Garrett GTBB Specs .

[discopotato03]

For a good read search Garrett_Cat 7 17 13

[MonstaS4]

It's a good read, but the part numbers and specs don't match with what the garrett distributers in australia (MTQ) are selling. It appears the relevent catalog is the "Ballistic Concepts" catalog as found on Ray Hall and GCG's websites.

I rang MTQ for a price on a GT30 and they didn't recognise the part number i gave them (out of the Garrett 7_17_13 catalog). They said they had 2 GT30's there, the SB8006 and SB8006A. The specs they gave me matched what is in the ballistic concepts catalog.

My conclusion is that the 7_17_13 catalog is for the USA market only????

[DoughBoy]

Yeah it's the American market... but like you would buy a Garrett locally

[discopotato03]

This is because only the REAL GT30's , GT35R's etc use the REAL GT compressor wheels . Turbo shops are only too willing to sell you the TO4S versions because they're cheaper and OEM on many DIESELS . Look at it this way HKS have NEVER used TO4S wheels in their range period . This is not to say that only HKS spec GARRETT GTBB's work , only that they don't like/want stone age compressor wheels either . As a point of interest TO4S wheels were available in the mid late 1970's , the BCI-18C (six bladed wheels) are about 15 years newer technology and also a generation later than the TO4E series .

When the demand is high enough for the right turbos thats what the turbo shops will sell , till then find someone who will import them and reap the benefits .

[MonstaS4]

Why wouldn't you buy a Garrett locally? My REAL GT30 has a GT40 compressor wheel, so am i missing something here?

[DoughBoy]

No, but your wallet might be

[MonstaS4]

So would you care to tell us what you would pay for a GT3040 imported, including any duties/taxes?

[DoughBoy]

If you get hit by the customs stick and paying premium DHL/UPS shipping can cost as much as $2,000. Get one in via EMS for as low as $1700 - that's just from an online shop such as www.cheapturbo.com. As always, helps to shop around.

[0HR-30T]

Disco,can the 7 blade TO4S wheels really be that bad? The smaller GT25's are rated at 400hp and 440hp,and aren't turbo's "rated" at 1 bar? Surely these comp wheels could efficently spit out 20psi odd,so you'd be looking at quite a good turbo???

:confused:

[discopotato03]

Correct me if I'm wrong , the turbo you mention is called (by some) GT2540R . This monstrosity has a major imbalence along the same lines as HKS's GT2540 only worse . The drama (aside from the stone age wheel) is that the turbine is too small to power the compressor wheel . Is is imperative that the balence of compressor wheel to turbine wheel is close to ideal . The yanks made a rough rule of thumb that the major dia of the turbine should be within 15% of that on the compressor wheel , in the above case 48 trim TO4S= 76.2mm and 76 trim NS111 turbine = 53.8mm . In this case it comes to approx 71% .

The real world experience of this is that you need higher exhaust gas speeds to drive the compressor into boost than would be the case with a properly speced turbo . So more revs to get it going and more exhaust restriction once it does . Hence lag in the first half of rev range and overheated detonation friendly EGT's in the second half . Talk to Brett from GCG , his customers are getting as much power with the GT28RS (60mm comp wheel in TO4B cover .86AR exhaust housing with same NS111 turbine) as those with the GT2540R . I see this happen all the time , people look at the compressors performance potential a judge the turbo by it . What people really really N E E D ! ! ! ! to do is look at the turbine and housing FIRST . This area is the main bottle neck and has to be sorted first . I realise its difficult and expensive to play with non std exhaust manifolds and or waste gates but if that what it takes do it .

Am running out of time and fingers here but also note another rule of thumb . The more blades and thickness of blade section a compressor wheel has the lower its pumping efficiency . Any extra work a turbine has to do shows up as lag or to use the correct term boost threshold , transient response suffers making the engine feel like a choked up torqueless dog .

chow A .

[MonstaS4]

If you get hit by the customs stick and paying premium DHL/UPS shipping can cost as much as $2,000. Get one in via EMS for as low as $1700 - that's just from an online shop such as www.cheapturbo.com. As always, helps to shop around.

So i guess paying $2k locally is not so bad after all......

[DoughBoy]

If you can get the turbo specs you are after. In the end if you pay $5,000 for a turbo, and are happy with it, does it matter anyway?

I don't think the compressor:turbine size "rule" is really that valid, considering the differences in flow amounts on various designs of wheels..e.g the T04E 57 trim wheel is the same physical size as a GT30R (HKS3037S) comp wheel yet the peak flows are more than 10 lbs/min different.

[0HR-30T]

Disco-Thanks for your reply. I've given up trying to keep up with the different names everyone gives to the GT series.The turbo(s) I refer to are TO4S comp wheel (48 trim) ,flowing 44lbs/min,rated at 400hp and 440hp with 0.64 and 0.86A/R respectivly.So yes,it seems we're refering to the same unit.

Now I'm no turbo expert,but I'd like to discuss this. If this turbo is not built well,and requires high exhaust gas speeds/more revs to get it up on song,that's fair enough....But,wouldn't this just mean less use of the wastegate for control.I mean if it needs more shaft speed to work,the wastegate wouldn't need to start opening as early/by-passing as much gas,etc to limit shaft speed,so would this really matter? If anything,the requirment for higher shaft speeds to generate good boost would ensure that these turbo's would be efficient at high revs(?)

Also,the issue of exhaust housings/wheels being a restriction at high revs,and/or generating "detination friendly" egt's...surely this wouldn't be the case (at least) with the 0.86a/r housing...on say a 2.0L engine? or do you mean the actual turbine wheel creates too much turbulance at high speeds? or am I no where near it?

I notice that some "GT30"s use a TO4S comp wheel (56 trim) and 55lbs/min flow,with 0.82 (84 trim) exhaust and rated at 500hp.... still with a TO4S wheel? do these turbos share the same disadvantages you speak of as the "GT25"s?

And just to confuse things (well,me) further,there's a "GT25" that uses a GT35 comp wheel,flowing 44lbs/min-(same as the above mentioned 'bad' GT25) uses a 76 trim exhaust wheel( same as above too) and rated at 400hp????????? so that brings me back to the same question again.....can the TO4S wheels, (and thus equiped turbos) be that bad?

Thanks for your time

[discopotato03]

These GT30's you mention dont have it so bad because the larger (higher flowing turbine) is closer to the correct balence of exhaust gas flow vs compressor airflow . In a perfect turbo world your engine would have equal boost pressure and turbine inlet pressure (back pressure) across the cylinder head . This is difficult to achieve but the major advantage is beating exhaust gas reversion back into the cylinders when both (or all four) valves are open . When reversion happens (ie exhaust manifold pressure is higher than inlet manifold pressure) HOT spent gasses flow back into the cylinder to mix with the cooler inlet charge to pre heat it and polute it . The whole idea of efficient turbo compressors and intercoolers is to create airflow that is cool or dense which per unit volume gives a higher weight or mass of oxygen . If it gets pre heated again you've undone all the good work and are MUCH closer to piston crunching detonation . Spent exhaust gasses don't burn very well or contribute to power production either . Another downer is that if what power the engine developes is partially used to push the exhaust gasses out of the cylinder through restrictive manifolds/turbines/housings/exhaust pipes its less power to drive us down the road . The simplist way to look at it is forced induction tries to turn the engine into a larger capacity one with larger capacity exhaust flows .

Back to the "GT30" . The honest retailers will tell you that there about 19 or 20 different turbo's using that UHP 84 trim GT30 turbine . If your curious like me and spent months digging up turbine and compressor flow maps you also would have noticed that identical turbine and housing combinations show different efficiency levels depending on what compressor and cover are hanging off the other end of the shaft . I put the question to a Garrett production engineer (and petrol head) I know of in the US why ? He said large capacity compressor wheels need lots of shaft torque to drive , they have more bite into the air they screw through . If the work needed to drive the compressor is realistically more than the turbine wants to give you get exhaust gas slip losses through the turbine . So with the turbine turning slower than the exhaust gas wants to flow to get through it (all in a vain attemp to drive that great galoot of a compressor) the restriction sets in and turbine inlet pressure climbs . Remember I said the more and thicker blades a compressor wheel has the lower its efficiency . Well these things as well as outdated blade shapes give a TO4S wheel more bite (and resistance to turning) than later designs . Most of you will have noticed that propper GT turbos claim quite high power outputs for their size particularly when compared to old TO4's . With todays modern turbos a lot of effort has gone into reducing markedly the rotating innertia of the turbines and compressors so that less exhaust gas energy is required to accelerate them . Their open blade forms make them highly efficient at higher rpm's than the old dinosaurs so they don't need to be physically huge to move lots of air and flow lots of exhaust . Compact is good in overcrowded engine bays . So we have light weight bits that are easy to accelerate and pump efficiently with low exhaust gas restriction . I'm sure the annular contact ball bearings were put there purely because Garrett knew the old bush bearings and thrust plate could never survive the extra rpm's , not reliably .

I think the GT30/TSO4 was early in the days of the Garrett GTBB when most of the development was aimed at the turbine , later evolutions used superior compressors that pumped cooler air and required less shaft power to drive . They also work better at higher pressure ratios than earlier designs . Diesel engine designers are pushing for higher and higher boost all the time so compressor and turbine efficiency becomes more critical to the success of the package . Garrett has been developing better internals for turbos which should be appearing soon , first for diesels and eventually petrol engines .

Hope some of this helps A .

[0HR-30T]

Cheers for the reply.Interesting stuff.So from what I can gather,the TO4S comp wheel equiped GT series turbos are not much better (if any) than an old school TO4? except with slightly better responce time,due to the ball bearing core. Or would that be negated by the comp/turbine inballance?

Pitty I bought my TO4S wheel'd turbo 4 years ago.....

oh well