The SC14 Supercharger Thread

[Pub247]

what sort of cross sectional area would a bypass valve need to be in order to have the desired effect?

Would it be possible to use an electric solenoid sort of valve setup running off a microswitch on the TB so that when its at idle it opens and equalises pressure across the blower? (just a thought cause thats the only time I need any sort of change to how it runs)

Wow totally missed this post. 30mm would be suffiecent. Yes the solenoid setup by your theory would work.

The point i'm trying to make about bypass is they have a lot more to offer than making your idle properly...

 

[needwork2-4fillhabbit]

I had come across the symptoms of the charger sucking against the tb butterfly before, but it seems to happen more on ata cooler setups. Darons seemed to be a good example cos i didnt need to go back many pages to find a pic. But his setup is the same as a few of are doing but with ata coolers.

 

[Pub247]

ok problem was probably accenuated by having a larger area/volume to fill on the outlet side of the charger. It seems strange to me that daron doesn't suffer many problems. THe only thing i can put it down to without seeing it in person is him running a MAF sensor which measures air flow compared to the map sensor which measure pressure

 

[bundysmurf]

I would say the problem is most defenitely related to the volume of air between the charger/TB and the engine as mine runs fine if i run as per a standard CRS setup with no cooler and associated pipework with the TB pre charger. It also runs fine with the cooler connected and the charger not driving (just being sucked thru). So i would say it is a combination of the two, mine runs a MAF also.

Im not at all phased by any other advantages i may forgoe with a bypass valve, i find that boost pressure comes on very smoothly with my current config, in fact it doesnt show boost at all unless i load it up a bit. As i said it runs perfectly except at idle (just a shame thats such a big exception) and if this works i will one happy camper:bow:

 

[Pub247]

Yeah bundy it might be worth trying your idea as you should be able to knock it up cheaply and the theory sounds sound enough.

 

[imnothereanymore]

its weird ive had the charger 6 yrs now on same car and done 250k's
the car has always had prem petrol from day one i really think that helps
it just keeps on going

 

[bundysmurf]

Hmmmm I hearby retract one of my earlier statements, it doesnt run perfectly with the charger not driving and the intercooler connected. It is a lot smoother but still want to stall and carry on when using the engine to brake and then coming to a halt.

What I believe happens is that the TB closes, the air is sucked out of the IC and pipework, the maf is still seeing air moving past it at this point (MAF just near plennum - not out front of TB), it keeps closing off the IAC until it goes too far but by this point it has near vaccum conditions in the huge volume of the IC and pipework so as it opens up again its not quick enough to get the volume of air it needs and so starves of air and stalls. When it does this you can here it still sucking air thru the TB to fill the IC etc back to atmospheric pressure.

So yes i think a bypass valve would help a little but its not the main issue i seem to be having unfortunately.

The way i have got around this to a certain extent is to open the TB a touch so the IAC cant completely close off the air intake and cause this huge vaccum condition - the down side a very high idle.

Old mate that tuned it was adament that a MAP tune would solve all idle drama and free up some more ponies.....I may just find out

 

[Pub247]

Bundy your setup goes tb-> sc-> inetrcooler-> maf-> plenum correct? It is a bad state but your maf is probably in the best position it can be atm. Maf have there good points and their bad. They a basically a low speed drivability meter and have little influence at full throttle or rpm above peak torque (stock) all it does is control fuel in light loads so the car can drive smoothly. Map tune would be the best way to go. If your going to stick with maf i suggest putting TB back in original location and maf in front of it (about 100mm) and run a bypass that will get it working the best

 

[bundysmurf]

Yeah i'd come to the same conclusion......got a bit excited last night when i thought we might be on to something, but no I failed again.

What about guys running say a buik engine (MAP) with TB pre charger and intercooled, are they running ok?

Whats the easiest way to go a MAP tune - is it still by running a VR computer or is there actually a way to make an ecotec computer accept a MAP input?(read somewhere thats how they were doin it these days)

And PUB you were right about the layout of my config, i refuse to put the TB after the charger cause it souns like utter poo!!! MAF is where it is based on advice from IBLOWN and seemed like pretty sound logic at the time (not entirely sure if its good bad or otherwise)

 

[needwork2-4fillhabbit]

http://forums.justcommodores.com.au...0d1212919099-sc14-supercharger-thread-ch1.jpg

Is darons maf at the throttlebody??