I believe they are too big for anything but a dynoqueen GT28R should be perfect for the street, but a small part of me wonders if the RS would be better 0.64A/R of course the 0.86A/R is way too big and laggy
Hi John too many Johns The picture isnt working have you got the link or is it on the Z1 site. Cheers
No way, they will be laggier but is better for a track car sitting at high rpm all the time, street is a little different but how often can you fully legally hit full sustained boost for anyway there is still a 3 litre V6 engine there pulling away. As with everything there is comprimises to be made and depends on ones specific application. I have spoken with JT Mark Leader and a few others in the US about good turbos for the track and our local views are a little different to that of our distant cousins. Here is a very brief rundown of what we hope to offer Garrett GT 2854R turbo kit rated to 500hp Garrett GT 2860R turbo kit rated to 560hp Garrett GT 2860RS turbo kit rated to 640hp Garrett GT 2871R turbo kit rated to 720hp Garrett GT 2871RS turbo kit rated to 800hp Then a dyno queen setup which will be capable of 1000hp plus with spray and a fully built engine. Once again this is very brief and not 100% confirmed
Apart from using NOS, the 0.64A/R is better. It better captures the exhaust energy to transmit it through the shaft, bigger isn't always better. The 0.64A/R housing harnesses the exhaust gas energies better so that it can transmit more power to the compressor blades, and allows you to spool up to a higher boost. In that thread Ash goes on to say that out of all the GT28R and GT28RS setups, the highest boost is achieved on the 0.64A/R turbine housings and not the 0.86A/R. http://www.twinturbo.net/net/viewmsg.aspx?forum=general&msg_id=1970645 Don't get too carried away with bigger is always better Fleet does quite well with his 0.86A/R Disco Potatoes, but he confessed to me when he was taking me for a spin that he perhaps should have gotten the 0.64A/R Disco's. And his is a track car... just a bit laggy... awesome when it's on boost though!
Cool finds as always Mattz The ultimate aim of the turbos for racing applications here is not necessarliy run them flat out at high boost pressures as the EGT's would sky rocket and heat would become a major issue. I believe the larger housings to produce a more useable boost curve and make power delivery a little less intense due to being a little laggier but once it hits fully the car will have more chance of keeping it all together. The slotcar is very twitchy under throttle due mainly to the .64 housings so its thought I should also note I think the turbos with the .86 housings and HKS housings have larger compressor and exhaust wheels which is basically a high flowed T3 style T28 turbo but will have to confirm with GCG there is too many options discussed all the time. rrrrrr confusing
Jason Mate - I too think something similar to Z1 300ZX GT675RS Turbo kit is best Maybe if you can get your own one which will be sitting on high rpm on track as you stated made just for you and maybe 1 other person who has a dedicated track car. But i think the majority would want a turbo that delivers good power with most importantly as less lag as possible because we are not gonna have the car sitting on high rpm around the streets like you would on a track. From testing Z1 even realised the .86 are too laggy for the zed engine unless you spend a fortune on other parts to help it to spool quicker. Where the .64 spools quicker without sacrificing too much power. This is the ultimate setup i would go for a zed. So please, maybe the a poll but from everything i have read the bigger .86 isnt the way to go for a street zed like 99% of us have. Just to add I love your work, and thanks heaps for this :zlove:
Here is the brief run down list of what will hopefully be on offer Ali Here is a very brief rundown of what we hope to offer Garrett GT 2854R turbo kit rated to 500hp Garrett GT 2860R turbo kit rated to 560hp Garrett GT 2860RS turbo kit rated to 640hp Garrett GT 2871R turbo kit rated to 720hp Garrett GT 2871RS turbo kit rated to 800hp Then a dyno queen setup which will be capable of 1000hp plus with spray and a fully built engine. Once again this is very brief and not 100% confirmed
I'm getting prices at the moment for the following turbo's (a pair of them): Garrett GT 2860R Garrett GT 2860RS I'm not interested in the kit, i only want the turbo's Will you be able to get a good price for members that only want the turbo's without the kit?
Yeah most likely but they wont fit without modifying the intake pipes to silicon joiners and altering the water and oil outlets or getting custom lines made up. You would probably also have to clock them yourself also Will find out .64 rears yeah
Lots fo good info Yes a bit bombarding with info and interesting what this guy Ash has to say. Yes I need bigger turbo's to help with more hp for drags as well as circuit. WE could actually use a little more lag or rather transfer of peak torque higher in rpm which will help. Also as Jason has raised the point of heat as will be less restriction and make same power with less boost with less heat. It is a suck it and see to a large extent with a experienced educated guess thrown in. Also a balance to get the right turbo for the job. As some cars get big injectors and sometimes too big for what is needed, and turbo too big with an engine not strong enough to be able to rev high enough to take advantage of the turbo's. Although V6 3 litre gets away with it and generally the bigger the better. Keep in mind we are talking bigger ball bearing and not hybrid ones, as in factory housings with bigger cores which are a miss match and don?t make that much more than factory turbo?s and are laggy. Factory turbo?s are bush bearing compared to larger ballbearing and set up right are not much laggier at all than the factory small ones. Compared to 2.6 litre RB26 motor, Zeds being larger at 3 litre and V6 so shorter crank and longer runners, longer stroke come on boost much sooner generally speaking although don?t rev as well as RB26 for all the opposite reasons. There are always individual cases of differences. See below virtually same turbos on my car as GTR in middle power run in red compared to The Slot Car in red. This was a Skyline Dyno day, and we were running race fuel I might add, which mainly makes a difference top end. The far right one was Top Secret GTR with huge T88 laggy drag turbo. Getting back to the GCG turbo kit we are working in closely with GCG to make this kit and it will be the best turbo kit with options on the market and very affordable. We will also have 2.5 and only one in the world to have 3 inch dumps right off the back of the turbo non divorce pipe. We are looking at a internal divider so best of both worlds. One of the options which Jason introduced was the external gate which is more involved and tight fit and not sure if can use factory cast manifold or larger cast manifolds like Mike Smith and others and will cost a lot more with price of pair of external gates. We can use HKS rear housings for this which are surprisingly not too much more cost wise.
Yeah 0.64A/R turbine housing Modifying intake pipes, yep I'll do that Oil lines, in this kit Water lines, i'll investigate my options Clocking, as simple as loosening some bolts and rotating the housing? Is the challenge simply getting the angle right? Cos it doesn't sound too hard... Yeah do you reckon you could pm me or post up on here some prices from GCG on those turbo's? I've got other quotes rolling in It'd kinda make GCG our one stop turbo shop if they could give us complete solutions, such as raw turbo's at the best price around or tailored turbo kit for our car
Is Z1 wrong in saying thi:: With The GT2871RS Z1 also used this turbo in its "stock" form for a few months, but quickly realized that this turbo (the Disco Potato) wasn't well suited for the output of 1.5L (one side of the VG30DETT). It's laggy and doesn't produce substantially higher output numbers to excuse it. Through modifications in compressor cover clearances and changing the turbine housing to a smaller A/R, we have increased the response of the turbo without significantly affecting the peak output. The A/R ratio of the compressor and turbine covers are the same as the HKS 2530, with the same Garrett ball bearing center cartridge. So im asking which one of the kits being offered locally will be exactly the same as the Z1, GT2871RS kit modified to spool quicker? And how will the local kit compare with power output and spool up time and cost of the Z1 kit.
Same turbo, big difference is the fittings. Turbo in standard forms comes with a .86 exhaust A/R, but it is also available with a .64 A/R which will spool faster on a smaller motor. The Z1 kit uses the .64 A/R cover so yes they are correct in saying this. They also offer a kit with a .86 A/R if required. The kit UAS are putting together will have the same turbos and same options but use somewhat improved fittings. Brackets/spacers/etc will have to be the same as the Z1 kit and will only available because someone has made a US kit available to tinker with. SO yeah to answer your question. Same turbo will be available (Garrett call it a GT2871RS, formerly known as a GT28RS aka Disco Potatoe, Z1 call the kit GT675RS), same style of mountings, but improved fittings and should be cheaper with Australian warranty.
BTW here is a good article on turbos which i think some could benefit from, specifically this paragraph as I'm not 100% sure everyone knows what ar is anyway??? whole article is here http://en.wikipedia.org/wiki/Turbocharger
It's a typo The disco potatoe aka GT28RS is the GT2860RS This is the GT675 kit that Z1 sell The GT2871R is a turbo with a bigger compressor than the disco potatoe, but the same turbine half (exhaust half). It's the GT725 Z1 kit. It's the turbo of choice if you have EXTREME portwork done, tomei 10.25mm lift cams, and solid lifters (the lightened valve-train should allow you to rev an extra 1krpm to take advantage of the higher rpm's required to flow enough exhaust to power this big turbo) If you go down this route, you should be spending big bucks on your engine. Z1 stage 4 portwork on your heads, 1mm OS intake and exhaust valves, ms or tubular exh mani, basically the works. throw ur chequebook at it. no thanks.
LONG POST SO GRAB A BEER BEFORE STARTING Okay further info on the two main culprits The GT28RS or GT2860RS Garrett part number - 739548 - 1 Has the following specs Compressor Wheel 47.2mm Inducer 60.00mm exducer 62 trim in a .60 Aspect Ratio A/R housing Turbine Wheel 53.8mm 76 trim in either a .64 or .68 Apect Ratio A/R housing (note the pressure ratio difference explained later on) http://www.turbobygarrett.com/turbobygarrett/catelog/Turbochargers/GT28/GT2860RS_739548_1.htm The GT2871 or the GT2871RS Garrett part number 472560 - 15 (correct number) Has the following specs Compressor Wheel 51.2mm Inducer 71.00mm exducer 52 trim in a .60 Aspect Ratio A/R housing Turbine Wheel same as 28RS 53.8mm 76 trim in either a .64 or .68 Apect Ratio A/R housing (note the pressure ratio difference explained later on) http://www.turbobygarrett.com/turbobygarrett/catelog/Turbochargers/GT28/GT2871R_472560_15.htm Now to pressure ratios. The VG30DETT is a small capacity engine when halved. For the purposes of this excercise I will refer to it as half an engine in 1.5 litre capacity. Being such small engine the calculated max pressure ratio capable from the engine is quite small (have exact calcs somewhere but have to find or work it out again and will post later) When you look at the differences in the pressure ration and total foot pounds per minute of airflow the larger housings are capable of higher flow at a lower pressure ratio. The same can be said when looking at the compressor maps. Print one off of each for easier veiwing. When comparing the two look at the pressure ratios and compare to the total volume of flow on the bottom. Note the larger turbo has more air flow at a lower pressure ratio again. So in my theory and I suspect my calcs back this up, the larger turbo will flow more air at A - less boost and B - at a lower pressure ratio which equals less heat and greater reliability. Back to pressure ratio again if you plan to run a conservative boost pressure of say 20psi to work out the pressure ratio roughly we add the boost pressure to atmospheric pressure at sea level which is 14.7 psia the total of 34.7 which is manifold absolute pressure is divided by the atmospheric pressure number being 14.7 which totals 2.36. At say 2.4 pressure ratio the GT28RS will flow around 28lb/min wheras the GT2871RS will flow more like 33 lb/min I can hear you all saying but its laggy and it will be laggier than the 28RS. fact of the matter is it will be but is it a bad thing, well that depends on your use. The compressor map for the 28RS is quite meaty with a very safe surge line compared to the 2871RS map you will notice it has a very lean surge line and could be a worry at low RPM having said that on closer analysis when comparing the two together in respect to plot points at different flow rates and pressure ratio points there is in fact little difference until you hit over 2.25 pressure ratio, the 28RS turbo stays safe with a ceiling limit of around 13lb/min of flow at a near maximum pressure ratio of 2.5. The 2871RS however requires more flow to keep it in check and quickly goes from around 15lbs/min at a 2.3 pressure ratio to an upper limit of 28lbs/min at 3 pressure ratio. So yeah all in all the GT2871RS turbo is a lot more flow capable and would require more engine work etc to realise its true potential, however could still be a really streetable turbo if careful dump pipes and exhaust systems were picked that actually increased back pressure slightly, this would keep the velocity of the exhaust gases higher and the turbo spinning faster providing bucket loads of boost as long as you engine can handle it. I am working on figuring out the whole shebang at the moment in relation to flow rates through the engine etc in an effort to see exactly what the stock setup can be pushed to before major engine work is needed. The slotcar pumps out 438 rwkw on current engine with GT28RS turbos .64 rear housings with stock plenum and throttle bodies, regrind cams and relatively minor porting etc so I am interested to see the calcs when finished PS sorry for the long post
On a turbo car, and I remember reading it on the Garrett website in a tech article by one of their engineers, that you want to minimise the amount of backpressure downstream of the turbine. Only on an N/A engine is backpressure helpful in a tuning sense. You want as large as possible (within reason) of a pressure drop across that turbine wheel, because that is what leads to the flow and performs the work on the turbine shaft. Increasing the pressure behind the turbine may only be helpful if the turbine was too small for the engine, and in this case it's not... I'm not sure that it's so simple - at what point do your heads/mani's start increasing the pressure without substantially increasing the flow? And you want your engine to flow more air at less pressure? Obviously at a much higher rpm, or how else do you expect to get your free lunch? hehe
From all the turbo gurus i have asked from Z1 guys to dom rigoli, they all tell me the same thing which makes alot of sense. No point in going with the bigger turbo because of the lag for street purposes. I think Jason for your own use what you want is perfect becuase your car is gonna be on the track and always hitting the redlines so you would want the bigger turbo setup. But on the street its a different story and least amount of lag possible is the better option. The Z1 turbo kit which i mentioned at the beginning of the post puts out big numbers up top but also spools up quick. Thats optimum for us, and thats what i would be looking for, because im sure not many people here will want to put $50,000 on the engine just to get it spool quicker as the same time as 99% of the cars here are for street use and not track and no nos systems. Just my 2 cent on what i think what will be best...for the kit being put forward....
