RPM switch).

Feels consistent though the rpm range. No boosts in power anywhere but really consistent.

 

Thanks for the info. I am considering to install ports sleeves inserts, and then if they help a little and increase the air consumption due to less pressure drops ("pérdidas de presión", "pertes de charge", sorry I don´t know the correct name in English) for the same rpm then I will be able to open de VDI little earlier.

I am also considering to install a N351 ecu as a rpm switch (cheaper than summit and with to rpm switches already set at 3800 and 5200 rpm), I am wondering if the ecu will close the circuits with just the voltage and the rpm sensor connected...

Searching in these and other forums I have found some interesting dyno tests, they were made by modified cars and as far as I am concerned it lots like the best opening point for the VDI continue being near 5200.. maybe the power lost is not significant