turbos,external or internal wastegate?

[dman78 1]

hey peeps i've been looking at turbos and wanted to know whats the advantages or disadvantages of an external wastegated turbo to one with an internal wastegate,cheers

[dman78 1]

?

[rodney 17]

some one who knows more will be along but external more plumbing usually and higher boost/flow abilities... but dobnt hold me to that

[dman78 1]

i know anything to do with turbos gets the vr6 professors out,lol

[golfrabbit33 0]

email c2 motorsport uk with your budget/plans and youll get the info needed.

[golfrabbit33 0]

but as a rule most run a garrett gt 35r - 1.06

£1200.

[dman78 1]

is that £1200 fitted?

[golfrabbit33 0]

lol. nope just to buy it, and you got lots more to buy. look at £5k for a fair set up.

[dman78 1]

its cool,i think £1200's a good price,i got all the info on here in the vault,plus i'll just bug mr fix it until he helps me,lol

[golfrabbit33 0]

pm`d you a list Dan, the only thing i forgot was at least a grand to replace all wear n tear items in your engine + arp`s all round + spacer + gasket + rod teatment. but the list will give you a good idea of parts needed.

[matty.vrt 120]

have a look on GT3 TURBO's website i got a garrett gt35 and a tial 38mm wastgate for £1200

[FishWick 21]

I would only run a 1.06 GT35R with a full 3" exhaust and no cat personally.

The 0.82R GT35R spools sooner and works well with 2.5" systems and 3" cats under 20psi, whilst still outflowing a GT30R at the top end.

Advantages between internal and external wastegates? Mainly cost, packaging and flow requirements.

OEs favour internal WGs to keep the costs down and make the installs neater.

External gates flow more. A lot more. In fact you will struggle to find a VR6 Turbo manifold that doesn't have an external gate outlet. There is more choice of turbos which run external gates too and they're simpler from having fewer parts.

The other disadvantage of internal gates is the housing can crack around the penny valve opening.

External gates are easily changed to allow for changes in turbo size. Internal gates are part of the turbo itself and therefore you have to replace the whole thing if you want a bigger gate....or get a turbo shop to modify it.

[matty.vrt 120]

I second that .82 housing work a treat.

[jims13 6]

dan its all about what you plan to run and how much scope for the future you need.

turbo specs are purely personal prefrence .. without a doubt the larger housing will make more power and for longer when pushed to high boost.

they also affect how the boost comes in and for how long it lasts . smaller turbos spool quicker but dont last as long

bigger units are visa versa

go external wastegate , because as said , you can change them easily and manifod choice is much better. i gained nearly 30 bhp from my 3" exhaust , but i also have a 3" downpipe .

3" units do not have to be noisy , as you no i run a custom made c2 unit.

as gary has said try c2 for a price on the bits you want/need

for refrence i run a .086 ( i think ) which as you know works very well.

i also run the c2 management , which is another choice you will have to make. personally i do not think you will find a better out of the box choice

thats my two pence on it

[dman78 1]

sorry lads you've lost me with the 1.06 and .82 jargon,when it comes to projects im an absolute novice so please explain,cheers

[jims13 6]

right basically , the smalle rthe cold side number, i.e .50 the quicker it will make boost.

the larger the hotside , i.e 1.06 the longer it will hold it for .

its not a exact science but may help you make a choice ..

google is your friend, google turbo sizing .

[dman78 1]

just saw your answer jim,now its making sense,slowly

[rodney 17]

Also Stealth do a kit worth a look

[jims13 6]

im guessing dan dont want a kit ? when you pop round dan you can take a look at my recipets , so you can see what you may get.. i can also fit the kit if you get it .. as others have said there are loads of choices and it really is personal preference ..

[FishWick 21]

3" units do not have to be noisy ' date=' as you no i run a custom made c2 unit.

[/quote']

I still need to hear your system :-) You don't run a cat do you?

[dman78 1]

his car is scary,not in a hurry to get in again.

[FishWick 21]

right basically ' date=' the smalle rthe cold side number, i.e .50 the quicker it will make boost.

the larger the hotside , i.e 1.06 the longer it will hold it for .

its not a exact science but may help you make a choice ..

[/quote']

Yep, Jim's right....

Time to dust off the Garden hose versus Fire truck hose scenario again :-)

Imagine the hot side of the turbo as your thumb over the end of a hose. You're funnelling a lot of water through a tiny gap. The water in that example obviously being exhaust gases passing through a manifold and into the turbine scroll.

The huge energy from this pressure build up is then used to spin the turbine wheel. The 0.82 and 1.06 AR numbers basically being a technical way of describing a garden hose, LOL! 1.06 AR would be your fireman's hose and piddly little 0.58 or 0.63 ARs would be your garden hose. 1.06 AR can let more gases through, so is less restrictive, but as you've probably guessed, if you take away the restriction, you remove the pressure and therefore the boost is slower to arrive, aka 'lag'.

"AR" means Area / Radius and is a complex relationship between the area of the turbine scroll and it's radius. Plenty of explanations on Google :-)

All you need to know is, big AR = more flow, more top end, more lag potential. Small AR = faster spool up, less lag, less top end, broken gearboxes ;-)

Another thing we should touch on is Pressure Ratio. Remember that huge pressure the exhaust gases are seeing as they're crammed into the Turbine scroll? That is back pressure. MASSIVE back pressure. This is why traditional norm asp exhaust pulse tuning gets thrown out of the window when you stick a turbo on! The ratio of this back pressure versus intake boost pressure is that Pressure Ratio. As a basic example, you might see 15psi boost at the throttle, but the exhaust manifold will could be seeing 30psi back pressure.

You hear of people saying 268 cams are no good for boost. The overlap lets all the boost escape. After reading the above (if you're still awake!), do you think that's true? If the exhaust gases are pushing backwards into the cylinders at a greater pressure than the boost is going in, is there a chance boost can "blow out of the exhaust" on overlap? Erm, no! So 268s are absolutely fine for boost :-)

if your boost was 15psi at the throttle and 10psi at the exhaust manifold, then yeah, boost can absolutely leak out on overlap, so this is more of an issue with superchargers.

Anyway, I'm trying to explain this as simply as I can and already it's getting bloody complicated and long! LOL!

So yeah, that's the hotside. It's the most tunable part since it governs the lag characteristics and you can get several different sizes and configurations to tailor the lag and top end flow to your needs. Sorry, I should say "onset of boost" as some nerds these days don't like the word "lag".

At the other end of the turbine wheel is the compressor wheel, which has a dual purpose. It has to suck in air and also compress it.

Basically, the blades you can see when looking into shiney side of the turbo are the inducer blades. Their job is pull air into the turbo. The bit you can't see and the most important bit is the exducer blades, which force the air through the scroll, thereby compressing it. Yep, it's a hotside in reverse!! :-) Turbos really are clever bastards. They take the gases you're throwing out anyway, and convert them into chunky power. Youv'e got to love that!

There is naturally a lot more to it, but just ask if you have any Qs.

Thankfully VR6s have been turboed for about 15 years now, so some of the guesswork has been done for us.

I would say the GT35R is the perfect turbo for a VR6. 0.82 for the street, 1.06 for the 1/4 track :-)

[dman78 1]

i went on google as jim said and now i've got a bloody headache and kev with that explanation you must work for NASA,lol

i understand now but i dont really want more than 350 bhp and im sure with the gt35 thats on low boost

[FishWick 21]

I wish, I might actually get a good salary working for NASA! LOL! That is just how I understand it mate. Other folk might think differently. You certainly get a lot of conflicting info on the net these days!

It is complicated when you first get into turbos, but the more start playing with these things, the more you learn, as with everything else :-)

If you only want 350hp, then a GT35R is barely into it's efficiency zone (another complicated subject!) at that power and you might want to consider a GT30R instead.

[dman78 1]

thought as much,i dont wanna go too extreme,then i'll have to be changing everything