555.6kw Ba Ute

[groper]

if you have a turbo that will spool at 2000rpm, then it must be a smallish one. sadly you cant have the best of both worlds here... ie big turbo, more power potential, more lag, higher boost threshold, and unless you can get more revs somehow, a narower powerband.

that's the issue here, with a big turbo and without more revs, you power band becomes too narrow to be what id call 'driveable' or 'street driven'. so you end up with nothing, nothing, nothing, WHAMO, instant revlimit.... repeat cycle in next gear and so on. its no good... so if you chase big streetable power, then you need to somehow chase more revs to ameliorate the high boost threshold....

the standard turbo has been proven to make around 500rwhp or high 300rwkws at its limit... slightly more with race fuel... and it will do it at around 5300-5400rpm... if you keep adding more boost at this level, you start chasing your tail with the added heat your generating in the intake charge and flow restriction on the exhaust side...thus you need to step upto a bigger turbo.

Id love to know more about why these engines cant rev... besides the longer stroke and size???

Edited 17/04/08 12:49 PM by groper

[senna_T]

^ just to add to this, alot of new turbos are being made of lighter materials and have better balance and ball bearing cartridges etc, so they spool up alot quicker - just take xradam's car, he is running a 100hp turbo there and it spools pretty well IMO. Remember we are running pretty big engines compared to the more mainsteam turbo engines out there (2.0L and 2.5L for example) so we have some drivability at low rpm, you can always drop it back a gear and use half throttle!

[groper]

comon senna, look at the dyno chart... his car only makes ~10psi at 3750rpm... its AT LEAST 1000rpm lower with the factory turbo...

[senna_T]

yeah I know, but imagine if that was an old school turbo, it would be 1000rpm higher than that - and considering that power is only the start of this turbo's efficient range, its pretty good! you said it yourself you can't have the best of both worlds, 10psi is a complete waste with this sort of turbo!

[groper]

another thing worth noting here, from that dyno graph you posted adam, it looks like you must have had some wheel spin on the dyno (very understandable) as the top of your graph is all over the place.

You can still extrapolate though, that your peak power is at around 5300-5400rpm. that's where these engine seem to like it... its interesting as to why yours isnt making it at higher rpm than this with that big turbo?

[RAP1D]

It would be great to see the timing map, and data logging for inlet temps

30psi would suggest she's out of her effiency range, maybe a larger exhaust housing will give better gains

[senna_T]

my bet would be on the exhaust having a restriction rather than the turbo being too small, these turbos are quite good IMO.

The GT-K turbos don't come with the option for different housings, they are rated in HP starting from 350 and going up to the 1000 - that's what the website says anyway...

[BFHOON]

keeping it simple the smaller turbo becomes a blockage in the exhaust at very high power levels no matter how much boost you put in if it cant get out it will restrict power.

somthing about the outlet nozzle sizing.

[senna_T]

^ Agreed, but this is the GT-K 1000, not exactly a small turbo Turbonetics GT-K Series

[BFHOON]

I ment the stock turbo vs an after market one.