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Turbo alternatives Garrett vs CT vs Turbonetics vs Holset vs other brand
Im interested in what the CT do - the part numbers dont make much sense to me so found it hard to try and work out what might be in the 2871 or k24 7200 range.
I run a turbonetics hybrid on my ADU. E50 compressor with KKK#8 hotside. Good for approx. 480hp on 98 octane.
On E85, it spools faster than a remapped RS2 does on petrol.
Torque plots from 2nd gear below. Boost profile pretty much follows the torque curve.
Shows my RS2 on E75 winter booze vs a remapped RS2 (torque at flywheel in the 480-530nm range) vs a 4.2L V8 in a S6+ (tuned, stock flywheel torque is 400nm).
Mine was running too rich when the graph was generated, thus the hesitation and late boost. 3rd and 4th gear runs show 1000-1500rpm earlier boost and more torque, but this plot is good for comparison of the Netics vs the RS2 turbos.
Torque at the wheels in the graph is approx. 295nm for the V8, 395nm for the remapped RS2 and 555nm at the wheels for my alky burner. Stock bottom end.
doing the calculations that garrett has on the website,this turbo has 60 trim for compressor/turbine.
However,it has 58/74.5mm inducer/exducer in both compressor and turbine wheels.Meaning it has identical wheel diameters.
That is what will make this turbo maybe spin later than the 3076R,but it may also have less surge as well,BUT i think it will have much less EGTs due to backpressure of the hotside and overall it will be able to push more hp out of the engine than the 3076.
Of course the 3076R as a BB turbo will have that edge of better spooling.... but will it? if it surges as well,then what is the gain?
Also i have been told by Justin in comp,that i should not go for a 0.82AR on this turbo,and keep it on 0.63 AR and i think that this will be good for better spooling.
Billlman's Holset HX40 hybrid with the K26hotside #6 reached full boost little before 4000rpm,bearily had EGTs to be of any concern(below 850 just at the beggining of the downpipe) and AFR around 0.8. EM RS2
So this comes to show that basically the turbo hotside and construction is basically the biggest reason why we see all those high EGTs in the first place and maybe just going bigger on the exhausts overall is not always a solution.
I initially plan to use the CT358 with the 3inch downpipe+Vband and keep the 2cats, and 2.75catback.
The thing with trim is not accurate in relation to spool, you must take into account the amount of blades
The 7 blade T04 spins quicker than the 6 blade Garrett BB
I've been talking to a turbo company about their hybrid garrett range and they can make a GT3076r or GT35r spool quicker and produce more flow at the same time with new blades and compressor.
but the problems with the 3076R is not spooling in the first place.It has to do with the facts:
1) small diameter of turbine impeller means higher EGTs sooner,thus may not be able to produce the amount of power that is made for
2) BB causes a rather fast spooling already which may get you into a surge area anyway esp. if you use a 0.63AR.So you end up regulating the WGFV to control boost in a way that you end up having top boost later in revs,while the turbo is made to provide it later.
Ergo(hehehe) if you go to 0.82AR you end up with a non surging turbo that can only give you 500hp crank,when a different combination in impeller size turbo may give you the same spool but much more hp
Actually i have 750-780 degrees C just after the hotside of the turbo on the downpipe when crousing with ca. Lambda 1. At full throttle the EGT drops according to the lambda value drop. With my setup now i saw on a steep hill on 5 gear 1.2 bar at 3300-3400 RPM. engine is stock ADU (appart from VEMS, injectors and turbo). I would like to make a dyno run but at this time i have money or time for this. I run now approx 1.65-1.7 bar till redline.
About spooling, you must also take into account the design of the blades and not only the number of them.
I am working on to get proper rr plots of some ct hybrids collected to same place.
Like mentioned in earlier posts, I have made quite a few projects, but as I do not have a rolling road of my own, I do not have plots, as most customers don't bring me the plots, or some even never go to have the cars tested.
There is also a friend going to rr with a Holset HX40super, soon.
Of course You now need to trust my word, as I do not have plots to back me up. I might have boost logs, but It is pretty hard to find proper ones, as I have like 10 000 logs on this laptop.
But yea, some hand to hand comparison to garretts:
2871 I would definately replace with a stg3 turbine ct350. Compressor is able to go to +500hp. Usually these push 2 bar to 3000rpm or earlier on road with big gears. Chris is about to test one of these in his red 90, soon. One of these gave 400hp/520Nm with 1,6bar from otherwise almost completely stock 3b. It was a non BB unit. I should have the dyno plot somewhere in my backup storage.
3071 I would replace with a stg4 ct355, as it is proven to give 400hp/550Nm with 1,4bar. Usually gives 2 bar at 3200rpm level. Below an RR plot with 2,1bar on a rally car with freaking short gearbox, so spoolup is a bit late. Car has an inlet restrictor, so that is not fully comparable plot. Another setup gave 530hp/620Nm with only 1,9bar, and that was a streetcar with no restrictors.
Instead of 3076 I would choose a CT3461. Chris (jogi710) proved it to perform pretty well, although his intake manifold and some other stuff prevented it from operating properly. Chris' turbo was netics, but the compressor is similar to CT one. Also, they used a T4 .82 turbine, which slows down the spoolup a lot, so I would definately use stg5 (63mm) turbine with .63 Ar on road use and .82 on track.
And finally, above 600hp level I always prefer the Ptrim or Stg5 4367. Gave 630hp/+700Nm at 1.8bar in an S4 with my EM and schrick cam. Customers have plots, I will post if I get my hands on them. I have sold and installed more than ten of these myself, and never seen a 67 to surge. As a 3b unit it usually gives 2 bar boost to 3700-3800rpm level, and still is able to push +800hp if stretched to max. We drove 10.1/228 on quarter with one of these. Gave immediate 3 bar boost on lauch at first gear btw....
We need to remember that it is hard to say exactly what kind of behaviour will You have with Your setup. a 42mm diameter exhaust manny may take spoolup 500rpm higher with otherwise same setup. Still the smalled diameter unit pushes same hp at the top.
repo,
why would you go for a CT4367 as a replacement on the 3076? if the 3076 can only make 525hp then wouldnt a better equivalent be a CT355 or CT358 for that power?
Also what is the difference between a CT358 and a CT4358?
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