[Mk2] [Turbo] Boost pressure question

[joemacmr2]

Hi, I have recently bought a mr2 turbo rev2, love it, I found plumbing for boost gauge that must have been in the car before. So I attached a boost gauge today to see what psi it's running and it came up at almost 10 psi at full throttle in 3rd. I know that stock psi is around 7 psi. Is it the aftermarket exhaust and induction kit giving me the additional boost increase above stock. If I added a mbc and upped boost is say 14, (after disabling fuel cut which I hope someone can show me how safely) would the 4 psi be a very noticeable bhp gain?

[Ryan S]

with a bigger intercooler 14psi is fine, and yes, it's a massive difference over stock, not only because of the raised boost but you also have to disable the tvsv, this limits the boost in 1st and 2nd, with this disabled you'll get the full 14psi in 1st and 2nd. you can get a FCD from Peter at s-bits decat, exhaust an air filter will see more gains,

[joemacmr2]

Hi mate, thanks for reply, am I correct in saying that I'm running almost 10 psi already due to exhaust and air intake? Also would there be any harm in using stock intercooler and upping boost to 14 psi?

[Ryan S]

Hi mate, thanks for reply, am I correct in saying that I'm running almost 10 psi already due to exhaust and air intake? Also would there be any harm in using stock intercooler and upping boost to 14 psi?

10psi is about right, i wouldn't run more on a stock cooler, it's a piece of crap mate, change that before you do anything, even the cheap ebay specials are better than the stock ones, providing you have a GTSchris shroud fitted

[joemacmr2]

Thanks mate, since I have a rev2 92, can I just plug the vacuum hose from map sensor to get rid of fuel cut even though I have teed off this for boost gauge?? When installing mbc, when disabling tvsv, do I only need to plug the end off the actuator or the other end as well, wherever that is?

[Ryan S]

Thanks mate, since I have a rev2 92, can I just plug the vacuum hose from map sensor to get rid of fuel cut even though I have teed off this for boost gauge?? When installing mbc, when disabling tvsv, do I only need to plug the end off the actuator or the other end as well, wherever that is?

no i wouldn;t do that, yes it will work, but you won't have fuel cut to protect your engine if something goes wrong, as for the tvsv, there is a blue electrical plug under the inlet manifold, unplug that, it's muuuuch easier than p1$$ing about with vac lines etc...plus, easier to revert back to stock if needed.

[joemacmr2]

Do you get to this from above or below?

[Ryan S]

Below the car, look up at the inlet manifold, you can't miss it

[joemacmr2]

Last question, when I attach mbc, one end to compressor, other end to left hand side actuator nipple, will I plug the right hand side nipple (which leads to vsv) with a screw even tho it's disabled as mentioned above

[Ryan S]

Ummmm, no. The boost controller fits between the turbo and the actuator, you need to cut that hose and fit the controller in between, there won't be any hose left that needs blocking off.

[joemacmr2]

Not sure I understand what u mean mate, there is a hose from compressor to actuator, and another from actuator to vsv. I thought u put the mbc between compressor and actuator ( left hand nipple if looking from passenger side) then u have the spare hose which currently runs from actuator (right hand nipple to vsv, which needs taken out at actuator end and plugged. Is this not correct?

[joemacmr2]

Think I now understand what u mean, because I'm unplugging the electrical connector underneath to disable vsv, are u saying I now have no need to touch the hose that runs from actuator to vsv??[/u]

[bobhatton]

Not sure I understand what u mean mate, there is a hose from compressor to actuator, and another from actuator to vsv. I thought u put the mbc between compressor and actuator ( left hand nipple if looking from passenger side) then u have the spare hose which currently runs from actuator (right hand nipple to vsv, which needs taken out at actuator end and plugged. Is this not correct?

Yes it is correct, plug the actuator right hand nipple

[joemacmr2]

If I plug this nipple, do I need to plug other end under car or is fine plugged at one end, if I don't go down the electrical connector route?

[Ryan S]

Ok, on the actuator, there is 2 pipes, one to the vsvs, don't touch it, the other goes to the turbo, the one going to the turbo you need to cut, leaving you with 2 open ends of pipe/hose these both go on to the MBC, then, disconnect the vsv plug mentioned earlier. Job done

[Peter Gidden]

Ok, on the actuator, there is 2 pipes, one to the vsvs, don't touch it, the other goes to the turbo, the one going to the turbo you need to cut, leaving you with 2 open ends of pipe/hose these both go on to the MBC, then, disconnect the vsv plug mentioned earlier. Job done

And ensure you get the MBC plumbed in the right way.

[Al-sw20]

You only need to cut the hose between the actuator and t/vsv OR pull the blue plug out from under the car. Not both. I recommend pulling the plug, it means you can revert to stock in a matter of minutes rather than trying to get a heap of hoses out of the way to plumb in a new vacuum line.

No problem pulling the boost pressure sensor vacuum hose out of its base. Just make sure you plug the hose to the intake manifold up (boost leak otherwise) or use that nipple for your boost gauge. You must understand you will have no fuel cut with this though. I only overboosted both my turbo sw20s twice. Both lived to tell the tale

[joemacmr2]

Thanks mate, I'm not going to push it too hard, probably to 14 psi max. I've heard u can keep stock ic and run fans all the time at 14 psi (diconnecting engine lid temp sensor instead of ripping out existing ic. Any truth in this?

[Al-sw20]

Disconnecting the temp sensor (which is just a matter of unclipping it) makes the fan run full time.

1 bar (14.5psi) is all I would run on pump gas.

[joemacmr2]

Excuse my ignorance mate, what do u mean pump gas, do u mean on standard ic? If I was to up boost to around 14, would I need ic fans on all the time?