ERA Mini Turbo - power spike
Turbo Mini Forums

Novice here!

Have an original ERA Mini Turbo, all the original controls in place, no additions.

I drive other Minis with injected engines, and I had noticed that not much happens under 4000 rpm
and then bang the power would come in complete with a little torque steer and clutch slip.

The ERA dashboard designers must have thought that the boost gauge was the least important of all and tucked it in the lower right hand corner of the group of 6 so it is not easy to see in normal driving.

Gauge is marked in Bar and the car does boast up to .5 bar when driven vigorously, although the guage does constantly move up and down during normal driving.

The car was on a rolling road this weekend on a Club bhp shootout, the results were a little concerning and I wonder if someone could give me the answer.

Engine power (corrected) was 92.7hp 4800rpm and Torque (corrected) was 102lbs/ft 4742
(power about right, torque higher than stated by Rover)

What is worrying is the way in which the power was delivered - nice rising line from 2000 rpm to 3000 rpm where 65 hp is reached. 62 - 65 hp is maintained 3000 rpm to 4200 when a sharp spike occurs to 4800rpm when the maximum power 0f 92.7 is reached. at 5000 rpm power falls back down to 65 then after 5500 drops dramatically.

The torque graph rises in a straighter line and peaks at the same rpm but does not drop away and remain in the 98 - 102 lbs/ft zone.

The operator showed me the boost gauge indicating what was happening with a flick from maybe .3 bar to .5 bar and back as the car passes through 4800 rpm.

My interpretation is the car is producing very little boost before 4000 rpm then spikes at 4800 rpm before losing boost.

I am assuming this is not what is supposed to happen!

Where should I start first?

I want the car to appear standard underthe bonnet - I know there are other ways I could control the boost - any advice anyone could offer would be appreciated.

that's a t3 turbo for you.....because i takes so long to spool, you need to change that to achieve smoother power delivery, suggest a quick search on gt17

"Cars are a lifetime of pain"

This is only a guess..... I remember reading somewhere about metro turbos running low boost (4psi?) until a preset rpm then it rises to 7psi..something to do with lowering the peak torque figure for gearbox longevity. Maybe the same is designed in to the ERA's. As for why the power runs out at higher rpm... no idea.

Check the hoses to your actuator and the boost controlling ecu, could be split/perished and not controlling the boost properly.

Hi Rob!

It's the 'ecu' that operates a solenoid to switch the boost from 4 to 7psi.

This is all normal and as above was done to aid longevity of the gearbox.

Unfortunately for you, Changing the turbo or fitting a bleed valve would be out of the question as ERAs should be kept original IMO.

In the 13's at last!.. Just

If you want to keep the major parts original and achive a smoother power delivery you could disconnect the "ECU", and run 4psi or use a bleed valve if you want more.

Hi Alex - I am impressed you noticed!

Thank you all so far for your suggestions, and verily I agree it is written thou shalt not tamper or outwardly change an original ERA!

You can see if the actuator is doing it's job by disconnecting the boost solenoid. My first one had a weak spring and produced a huge spike of boost which then tailed off. However, those boost figures sound about right. The more worrying thing was that you said its detonating when the boost comes in.

Did they check timing and mixture for you when on the rollers?

Also if the actuator hose was split you'll see a lot more than 8psi!!!

I think perhaps spending a few quid on a proper rolling road tune might be worth it? It's not hugely expensive and is the best way to find any faults and get the most from the engine. I need to do that on mine when it's MOTed (haha! - like that's ever going to happen!)

The mixture was good all through the test. The operator did say something about the rolling road being upset or confused by the severity of the spike.

On reflection and having read all your comments (bearing in mind I dont know what I am talking about!) 60ish hp to 4000 revs is clearly with no boost at all, then the ECU trips in at 4200 and i get maximum standard boost 7.5psi. Now the rolling road printout says the power drops off - but driving it you wouldnt say that! So maybe the problem is I am not getting my 4psi to start with! The rolling road printout which I shall edeavour to paste up here later shows hp dropping after the spike - but torque continues - is that odd?

The fear I have is getting someone to look at it who "says" they know what they are doing - but actually dont have as much experience as the lovely people in this forum!

Just read the Rover Owners manual and it says "Smooth power delivery up to maximum boost 7.5psi at 6200 rpm!

Now am I being picky expecting a 22 year old car to perform to Rover's claims!!

To get 90odd bananas at 4800 would need way more boost than 4psi.

Something is definately odd with your results.

Fastest 998 mini in the world? 13.05 1/4 mile 106mph

I think your right about not getting boost before 4200 rpm.

Thinking about the metro unit, it ran a high compression ratio so 60 bhp sounds about right for na operation.

So I would guess that below 4200 rpm the actuators allowing to much bypass to let any boost build. I would also guessthat at that magic 4200 rpm the ecu shuts the actuator and hey presto massive boost surge.

I'm not that clued up on metro ecu - does it monitor boost or does it just open and shut the actuator a given amount?

Maybe if it monitors boost there is a hose split or partially blocked?

And if it doesn't monitor boost them the actuator may need the correct pre load to give said boost as original

Something to think about!

Edited by almichie on 23rd Mar, 2011.

Well here goes!

Should be a copy of the rolling road report:
http://i1186.photobucket.com/albums/z363/r...pg?t=1300906685

Just the one picture I have on my pc at work:

http://i1186.photobucket.com/albums/z363/r...pg?t=1300906783

More to follow!

Hopefully this one will be bigger!

http://i1186.photobucket.com/albums/z363/r...pg?t=1300906959

very nice!

Really this needs to go back on the rollers with someone who knows what they are doing.
I would personally remove the boost modulation stuff and wind the actuator up to give around 7 psi all through the rev range. Then run it on the rollers and see what it does then. It may be something daft like the actuator has gone weak over time.

That looks bloody clean!

nice, there lovley cars, classic!

have seen similar if the actuator is sticking, but tbo thats a wild guess, the car really needs to go infront of someone who knows there way about it.

turbo 16v k-series 11.9@118.9 :)

Denis O'Brien.

Did the ERA use the same boost modulation system as the Metro?

Fastest 998 mini in the world? 13.05 1/4 mile 106mph

The ERA did use the same boost modulation system as the metro, but the ECU was modified slightly to give greater than 4 psi boost sooner (but still a maximum 7 psi).

This is taken from the yellow bible and shows how the boost should rise.

Interesting, cheers.

Fastest 998 mini in the world? 13.05 1/4 mile 106mph

i 'd agree with denis ,looks a lot like a sticking actuator .

lots of wd40 or plus gas and wiggle it open and shut with a spanner might be worth a try .(if you can get at it )

and of course check its pipe .

Medusa + injection = too much torque for the dyno ..https://youtu.be/qg5o0_tJxYM