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The mkiv Supra Owners Club

Boost levels


Keith C

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Easy one this - what's the max recommended safe boost for a UK with stock turbos and IC, running normal Esso SUL. I don't trust Optimax, and I can't be bothered faffing around with octane boosters.

 

I have been told 1.3bar is perfectly safe, but want to check.

 

In addition, is there anything I need to do to the timing to take into account the extra boost?

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It depends how long you want things to last. Once I have fully tested my UK spec Im going to be happy running up to 1.3bar, it has 550cc injectors and steel turbo internals so it takes that bit more abuse than an import. I accept the turbos might only make another 20,000-30,000 miles but thats something Im happy to take on board (remember this is a 116,000 mile car).

 

So long as you keep a close eye on the boost and dont hold it at 1.3bar for long periods of time then it should be fine. Somebody like Justin would and can drive a car at that level of boost for a long time, Im a wuss and back off way before I starting getting spiralling heat problems.

 

JB

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Originally posted by Branners

It depends how long you want things to last. Once I have fully tested my UK spec Im going to be happy running up to 1.3bar, it has 550cc injectors and steel turbo internals so it takes that bit more abuse than an import. I accept the turbos might only make another 20,000-30,000 miles but thats something Im happy to take on board (remember this is a 116,000 mile car).

 

So long as you keep a close eye on the boost and dont hold it at 1.3bar for long periods of time then it should be fine. Somebody like Justin would and can drive a car at that level of boost for a long time, Im a wuss and back off way before I starting getting spiralling heat problems.

 

JB

 

So from this I take it that a J-Spec would just eat the turbo's faster with that boost and with smaller injectors maybe dett...??

 

So, whats a safe level with a J-Spec with cats...? 1.2bar at short spurts...? 1bar with more stick maybe....??

Just wondering as to what to set mine to as I pick it up Saturday and don't wanna wreck it in the first ten minutes.:(

I am gonna talk to Chris about having the cats out when Mr Bank man tells me I can.

 

I've hijacked here haven't I. I'll get me coat.:baa:

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well....I ran my import on a 3" downpipe which meant uncontrollable boost. I saw it hit 1.5kg once, but mostly it sat around 1.3-1.4kg. I ran it like that for about a year and nothing serious fell off (blew a crank oil seal but that could have been anything). I then sold it to Barry and he blew both turbos all over the m25 after a week of owning it.

 

So what conclusion can we draw from this? I was either very lucky, Barry was driving like a fruitcake, or the turbos had a vastly shortened life span (not just cos I sold it to Bazza).

 

On an import I would say 1.2bar is safe, you can run at that boost for years without anything serious going wrong. I know Pete Betts has had his running near that for about 40,000 miles.

 

I never actually heard the car det, but then chances are you wouldnt, as by the time you hear the det its too late. What I did do was modify the car slowly so I got used to the power and how it felt and then if it felt iffy I would know. My UK spec is going the other way, all the mods at once.

 

JB

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What I did do was modify the car slowly so I got used to the power and how it felt and then if it felt iffy I would know. My UK spec is going the other way, all the mods at once.

 

JB,

 

Was slowly like this then -:

 

1st Mod :rolleyes: 2nd Mod :cool: 3rd Mod :) 4th Mod :p 5th Mod :D

 

And all the mods at once -:

 

:eek: :D :devil: :flame Dev

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Originally posted by Matt C

Isnt 1.2bar high if the stock cats are still in....?

 

Nah, the cats are long gone - one is usefully propping up a shelf in the garage :D

 

Barry - I've heard stories about it doing blahblahblah to turbo cars, ie the Scoob guys with their Link ECU's report increased knock on Optimax over SUL, a couple of the 200 guys have mentioned that their EGT's were higher, a couple of people I know have trashed plugs. Basically, just enough for me not to want to take a chance on my own engine - I can just about afford to keep it fed at the moment, let alone repair!

 

If I should only use 1.2bar, that's all I'll use, no problem. I don't use full boost all the time, and indeed usually keep no.2 for when something worthy wants a race :flame Dev

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Originally posted by Branners

well....I ran my import on a 3" downpipe which meant uncontrollable boost. I saw it hit 1.5kg once, but mostly it sat around 1.3-1.4kg. I ran it like that for about a year and nothing serious fell off (blew a crank oil seal but that could have been anything). I then sold it to Barry and he blew both turbos all over the m25 after a week of owning it.

 

So what conclusion can we draw from this? I was either very lucky, Barry was driving like a fruitcake, or the turbos had a vastly shortened life span (not just cos I sold it to Bazza).

 

On an import I would say 1.2bar is safe, you can run at that boost for years without anything serious going wrong. I know Pete Betts has had his running near that for about 40,000 miles.

 

 

JB

 

So was this with the cats in then JB....? Sorry if I'm being a moron......rough week!:baa:

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If the cats are still in and you have a standard exhaust and no boost controller or bleed valve then the boost stays at stock levels. Decat and it goes to about 14psi, aftermarket exhaust and it can go to 20psi or more. Leave the cats in and fit aftermarket exhaust and it can get up to about 13psi. Stick in a boost controller and you can set it to what you want, but the more resitriction in the system (cats or stock exhaust), the less easily the air can flow and so exhaust gas temperatures can go up.

 

Its all a fine line really.

 

JB

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Cheers for info JB.:thumbs:

 

Well, I pick the car up tomorrow so I'll be having a proper look at what it's got on again (And no doubt on Monday posting a list of what to do with them all so get ready for that!) in detail instead of the passing glance as I did before. I did see the car was boosting a 1bar though on the boost gauge it has fitted and I'm sure it has cats in place.

However, it does (Using my memory here) have a HKS F-CON (What you do with this I have NO idea!), some sort of graphical display thing (Not technical in the description there I know) and a boost controller of some sort. It also has a 5.5" exhaust on the back...think it's a Greddy if I remember rightly.

 

So, assuming I don't find anything else upon further inspection do you reckon I'm better off running it down at 10psi until the cats are out and the odd spurts at say 1bar...? I don't wanna wreck my new toy you see.....

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