SBC-ID can reduce max boost without restricter ring?

Hi guys,

I'm having a debate with a trader about wether a Blitz SBC-ID will prevent the turbos from freely running to whatever boost if you decat WITHOUT a restricter ring.

They say it will decrease boost.

I say not.... you say....

No mate.

My answer would be UK = Yes J-spec = No

edit: bugger someone competent posted as I was typing

I'd say, who's the trader?

-Ian

I'd say, who's the trader?

 

-Ian

Let you know if enough people tell me I'm right

I know JPS thought he could...but I bet that was on a UK spec.

I know JPS thought he could...but I bet that was on a UK spec.

you agreeing with me Alex? Nope, not JPS.

Nope - cannot decrease

A boost controller will only RAISE the boost over and above the wategate spring pressure. A restrictor ring will lower it by introducing more exhaust system back pressure. The problem with the J-Spec Upras, and many UK specs is the wastegate will not flow enough volume of bypass gasses to control boost one the exhaust is derestricted.

I'm agreeing with you Pete. I'd say not on a UK spec either. If the wastegate is wide open, you are at your minimum boost level A boost controller can't make the wastegate physically wider...

Unless it's not plumbed in right and vents a load of boost

-Ian

hi there all,

regarding this thread lets clear it all up,

pete emailed us asking about decats, i think he has got a bit confused with boost controllers.

the question asked in the beginning was:

"Why do you not recommend a reducer ring?"

"Also boost controllers CAN NOT lower boost, only raise it. I feel you're heading for legal trouble if you advise someone to fit a decat and not fit a restricter ring as the turbos could reach boost levels which drastically reduce the life of the turbos. Not to mention hitting fuel cut and the troubles that will cause!"

At no point did we say that a boost controller is capable of reducing boost below the factory preset level, it can only control boost of a higher level than standard, due to the mechanics of the vehicle.

On a jap spec you would still need a restrictor ring which we put into the first decat. purely because jap spec turbos wastegates are not capable of flowing a large enough volume of air.

Thanks

From your site, which I have just had a look at, under the "Exhaust" section:

"Being a 3inch Bore it will induce over boost on a standard car, an SBC ID or similar boost controller is recommended for safe operation. Reducer washers can be used to reduce gas flow but is not recommend.

We can supply an BLITZ SBC i-D BOOST CONTROLLER III for £399.99 + VAT if bought with a Trac Art De-Cat"

I'd change that, if you don't mind me saying so, a boost controller will NOT give safe operation with de cat pipes, it's the last thing someone wants unless they ALSO fit a SMALL restrictor to allow a lot less than 1.2 bar boost, THEN use a boost controller to pull it up to 1.2 bar max, which would seem an odd, and expensive thing to try and do, and which would put uneccessary loads on the engine and turbos to achieve the maximum safe boost.

hi there all,

regarding this thread lets clear it all up,

pete emailed us asking about decats, i think he has got a bit confused with boost controllers.

the question asked in the beginning was:

 

"Why do you not recommend a reducer ring?"

 

"Also boost controllers CAN NOT lower boost, only raise it. I feel you're heading for legal trouble if you advise someone to fit a decat and not fit a restricter ring as the turbos could reach boost levels which drastically reduce the life of the turbos. Not to mention hitting fuel cut and the troubles that will cause!"

 

At no point did we say that a boost controller is capable of reducing boost below the factory preset level, it can only control boost of a higher level than standard, due to the mechanics of the vehicle.

 

On a jap spec you would still need a restrictor ring which we put into the first decat. purely because jap spec turbos wastegates are not capable of flowing a large enough volume of air.

 

Thanks

You are correct, but if Chris's quote above is correct you can see why Pete thought you were talking about boost controllers reducing boost.

All sorted now though

You are correct, but if Chris's quote above is correct you can see why Pete thought you were talking about boost controllers reducing boost.

That and the emails I got

i dont mean to argue with you if the mechanics of your vehicle can allow you to go to 2.0 bar and you set your sbc id to run 1.0 bar all your car will produce is 1.0 bar because when you get to 1.0 bar the sbc id will tell the actuators to open the waist gates and stablise the boost at 1.0 bar.

It states that it is recommended that you use the SBC id which you can set exactly what boost pressure you require, nothing more nothing less.

iam sure there are others like this on the market but we have found the blitz products to be most reliable. if this is not an affordable option for you then we retain the reducer washers which is inserted into the first decat.

the reason why it is recommended to control the boost than rather let it run what it likes is because eventually the reducer ring will burn out larger than its original size therefore will allow a greater flow which will increase boost pressure which will then cause you damage to your turbos, possible engine......

hi there all,

regarding this thread lets clear it all up,

pete emailed us asking about decats, i think he has got a bit confused with boost controllers.

the question asked in the beginning was:

 

"Why do you not recommend a reducer ring?"

 

"Also boost controllers CAN NOT lower boost, only raise it. I feel you're heading for legal trouble if you advise someone to fit a decat and not fit a restricter ring as the turbos could reach boost levels which drastically reduce the life of the turbos. Not to mention hitting fuel cut and the troubles that will cause!"

 

At no point did we say that a boost controller is capable of reducing boost below the factory preset level, it can only control boost of a higher level than standard, due to the mechanics of the vehicle.

 

On a jap spec you would still need a restrictor ring which we put into the first decat. purely because jap spec turbos wastegates are not capable of flowing a large enough volume of air.

 

Thanks

Hello...

have you paid a traders fee?

JB

...The problem with the J-Spec Upras, and many UK specs is the wastegate will not flow enough volume of bypass gasses to control boost one the exhaust is derestricted.

Well mine (late UKSpec) would not boost *half* a psi more even with both cats out and the 3+" full exhaust (and rather cosmetic backbox lol)

The moment the actuator boost signal is manipulated, everything works as expected.

To me that indicates that the UKSpec wastegate is bloody well-sized. Am I missing something here? Early UKSpecs didn't have smaller wastegates for example, did they?

JohnA, it appears that production tolerances in the wastegate flow make a big difference, some UK models show a lot more boost de catted, some need the controller. the Jap ones differ too, but I haven't come across a single one that doesn't show a considerable rise when de catted, some go wild

Is the Supra unique in this way, or do all turbo cars have a similar reaction with this free spooling after decatting?

it helps on most turbo cars as it removes the restriction in the exhaust system. I dont think there many that get quite such runaway boost when you take both cats out but I could be wrong.

JB

...production tolerances in the wastegate flow make a big difference, some UK models show a lot more boost de catted, some need the controller.''

Production tolerances that vary so much?

From the people who fit matched set of pistons?

The UKSpec has wastegate 10mm wider than than the JSpec right? That would account for a LOT of flow (i.e. no runaway boost)

If you've had UKSpecs raise boost just with decat then there *must* be something else different.

What I've found from using mine is that if you leave it set to off it does reduce boost from stock.

Both the Skyline and SX were running stock solenoid systems and with the decat were hitting about 0.8/0.9 bar respectively. When you removed the stock solenoid and fitted the SBC, if you turned it off, you would only get as much boost as the spring/actuator on the wastegate was at. Each car dropped to around 0.6bar with the Blitz in the off mode.

So I would say it can decrease boost over stock, and also up it more too. Obviously thats not with a Supe though, but just speaking generally........

Depends on the setup. If the stock boost control solenoid/VSV has to pulse the wastegate open/shut to achieve stock boost, then by effectively wiring the wastegate fully open via a boost controller will reduce boost. Most stock setups will need this solenoid pulsing to achieve maximum boost otherwise why bother with a wastegate control mechanism? The off-the-shelf turbo the manufacturer selects will be able to deliver a bit more boost than the manufacturer wants, because that's the only safe way to spec it out - spec one that is running on the ragged edge of it's efficiency map and you are shooting yourself in the foot on several fronts - power, detonation risks, overspeeding failures... That's why we can up the boost on stockers and get noticeable power gains.

However, the rules of the game change when you decat. Suddenly the exhaust system is so unrestrictive that wiring the wastegate fully open isn't enough to hold stock boost - the wastegate apeture is just too dang small to make enough of a difference so boost creeps higher and higher, especially in the higher gears.

So I'll make the point again - if the wastegate is fully open, whatever boost the turbo produces is the absolute minimum boost it can produce (under full throttle). It's physics dontchaknow. You CAN affect this by changing the exhaust backpressure - either by restrictor ring or putting a CAT back in. The overall exhaust flow is lower so the minimum boost level drops. You CAN'T affect this by any form of wastegate control - i.e. a boost controller - because it's already wide open! What else can you do to a wastegate? Open it a bit more? Nope.

So you see, saying you can set exactly what boost pressure you require with a boost controller, after decatting a Supra, is misleading at best:

"when you get to 1.0 bar the sbc id will tell the actuators to open the waist gates and stablise the boost at 1.0 bar." well, no - if the wide open 'waist gate' can't hold boost below 1.4 it isn't going to achieve 1.0...

You can set whatever you want over and above the minimum boost - but with a decat J-spec Supra this minimum boost will probably be well north of 1.0bar. Probably beyond 1.2 in fact, which is turning out to be the best fuelling/longevity/power level of boost on stockers.

Really this shows that it's best to speak to someone who knows the car when you want to modify it. Yes, a boost controller will control boost, it says that on the box, anyone can read it. But it doesn't say for a decatted J-spec supra application you'll need a restrictor ring in first...

-Ian

we have not paid a traders fee because we are not acting as traders fee.

yes we are traders but not on here.

we have our right to speak out and to clear matters up

yes we are traders but not on here.

Are you sure?

http://www.mkivsupra.net/vbb/showthread.php?t=48244

-Ian

we are allowed to sell an item, just not bulk items!

its just like say for example you selling your cat say well we was selling a decat system, no harm surely