[Mk2] [Turbo] Compressor Surge

[mr2_rich01]

Hi Guys,
Just wondering if anyone can give me any advice on what to do, I have an MR2 Mk2 rev3 with a tdo6 turbo conversion running an apexi power fc management system, had the car mapped by Ryan at 2bartuning made 390bhp but the car in 4th and 5th hesitates really bad when under full throttle which I have been told is compressor surge, anyone know how I can stop this happening? could it be something to do with the old greddy BOV I have on the car?

Thanks for any advice guys

[bobhatton]

Hi Guys,
Just wondering if anyone can give me any advice on what to do, I have an MR2 Mk2 rev3 with a tdo6 turbo conversion running an apexi power fc management system, had the car mapped by Ryan at 2bartuning made 390bhp but the car in 4th and 5th hesitates really bad when under full throttle which I have been told is compressor surge, anyone know how I can stop this happening? could it be something to do with the old greddy BOV I have on the car?

Thanks for any advice guys

I would take it back and get it mapped correctly, it should not do that and it will not be compressor surge. Plot your air flow on the compressor map and check it

[2mad]

Agreed with Bob .. you should not have this problem ... nice stats by the way .. your probaby talking about the turbo inhalling more than the engine can handle ... take it back to ryan .. get it sorted .. nice stats though buddy , bet its fun to drive

[ashley]

What size turbine housing do you have on there, and what's your exhaust set up?

Also- what's your fueling system? Diameter pipes/ pump spec/ injector sizes/ regulator.

[Peter Gidden]

Highly unusual for Ryan to not get it right.

"Hesitates under WOT". Is that at any rpm, any boost? Thinking there may be an issue elsewhere as opposed to the mapping.

[ashley]

Highly unusual for Ryan to not get it right.

"Hesitates under WOT". Is that at any rpm, any boost? Thinking there may be an issue elsewhere as opposed to the mapping.

Yep- hence the questions...

[ashley]

Another question- what cam's?

[mr2_rich01]

Hi guys thanks for all the replies 😊 the car has standard cams and only does it under full load say 4k rpm upwards and only in 4th and 5th it's as though the turbo keeps stalling .. The car was mapped the first time on this turbo but on standard injectors and made 308bhp but no hesitation the car now has sard 800cc injectors and is running a st205 charge cooler, I spoke to Ryan about this and he told me its compressor surge, something to do with the head not being able to get rid of the boost quick enough and suggested cams but I thought the Rev 3 cams were good for 400bhp? I have an old gredy bov on the car do you think if could be anything to do with this?

Forgot to add it has a blitz nur spec exhaust


Thanks lads 😃

[mr2_rich01]

I'll give you an instance when driving say on the motorway at 70mph and go to overtake a car in 5th put you foot down and the car has no power and gives the chatter sound and the dump valve noise feels like it's misfiring I'm about to put this engine in a new shell so while its out if there is something you guys suggest I do I can do it when the engine is out 😃

Really appreciate the help guys 👍

[Peter Gidden]

So just to clarify:

Have any changes or mods been done to engine since it was last mapped by Ryan?

[mr2_rich01]

Hi peter no no modifications have been done since the mapping it did it on the way home from mapping and Ryan said it was compressor surge and that the charge cooler I had fitted was too efficient something along those lines anyhow, I bought the nur spec exhaust off you ☺️ And you also re routed my screamer pipe don't know if you remember!

[jimGTS]

i didnt think a turbo that size was big enough to cause surge.

i cant imagine a st205 cc is classed as efficient at those hp levels to be honest

if its not a mapping thing, perhaps consider a more progressive boost control setup. ie 1bar creeping to 1.2, as opposed to 1.2 all the way through.
just a suggestion anyhow.

[mr2_rich01]

Yeah I know what your saying but the car was mapped last summer and Ryan said the car didn't get above 37 degrees charge temps which I thought was really good, do you think its worth changing the dump valve? maybe put the standard one back on? or could it be anything to do with the wastegate? only asking these questions as I bought these items second hand..

[jimGTS]

could try blocking off the dump valve altogether to see if it helps.
(just make a small metal plate, couple of holes in it and bolt it up where the bov is, saves forking out for a new bov to test).

i believe surge is caused by too much air flowing into the engine from the turbo.
so potentially either run less boost.
restrict the inlet a little (smaller air filter may work)?

i didnt think a bad bov or wastegate could cause surge to be honest, i could be wrong though.

[mr2_rich01]

Ahh ok, so do you think if I kept the car as it is and put some piper 285 cams in that would help deal with the air flow? ill try blanking the dump valve totally and see if that helps..

Thank you for all your help Jim

[jimGTS]

i did think the rev3 cams flowed pretty well, well behond 400hp, like 500-600.

id hate to advise the expense and hassle of uprated cams, especially if it doesnt solve your problem.

there are more knowledgeable on here than me, hopefully some will chime in in this regard.

[mr2_rich01]

Ok Jim well thank you for your time and help really appreciate it could just do with getting the issue sorted as I said the engine is coming out and going in a new shell so while its out its easy to do work on, if its a problem with the turbo as its running near its max capacity maybe I should go for a GT3076 or something like that or would that make things even worse? just such a shame I have got the car to the power I want and its kind of made it un drivable

[bobhatton]

What is the compression ratio of the engine, piston to head clearance and max boost run. What fuel do you use?

Foot to the floor in 5th at 70mph is going to put the maximum load on the engine, is it over boosting at that time?

You may well be getting lots of knock and think it sounds like surge

[ashley]

You may well be getting lots of knock and think it sounds like surge

Pretty sure Ryan would've noticed if it was knocking when he mapped it.

[mr2_rich01]

Not sure on compression ratio but the car is run on shell v power and I think it boosts at 1.6bar max using a gizmo boost controller.. And like has been said if it was knocking Ryan wouldn't have let me leave in the car

I don't think its knock as when it's starts to surge the dump valve keeps going and it starts chattering like the air passing the turbine on the turbo and won't go any higher up the rpm but if I let off to say half or quarter throttle it will..

If I go through the gears full rpm into 4th and 5th there is no problem it's only when it's under heavy load..