discopotato03

Compressor and turbine maps are very different because of the environments they live in and what is expected of them . The purpose of the compressor is to push a greater weight or mass of air into the cylinders than atmospheric air pressure can achieve on its own . The problem is that air mass or density changes with temperature so in order to keep the density up compressors need to be highly efficient . The aim is for the engine to inhale more air so we can burn more fuel to develop more horse power . Desirable qualities in a compressor are low mass - less weight for the turbine to drive , mechanical strength - ability to withstand the centrifugal forces at high rpm without bending and breaking the blades , ability to slice cleanly through the air its pumping - minimum friction and less drive load to be shouldered by the turbine . Compressor maps are invaluable for showing the capacity and limitations of a set compressor and housing combination . They show the all important surge line and efficiency islands plus mass flow generally in pounds vs pressure ratio , the speed lines are important too . With some formulas its possible to crunch the numbers to assess a compressor/housing's suitability for any engine . The turbines purpose is to recover as much energy as possible from the engines exhaust gas flow whilst posing the absolute minimum restriction to its flow . I'm told that a third of the heat energy developed in the combustion process goes out the tail pipe , some of this energy can be used to drive our compressor . Turbine maps look different to compressor maps because we are mainly interested in mass flow VS pressure , note the flow line rises to a certain level and beyond this point does not increase with pressure . This is called turbine inlet pressure and is a measure of resistance to flow . Also note that flow rises with ARR (Area Radius Ratio) for a set turbine trim , so its not possible to rate a turbines flow by merely looking at its exducer diametre or the housings at this point . I'm not sure as to how they work out the efficiency number , it seems logical that the shaft power generated vs mass flow and temperature drop across the turbine is how it works . Obviously higher is better meaning more energy rcovery for less flow restriction . The general consensus is low turbine efficiency = more turbine lag . I believe correct turbine/compressor matching is about have equal pressure in both manifolds under boost so that the engine gets to scavange properly on the valve overlap period . Poorly thought out combinations that lead to ratios of 2.5 to 1 (typical and can be worse)exhaust manifold pressure (EMP) vs inlet manifold pressure (IMP) lead to reversion and pumping losses . Turbo production engineers (of the petrol head variety) agree that keeping the turbine diametre within 15 - 20% of the compressor makes for similar tip speeds or mach factor . If one reaches its mechanical speed limit appreciably before the other then potential is wasted for no good reason . Have to go will round this off later . Cheers A .

The GT30 and GT28 exhaust housings are very different internally both being based around their native turbine major diameters ie 60 and 54mm . They modified or cropped the 60mm to the maximum size that would fit in an overboared GT28 housing and came up with 56.6mm . The Hub is too big and heavy for the shortened blades and the blade form is not the best in shortened form . The GT28 nozzle form was designed for GT28 turbines and so not optimised for the diametre of the hybrid . Turbine efficiency suffers and shows up as lag .

Dale unfortunatly exhaust housings cant be machined smaller and this is why the problem exists . Neither Garrett or HKS offer an integral gate T3 flanged GT28 exhaust housing for the 76 trim NS111 turbine . Out of time . Cheers A .

Difficult to say , depends on the power curve you want and what you use the car for . First off you need to choose an exhaust manifold and style of wastegate as this will dictate mounting flange size and integral/external gate . If you used a GT30R in large turbine housing form (1.06ARR) its fair to say it'll have a bit more response than its larger brother . You also have a .82 housing to come back to if its boost threshold is a little high . The GT35R is getting a bit more serious but if its airflow is what you need use it . I would start with the .82 exhaust housing if you do this , there is a .63 housing for it but the penalty for waking it up too early is compressor surge . I've not had time to research it but I think there are a couple of different trims for the 82mm GT40 compressor , the GT35R uses the largest 56 trim size . The HKS version of the GT3040 uses a 50 trim version of it and the BA XR6's GT3540 I'm not sure . The last one uses a .50 ARR T04E compressor cover with the smallest diametre snout on it which I'm not sure a 56 trim would fit in . If anyone has one of these XR6T turbos could you tell me the diametre of its inlet in mm so I can work out the approximate trim size . A small trim compressor GT35R would come on a little earlier and still not be short of breath at the top end again depending on what its used for . Cheers A .

For those wishing to see the elusive GT3071R do a search on Garrett Catalogue 4-02.qxd . Click on the second title down to download the 5.19 mb of catalog . The GT3071R is on p26 of the pdf . Cheers A .

I'm curious to know if it has aggressive camshafts in it as that would show up as reversion with a single common throttle plenum manifold . I think Nissan used the std multi throttle system so that longer overlap cams , that breath and scavenge well , don't get the reversion problem . Could the noise be a boom box effect from having all the inlet ports open to the plenim volume . Jun being aftermarket may not have put much thought into sound suppression . Also the high power engines that use these inlet manifolds , do these have huge turbos sort of flat out or nothing power delivery ? I'm curious as to why you would use this with more response friendly turbos . Please note I'm not having a dig at you just wondering about maximum effort manifold with road user friendly turbos - would they compliment each other . Cheers A .

No I can't either , all I get is a while box with a small red X in it . Cheers A .

The HKS version uses a 50 trim rather than the 56 trim compressor version that Garrett sells as CHRA No 700177-0014 . Cheers A .

I was bashing out a long reply and lost it to cyber space - DOH ! Take 2 . The original Garrett GT3071R is shown in an earlier catalogue at - Garrett_Catalogue%207%2017%2013.pdf . I can't make it work in a search it's just on my desktop . The turbo dosen't have an assembly number only a cartridge (CHRA) number which is 700177-0023 . This is the real one with the 59.9mm UHP GT30 turbine . A contact in the US had an early one from ATP Turbo and its ID Tag had 755270-1 top line and 89004-27 underneath . ATP and Garrett are also selling a GT3071R "Wastegated" version which HKS call their GT2835 series turbos . These use a ground down (cropped) UHP GT30 turbine at 56.6mm in 84 and 90 trim . The cartridge numbers are as follows : 1) 84 trim turbine CHRA No 700177-0003 Turbo assembly No's 700382-0003 , -0007 , -0019 . -0024 . 2) 90 trim turbine CHRA No 700177-0004 Turbo assembly No's 700382-0004 , -0020 , -0021 The turbo assembly numbers are different because of variations in housing style and ARR . I was talking to a Garrett production engineer a couple of years ago and he believed that the cropped turbine and bored out T28 exhaust housing was a desperate because Garrett didn't have a GT turbine in between the T28 (NS111) and the GT30 UHP . The want to have a bit more exhaust flow and mounting convienence (integral gate T28 flange) ended up being an inefficient laggy dog . Have a look at the turbine maps in the current Turbobygarrett catalogue for the 3076R (real GT30 turbine) and compare with the two GT3071R's . Not too flash eh . Also that catalogue has nothing like the full GT30 based range , the count so far is 18 CHRA's and 33 complete units . Also have a look in Turbomaster-Catalogue-garrett-GT30 , and Turbomaster-Aplications-Racing turbochargers-Ball bearing turbos . This is not the whole picture but covers most so don't let the local dealers tell you "na mate no such thing" . Cheers A .

Hi Geoff, I've spent more money on suspension than the engine...LOL...Whiteline everything they make for R33 and Bilstein, Strut Braces Front and Rear, Adjustable Caster Rods, Adjustable Upper Rear Camber Rods. And Brakes have been hugely upgraded....Ohh and one of your magnificent Hicas Lock Bars. Ian <{POST_SNAPBACK}> Just to throw another spaniard in the works , there is another exhaust housing by Garrett thats 1.06AAR and twin entry T3 flanged for the TA34 turbos that could work . It has no waste gate so not a straight fit but may work for some . Cheers A .

I would not waste time let alone money bolting that thing onto an RB26 . As has been said before show us an across the board gain and it'll sell . I think they're hideous looking things and a better all round result would come from std bits . If they can prove to function better I'l gladly eat my words . Cheers A

Fair enough , the GT28RS would do that but be at the end of the compressors flow capacity . Let us know the part numbers on the plate riveted to the turbos bearing housing so it can be identified . Cheers A .

Yeh I'll drink to that , I had a look in your site and woke up to the Pintara FJ bit . Like you said to each there own . Most of my road miles for the last 10 years have been with two FJ20's so no mysteries here . My leaning is towards higher capacity engines because they do it effortlessly is milder states of tune (RB26/31DET) . I am curious to know how the FJ feels in the heavier R31 body . Cheers A .

Hi Roy , all the turbine flow maps I've seen are a graph with graduations of corrected flow (in lbs/min) up the LHS and pressure ratio across the bottom . Some turbo combinations , such as the GT3071R , are a bit more biased toward extra exhaust gas flow than others . If you consider that both the 3071R and the 2871R can use the same 56 trim GT35 compressor the effects of using a 54 vs a 60mm turbine can be considerable . I had a look at the turbine map for the GT3071R and the GT28RS (same turbine map as the GT2871R) to see the differences . Using Garretts smallest .63ARR GT30 housing on the 3071R the graph is very similar to the larger .86ARR housing option for the GT28 turbine used in the GT28RS and GT2871R . So using a larger diametre turbine for the same gas flow capacity pays off in terms of turbine power . Doing it the other way with the larger ARR GT28 housing/turbine combination puts you at a maximum as there are no larger housings than .86 . Area Radius Ratio has nothing to do with the exducer diametre of an exhaust housing . The exducer size is dictated by the turbines trim because the exducer side of the turbine varies but the major or inducer diametre stays the same . Turbine flow maps clearly show the flow of the housing rising with the ARR even though the exducer size stays the same . Its not possible to rate a housing or turbines flow by itys exducer for that reason . The GT turbines have much wider inducer tips and the housings wider nozzles and thats why they have much higher flow ratings size for size than T3/T31/TA34/T04 types that they replaced . Cheers A .

The 2000cc six is a bit harder as it needs to work over a such a wide rev range . I would look at the GT28RS as well if the T28 flange was being adapted to the T3 pattern manifold . Basically the GT28RS's 60mm compressor is against the wall at something up to 33-34 lbs of airflow . The rough rule of thumb puts its power potential at 340-350hp . The GT2871R in 56 trim is supposed to flow 44 lbs/min or 440-450 hp potential for the compressor , not sure if the turbine can pass the required exhaust gas flow for power claimed though . Trying to guess what feels good for you is the hard part , for me the broad flat torque curve is what its all about . I personally don't need a power number from my car to make life livable . I already own a GT28RS so thats what I'd try first , it was a ball tearer on an FJ20 (for road) though it had quite reasonable off boost torque from aftermarket management . I would not use either of these turbos without the .86 turbine housing , the 28RS doesn't know what lag is with it anyway . The GT3071R is a factory hybrid , the $64 question is can you get sufficient exhaust gas speed through it for good boost response on a daily driver . The smallest ARR turbine housing is the HKS T28 flanged .61 and their next is the .73 which the SR20 brigade like on the HKS GT3037 52 trim . Garrett now do a .63 version in T3 flange but where to start ? If you use this turbo make sure you get the propper full sized GT30 turbine version as the "3071R Wastegated" version has the cropped turbine and GT28 exhaust housing resulting in woeful turbine efficiency - lag . So for a mild upgrade a GT28RS or for more and higher rpm urge a GT3071R and fiddle with the small medium GT30 turbine housings . The only surefire way is to drive some modified cars and copy the result you like best . Nite all ................

I got some links from the forced induction section on the internals of short and long nose R200's . They say the carrier dimensions are the same but the crown wheel bolts are larger again . I know that R200's DR30 style can have 10 or 12mm crown whee bolts (turbo or non turbo according to the Nizmo catalogue) but not sure about the later short nose variety . Anyone been inside them and know what they use ? Cheers A .

I must have missed something here , HR31's come with RB20DET's do they not ? If so RB30's (in DOHC form) bolt straight up to the gearbox and engine mounts this is easy . I detect that the love affair with the FJ20ET is alive and well which is OK but there are other capable engines out there as well . I just like the idea of 182 cubic inches compared to 122 cubic inches . They are far cheaper to buy/rebuild/maintain than a really flying FJ20 and in delux form (RB26 top end) they are more than capable of walking all over any FJ20 in any form . Your call but as food for thought it would have been interesting to see the Grp A spec DR30's take on the GRP A R31 GTSR's , I know where my money would be . To the moderator , how old does a Skyline have to be to class it as a classic ? Does a 1989 R32 GTST qualify . Cheers A .

Does anyone know this or have a picture of its ID tag , I tried searching first . Cheers A .

What a controvercial topic . I think its possible to argue either case or should I say back either team . IMO its not relevant to compare in line 4's to inline sixes because of their firing order and 180 vs 120 degree crank phasing . There is something to be said for two waste gates and their flow potential particularly given the 3 cylinders and the mass flow from them . I've often wondered if the twin turbos for FIA Grp A used restrictors or was it the blow off valve that limited maximum boost . Also importantly exhaust manifold design , the short three branch may have less potential flow restriction and heat loss than a divided 3+3 into 2 single turbo design . At the end of the day I'm going with a med-large single to get around the plumbing nightmare that exists with twins . With 3 litres and an RB26 top end I think a GT3540R possibly with an integral gate should be fine . I'm not that concerned what it'll look like but factory as much as is practical . I don't need race pace just nice lazy torque and enough squirt to keep the Commos and Coons in their rightful place (rearview mirror) lamenting in their expensive mobile lounge sweets .......... Cheers A .

Good to see something different but why an FJ20 when an RB30 falls in ? The RB30 bottom end + RB25DE head is too easy and not that expensive if you shop around . Not flameing you but I could not resist the temptation of a 50% increase in capacity and torque especially when it bolts in . The RB30E is the 186 red motor when it comes to buying rebuild bits . Good luck with your project .

Cubes the 700177-14 cartridge should have a 56 trim GT40 compressor on it . Most people call them a GT3040R . HKS did a similar thing but with a 50 trim GT40 compressor wheel . Turbo bearing systems . The annular contact ball bearings have very little contact area with the inner and outer races . The reason they have small oil restrictors is that high speed ball race bearings suffer drag losses if too much oil is present . Clearence on ball race bearings can be much closer than bush bearings in high speed applications meaning less "orbiting" of the shaft . This allows less clearence between the wheels and housings raising the efficiency of the compressor and energy recovery of the turbine - less slip losses . What happens with floating bushes in turbos is a large contact area between the turbine shaft and the oil cushon . The large contact area initially gives a drag or oil shear effect that slows the acceleration of the rotating assembly from low speeds - lag . The collar and plate thrust bearing also has the large contact area drag problem . If there is a carbon compressor end seal (mechanical face seal) its more drag again . The reason turbos with very low drag bearing systems contine to revolve when the engines shut down is because the mass of the rotating assembly has little resistance to revolving for a short time . The lubricating oil is hot and thin as well . Cost aside I can't think of any good reason to use a bush bearing turbo if a ball bearing alternative is available . Lastly would you believe me if I said Garretts GTBB turbos have a lower part count than the bush bearing ones ? Believe it .

Sorry that last one (GT30R) should have read CHRA no 700177-7 , for turbo assembly no 700382-12 . There are at least 14 GT30 turbine based cartridges I know of and have the part numbers for 11 0f them . Compressors range from GT35 to GT37 to T04S to GT40 . Cheers A .

R32 GTST master/booster goes bolt and much closer to the firewall , works for RB20/25/30DET conversions . Moving the 4 cylinder back creates handling issues rather than solving them . Remember , need some weight on the front tyres for steering and braking grip . The DR30 was a homologation special and Nissan got it right . The only viable reason to move the engine back slightly is to make room for a viscous hub cooling fan on the water pump as thermos are inadequate for cooling high output engines . Cheers A .

Cubes , SB8006A CHRA ? . I dug through all the good and not so good GT30 CHRA no's eg 700177-10,11,12,13,14,15,18 and the best 700382-12 . What does that number you gave show or what listing is it from . I've been trying to remember the name of the turbo dealer in north QLD as his site used to have some early Garrett parts lists . Cheers A

Interesting idea Cubes , where does it go from single to double and does it go back to single down the back . I had a bad experience with noise on an FJ20ET with a GT28RS and 3" tube . The dump pipe was formed to match the turbo outlet flange ie not a saparate waste gate pipe . There were no soft spots and the noise at cruise was LOUD . I think turbos that vent into a large volume and large pipe promote the dreaded drone . The split dump seems to have performance benefits and less noise as well . I've often wondered if the pipe venting the turbine is similar or a smidge larger that the outlet promotes flow and forms an anti reversion restriction when the pipe opens out to the main pipe diametre . I think large pipes can act as an auxilary engine tie bar if the exhaust has no give ie those braid covered stainless steel bellows gadgets , and can transmit engine noise directly to the body making it a boom box . Corky Bell says that gas velocity is directly related to pipe size and quotes pipe diametres in relation to power output . I think the golden rule is to try to keep the exhaust manifold pressure as close to inlet manifold pressure (on boost) as possible . To do this exhaust pressure needs to be measured pre turbo , post turbo and before and after every cat/silencer in the system . Remember the turbo can be a sizeable restriction in the exhaust system which is why I keep harping about the importance of efficient (free flowing ) turbines and housings . My 2 cents only A .