Nizpro Style Boost Control

[T04GTR]

hi all.

i know what your all thinking but.. im in the proces of helping to build up a s14 race (nizpro s14) car that uses a bleed off style boost control:o using stock gtr bov's

im tempted on trying this method.

thing is i cant find any info on it:s like how to configure it up etc etc autospeed has an artical on it but i couldnt be assed to pay for the subscription to read on..:

ps.. its running map sensor. so am i......

[Craved]

is this like the boost control they used on the Group A skylines?

[Adriano]

NIzpro use an electronic blow off valve which is driven by an auxillary output by the motec to control boost

[ish]

I will keep watching this ... My friend in adelaide rigged his Fj20 to work like this. He was told not to do it as the turbine keeps spinning flat out and the Turbonetics may not have the oil system to cover it ....

Guess what ... the car absoulutley Hauled ASS until the bearings cooked...

Nizpro...Simons a smart mofo... he would of had it rigged up through the motec and totaly trouble shot with his vast knowledge ...

There ara few ZOOMs that explain this method ... but be warned

[T04GTR]

well i think il just give it a crack. using the pressure over type wastgate hook up with my profec b.

not to much info on it anywhere

ps. i know exacly how it works but was looking for some third party input on the subject

[Busky2k]

I can't see how this works so well. First of all you are spinning the shit outta the compressor/turbine. This means more heat from the compressor outlet and more exhaust backpressure (due to no wastegate bypass). Hmm..

[discopotato03]

Yes its hard to imagine good boost control without any real means of turbo speed control . Sizing a turbo so that the hot side won't choke at peak engine power and revs usually means big so not a real lot of go down low . I suppose if he could control the turbos speed by varying the compressor vent valve accurately he may be able to have a handle on the pumping loads that the turbine side has . In other words if he can "unload" the compressor the turbine has very little to push against so it would tend to windmill faster . The extra rotating group speed and the lack of exhaust manifold pressure would help the trade off of restriction vs turbo excitation but the vent valve actuation and Motec programming would have to be spot on . It would be a real juggle to make sure that turbo speed did not run away with itself and damage the wheels and bearings .

The want to delete the waste gate is valid , they are costly and a pain to fit and plumb but just about everyone uses them in petrol apps . Its a pity that F1 banned turbos when they did because they would have evolved at a faster rate with the development dollars F1 has . The future is probably the VATN or variable area turbine nozzle though how well it can be made to cope with petrol engine EGT's is hard to say . The electronic control will have a large say on how effective it will be .

I think there is a way to go yet with the conventional BB turbo but getting Garrett to give us the wheels and trims we want with effective integral waste gates is the issue . It is not impossible to get integral gates to work well as WRC has proven but it means strict control of turbine inlet pressure (so as not to force the flat valve open) and power through greater airflow rather than vastly higher boost pressure . This is why I thought for a while about something like an integral gate GT3540R but with a smaller trim GT40 comp (50 rather than 56) or the compressor side of a GT3076R . It also means an engine with a good head and cam profiles because the turbo can't do it all by itself .

Lastly look at HKS's GT Pro S exhaust housing and dump pipe design , they went to a bit of trouble to make the waste gates flow path good given the available space . They could make money out of selling GT35/TO4Z/GT40 versions as well .

Cheers A .

[rob82]

The transition from off boost to on boost will be the hardest part. What you want to do is be able to vent under cruise condtions ie- low throttle conditions and then shut the vavle under high throttle angles until you acheive the desired boost and then slightly bleed the required air.

ie Boost control Map - MAP vs RPM with the variable being duty cycle. So at low pressures you have 100% DC on the solenoid so all of the signal to the BOV is removed so as to vent the air. Once the desired boost is acheived you want the signal to be returned to the BOV so it can vent and stop over boosting so you would have 0% DC on the solenoid at this point.

You really want to use a properly designed venting valve. We use them on big HP superchargered cars where you need to vent alot of air in cruise and low - medium speed driving. Procharger make one, from memory it uses a little throttle type system.

[T04GTR]

it a t66

[T04GTR]

using my standard gtr bov's. with a profec b. (knob type) autronic smc. im gonna have a go at it this weekend. and i shall tell of the results.

il be able to tell if the turbo is to small for this aplication coz is quite an audible compressor. typical t04 sound

[T04GTR]

update... 1 gtr bov isnt enough. (i had one held shut.)

starts leaking of at .6bar

[T04GTR]

ok...

final result. using my boost controler set in "external wastegate"mode onto the stock bov's

it workes really well and holds boost very steadily. no spikes or anything

the turbo still makes the same noises so its not overspeeding.

but... i rekon i lost about 60kw posibly due to turbine back pressure.

so summing up. it works well but you loose power compared to using a wastegate style boost control.