just wondering if you were to run the bnr's at say 17psi for instance..

stock pattern is 10-8-10

if the bnrs are 17psi would the boost pattern then be 17-15-17?

sorry if this sounds dumb but im just curious?

 

Most people are rarely ever able to generate full boost on the first turbo when going with higher boost in sequential mode. This is why the sequential system becomes a hindrance with high boost applications and people opt for non-seq. What I've seen would usually be something like 14-12-17.

IMO, for the stock sequential system keep boost at 15 PSI or below. For 16 PSI and above, non-seq.

 

The stock solenoids probably won't support anything over 15psi with consistency.

Dave

 

do the stock solenoids just give out pretty easy? and what about the rob bailey solenoids? they work better??

i think the bnr's at 17-18 psi would kick total **** in sequential mode if can be made reliable!

 

If you put a pressure regulator on the pressure tank you can protect the turbo control solenoid from high pressure. I haven't tried it but the theory is perfect and many others say it works well.

 

is there a write up on doing such a thing?? im just not familuar with such things? it it pretty much like doing a manual boost controller in line to the solenoids?

 

I've gotten 14-10-14, using completely stock sequential system (as in, restrictor pills and all that jazz, all the solenoids) controlled by the Power FC.

 

I get 14-15 psi on the first turbo no problem and fairly early. My transition is so fast I can't really say how much it dips in psi, but there is a very short moment of less power. I should Datalogit it as the dip isn't long enough to see on my boost gauge. The 2nd turbo comes on smooth and isn't an upsetting power rush some complain about. I think this is due to the PowerFC smoothing out the transition and my larger intercooler adding just a slight lag. My I/C setup is probably 1-1.5 psi less pressure drop so it may explain why my 1st turbo winds up so easily. If I lose traction it will usually be at the top of first or second gear. I do have a problem holding my boost down when it's very cold or using a low boost setting. The PowerFC and turbo system doesn't work the same anymore when heavily modified. I think it's still worth it though over non-sequential but a single turbo setup should be a consideration. I'm using the stock solenoids and wastegate pills and Viton check valves with simplified sequential. The problem with the solenoids is they are not very reliable even at stock boost levels. New ones can even have problems. The Viton check valves are cheap and do seam to be an improvement.

 

Running that much boost with the sequential setup yields a horrible power band. There is a huge drop during the transition and when the 2nd turbo engages it comes on hard. This can send you straight into a wall if you are mid corner on the track.

 

That's not my experience at all at 15 psi but maybe something is wrong with my 7. Of course, no 2 setups are the same when running this much boost. I will say that by changing a few PowerFC settings that transition problems can be smoothed out.

 

mahjik is right on the money again

 

Running @ 17 psi on the pfc, I get 14-10-17 with my BNR's so again Mahjik is spot on. The transition on the dyno is huuuuuge its between 4300 and 5300rpm but in the car you cant feel it. Im picking the car up tmrw after being fully tuned with uprated solenoids, fpr & bosche 044 so will let you know how it drives

 

There is going to be a lot of variance here depending on set up. BNR's are not going to behave anything like the '99 spec turbos because of differences in turbo size. A mostly stock 7 isn't going to have the turbo response or max flow of a highly modded 7. Throw the theories and expectations out and do some real world testing.

 

I know with my set-up with only 13psi, i get a 12-12-13 pattern. This is with Rob Bailey's solenoid kit, ported wastegate, powerfc, and the knightsports EBS III boost controller. I'm in the process changing some things and an overall tune-up so we'll see if i can get a solid 13 the whole way.

For those saying that the sequential gets too harsh once above 15psi, why not get the datalogit and change the transition point to a lower setting to tune out the harsh jump. Maybe 3800-4000. I know that's my next "performance" mod. Properly set up, it should act as a non-sequential in theory without all the lag.

 

I have definately noticed that the secondary turbo feels like it comes on way harder after the transition. But part of that is just because when you get a ported motor it's going to pull harder up top... even with a stable 14-10-14 pattern. The midrange dip in power can be a bit unpleasant, but you get used to it.

but damn, the stock sequentials are so responsive... I really notice a difference between the sequential twins and my single turbo 2nd gen (ported engine with a T04S). At 1/4 throttle it will effortlessly get into boost.

 

so how do i put a restrictor inline to my solenoids so they only see max 13-14psi?? i dont wanna fry my solenoids by running 17-18psi! witht he BNR's

 

It would have to have some type of regulator to bleed off the excess boost. And each line that see's bost pressure would have to be plumbed into the regulator. Seems like it'll make a complicated system even more so of one.

I honestly would look into the Rob Bailey solenoid kit. It'll make the sequential system a care free set-up.

 

https://www.rx7club.com/forum/showth...or#post7209638

 

i got rid of my transition completely while pushing 16psi on the stock twins by using a needle valve in the precontrol line (in place of the solinoid) with a manual boost controller. i'm sure it could be done using the PFC also but in order to control boost you need to adjust the needle valve as well or else you will get a huge spike/lag during the transition.

 

That would only rarely be an issue. Once you are on the track, you are in non-sequential nearly the entire time, if you are driving the car correctly. The default PFC setting will keep the car in non-sequential until you drop back below 3k rpm. This should never happen on track, even with downshifting for corners.

Auto-x can be a different story....I have spun there because of the transition.

 

is rob bailey still making those solenoids tho?

 

It's made to order

 

I get 15-10-16.5 with the pfc controlling boost. I posted a few logged charts here

https://www.rx7club.com/showpost.php...59&postcount=1

I have a KS EBSIII boost controller that I used when I had the M2 ecu but took it out when I installed the pcf, should i use it? it controls boost the same way the pfc does with the stock system, could it make a difference?

 

Lots of good comments in this thread. Very few know how to tune the transition using datalogit (I'm not expert but have played with it a lot) and you can do amazing things with that tuning. Comment to Stix -- with the BNR's I found the primary is soo strong i actually moved the transition up rather than down so that I have full/quick primary response longer and it doesn't bring on secondary until you really need it. BNR primary has no problem going 15+ up to a good 4-5k. Sorry, hard to explain some of this clearly. . .
--Jeff

 

I have Greddy ebc and not familiar with the KS, but I can't imagine any aftermarket boost controller working the same "way" the stock does! Any ebc I have seen actually measures the boost and controls accordingly. . .the stock system does not do this. I tried staying with the stock boost system way to long -- go to ebc if you want reliable control.
--Jeff