olddragger

iTrader: (3)

I thought this section of the forum need a true TECH post and most of yall know how crazy I am--so here goes.
This pertains for boosted engines only.
For those that do not know--i have been running the Pettit S.C. since 2007. I have learned a lot through experience and others help.
One thing I have discovered pertaining to the title of this thread is that I no longer require the VDI or the SSV in the LIM. Why is that?

Well I am not to sure about the turbo's--I just dont have enough experience with them and maybe someone else can join in to discuss those--but for the supercharger folks--the SC makes air much more easily available than when the engine is NA. The SC is a volume pump and it is working the intake air all the time, and when not "in boost" the bypass valve assists in that air movement. So with a SC the intake air velocity is better than NA--even while not in boost--and effectively the system has shortened the overall length of the intake runners. My car runs better with the SSV locked open and no VDI.
Eliminating those valves helps to simplifies the lim. Is that important? Yes--I lost a good engine once when a vacuum line popped off that supplies the SSV--the valve closed and i had a boost spike that leaned the a/f and I blew a seal. I was on the back straight at Road Atlanta when this happened. No warning--it took about 0.5 secs!
So I only have the apv to bother with--right? Thats good!

But still I have all that injector staging to deal with. So my thought is:
Is it possible to run the engine using the primaries and P2's working at the same time? Then open the apv and secondaries earlier?
I think it is possible--but would require some work to get it done. The real question I suppose is would this reduce the complexity of tuning and add to reliability?
The S2 model went to four injectors remember........
All thoughts and experience welcome--and please feel free to blow holes into this thought.

j9fd3s

can you clarify a bit? do you mean to run all 6 injectors all the time? or run on the primaries, and then have the other 4 come on at once, instead of stage?

as far as the APV/VDI stuff, you're kind of right, the turbo rotaries never used them, its not that they don't work, i think the turbo/supercharger just works better

olddragger

iTrader: (3)

Ok--my thought is to have the primary and p2 running the engine most of the time with the ssv locked open. Then at higher loads/rpms the secondaries engage.
Now I do realize that the injector sizes and tuning would have to be redesigned --but maybe not that much? The p2's come on board when the ssv is activated--basically speaking of course. They are activated per oem at around 3.4K rpm and a certain load--correct? This means that those injectors are coming on and switching off pretty frequently.
I would also like to see the secondaries engage at an earlier rpm.

HiFlite999

iTrader: (2)

Running air-only through any of the forced-open ports seems like a singularly bad idea. At some level, the "sensible" solution is to use throttle body injection and ditch the port injection altogether.

Brettus

iTrader: (2)

Thinking about why your engine blew . I believe what happened is that when the SSV closed the position switch also cut off the fuel to the secondaries . Your boost went up because the air flow was suddenly more restricted yet flow remained the same. It wasn't the boost spike that killed it so much as the sudden lack of secondary injectors while flowing the same volume of air .
So I do have to agree that in a SC application locking open the SSV seems sensible.
In a turbo application I don't believe the same thing would happen because as soon as flow became restricted - the turbo would produce less air .

I don't really understand why you think this is a problem that needs solving . My experience is that the injector staging can work perfectly well in an FI'd engine . where I see issues is when people veer too far from the stock step up ratios .

IE going 280 /900/900

I do believe that it's a good idea to fit yellows into P1 though because the reds run out of flow before the next stage with a fast spooling turbo .

So my advice for perfect injector setup is to go with yellow/blue/blue 380/480/480

or if you can get them green/brown/brown . 380/500/500


Not a fan of buying large after market injectors , for the above reason ,plus the fact that very few people know how to set up the latency tables and scale them correctly.


Also : I don't think the ports without injectors are a biggie . The secondary port being open all the time is not flowing much air up until the injectors come on stream . And the aux port already does that anyway . It doesn't flow more than perhaps 25% of the total airflow when it comes on stream.

olddragger

iTrader: (3)

I agree Bret--i think that is what happened also.

From a tuners perspective what would it take to run the engine without the ssv, with the apv/secondaries and to bring the primary/p2's on at 2K rpm? And I mean run it well. Not just have it running.

Brettus

iTrader: (2)

It would be really simple to do if I knew which maps control those things in Mazdaedit . But I don't .

olddragger

iTrader: (3)

why dont you move to the states man--dang!
Guess I will talk to my tuner about this--Steve Kan.