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The mkiv Supra Owners Club

Advice - New turbos


markybhoy86

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i didnt think you were supposed to run the Jspec turbos up at 1.2?cant really afford them poppin just yet either lol

i have an electronic boost controller fitted but the other thing i noticed is when i was setting up the boost if i did go over 1.1 say, it felt like it misfired/staggered a lot, it never liked it lol

 

1.2bar is the generally accepted efficiency limit of the stock J-spec turbos and the stock fueling. If you are only running 1bar at the moment, 1.2bar should give you a significant power increase without spending big money on new turbos.

 

Over 1bar and you'll need cooler grade plugs to prevent misfire, see FAQ section HERE.

 

What boost controller do you have?

 

Also read here if you haven't already -> BPU

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TT/hybrids @ upto 1.3bar

NGK - BCPR7ES (3330) - gap 0.7mm

NGK - BKR7E (6097) - gap 0.7mm

NGK - BKR8E - gap to 0.7mm

NGK - BCR8ES (3330) - gap 0.7mm

NGK Iridium - BKR7EIX - leave gap alone

NGK Iridium - BKR8EIX - leave gap alone

Denso Platinum - PK20R8 - gap 0.7mm

Denso Iridium - IK22 - leave gap alone

Denso Iridium - IK24 - leave gap alone

 

So anything from this column I'm aiming to get,il probably go platinum midway price and midway compared to copper and iridium

 

Cheers nic

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Right I fit different plugs gaped to 0.7 ad turned the boost up but doesnt seem to get to 1.2 fully until 3 and 4th gear,the restrictor ring I have in the exhaust is smaller than the one stated to get because I thought it was overboosting when I first got it done-I now know better.

Do you think switching to the other RR will allow 1.2 consistently? Also my boost gauge when I go over 1.0 has a red warning light that comes on?havnt got a clue what type of gauge it is,was already in the car-do I ignore it?

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Right I fit different plugs gaped to 0.7 ad turned the boost up but doesnt seem to get to 1.2 fully until 3 and 4th gear,the restrictor ring I have in the exhaust is smaller than the one stated to get because I thought it was overboosting when I first got it done-I now know better.

Do you think switching to the other RR will allow 1.2 consistently? Also my boost gauge when I go over 1.0 has a red warning light that comes on?havnt got a clue what type of gauge it is,was already in the car-do I ignore it?

 

The boost gauge you have is a warning indicator. If you have the manual for it you will be able to adjust it in order to come in after 1.2 rather than 1.0. For the meantime just ignore it as it is only an indicator based on a setting.

 

As for the boost in the lower gears, if it's an electronic boost controller I would suggest upping the gain setting(if you have it) while leaving the boost setting at 1.2. The gain is what controls the ferocity of the boost (basically). In the lower gears the engine isn't working as hard as higher up, so it needs to be a little more agressive with the boost control. Don't go nuts with the gain as you can easily overboost. A little bit of overboosting at the start is OK as long as you don't run lean (the changeover can be a little lean). Most of the folks on here run like that just fine though :)

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I had the gain turned from soft right around to sharp and the boost seething on the controller at max as well thats what made me think this smaller ring is causing the grief. The reason I put the smaller on in was because it felt like it was misfiring but now I have set the plugs up it seems good just lacking the boost pressure? Sorry if that doesn't make sense it's been a long day lol

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I had the gain turned from soft right around to sharp and the boost seething on the controller at max as well thats what made me think this smaller ring is causing the grief. The reason I put the smaller on in was because it felt like it was misfiring but now I have set the plugs up it seems good just lacking the boost pressure? Sorry if that doesn't make sense it's been a long day lol

 

Hmm, sounds like something isn't right mate. Your boost controller will most likely be able to control up to 2.0bar, the fact that your car isn't overboosting like mad would tell me something is wrong somewhere. Maybe a split vac line or something like that. I would turn the boost controller down and take it from there.

 

Do you know what size the restrictor ring is? I have a 1.0bar RR in my car and I am boosting at 1.2bar absolutely no bother. An easy way to tell is to turn off your boost controller and see what boost level you get. You don't want to restrict your system too much or you will end up with high EGTs.

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Can't Remember I fit it ages ago,I will measure the one I have in the shed 2moro.il leave the boost the way it was for now and give everything a check over 2moro.Been hammering around in it all night so if theres any damage done itl be done by now lol.before I changed the ring the car could reach over a bar no bother but il check over the lines 2moro and then try the other ring,perhaps I'm restricting a bit much ...oops

 

Cheers Scott

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Can't Remember I fit it ages ago,I will measure the one I have in the shed 2moro.il leave the boost the way it was for now and give everything a check over 2moro.Been hammering around in it all night so if theres any damage done itl be done by now lol.before I changed the ring the car could reach over a bar no bother but il check over the lines 2moro and then try the other ring,perhaps I'm restricting a bit much ...oops

 

Cheers Scott

 

 

If you turn the boost controller off that will show you what the restrictor ring is holding the boost to. The boost controller can't lower the boost, it can only raise it, so if you turn it off the car will then boost to it's "natural" level. The level will be dictated by the restrictor ring, ergo telling you approx what size it is.

 

The problem with split vac lines will mean you will be potentially overworking, over speeding the turbo. It's running on borrowed time. Think about it as running the car at 1.4bar, 1.2bar is what the manifold sees while 0.2bar is lost through the leak. It might not go straight away but it WILL go eventually as 1.2 is the maximum safe limit for the turbos to be producing. It would be better to drop the boost down so that you aren't chancing running the turbos outwith their efficiency.

 

Last thing you want to do is lose a set of turbos over a split vac line.

 

You will probably find you are restricting it a little too much, I am at the moment too as my EGTs are a little high. My natural boost is around 0.9 with the RR in, I want to have it 1.0 in low gears and around 1.1 in the higher gears, I'll need to attack it with a dremmel to get it up to spec. That way I am only forcing another 0.1/0.2 out of the system, from it's natural boost level, therefor keeping the EGTs at a safer level.

 

If you need any help give me a shout :)

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Turned the boost controller of today peaked at 0.8 so the ring is restricting a fair bit is it not?

 

Yeah that's a little low mate, I would up it a bit as running 1.2bar would raise your EGTs a fair bit which isn't good. I would either take it off and be bore it out a little with a dremmel or try the spare one you have and see what you get with it. You want to aim for around 1.0bar in the summer (now) from the RR on it's own so see what you end up with and adjust accordingly.

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