Overboost?

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RustySkull

Active Member
Posts
166
Location
Stanford-Le-Hope, Essex
Hello everyone, I hope you all had a great christmas!

I've been messing around installing a slightly bigger Hybrid Turbo onto my Discovery TD5, I am looking for some help in what happens when it goes into overboost? As far as I know they're programmed to go into it at 20psi, right? My new Turbo came with the actuator preset to where it was supposed to be, however there was no power, I know there will be lag with a bigger Turbo on the stock map but there was nothing all the way through the revs, so I shortened the rod.

Now I have boost, not as much as the old Turbo seemed to have but it's much better. However, in 5th, on full throttle while climbing up to 70mph and I assume on full bost it judders at around 60mph, then has very little power. Once slowed down and stopped, it then has the full power again. I've checked everything uner the bonnet, so I'm wondering if that's overboost? I know it will need a map to run correctly with that Turbo, but is overboost what I'm dealing with most likely?

Nothing seems to be wrong under the bonnet.

Cheers!
 
Of course you could have been sensible and left it alone and kept it standard. But suppose it's your car to ruin if you want to.
 
Dont listen to the **** above. :p You'll make it better if you do it right.

How is it in the top end in lower gears?

I had to fit a bleed valve to properly control the boost on mine or I had boost creep. The MAF sensor aslo didnt like the top end so you should check and see if thats faulty (Nanocom or similar) only fit a genuine one

If you are playing with boost you need a way of keeping an eye on it either with a boost gauge or with diagnostics. Do not play around without knowing exactly what youre doing.

Overboost will usually cut power and some turn on the engine warning light.
 
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Dont listen to the **** above. You'll make it better if you do it right.

How is it in the top end in lower gears?

I had to fit a bleed valve to properly control the boost on mine or I had boost creep. The MAF sensor aslo didnt like the top end so you should check and see if thats faulty (Nanocom or similar) only fit a genuine one

If you are playing with boost you need a way of keeping an eye on it either with a boost gauge or with diagnostics. Do not play around without knowing exactly what you're doing.

Overboost will usually cut power and some turn on the engine warning light.

Exactly the point being made. Corrected your punctuation also. Have a nice day.
 
Of course you could have been sensible and left it alone and kept it standard. But suppose it's your car to ruin if you want to.

Well, I needed a new one because the old one gave up on the M3 in September. The Turbo Centre recommended a Hybrid when I mentioned I wanted a little more low end power. I think it would be a little more ruined if I'd have kept the old one on to be honest...

Dont listen to the **** above. :p You'll make it better if you do it right.

How is it in the top end in lower gears?

I had to fit a bleed valve to properly control the boost on mine or I had boost creep. The MAF sensor aslo didnt like the top end so you should check and see if thats faulty (Nanocom or similar) only fit a genuine one

If you are playing with boost you need a way of keeping an eye on it either with a boost gauge or with diagnostics. Do not play around without knowing exactly what youre doing.

Overboost will usually cut power and some turn on the engine warning light.

Well, with it set to how it arrived which was apparently the correct setting it was as if there was no boost at all. The revs were very slow to climb.
After checking oil feed, boost pipes, exhaust joins etc... I then shortened the rod one turn at a time until I started to notice boost. I turned it 6 turns in total before I felt I should stop until I have a way of measuring the boost. But I must say it still isn't anywhere near what it was like with the standard Turbo. It would pull up a steep hill in 4th at 1500rpm(ish) very well but now it just dies.
I do expect to have to have it mapped to account for the new, bigger Turbo but I do feel something isn't right anyway... But my real question was what happens if it goes into overboost while driving? You say it does cut power? So that plays true with what happened to me then, the light didn't come on though and once I stopped at traffic lights, it was fine again and didn't do it on the way home when I was trying to make it do it.

I must point out I'm not a cock on a drive away messing around without any knowladge I've built a few engines including my Focus RS MK1 build but I'm not too clued up on the TD5 when it comes to how they react to mods etc...

Thanks for your replys :)
 
No problem. But i do at times wonder why people who don't have a bloody clue what they are doing take this sort of thing on.:(:D
It's not a hard thing to do really is it, and I was simply asking what happens when it goes into over boost, I susspect it is, and if it cuts power temporarily then that's my problem solved. I didn't want to take it to be mapped and find out there is other issues that I thought were just overboost.
I know loads of people don't but when I take a car in to be tuned I make sure everything is good to go so they don't start finding issues that I could have made good myself.
I'm not always a good customer, but I try.
 
Hello everyone, I hope you all had a great christmas!

I've been messing around installing a slightly bigger Hybrid Turbo onto my Discovery TD5, I am looking for some help in what happens when it goes into overboost? As far as I know they're programmed to go into it at 20psi, right? My new Turbo came with the actuator preset to where it was supposed to be, however there was no power, I know there will be lag with a bigger Turbo on the stock map but there was nothing all the way through the revs, so I shortened the rod.

Now I have boost, not as much as the old Turbo seemed to have but it's much better. However, in 5th, on full throttle while climbing up to 70mph and I assume on full bost it judders at around 60mph, then has very little power. Once slowed down and stopped, it then has the full power again. I've checked everything uner the bonnet, so I'm wondering if that's overboost? I know it will need a map to run correctly with that Turbo, but is overboost what I'm dealing with most likely?

Nothing seems to be wrong under the bonnet.

Cheers!
that is the same symptoms as over boost, it wasnt uncommon for waste gate to seize and give such
 
Hello everyone, I hope you all had a great christmas!

I've been messing around installing a slightly bigger Hybrid Turbo onto my Discovery TD5, I am looking for some help in what happens when it goes into overboost? As far as I know they're programmed to go into it at 20psi, right? My new Turbo came with the actuator preset to where it was supposed to be, however there was no power, I know there will be lag with a bigger Turbo on the stock map but there was nothing all the way through the revs, so I shortened the rod.

Now I have boost, not as much as the old Turbo seemed to have but it's much better. However, in 5th, on full throttle while climbing up to 70mph and I assume on full bost it judders at around 60mph, then has very little power. Once slowed down and stopped, it then has the full power again. I've checked everything uner the bonnet, so I'm wondering if that's overboost? I know it will need a map to run correctly with that Turbo, but is overboost what I'm dealing with most likely?

Nothing seems to be wrong under the bonnet.

Cheers!

firstly what are your boost readings ..i am amazed some times people play with there turbos and forget to install a boost gauge other wise its just a guessing game
many people dont understand how a turbo works

you may find the different turbo has a different A/R ratio specially if its larger
when the hot side of the turbo becomes hot it runs more efficient more heat more energy = more kenitec energy to push the turbine due to expanding exhaust gasses

you may find you will have boost creep engine load plays a very big role for example at higher speeds the vehicle has to push through wind resistance this then means more engine load means more fuel means more heat

this also apply to when going up hill and full throttle in a high gear .. a boost gauge or even a scan tool that reads boost pressure will give you an idea on how boost can be affected ..and high rpm doesn't exactly mean high boost as many think that a turbo works on flow out of the exhaust

you could start with a base line just keep winding down boost untill its happy but this then puts you on the border line of climate change ie hot day cold day

i do like the idea of people chasing more boost more power ..but at what stage is your stock intercooler runs out of room ie efficiency and then just pumps in hot compressed air ?
you may find adding in a larger intercooler to drop some boost and intake temps might fix the issue
 
firstly what are your boost readings ..i am amazed some times people play with there turbos and forget to install a boost gauge other wise its just a guessing game
many people dont understand how a turbo works

you may find the different turbo has a different A/R ratio specially if its larger
when the hot side of the turbo becomes hot it runs more efficient more heat more energy = more kenitec energy to push the turbine due to expanding exhaust gasses

you may find you will have boost creep engine load plays a very big role for example at higher speeds the vehicle has to push through wind resistance this then means more engine load means more fuel means more heat

this also apply to when going up hill and full throttle in a high gear .. a boost gauge or even a scan tool that reads boost pressure will give you an idea on how boost can be affected ..and high rpm doesn't exactly mean high boost as many think that a turbo works on flow out of the exhaust

you could start with a base line just keep winding down boost untill its happy but this then puts you on the border line of climate change ie hot day cold day

i do like the idea of people chasing more boost more power ..but at what stage is your stock intercooler runs out of room ie efficiency and then just pumps in hot compressed air ?
you may find adding in a larger intercooler to drop some boost and intake temps might fix the issue

Thanks for your reply!

Well, I wasn't actually chasing more power at this stage, I do plan to but not yet, I only got this Turbo because the old one exploded so I used the chance to get an upgraded Hybird one because I could run that with the stock map and parts for now. The VGT one I was going to get, as you know would need a bigger intercooler and manifold. My aim is to always keep tempretures down but you may have guessed by now, my goal for now is to simply get the car running well enough to use until summer because I don't have any time at the moment to be messing around with it. I was told by the Turbo Centre who sold me the Turbo that this one although bigger would work quite well simply bolted on, but with slight lag at low end. Now I wasn't worried about that for a few months. But as I said before, the lag was so much it wasn't drivable, which is what lead me to try and shorten the rod enough to make it driveable for now. I have a boost guage ready to install in the big box of parts I've been collecting ready for summer, I may have to install it but I didn't want to mess around with it just yet in this rain and cold. I didn't expact the boost to be much more than the stock Turbo to be totally honest, before tuning I mean.

Anyway, I've only had the possible overboost symptoms once, as I explained above.
I've noticed as I've been driving it more it's getting better, maybe it was due to sitting with no battery, half in bits on the driveway for 4 months after the old one blew but I went out this morning and I noticed the power was getting more and more as I drove. I went up hills, and it started pulling like it used to. There is still lag at low end but nothing like it was at first... Was I too impatient? Maybe... The actuator is still 6 turns shorter than stock, I may put it back a bit to be safe for now...
 
That is a good point. Should only ever fit larger/hybrid turbos after a bigger intercooler!
I know lol.
I was going by the information given to me by the people who exchanged my old one and built this new one for me. I told them I was running everything stock, they suggested this one... So I mean what do I do they're supposed to be well respected people who know their stuff :/

http://www.theturbocentre.co.uk/
 
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I know lol.
I was going by the information given to me by the people who exchanged my old one and built this new one for me. I told them I was running everything stock, they suggested this one... So I mean what do I do they're supposed to be well respected people who know their stuff :/

http://www.theturbocentre.co.uk/
there is an old saying i picked up a very long time ago while living in the UK.... ozzy here dont understand
they advertise oxo cubes on the side of the bus but does this mean they sell them when you get on board ?

i did mention about your size of intercooler these are one of many factors this should of been allerted to your attention when purchasing your larger turbo ..along with with many others for example how does the company supplying you the turbo knows how well your engine was performing from stock ..injector grade and performance EGR ? boost leaks or a clogged exhaust
i also bet they never told you when installing this new turbo engine oil and filters are to be changed as well as air cleaner reason being this voids warranty

start off with a simple boost gauge reading manifold pressure not waste gate pressure you may find your over boosting under loads
not every spring has the same tension to another the threads and lengths is only a basic guide and not exactly accurate
 
there is an old saying i picked up a very long time ago while living in the UK.... ozzy here dont understand
they advertise oxo cubes on the side of the bus but does this mean they sell them when you get on board ?

i did mention about your size of intercooler these are one of many factors this should of been allerted to your attention when purchasing your larger turbo ..along with with many others for example how does the company supplying you the turbo knows how well your engine was performing from stock ..injector grade and performance EGR ? boost leaks or a clogged exhaust
i also bet they never told you when installing this new turbo engine oil and filters are to be changed as well as air cleaner reason being this voids warranty

start off with a simple boost gauge reading manifold pressure not waste gate pressure you may find your over boosting under loads
not every spring has the same tension to another the threads and lengths is only a basic guide and not exactly accurate
Well I told them The EGR is removed and the exhaust is completely straight through, they said the cat would need cleaning but, there isn't one so there are no blockages there :) No boxes either, just a pipe.
And I always change the oil and filters when changing a Turbo, but yes they did tell me that also. I did my own leak test with a bung on the intake manifold and an air fitting where the filter goes and it held 2bar but that was a month or so before the old one blew so, I know things could change since then. Also that only tests the pipe work and intercooler for leaks, I know that.
I've just thought, I often forget when people think of "Stock" They litrally think stock, which is right... I meant stock mapping. As I said, EGR is removed and the exhaust is straight through.

P.S this is a nice conversation :)
 
Well I told them The EGR is removed and the exhaust is completely straight through, they said the cat would need cleaning but, there isn't one so there are no blockages there :) No boxes either, just a pipe.
And I always change the oil and filters when changing a Turbo, but yes they did tell me that also. I did my own leak test with a bung on the intake manifold and an air fitting where the filter goes and it held 2bar but that was a month or so before the old one blew so, I know things could change since then. Also that only tests the pipe work and intercooler for leaks, I know that.
I've just thought, I often forget when people think of "Stock" They litrally think stock, which is right... I meant stock mapping. As I said, EGR is removed and the exhaust is straight through.

P.S this is a nice conversation :)
a turbo is just like a light bulb it can let go at any time... hopefully they also explained about turbo times and other turbo savours on the market to protect your investment
your compression test and leak down test mean nothing at this moment in time ....you may need to monitor EGTs and boost levels
but now i see you have the egr done and straight through pipe this tell me your looking for power along with a larger turbo set up

since you have covered all the hard work a basic boost gauge should be easy to install

engine load plays a big role mate and the fuel map changes during the powerband of the engine allong with engine rpms it appears you might be asking for to much out of the desired engine load and gearing rpm and speed ... and the ecu is detecting this putting into derate mode
 
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Tell me about lol. I think I've spent more time messing with Turbo's on my Focus since 2011 than I've spent driving it.
As for this Discovery, I don't have a Timer installed but I always warm up and cool down, I'm always still sitting in the car park while the mrs is already in the shops lmao!
on a side note, I've noticed I know people who don't warm up or cool down and they never have issues, then there's me who warms up for 5mins and cools down for 5mins or more and my ones are the ones to go lol.

And yeah well I did the straight pipe because I wanted that nice whistle as it spools, the old Turbo sounded the nuts, constant spool whistle. This new one doesn't make that sound actually for some reason.
And I removed the EGR because I didn't like the look of the intake manifold caked full of carbon when I removed it so I cleaned it and took the EGR off to stop it happening again.
I did all that back in 2012 when I bought the car, but as you said it's alright now because it's work already done now I'm after more grunt low down in the RPM's.

Anyway, I'm going to have a look for a place local that can map it and see what they say, right now due to other commitments I can't afford an intercooler (Which is why I was waiting until summer) so I might see if they can map it to run with lower boost to be safe for now maybe... I don't want to make damage and more work and money for me later on of course! I know mapping is the last thing to do, but as I said above I can't.
Anyway, I'll get them to have a look and see what they recommend.
Are there any places near Basildon, Essex you recommend?
 
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