Jump to content
SAU Community

Recommended Posts

Hi, I was hoping someone could help with trying to maintain boost in between gear changes. It hits 16psi then drops right down to around 3psi. It takes a second or two and then gets back up there. Just not sure if this is normal for my setup which is as follows.

R33 GTS-t RB25DET

GT3540R .86

Turbosmart 48mm ext wastegate

Tomei poncams

Blitz SBC id3 boost controller

Apexi N1 exhaust/ hi flow cat

Fmic

all required supporting mods... makes 434 RWHP

Any suggestions would be greatly appreciated

Link to comment
https://www.sau.com.au/forums/topic/222175-boost-drop/
Share on other sites

Either of the two will help obvious double clutching will keep the revs up during changes but the atmo bov kills boost as vents air instead of recirculating.

there wont be a difference in how boost is held between an atmo and recirculating bov, they both do the exact same thing bar the obvious part where on recirculates back into the intake

its normal for a turbo that size to take a second to respool inbetween gear changes. If you dont have a bov at all, that can cause the turbo to "lag" inbetween gears due to compressor surge, so get a nice sized bov thats going to breathe well and that should help.

Other than that, theres no real streetable solution, unless you like flat changing, antilag etc etc, its just the joys of having a large turbo on a smallish displacement engine

Link to comment
https://www.sau.com.au/forums/topic/222175-boost-drop/#findComment-3915317
Share on other sites

Well you'd think that but how many people do you notice running insanely low psi gate opening or insane high gate psis? heaps..

So if it opens to early leaks, opens/doesnt open well/dose etc means boost is going to drop off because air is not correctly exiting the system.

Dont forget youve got that gate on there.. spring??

sorry i couldnt make out any of that lol

Link to comment
https://www.sau.com.au/forums/topic/222175-boost-drop/#findComment-3915353
Share on other sites

Thanks for the reply.....yeah should have said. It has an atmo BOV with a soft and hard setting. I think it may be on too soft. I will adjust it and see what happens. It was on the car when i bought it...is the adjustment option just a rice thing?

Link to comment
https://www.sau.com.au/forums/topic/222175-boost-drop/#findComment-3915422
Share on other sites

Thanks for the reply.....yeah should have said. It has an atmo BOV with a soft and hard setting. I think it may be on too soft. I will adjust it and see what happens. It was on the car when i bought it...is the adjustment option just a rice thing?

adjustment option will be for your bov spring to suit your vac/boost. if it's too tight it will comp surge, which is why they can be adjusted.

Link to comment
https://www.sau.com.au/forums/topic/222175-boost-drop/#findComment-3915434
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now


  • Similar Content

  • Latest Posts

    • Please ignore I found the right way of installing it thanks
    • There are advantages, and disadvantages to remapping the factory.   The factory runs billions of different maps, to account for sooooo many variables, especially when you bring in things like constantly variable cams etc. By remapping all those maps appropriately, you can get the car to drive so damn nicely, and very much so like it does from the factory. This means it can utilise a LOT of weird things in the maps, to alter how it drives in situations like cruise on a freeway, and how that will get your fuel economy right down.   I haven't seen an aftermarket ECU that truly has THAT MANY adjustable parameters. EG, the VAG ECUs are somewhere around 2,000 different tables for it to work out what to do at any one point in time. So for a vehicle being daily driven etc, I see this as a great advantage, but it does mean spending a bit more time, and with a tuner who really knows that ECU.   On the flip side, an aftermarket ECU, in something like a weekender, or a proper race car, torque based tuning IMO doesn't make that much sense. In those scenarios you're not out there hunting down stuff like "the best way to minimise fuel usage at minor power so that we can go from 8L/100km to 7.3L/100km. You're more worried about it being ready to make as much freaking power as possible when you step back on the loud pedal as you come out of turn 2, not waiting the extra 100ms for all the cams to adjust etc. So in this scenario, realistically you tune the motor to make power, based on the load. People will then play with things like throttle response, and drive by wire mapping to get it more "driveable".   Funnily enough, I was watching something Finnegans Garage, and he has a huge blown Hemi in a 9 second 1955 Chev that is road registered. To make it more driveable on the road recently, they started testing blocking up the intake with kids footballs, to effectively reduce air flow when they're on the road, and make the throttle less touchy and more driveable. Plus some other weird shit the yankee aftermarket ECUs do. Made me think of Kinks R34...
    • I do this, I also don't get the joke  
    • Return flow cooler will be killing you I reckon. You can certainly push more through a low mount setup but they're good numbers for a stock looking engine bay.  Mine made 345rwkw (hub) at 22psi on 98 with a "highflow" on a stock manifold but it's a long way from a normal high flow or standard engine. I used one of those Turbosmart IWG-75's and it was great with the Motec running closed loop boost with pressure being applied to both sides of the diaphragm. 
    • Hey man do you have pic of adaptor plate by any chance I need to match up the bolt holes as my gearbox adaptor plate ones are way off the only bolts of starter motor are matching thanks 
×
×
  • Create New...