un ptit nouveau projet de ligne p17

sebar · 12-03-2006, 19:47:46 #26

en tt cas ce post n'est pas pour parler de budget, on ne compare pas un t70 ssa a un gt2540 hks (il peut achter plus petit tjrs en SSA). Sebar demande juste si ca peut aller et la reponse est non car trop gros. fiftyone51 a un t04E et c'est déja trop gros (spooler a 4500 c'est trop loin) en général il faut essayer d'etre full boost vers 3500max sinon ton exploitation sera trop mauvaise.

voici un post hyper instructif du forum SXOC.
Si vous avez des pb de traduction demandez moi:

I did a little exercise with a turbo calculator, potentially looking to size a new turbo for after I add the few mods Ive been collecting in boxes for the last couple of years... And these below are the comments on the main candidates.

The calculator and a few other bits are available here http://www.squirrelpf.com/site/index.php?page=Tech

Just to put the comments in context, I was working to something that would have to supply air for in the region of 450-500hp at 23psi which I believe is probably reasonable with the planned mods. Made a few assumptions about the engine efficiency, and assumed it would be revving to 8000rpm. Maybe they will be of use to someone one day?

Obviously T3's are too small so ignored them, T70 was included for a laugh

T04E 46 Trim

Compressor capable of providing about 0.8 bar by 3000 rpm, 1.1 by 3500, full boost by 4000. Good mid range efficiency, but not capable of holding 23psi to 7000 rpm. Able to hold 1.4 bar to 8000rpm but efficiency drops off below 70% over 7000rpm. This compressor looks to be a reasonable choice for 7000rpm, moderate boost levels (1.5 bar or less) on medium tuned engines, and will provide good boost response, but not suitable for higher levels of tune.

T04E 50 Trim

Compressor capable of reaching about 0.9 bar at 3500rpm, full boost by 4000. Efficiency is good at 75% through the mid range, and it maintains about 72% at 8000rpm. Overall, this is an excellent match and the wide range of efficiency means it will work well at lower boost or lower rpm applications as well.

T04E 57 Trim

Compressor capable of providing around 0.9 bar by 3500rpm, full boost should be available by 4250rpm. OK mid range efficiency at 5-6000 rpm. Unfortunately shows poor efficiency at 7000rpm (60%) which is where it reaches the choke line. Would be unable to hold over about 1.2 bar at 8000rpm. Not a suitable choice for this application. Would actually be OK for 7000rpm in a moderately tuned engine, running up to 1.5 bar though, but the 50 Trim will generally be the better choice.

T04E 60 Trim

Compressor capable of making about 1 bar by 4000 rpm, with full boost in the mid-high 4000's. Good mid-high RPM range compressor efficiency with 78% efficiency at 7000rpm, and 74% at 8000rpm. Appears to be a good overall choice for this application, although will definitely sacrifice some boost response compared to the T04E 50 Trim. Looks like it should be able to hold 25psi to 8000rpm.

GT28RS 60mm 62 Trim

Compressor capable of making about 1.3 bar by 3000rpm, full boost by the high 3000's. Good efficiency to 5000rpm, unfortunately it then drops off rapidly. Will be unable to hold boost past 6000rpm. This turbo is simply too small for this intended use. At lower boost, around 1.2-1.3 bar in a mild-moderately modified engine it would make a decent choice, with good efficiency. Could run 20psi but efficiency would drop off to about 60% at 7000rpm.

GT2540R 76.2mm 48 Trim

Compressor capable of making full boost in the high 3000's rpm range. Shows very good efficiency from 5000 through to 7000rpm, and still decent (approx 70%) efficiency to 8000rpm. It looks to be a good match, although not quite as good as the 56 Trim GT30R at the top end.

GT2871R/GT3071R 71mm 56 Trim

At 23psi compressor will be capable of making full boost by 3500rpm, and about a bar at 3000 rpm. Compressor coverage is excellent through the mid range with the 5000rpm demand line in the centre of the highest efficiency island (77%). Efficiency at 7000rpm is good at 72% but will dip into the high 60's at 8000 rpm although it will hold boost. Overall the GT3071R will have a quicker spool up than the GT30R, but will not be quite as strong at the top end.

GT30R 76.2mm 56 Trim

At 23psi, compressor will be capable of full boost by 4000rpm, about half that by 3500 rpm. 5000-8000 rpm within 72% efficiency, with 6000 rpm going right through the middle of the central 78% efficiency island. This compressor is an excellent match, which should allow for good boost response and no real bad points.

GT35R 82mm 56 Trim

Compressor will be capable of making about 1.3 bar by 4000rpm, and full boost at 23psi in the high 4000's. There is reasonable compressor efficiency at 5000rpm. It starts going into the "sweet spot" from 6000rpm upwards, this being in the 72% efficiency zone. 8000rpm is in the highest efficiency region (79%). Definitely one for more highly modified engines, as it has a lot more potential but capable of a surprisingly quick spool up for its size.

GT42R 94mm 56 Trim

Compressor capable of providing about 0.7 bar boost by 4000rpm and full boost by 5000rpm. Good efficiency with 5000-8000rpm being in the 74% region. Not bad match, but its a little larger than strictly necessary and in this particular application would not offer anything over the GT35R. Capable of supporting much more power, and much higher boost levels.

T61

Capable of full boost by 4000 rpm. Good efficiency from just under 5000 rpm onwards, with 7-8000rpm in the highest (76%) efficiency island. Looks to be a very good choice, with plenty more potential for higher airflow demands and increased boost (2 bar+).

T70

Compressor is unsuitable for this application. Its just too big. Will struggle to make a little boost at 6000rpm, and probably will never achieve full boost. Surging likely to be a problem. One strictly for very highly modified engines running lots of boost (could potentially run 40psi), wild cams etc. Even then, I think I'd prefer the GT42RS.

TD06-17C/T517Z

Compressor capable of providing full boost at 3000rpm. Reasonable efficiency at 5000rpm, however it is not capable of holding boost after 6000rpm. Overall it is too small for this use. Limiting boost about 1.2-1.3 bar in a mild-moderately modified engine will see it give excellent response and good efficiency through most of the rpm range.

TD06-20G

Compressor will be capable of providing around 1 bar boost as low as 3000rpm.The full 23 psi will be available around 4250rpm. Good efficiency through the mid range, with 5-6000rpm lines being in the 72% efficiency zone and good efficiency at 7000rpm. Looks as if there will be a slight boost drop off before 8000 and efficiency at this point is down to 68%. Looks similar performance to the GT3071R 56 Trim compressor wheel although that has the edge, and is a reasonable choice. Would be a very good choice if revs limited to 7500 or at slightly lower boost.

T04B 60-1

Capable of making about 1 bar boost by 4000rpm full boost should be achieved in the high 4000's. Unfortunately, it shows poor compressor efficiency with the demand lines staying in the 65% region until around 8000rpm where it just creeps into the 70% island. At lower boost, around 1.1bar, efficiency is better with 6-8000rpm being in the 70% region. There are far better choices, however.

T04B H3 Trim

Will not really start making significant boost until well into the 4000's rpm range, full boost should be achieved around 5250-5500rpm. There is reasonable compressor efficiency at 70% from 6000-8000rpm. Not really recommended, as there are much better choices that should see a lot better boost response in the T04E and GT ranges.

T04B V2 Trim

Should make about 0.5 bar by 4000 rpm with full boost being achieved in the high 4000's. Good mid range efficiency, 74% at 5000rpm dropping slightly to 72% at 7000rpm. However efficiency drops off to 65% at 8000rpm. Not bad, but there are choices with better response and efficiency.

Final Point

One point people should be aware of is the "spool up" I have mentioned. This is purely when the estimated engine airflow demands cross into the compressor map. This doesn't take account of the turbine side of the turbo which also has a (major) effect.

So if you chose a T61 with a big 1.00 a/r turbine housing and P trim wheel, it would not in reality be at full boost by 4000rpm. So they should be considered as guides to minimum rpm at which that boost level is possible with a particular compressor wheel (with the engine parameters I used). Not as definative statements