help on loss of power
Turbo Mini Forums

Hi all , ive not done much investigating as yet but thought id get the ball rolling with you guys .

My car ran perfect last year , ive had the engine out to swap the cam , gone from a kent 266 to a phase 2 and swapped my t3 for the gt20
Gone back to the rollers and I'm 20 hp down from last year but more boost !!!!
I drove the car last week and if I floored it it comes on boost then 5k ish it just looses power and doesn't want to rev like its lost its boost , this has shown on the rollers !!
We have fuel , plenty of boost and timing is ok , car doesn't miss or run funny but just wont pull the power ?

Any thoughts or things I can or should check !

thanks men , ps the graphs show last years run to todays

Cam definately timed in correctly ?

Phil.

WWW.TURBO-MINI.COM

turbo intake pipe sucking flat?
was any tuning done on the dyno? maybe it needs more/less advance?

mine used to hit a wall at 6200 ish rpm i always put it down to the na/mg cam

i didnt like the P2 cam on my first build but many people get great results with it

Yes i moved to the darkside

Instagram @jdm_brett

Phil , I'm going to say yes but suppose it's something that needs checking !
It can be done in the car easy enough carnt it ?
Brett , altered timing and leaned fuel off a bit but nothing mate much difference .

With the 266 in I had the rev limit set at 7200 but it felt like it would just keep pulling !

Does the boost level actually drop at 5k?

In the 13's at last!.. Just

No it stays the same

good valve springs ?

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

Blue role in the intercooler?

Ha ha, ive allready checked for blue roll .

Id like to say the valve springs are fine but somthing else to check thankyou

So does the engine itself seem healthy ?

Does it run fine ? despite the alleged drop in power ?

Does boost behave as expected ? No strange changes in AFR ? Has timing been confirmed as accurate at all times ?

Is ignition system good ?

And of course the other mechanical items mentioned, valve clearances, springs, cam timing etc.

9.85 @ 145mph
202mph standing mile
speed didn't kill me, but taxation probably will

How do the plugs look? might need regapping

Have you got a bleed valve fitted? With the gt17 on the upside down skip we had to have a welding tip inside the middle leg of the bleed valve before we could get a decent anoint of boost out of it. On the rollers with a 2 mm restriction we could only get 14psi.

Car runs and drives fine , no misfires , spitting back , doesnt run warm good oil pressure , doesnt breath heavy etc , timing all good , plugs looked good , it doesnt alter or afr or drop boost but just wont pull any power over 5
On the road it spools up the turbo very fast and sounds like its going to unleash hell !! You then keep your down and it comes on boost but hits a brick wall as if its lost all boost but it hasnt !!
Afr and boost all backed up by my gauges in the car showing the same as the rollers

clutch slip?

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

I had similar once, was the mesh I was using as an air filter.

Also what turbine size was the T3 and what size is it now?

And is your boost pressure measured at the manifold? or further upstream

turbo 16v k-series 11.9@118.9 :)

Denis O'Brien.

also, its a bit sketchy but try a run with the wastegate pipe disconnected (using your right foot and common sence to keep safe) if boost still limited you have a serious restriction or leak somewhere. i.e. wastegate is likely fully shut at high rpm strangling the hell out of the engine.

turbo 16v k-series 11.9@118.9 :)

Denis O'Brien.

Definitly not clutch slip

Boost pressure is measured in the manifold
Not sure in turbine size comparison , im still running the same air filter .

Its producing the boost and does creap up slightly at the top end of the revs !

Could you have accidentally moved the rev limit down to 5k?

In the 13's at last!.. Just

No , it will rev right up to the 7200 limit

The way that the power curve has swivelled around the 5000rpm value, I would guess that the Dyno settings may have been changed.

Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
Stephen Hawking - "The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge."

Just read your build thread.

Did you tell the Dyno man that you had changed the FD ratio?

Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
Stephen Hawking - "The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge."

Yes told him about the final drive and we looked to see what it had given me from last time . 8 mph

If you went from a cosworth or larger t3 exhaust housing to a gt20 housing thats suited to a diesel thatll do it. I picked up serious top end swapping out to bigger exhaust housings and wheels on th same compressor when i was playing with turnochargers.

turbo 16v k-series 11.9@118.9 :)

Denis O'Brien.