[Mk2] [Turbo] TVSV noob question

[Will_bmx]

reading about mbc etc. and was thinking, I'm not fitting one right now, maybe in the future. But can I disconnect the TVSV anyway on a stock block to gain boost in the lower gears in the same way? If i'm understanding it right i should be able to, but it's just in case I'm being a noob! Be nice to finish the decat tonight and get even more of a kick in the lower gears
Cheers
Will

[Will_bmx]

Oh and it's a rev 3 turbo sorry!

[dantheman]

nope, you will get less. The TVSV is a boost controller and fundamentally works in the same way as a manual one, bleeding boost away from the actuator. if you unplug it the actuator will open at a lower boost pressure.

The reason you unplug it when you install a boost controller is because if you dont, you will have 2 boost controllers, one you can control yourself and one you cant. the one you cant control (TVSV) interfers with the one you can (mbc) rendering yours uncontrollable too.

[Will_bmx]

Thanks for the quick response!
With you now, when reading about it on the MBC threads it didn't 100% come across if it could be done on it's own, prob the way I'm reading it though!

[Will_bmx]

Right, gona get an MBC if the following is answered

Currently running a stock engine, apart from xs power decat and buddy club spec II.

also have an Apexi boost guage so can keep close eye on spiking.

Will I be safe running an MBC on 1.1 bar with a stock I/C or will the intake temps be too high?

Cheers
Will

[Marf]

I wouldnt personally.

Before I upgraded to an ST205 chargecooler, on hot days the ECU would often back the boost off as it felt the intake temps were too high.

That tells me that the stock IC isn't even capable of cooling the charge at standard boost levels in all conditions, let alone when you increase the boost.

Bear in mind that if you do increase the boost, you remove the ability of the ECU to reduce boost to combat high intake temps.

As such you want to be 100% sure that your cooling system can cope with all boost levels in all weather conditions.

[Will_bmx]

Hmm thanks for the info!

Just thinking, for a little extra, but not being greedy, how would an MBC on, but set to literally just like 0.95 bar, but so that I can disconnect the TVSV to get more in first and second and then just disconnect the engine bay temp sensor so the IC fan is on all the time? then when I do get a better IC I can increase it to 1.1 ish?
Or is that still risky?

[djpkins]

pop...the first "upgrade" that everyone does is bigger IC and free flow in and out...why risk it? if your that hungry for a bit more power, the temptation to crank it up to 1.2...just one time...too much matey. Learn from a lot of other peoples mistakes and do it propperly, I bet if you were resourcfull, you could get an st205 charge cooler package together for a 1'er or an ebay IC core.

[Will_bmx]

Fair one!

I'll get on the money savings and try and pop a better IC on the side, rather than a chargecooler tbh.

I'll get searching.
Cheers for keeping my head straight

[djpkins]

Lust for power is a dangerous thing man I have hi boost set at 1.2bar but when I was propper hanging onto the back of this Fezla down the lanes...I spiked at 1.49!!!! soooooo easy to get caught up in the moment mate.

[Will_bmx]

Partly the reason why when I get the new IC and up the boost I'm going to run about 1.1 and not get an FCD so that in a round about way I have some sort of protection against overboosting! Although I imagine fuel cut is hardly ideal for the engine either, I see it as a lesser of evils!

I should make do with it as it is, it was running 257 before the decat was fitted so it's not exactly slow, just want more oomph :p Plus with the decat it sounds evil should be happy to contend with the spool up and down noise + flames

[djpkins]

You could fit an uprated actuator...a 1bar jobbie then you would be holding a bit more boost and still safe as houses mate...tbh if your upping the boost, the fuel supply should increase aswell...my mates rev3 was mapped at 295bhp fw with the equivilant of torques using a power fc and avcr set to 1.15bar hi boost also running a radtec charge cooler...he used it every day so required a reliable, safe tune up...295 is what Lyndon gave him, and he knows a thing or 2 about mapping.
Your prob kicking the 270bhp fw now and bet you get heat soak galore in the summer when you've been booting it...I reckon 1 bar would put you on the limit of your standard fuelling and quite possibly start to tell on the clutch.

[1998mr2]

nope, you will get less. The TVSV is a boost controller and fundamentally works in the same way as a manual one, bleeding boost away from the actuator. if you unplug it the actuator will open at a lower boost pressure.

The reason you unplug it when you install a boost controller is because if you dont, you will have 2 boost controllers, one you can control yourself and one you cant. the one you cant control (TVSV) interfers with the one you can (mbc) rendering yours uncontrollable too.

is there a way still to keep the tvsv and boost it..
not with a actuator but something els

[1998mr2]

is the tvsv a boost controler or a part that saves the engine
i have read that it gives 3 psi more boost
if the water temp is oke
or there is no knock detected
and the intake air is oke
if every thing is passed the vsv gives you 3 psi more boost

whes somthing fails it gives 3 psi less boost.

so i thinks it is more a tool to prevent then it is more like a boost controler
corect me if i am wrong

[Marf]

The TVSV is not a boost controller in the aftermarket sense, but it is what the ECU uses to allow increased boost and what the ECU uses to save the engine if it thinks that everything is not OK based on sensor readings.

[1998mr2]

The TVSV is not a boost controller in the aftermarket sense, but it is what the ECU uses to allow increased boost and what the ECU uses to save the engine if it thinks that everything is not OK based on sensor readings.

oke so it would be possible to set a mbc en keep the vsv
because it sense the sensor..

and it not wil interfer withe the aftermarket boostcontroler

every where you see tyhat they disconect the vsv when instaling
a boost controler..

i want to keep the vsv for the savety..

[Marf]

I don't think so.

[dantheman]

The TVSV works like this (for rev2):

Actuator opens at 7 PSI. TVSV will kick in for 3rd gear bleeding off 3PSI so that actuator opens at 10PSI. You could set up a boost controller with TVSV enabled but you will never have control of 3PSI, you would need to set your controller up for max boost in 3rd which means you will have 3PSI less than you want in 1st and 2nd gear.

For a rev3 car the TVSV isnt binary, it can bleed off up to 7PSI and will do so as it pleases. Thats just a no go.

If you are worried about your boost pressure use a boost controller with an upper limit or warning feature to it that will back the boost off if it is overboosting.

[1998mr2]

i want to keep the vsv engine saving options..

i do not know if a aftermarkt boostcontroler can detect knock
and set the boost 3psi back..

[Al-sw20]

The TVSV works like this (for rev2):

Actuator opens at 7 PSI. TVSV will kick in for 3rd gear bleeding off 3PSI so that actuator opens at 10PSI. You could set up a boost controller with TVSV enabled but you will never have control of 3PSI, you would need to set your controller up for max boost in 3rd which means you will have 3PSI less than you want in 1st and 2nd gear.

Total garbage. The TVSV has no idea what gear you are in. The reason you boost less in lower gears is simple gas velocity because of the lower load on the engine in the early gears.

On my new car I don't have my ebc plumbed in yet. Just feeding a boost reference from the manifold and electrical connection. I have a Berk 3" dp and 3" custom exhaust. The factory t/vsv is still functional.

When the parameters are not met

1) Coolant temp > 160F
2) Ambient temps > 32F
3) Manifold pressure positive.

I get 0.5bar. When they are met I make 1 bar in 1st gear, 1.1 bar in 2nd, and a tad higher in the rest.

OP. Don't fret about the magical engine saving properties of the t/vsv.
You still have the best ones as factory. The pig rich running under boost and the knock sensor. Any chance of det and the knock sensor will retard timing severely. The car would fall flat on its face. You really notice it, but I've never experienced it on a higher octane fuel like 98 or higher.