Over 1.2bar in TTC with a 1.2RR?

Just fitted my fuel pump yesterday and decided to run the car in TTC and loved it

After taking it a spin I hit the memory button on the boost gauge and it was showing just over 1.2bar...even though I have a 1.2bar restrictor ring fitted.

How can this be and also is it safe to be running at this?

With TTC you can get a nasty boost spike just after the normal sequential turbo change over point. It's one of the common issues with TTC mode, best to use a boost controller with this, but it doesn't always react fast enough to counter it.

Anyway, peak boost pressures vary all the time, boost is dependant on a lot of external factors like air tempurature, air pressure, etc..

Thats why in the winter BPU car will produce an lot more boost and power than in the summer

Is the guage accurate?

Maybe you need a smaller restrictor ring and to gently file it out in a trial and error fashion

It can depend on air density too. Best with a boost controller and dial it down a tad.

Not that helpful bud. Sorry. I wouldn't like to run above 1.2 just in case there's a weak point in the system. But I'm overcautious.

Edit: Homer's on the case. Forgot about the spike too. Haven't seen a lot about that but have heard of it.

With TTC you can get a nasty boost spike just after the normal sequential turbo change over point. It's one of the common issues with TTC mode, best to use a boost controller with this, but it doesn't always react fast enough to counter it.

 

Anyway, peak boost pressures vary all the time, boost is dependant on a lot of external factors like air tempurature, air pressure, etc..

 

Thats why in the winter BPU car will produce an lot more boost and power than in the summer

Yeah been looking for a boost controller for a while no. Feels pretty ferocious when it hits 4k maybe i'm just not used to it ha but don't want to blow another turbo

Is the guage accurate?

 

Maybe you need a smaller restrictor ring and to gently file it out in a trial and error fashion

Gauge is accurate

Thats an idea but agree a boost controller would be a good thing to have

It can depend on air density too. Best with a boost controller and dial it down a tad.

Not that helpful bud. Sorry. I wouldn't like to run above 1.2 just in case there's a weak point in the system. But I'm overcautious.

 

Edit: Homer's on the case. Forgot about the spike too. Haven't seen a lot about that but have heard of it.

I've alraedy blown a 2nd turbo by overboosting when it hit 1.3...1st and last time

Meant to say before I went TTC it was only hitting just shy of 1bar so why now is it hitting over 1.2?

A boost controller can only increase boost. I guess Homer meant use a 1 bar ring and a boost controller, but i would imagine you need one with a very fast solenoid to catch it.

Yeah been looking for a boost controller for a while no. Feels pretty ferocious when it hits 4k maybe i'm just not used to it ha but don't want to blow another turbo

It feels like more of a kick because you're going from zero boost, whereas sequential mode is deliverying more torque at that point. It will also feel quicker because the car is running leaner and overboosting, thus creating a bigger and more sudden kick.

A boost controller can only increase boost. I guess Homer meant use a 1 bar ring and a boost controller, but i would imagine you need one with a very fast solenoid to catch it.

Yep Rob, thats what I meant, sorry for not being clearer.

With TTC the restrictor needs to be a lot smaller and then use the BC to raise the peak. it'll still spike, but not as bad.

TTC is a nasty bodge IMO, really not worth the risk of boost spike and det after then changeover point.

I tried TTC just now, and had similar results... just wanted to clarify if anything is amiss with my car and if I need to replace anything... basically im BPU; twin 3" decats into superdragger, walbro, VFCC, stock airbox with apexi filter, NGK BKR7EIX plugs plus a 1.2 RR. In stock sequential mode the boost peak recall shows just over 1 bar, but it generally holds boost at just under 1 bar. With the 5 min TTC mod the peak recall is at 1.25 bar (due to the common spike issue) and holds boost around the same value as before; 1 bar ish. Does this indicate there are no issues, and that I will simply need a boost controller to raise boost safely to 1.2 bar?

I tried TTC just now, and had similar results... just wanted to clarify if anything is amiss with my car and if I need to replace anything... basically im BPU; twin 3" decats into superdragger, walbro, VFCC, stock airbox with apexi filter, NGK BKR7EIX plugs plus a 1.2 RR. In stock sequential mode the boost peak recall shows just over 1 bar, but it generally holds boost at just under 1 bar. With the 5 min TTC mod the peak recall is at 1.25 bar (due to the common spike issue) and holds boost around the same value as before; 1 bar ish. Does this indicate there are no issues, and that I will simply need a boost controller to raise boost safely to 1.2 bar?

I would recommend getting a 1bar RR and a boost controller. That's what I got recommended to me but I decided to stick with sequential.

Although if I go TTC again that's what i'll be doing

i run a uk 6sp bpu and always have mine in TTC, found it a better power delvery for track use and is less stressless on 2nd turbo, i dont have any spikes in TTC but did in sequential, i have a boost controller and no ring as its a uk, i mainly run 1.4 but on my last trackday at Llandow was running a mild 1.2 with no spike's at all, the only way round the spike issue it to have a emange or standalone ECU mapped to TTC.

Forgot to add when i was at SRR they did a run with TTC then with sequential, made the exact amount of BHP but power came in ealier and more torque in TTC as i thought it would, 1.2 and made 413 at the fly so was happy with that.