boost control using nistune experiences anyone ?

PL · Post by PL » Sun Mar 22, 2009 9:42 pm

Yeah, I reckon it's way late for a 2871 with 0.64 housing. I suspect wheelspin may have been skewing the results though. It actually felt really good on the road.

Looks like I'll be getting another go at it anyway. This time I'll disconnect the hose to the WG completely and do a partial run. Then I'll know what it's actually capable of.

I still believe that the ball'n'spring type valves offer the best response you'll get.

PL

chris2712au · Post by **chris2712au** » Sun Mar 22, 2009 10:04 pm

yeah I hear you...

what I have done is just tuned the boost control for 2nd gear on the flat.. If I hit it on a hill I get a spike that pushes the TP limit and fuel cut... On the flat I can launch it as as long as I dont get too much wheel spin it holds on ok..

Still I feel that the load is an issue.. It would be nicer if we can go more aggressive at low loads and less aggressive at high loads.. I am doing some boost leak tests just to be sure that I dont have any underlying issues.. They say that the standard BOV on the s15 is only good for 15PSI ? is graeme still using his standard one ? I will also test that as well on my car..

I am going to move to the hot side and make the hose runs really short.. then I am getting my hands on A ID3 blitz where I will do some baseline runs and compare to nistune when I get the time..

PL · Post by PL » Sun Mar 22, 2009 10:48 pm

Yeah, that's the thing with boost control. The response is quite load dependant. As well as a host of other things - mainly ramp rate. I always use the same ramp rate on the dyno - so one car is compared fairly to the next. But comparing this to cars being tested on the road won't give the same ramp rate.

This is why it's so hard to design a good EBC - and why the really good EBC's can be wonderful things. I guess ideally you'd have different response rates for different gears. Which some of them have.

Boost control - it's hard to get it right!

PL

chris2712au · Post by **chris2712au** » Tue Mar 24, 2009 8:16 pm

hey pete,

any chance of getting some pics of the scope traces you did ?

What was the base frequency ? could you get me some pics ?

Chris

PL · Post by PL » Tue Mar 24, 2009 8:43 pm

I didn't take any photos - it wasn't anything special. 0 to 12V pulses. The frequency was quite low. Most solenoids won't handle high frequencies cos they just can't move fast enough.

I'll take some shots when I investigate S14 boost control.

PL

chris2712au · Post by **chris2712au** » Wed Mar 25, 2009 5:15 pm

was thinking of making a pic... or stamp based boost controller that uses the duty cycle of the solenoid output from the ecu.. as the set point and the load reference from my delphi 3 bar MAP then using a PID control loop to see how well it controls boost..

thats if I can find all my gear from the time I was studying..

chris

Matt · Post by **Matt** » Thu Mar 26, 2009 10:40 am

dont worry i'm going to get some scope traces when i get around to it for my mapping guide... wont happen overnight but will happen

its just a matter of time (as usual). I'm rehashing all the address files at the moment and going to finish up documentation on Type1/2 maps

Once I've done that going to start working through the 16 bit ECUs and tidying those up

chris2712au · Post by **chris2712au** » Thu Mar 26, 2009 8:23 pm

In saying that I was more than happy with the rom controlled boost. The only thing I didnt like about it was how strongly it relied on load you tweak the tune for a lighter load and it goes alot better however if you hit it on a hill and boost comes on a bit sooner it will spike, then you tune it out and then you suffer on the flat.. Well I believe so. It really needs a correction from the manifold pressure... however getting the boost signal from the hotpipe with the block method worked the best... if you are going to have a try when i say hotpipe I mean right at the exit of the compressor cover..

chris

chris2712au · Post by **chris2712au** » Sat Mar 28, 2009 8:01 pm

finally got the chance to pressure test my system...

found 2 leaky clamps @ 7psi and up , my bov is stuffed it leaks from the get go.. and the PCV still needs replacing..

with this in mind I sought of can see my top end figures on the boost maps may be a little harsh for a non leaky setup.. they were not big leaks but when you play with the maximum I need all the air I can get..

And for another thing why is nissan making the boost solenoid inactive before 2000rpm.. can we change it ?

chris

chris2712au · Post by **chris2712au** » Mon Mar 30, 2009 4:53 pm

new bov and a PCV on the way...plus going to get rid of all those tbolt clamps as they have given me nothing but dramas..

chris2712au · Post by **chris2712au** » Wed Apr 08, 2009 7:29 pm

well i am still in the process of fitting the new BOV.. I had to make the recirculation flanges.. they are fabricated now... I am waiting for someone else to try. ?? no replies as yet... my main thought is how does the standard boost control go running an external wastegate ??? I am expecting big things with using an external w/g but its not likely I will put one on my car unfortunatly..

I am running a blitz at the moment and well I can get the tune quite well with my nistune however the blitz is just so much more versatile and then again it should be for the cost...

your control with the blitz can be so much tighter with an external w/g.. so that in mind if you can get a faster response from the wg.. it should be even better with nistune also..

PL · Post by PL » Thu Apr 09, 2009 3:11 pm

Hey Chris,

Yeah, the Blitz EBC's are certainly the pick of the bunch. But I wasn't aware that you could change your boost level with RPM like you can by mapping the factory solenoid?

I'm not understanding why an external WG would be better? Surely if an internal WG is flowing enough (which yours is - otherwise you couldn't control your boost) then going external would be pointless?

PL

chris2712au · Post by **chris2712au** » Thu Apr 09, 2009 9:51 pm

it is hard to explain but the external's just give much better boost control... the blitz cant be programmed by rpm.. however I can map the result using my map on the DLP and do some comparisons..

Internal wastegates just have more delay (slower to react).. on the blitz you can run pretty high gains (sensitivity) with an external like 70 - 80 however on the internal I am limited to 40 max at 50 it tends to spike with the internal a little but thats ok for me..

somebody do a nistune on an external I am keen to see the results.. go hot pipe and use block method.. The stock solenoid is a little undersized and the spring a little too weak when it was drilled out...

Pete is there an aftermarket one that you have used before ? that wont blow up the transistors on the boost control circuit ?

PL · Post by PL » Thu Apr 09, 2009 10:08 pm

I always use "MAC" valves (as used by many of the aftermarket ECU guys).

Not sure if the factory driver would work on them. Just gotta measure the resistance I guess...

PL

chris2712au · Post by **chris2712au** » Fri Apr 10, 2009 7:17 pm

any chance of a bench test ?