47 replies to this topic

[Lps]

Does anybody actually bother rebuilding KKK's or is it just a case of the bits are so expensive you may aswell just buy a new one from Courtneys or the like?

And secondly, with the growing number of people i'm seeing on here using different exhaust's & getting their own made (yes you Nev!) why arent more & more Tubby owners swapping over to Garretts??? All i ever read on the other forums Vauxsport/Astra owners/Migweb etc etc is how p*ss poor our OEM/VXR turbo's & mainfolds are. Cracking, failing after very few miles seem to be the norm over there (one guy had 4, the last failing after 900 miles??) from what i can see. More & more of those boys are going for Garrett's, so why don't we see more of it happening over here??

Is it just a space restriction thing that we can't squeeze a manifold down the back for one, or is it that most people CBA? I know thorney had a super duper bells & whistle one made up yonks ago that cost the inveitable £1908623754895 but can't say i've ever seen anything else about them.

For instance....

< Linky >

"Turbo Chris" sells these Stage 2 Garrett T3's & tubilar manifolds over on the Astray forum for £650! (only about £150 more than a new VXR unit!)




Now i'm not saying ok, go ahead and squeeze a T3 in (doubt it'd fit easily?) but surely a T25 would go in?? plus there'd be bugger all lag with one of them? You could even go down the roller bearing charger route and sling on a GT25 family unit which are supposedly good for up to 330Bhp or for you Stage 4+ boys get a GT2871R for 460Bhp!

< Garrett Clicky >

Why is this not an option?

[Duncan VXR]

I have gone with a hybrid VXR unit which can be rebuilt from your std poor vxr unit. Info from the turbo company below; 'Main differences are the high flow 35Lb/min compressor wheel, motorsport 360 degree thrust bearing for high boost pressure, flowed and ported manifold and wastegate, CNC re-profiled compressor cover and uprated actuator. The actuator is set to 1 bar (14 psi) and we are seeing so far 340HP from this unit.' I am also getting my manifold ceramic coated to help with engine bay heat and also should help with when the rain gets on my previous glowing manifold Cheapest option to step up from a std vxr unit which WILL fail at stage 4 as everyone knows (how long depends how you drive but will fail) A rebuil of std vxr turbo is about £270 all in so if your manifold is ok this is a cheaper option. Brand new vxr turbo is more like £475 GT2871 would be a nice setup and did think about going down this route but think 315bhp lag free will be enough for now and of course reliability which the std turbos do not give. Also once above 350bhp you really are going to have to start thinking about rods and in my view if your changing the rods you might as well have a play with the crank (l/B) and then change the cams and all a sudden you have sold you 2nd kidney to pay for it all lol LEH engine internals will be fine at sub 340bhp so cheap option for me - cams only getting done as the head is off to get a snapped bolt out. May do the bolts while the oil is out but again if I am going to do this I would be tempted to baffle the sump lol - cant help myself Hope that helps a bit - need to stop working on other cars and finish my own

[Lps]

Thanks for the reply Duncan, it was more of a theorectial question rather than a "i want to do this this and this blah blah" etc

Could i ask where you got the quotes for the turbo rebuilds please? Im toying (still) with the idea of going VXR on mine but as you say, eventually it will/may fail. It's the manifolds i find so dissapointing tbh, i mean you regularily see big power Cosworths still with standard manifolds (ok so some 2wd ones do suffer) but in the main they hold up fine! These Vxl ones seem to be made of cardboard

[Winstar]

One of the reasons that people stick with the KKK, is that it is very well matched to the engine to give low lag and the compressor wheel design on the Astra VXR turbo is very efficient desgn. The probelm with comparing to what other ZLET instalations do is that they are oftern not bothered as much about lag as you would in a light weight mid engined car. A big turbo will make you fast in a stright line not nessesaryly round the corners. What we really need is the manifold cutting off at the volute crtical area and a flange welding on then you can get a proper maifold made.

[Duncan VXR]

AET turbo's Andy the director knows his stuff One reason for ceramic coating is to try and help witht the bog manifold issues, I am STILL toying with the GT turbo option on mine lol so could always sell you my hybrid vxr turbo / manifold? VXR manifold is a lot better for not cracking than the LET turbo version

[Duncan VXR]

One of the reasons that people stick with the KKK, is that it is very well matched to the engine to give low lag and the compressor wheel design on the Astra VXR turbo is very efficient desgn. The probelm with comparing to what other ZLET instalations do is that they are oftern not bothered as much about lag as you would in a light weight mid engined car. A big turbo will make you fast in a stright line not nessesaryly round the corners.

What we really need is the manifold cutting off at the volute crtical area and a flange welding on then you can get a proper maifold made.

That is my big worry that it makes driving fast in the corners a bit - well difficult lol

Do not think something like a 2871 or even 2860 would be that bad on lag but hard to say as I have no idea about matching turbo's to this engine

Winstar do you think there is that much gain to be had from playing with the manifold for the vxr / vxr hybrid turbo's? Or is it just to help the cracking issue?

Thanks

[slindborg]

good boost control is they key for driveability really. Lee, just nick a VGT off a 2.4 transit and see how long that lasts lmao. Would be excellent driving though

[Winstar]

AET turbo's Andy the director knows his stuff

One reason for ceramic coating is to try and help witht the bog manifold issues, I am STILL toying with the GT turbo option on mine lol so could always sell you my hybrid vxr turbo / manifold?

VXR manifold is a lot better for not cracking than the LET turbo version

I'm sure he does but how much time, parts, development, etc are they going to invest for a very small market ie the VX, your far more likely to just get what they've seen work on a astra or other hatch.

I'd be wary of ceramic coating the cast maifold as the cracking is caused by thermo-mechanical fatigue the hotter the maifold gets the more thermal stress so the less cycles it will take to crack it. It could work by coating the inside of the runners but would be difficult to make sure you didn't restrict the flow

That is my big worry that it makes driving fast in the corners a bit - well difficult lol

Do not think something like a 2871 or even 2860 would be that bad on lag but hard to say as I have no idea about matching turbo's to this engine

Winstar do you think there is that much gain to be had from playing with the manifold for the vxr / vxr hybrid turbo's? Or is it just to help the cracking issue?

Thanks

As said above aftermarket matching is oftern done on trail and error/ whats worked before on the turbine side than the comp map matched properly the garrett turbos are alright but not the best maps I've seen the do have the advantage of being ball bearing though which makes them perform better.

you could inicrease the flow rate though the turbo and also the high expansion ratio efficiency be opeing out the critical area of the volute but it can cause alsots of other problems, I could go on for hours about the pros cons effects etc. But the main effect would be to remove the part of the housing that is suseptable to cracing

good boost control is they key for driveability really.


Lee, just nick a VGT off a 2.4 transit and see how long that lasts lmao. Would be excellent driving though

2.4 is too samll you need about a 6l a dodge ram for example I reckon one of the Holset sliding vane VG would be up to temps only problem in they are about half the size of the engine lol.

Edited by Winstar, 24 February 2009 - 11:04 AM.

[Duncan VXR]

I'm sure he does but how much time, parts, development, etc are they going to invest for a very small market ie the VX, your far more likely to just get what they've seen work on a astra or other hatch.

I'd be wary of ceramic coating the cast maifold as the cracking is caused by thermo-mechanical fatigue the hotter the maifold gets the more thermal stress so the less cycles it will take to crack it. It could work by coating the inside of the runners but would be difficult to make sure you didn't restrict the flow

----------------

As said above aftermarket matching is oftern done on trail and error/ whats worked before on the turbine side than the comp map matched properly the garrett turbos are alright but not the best maps I've seen the do have the advantage of being ball bearing though which makes them perform better.

you could inicrease the flow rate though the turbo and also the high expansion ratio efficiency be opeing out the critical area of the volute but it can cause alsots of other problems, I could go on for hours about the pros cons effects etc. But the main effect would be to remove the part of the housing that is suseptable to cracing

Thanks for the reply, the more I learn the less I understand lol

Interesting regarding the ceramic coating - did wonder if cracking would be an issue but Zirotec seem to think it would be ok. Camcoat are the other main ceramic coating company and they do treat the inside and outside of the manifold but again did not like the idea of it been inside the manifold before the turbo. Sure they said it was 0.018mm thick and is a cemical coating which is different to the Zirotec method.

Agree that this turbo has been developed from the Astra VXR setup as this is a lot bigger market. The big thing for me originally was more reliable unit over the VXR until but any extra flow perfiormance was a bonus

Winstar from your experiance do you think it is the best way forward to get the manifold and complete exhaust ceramic coated (this was what I going to do) but now wondering if I should leave the manifold alone and just get the exhaust done????

Thanks again
Duncan

[Winstar]

Winstar from your experiance do you think it is the best way forward to get the manifold and complete exhaust ceramic coated (this was what I going to do) but now wondering if I should leave the manifold alone and just get the exhaust done????

Thanks again
Duncan

In my previous job at holset/cummins turbos we did alot of work to do with housing cracking, admitadly it a little different diesels don't get as hot therfore the stress is lower but they heat up and cool down alot. Where as a petrol engine gets alot hotter but generaly only goes though one cycle every journey. so if you think about breaking a paperclip a lots of little bends back and forward or a few big ones, and the bigger they are (ie the hotter the petrol turbo gets) the less it takes.

My personal opinion would be to leave the manifold as is and just do the rest of the exhaust. If Camcoat could garantee an even layer through out the inside then I'd go that route as it would improve the turbo performance and reduce the temp of the metal. But there are alot of potentai problems with applying it evenly and the last thing you want is a big blob of coating in the volute not only will it loose perfomance but it can cause a pressure spike that can in turn snap a blade in a few hours through high cycle fatigue.

[Lps]

One of the reasons that people stick with the KKK, is that it is very well matched to the engine to give low lag and the compressor wheel design on the Astra VXR turbo is very efficient desgn. The probelm with comparing to what other ZLET instalations do is that they are oftern not bothered as much about lag as you would in a light weight mid engined car. A big turbo will make you fast in a stright line not nessesaryly round the corners.

What we really need is the manifold cutting off at the volute crtical area and a flange welding on then you can get a proper maifold made.

But a T25 is pretty tiny really, i mean say you took the smallest of the family thats good for up to 270Bhp according to Garrett which im assuming would be about spot on for up to stage 3ish? They have bugger all lag, and surely would hold together better than our OE units and possibly the VXR one. I tend to read a lot about manifold failures, which in turn means new turbo thanks to the fantastic design i just wondered why nobody took the plunge and went over to Garrett tbh.

I'm not after a huge turbo with tons of lag (been there done that) it's just Garrett offer far more scope turbo choice wise as opposed to our 3 (Let,Leh & Leh hybrid) I havent looked at how many of the FWD lads suffer with cracked manifolds, doubt it's so common as they obviously don't have to suffer the heat build up we do.

[Winstar]

But a T25 is pretty tiny really, i mean say you took the smallest of the family thats good for up to 270Bhp according to Garrett which im assuming would be about spot on for up to stage 3ish? They have bugger all lag, and surely would hold together better than our OE units and possibly the VXR one. I tend to read a lot about manifold failures, which in turn means new turbo thanks to the fantastic design i just wondered why nobody took the plunge and went over to Garrett tbh.

I'm not after a huge turbo with tons of lag (been there done that) it's just Garrett offer far more scope turbo choice wise as opposed to our 3 (Let,Leh & Leh hybrid) I havent looked at how many of the FWD lads suffer with cracked manifolds, doubt it's so common as they obviously don't have to suffer the heat build up we do.

the 270 bhp refers to the comp wheel size not the turbine stage size that is what defines the lag of the turbo really and I suspect that as is offtern the case with the high volume turbo makers it's a one size fits all tubine stage.

I agree that the design isn't good but does it last the warrenty period for 90% of the cars? yes. Then I assure you the manufacture will be happy and the turbo manufacturer even more so as the parts markup is hidious.

I think you also underestimating the amount of pipe work etc that will need to be changed. I'd expect it to cost more than twice what an astra VXR turbo cost therfore unless you want better performance ie more power, is it going to last longer than 2 KKK's?

Edited by Winstar, 24 February 2009 - 12:01 PM.

[drew]

What you want m8. is the GT 28;60 RS this will give you 360 hp. there is one a bit smaller the gt 28;60. ok for about 290..hp. the rs one is better as it will give scope for later tuning. 0,64 exhaust housing is probs the best one. .

Edited by drew, 24 February 2009 - 03:55 PM.

[VXR 43]

good boost control is they key for driveability really.


Lee, just nick a VGT off a 2.4 transit and see how long that lasts lmao. Would be excellent driving though

Is there any reason why no one is running a boost controller on a modded VX?

Any high powered/modded jap Sub/Evo all seem to have a controller to help smooth the driveability.

Its something that i am thinkin of fitting myself.

[drew]

one will be going in mine m8. allready got one a blitz twin sbc. a bit old but very easy to use. D .

Edited by drew, 24 February 2009 - 05:10 PM.

[Lps]

What you want m8. is the GT 28;60 RS this will give you 360 hp. there is one a bit smaller the gt 28;60. ok for about 290..hp. the rs one is better as it will give scope for later tuning. 0,64 exhaust housing is probs the best one.

I'm not thinking for out and out BHP i just fancied something not made from Cadburys

[Duncan VXR]

What you want m8. is the GT 28;60 RS this will give you 360 hp. there is one a bit smaller the gt 28;60. ok for about 290..hp. the rs one is better as it will give scope for later tuning. 0,64 exhaust housing is probs the best one.

I'm not thinking for out and out BHP i just fancied something not made from Cadburys

Then the hybrid should tick the box turbo technics do one as well but not cheap!

I have a HKS boost controller but not used it yet as stayed OE

[Lps]

What you want m8. is the GT 28;60 RS this will give you 360 hp. there is one a bit smaller the gt 28;60. ok for about 290..hp. the rs one is better as it will give scope for later tuning. 0,64 exhaust housing is probs the best one.

I'm not thinking for out and out BHP i just fancied something not made from Cadburys

Then the hybrid should tick the box turbo technics do one as well but not cheap!

I have a HKS boost controller but not used it yet as stayed OE

Is that from AET Duncan?? had a brief chat with them today re: my concerns with the OE Vx kit seems a very helpful bunch!

Are you having yours modded to Hybrid or just getting one off their shelf?

What benefits is the hybrid supposedly meant to give over the OE LEH unit?

[Nev]

Good to chat to you tonight Lee. Looking at the pic of the manifold on the Astra forum, I think it sticks out a bit further than the OEM one, and might foul the bulkhead on the VX220... When I take my floorpans off in a few days, I am going to measure the distance from the cyl head to the bulhead so as to know how far out the manifold can reach. However, it would be wise to keep the exhaust runners a certain distance away from the bulkhead or they might melt it (with the fuel tank right behind!!!!!!). Nev.

[Lps]

Sounds like a good plan Nev, would be interesting to know just how much room to play with there is... keep me posted with how you get on