Hi guys, i'll start with my spec first MD321H Turbo with standard size silicon inlet pipe, Gt spec headers, Power Enterprise 550cc injectors, K&N induction kit, Hybrid front mount, Fuel lab pressure reg., HKS SSQV, Blitz Nur spec R with 3" open neck down-pipe, Ecutek'd ECU done by Zen Performance 3 weeks ago, there are the main bits, but the reason for my post is due to the compressor surge that i'm getting, it's loud as F*CK! I've spoken to Mark(top bloke) at Lateral which is where i got most of the parts from and he says that the MD321H is not a 'Surgy' turbo normally , i've read so many good things about the turbo, so it must be my setup that's causing it. I get surge at part throttle and full throttle! And like i said it's LOUD! Does anyone have any tried and tested things that they have done to reduce the surge, can Zen Performance alter the map to reduce it?? Help would be much appreciated, cheers

 

I have read about reducing the inlet pipe somehow, but won't this effect the performance?

 

Hi, I ran an MD321H for a couple of years with no hint of surge, even with loads of duty. You say you have a standard size inlet pipe... I thought all H's had a 3" inlet, therefore requiring an uprated samco type intake pipe? Maybe you're getting surge due because of this Just a thought.

 

I recall having a conversation about this with you, and the thing that is really confusing is your comment regarding surge on "full throttle" !

I did actually speak to a couple of mappers about this, and they too were baffled.

I certainly think it would be worth speaking to Paul at Zen, and seeing if it can be run on his rolling road, where it can be checked under the bonnet whilst running.


This is the first time I've ever come across a turbo surging on full throttle !


Mark.

 

slightly off topic, but what does a surging turbo sound like? been reading this and im a bit confused

 

...loads on you tube.

here's a good one...

YouTube - True Compressor Surge

 

The inlet pipe is the standard size mate, from my understanding you need the 3" inlet with the MD321T and not the H. Mark from Lateral supplied most of the bits. From what i've read mark's inlet pipe is better than the Samco inlet pipe anyway.

 

I get quite a bit of surge on my 321T, watching that youtube vid has scared me a bit now, as it does happen on full boost, and sounds like it is "bouncing" also the boost guage is flitting up and down as well.

 

Hi Mark, cheers for your help mate, i know Paul is very busy all the time so it's quite hard to get hold of him, I certainly might be wrong with what i'm hearing but i do know what compressor surge sounds like, as my old Renault 5 GT turbo had lots of it, running no dump valve like an idiot at 21 psi of boost. I've spoke to Sam at Zen and he's been very helpful aswell, i've also e-mailed Bob Rawle and he says that alterations can be made to reduce the surge at part throttle through the Ecutek map, so that the boost doesn't come in so aggressive, he says the boost response can be profiled. From what you've said Mark, i'm definitely going to get it back on the rollers with bonnet up like you said mate, i'd like to take you out in my car mate, to see what you think, but that's not really possible. I'm going to see when the next rolling road day is around my area and get to it, and i'll keep you updated. It's sounds like i might be wrong with the full throttle surge, i hope i'm wrong. Cheers mate.

 

With my air filter i had to cut down the Samco hose to the air filter for it to fit, which has made it alot shorter than the original setup, i wouldn't mind getting the APS cold air kit but it wouldn't fit with my intercooler, my next setup will be the Lateral intercooler/rad. setup.

 

Hi Daz

I'm running a 321H on an 03STI making a tad over 400bhp. My spec is virtually the same as yours and I also had it mapped by Paul, who did a brilliant job I might add. There's not a hint of surge anywhere in the rev range regardless of throttle input.

The only real difference in our specs is that I'm running a Hyperflow topmount intercooler - not a FMIC. Funnily enough, I did have a Hybrid FMIC fitted but decided to swap back to TMIC because I wanted a sharper throttle response than I was able to get with a FMIC. Having said that, I can't see why a FMIC would automatically equate to more surge

I suggest you take it back to Paul and get everything checked over thoroughly.

HTH matey
Andy

 

PS - having looked at your engine bay pic, I should also add that another difference is that I have a Hyperflow CAI mounted in the wing

 

Cheers for your comments mate, i'm certainly not blaming anyone for why i'm getting surge, it's just one of those things that Mark says happens when the engine is flowing so well and the engine can't consume the amount of air that is being produced. As far as throttle response is concerned, i really don't mind the front mount, it drives really well, power is nice and strong! I think the setup that i went for is perfect for a road car, and the parts from Lateral are the best quality i think money can buy. The only cheap thing i bought was the hybrid front mount which is good for the money and works! I'll get it sorted mate, cheers for you advise.

 

It's not a question of blame. It's just that you've invested plenty of wonga into getting a quick, driveable car and it's not quite how you want it. You just need to dig a bit deeper and find whether there's any particular component or combination of components that are giving rise to the problems you describe. This is where the advice of an expert tuner becomes invaluable. Good luck with it.

PS - I've also dealt with Mark at Lateral and agree that all the kit he sells is top notch

 

You 'knocked the nail on the head' there mate', i'll keep everyone updated. Cheers.

 

Hi mate, when the boost gauge is affected, it means that the air fluctuations are going past the MAF sensor, which is bad from what Andy F says!!! This will effect the readings from the sensor, which could cause detonation. I've got a new Blitz MD boost gauge coming next week so i'll see if mine is also effected.

 

Try swapping back to the stock recirc DV.

I had bad surge on a 20g due to a HKS VTA. I swapped back and it cured it right away.

 

may not be connected, but i had surge on a 53STi(VF35), fitted a 3 port solenoid with a map tweek and was spot on after that.

Lee

 

I had surge problems with a VF35 and a TD05-16G, ever since fitting a FMIC. It couldn't be mapped out. Without getting into the theory of it all, lots of little things almost completely cured it. 1: swapping my Forge recirculating DV back to an OE black plastic one. 2: swapping my big bore silicone inlet pipe for an OE black plastic one. 3: swapping my quiet STi backbox for a Prodrive one, slightly noisier, but made a huge difference to turbo response.

 

I've read that the version 4 recirc valve is the better one to have, why is the version 4 so good? Would the standard recirc valve be alright at 400bhp??

 

Hi mate, i didn't say in my spec but i have a Perrin Performance 3 port boost solenoid, cheers anyway.

 

Interesting topic.


Please take note that fitting any type of dump valve doesnt cure surge at all, what it can do is recirculate the excess pressure, but it only does this if the spring in it isnt actually strong enough to do its job correctly because with a strong positive pressure in the inlet it shouldnt be open at all.

I wonder if many of your are confusing actually on power, throttle open compressor surge with the noise you would normally get when you back off the throttle? (Often wrongly reffered to as wastegate chatter...)

 

I had liftoff / part throttle surge on a vf34. To make matters worse i was also getting maf reversion ! So knock counts quite high eek.

Running - larger avo silicon intake, 4-1 headers , 3"tbe and PFC.
It seems common with silicon intakes on good flowing engines.

My solutions - fitted an AVCR to tailor the boost profiles vs rpm. Lower boost levels at lower rpm ranges. Also i suspect the boost control with the avcr solenoid is better than factory.

BOV to atmosphere solved the Maf Reversion. After i put the p20 on i found i could return to recirc.

Then later I swapped the p18 housing on the vf34 to a larger p20 exhaust housing.

Possibly if all else fails can you change the housing on the md321h to something larger - or run a 321T ?

 

I have not come across surge on the 321H but when I have come across surge on TD05-06 20G it has been possible to reduce or eliminate this by constricting the silicon inlet tract just prior to the turbo compressor inlet. The effect of this is to speed up air flow before it hits the turbine, I guess.
I think the cause of the surge on the 05-06 is a mis match between the exhaust and turbine wheel. The problem does not occur on the 18G as that is clearly less of a step.
Given the above and everybody agrees the 321H is not prone to surge I think the advice you were given by Bob Rawle is spot on and he would be able to substantially map out the surge you are experiencing or identify the root cause of the problem if it was not actually down to pulling the boost in too quickly. It is very tempting to pull the boost in quickly but sometimes that manifests itself with surge.