I have been out tuning the van lastnight, wound the boost up to 1.6 bar. Current turbo is gt2560r.
Im getting a bit of 'surge' between 4.5/5.5k when on boost. The induction noise doesnt sound clean, and once it hesitated on a long pull in 5th.
I can only assume this is down to running way too much boost and the turbo is probably way off the map. What can i look at to solve the issue, possibly different cover & comp wheel??
Isn't surge when the compressor is flowing more air then your engine can consume.
So maybe try limiting the boost till 5.5kor a smaller compressor housing.
That's exactly what Adam taught me it was. The turbo will be fine up to a point but will then begin generating too much air and you don't have as much torque as is required to cope. Hence "compressor stall" which is what it sounds like you're experiencing. Compressor surge comes afterwards as the compressor wheel has now slowed down, used up the excess air so the torque increases once more. The thing is, at the same time, the resistance on it has decreased, but the torque is too high for the lower levels of resistance. This is when you get surge, it suddenly leaps. Problem is that it falls again, then leaps, then falls (Surge and Stall).
**Geek**
Briggs, why don't you call Adam, I'm sure he'd love a break from the usual muppets he gets on the phones at work - 02085 603927
A bigger turbine housing might help if you can tolerate some extra lag ? A smaller a/r compressor can help too but it won't be as effective at making power as the bigger turbine housing of course
Or buy glens old blower £250 has the larger rear housing. I think they share the same rear turbine wheel don't they? Then sell the 28rs with the smaller housing on it.
Last edited by Logg; 02-02-2012 at 12:33.
I could actually cope with more lag, it's pretty responsive with the .63 that's fitted now. Would my setup be able to spool an .86 without gas?
I'll give adam a bell tomorrow dawn, got work to do this afternoon for a change
Bugger just looked the 28rs has a 53.9 rear wheel yours has a 53.
Briggsy,
Pop the compressor map up so we can have a look. Would interesting to see where the surge line is. My BW sx turbo has quite a narrow map in that it's at its best/efficiency at 2 bar roughly 73% and surge would be a problem +/- 25%. Did you do any calcs for your given BHP / boost requirements when selecting the turbo?
The map is on here Matt under gt2560r
http://www.turbobygarrett.com/turbob...t/turbocharger
I did do a fair bit of research but couldn't find anything 100% ideal for my setup. I mean what small turbo caters for mega boost on a small cc engine, the more I looked into it made me realise that my whole setup is pretty poor with the massive pressure drop between turbo-inlet manifold etc. In the end I went for a unit that wasn't a million miles away from my last turbo.
I run a gt28r mate but with a .49 rear housing ... I peak boost at about 24psi ... Not sure what it holds tho ... Hope to find out at scoffs event ... The induction noise doesnt sound very smooth when high up in the rev range ... I also thought it maybe compressor surge .. But then I also thought it maybe down to the type of turbo ... As the car does pull smoothly.
What about going vnt?
Can anybody point me in the right direction for a bigger ex housing?? Ive been looking but not found anything yet.
This is the spec
Turbo Compressor Turbine
Turbo PN CHRA PN Ind Whl Dia(mm) Exd Whl Dia(mm) Trim A/R Whl Dia(mm) Trim A/R
466541-1 446179-12 46.50 60.10 60 0.60 53.00 62 0.64
466541-4 446179-38 46.50 60.10 60 0.60 53.00 62 0.64
the next one i can think of is the .86 off a pulsar? prob too big tho?
That would do assuming it would fit, pulsar units are journal bearing so probably different?
yes thats right im sure iv seen some bb turbos with 86 housings? some gt28rs have them iirc
would this be of any use?
http://www.ebay.co.uk/itm/Garrett-GT...#ht_2257wt_952
That is a T3 so for one wont fit the manifold and two the ar ratio = much larger flow ratings even though the numbers close its a whole different ball game.Originally Posted by BluntyR5GTT
yes i just noticed it was bloody t3 after id fount it
Could try sourcing an anti-surge comp' housing instead?
.86 hotside will be miserably laggy. imho.
.86 is laggy on a b18ft even with the extra capacity etc...
the 86 is quite laggy on a 2.0 16v
Stop being a tart and get the bigger housing, probabley end up making more power at a lower pressure as well, win win
about as much as a chocolate tea pot with out the manifold to go with it
Ive had a sniff round for an anti surge comp with little success, any ideas??
The plan was to bang some gas on if its too laggy with a .86 or rev it to the moon like stu clark did
If your going to use abit of gas then i say an .86 might be an idea although how much gas would you consider using?
The plan is to go mappable ign so probably a fair bit. Im sure glen said i could whack a 100 shot on my engine with no problems providing its set up right.
.86
Will a .86 really be that laggy?? the current .64 isnt bad at all, full boost by 4.5-5k.
I dont even need to flat shift on the road to keep it moving. Even 1st gear is quite lively providing you can get the power down
If your getting full boost on the .64 around those revs thats good, obviously an .86 will increase that abit but if you shoving some gas in there then you'll loose that extra lag gained. I think only way to see how it performs is try itWill a .86 really be that laggy?? the current .64 isnt bad at all, full boost by 4.5-5k.
I dont even need to flat shift on the road to keep it moving. Even 1st gear is quite lively providing you can get the power down
I found out why my old .64 set up was so laggy, wish i got that sorted as was interesed how it would have performed.
Was yours journal bearing or bb?? i can imagine a journal bearing turbo to be a bit miserable but the bb units seem to be good.
Mine was journal mate, it also helped if i plumbed the external wastegate properly too!
First time i did one for my car and got it horribly wrong!
Get your housing machined mate, its nowt fancy....
If you're going efi, you can map out surge.
I'm sure ATP did an a/s housing for the GT25/28 range. If not, Ashy's on the money.
Ive had a sniff round atp's website and cant see one listed. So where could i get my housing machined to suit??
Ive got the same size intercooler as you and a t28 turbo, my car started hesitating after i worked on my carb, retard the TDC so i could run 27psi, but at the same time this was also when outside temp got lower 8' to 13 deg, car would hesitate once on boost in any gear above 2nd, me thinking turbo surge but ive had this before on my old 5 with the turbo blade hitting the outside wall of the turbo as it had play in it, i was pissed off- checked the turbo and no play it luked in gud con, so i turned the boost down to 20psi ,i checked the spark plugs for .5mm gap and adjusted them but still hasitation
p.s this was also between 4.5/5.5k when on boost
Mine pulls hard in any weather/gear mate...it will absolutely bury the speedo with ease
The problem is the induction noise sounds choppy and i dont want the turbo to self destruct.
A certain boost-hungry individual I know had a compressor housing ported recently by owen developments. I remember him saying that it cost a lot less than we both had imagined, like 80 quid or something. But, only certain housings can be ported - only a few have enough material in the casting to do the job. I think that if it's a 3" inlet there may not be enough. It's worth a phone call though.
Failing that, having an 0.42ar cover machined for the wheel won't cost you any power I think. It never made much difference for me, except that the 0.60 would surge until about 6500rpm.
1.6 bar is not a lot of boost, my turbo did sounds good till it goes as u txed choppy as it hesitates at 5k in 5th gear, i cant see how you can get carb freeze with the temp as it is in the day at that rpm but it did. hope you get it sorted as its one of the best vans ive sin in this club over the last 8 years
Ill give owen developments a shout scoff
Brigsy, Glenn might have an 0.86 left over ? Can't remember if he bought a whole new turbo last time round or just a core. If he does it will have had the penny welded up so might not be any use unless you had an external gate. New housings are like £200 if they're ordered specially through a garrett dealer.
Could you not just buy an old pulsar/gtir unit and swap the rear to see how it goes?
No, brigsy will have a ball bearing core which will not fit in to an old skool housing. Besides, I think his turbine wheel will be larger than the old T25/T28 ones.
Ok shows what I know thenwould there be a be a lot of difference in spook between a bb core and a journal then?
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