Sunday, April 08, 2007 - 11:29 am, by: Brad Newman(Toolman_999s)
I got my Aristo in January and noticed it to be sluggish down low and the first turbo makes a whineing noise which i don't here when the second turbo comes on line.I put a boost gauge on and it went into positive boost at 2200rpm and at 3000rpm it had 6psi of boost.At 5000rpm when the second turbo is on line it has a max of 11psi of boost.Should it go into positive boost sooner and should the turbo make whineing noise?Is it common for the first turbo to play up?My car has 97000kms and a 3inch exhaust with the original down pipe.Thanks.
Sunday, April 08, 2007 - 03:47 pm, by: Mite Paunoski(Mr_aristo)
its not that the turbo is playing up rather it is the sequential system of the turbos which causes that delay in the turbo kiciking in. As for the whining noise that is just spool
Sunday, April 08, 2007 - 05:08 pm, by: Wayne Koh(Teknoboi)
strange, my first turbo kicks in around 2000rpm, then the 2nd one comes online around 3800-4000rpm? i dont think your 2nd turbo comes online that late, possibly making max boost by 5000rpm?
Sunday, April 08, 2007 - 09:15 pm, by: Steve England(Stevee)
Hi Brad,
That level of boost at that rpm is abnormally low, I think you have a problem. In stock form my Aristo made about 0.85 bar (12psi) by 3000 rpm and held that all the way up, except for a slight drop as some of the flow was diverted to spool the second turbo at about 3500 rpm.
"Sequential Symphony in Boost Minor" gives a great description of how our system works, and "boosting the beast" gives what appears to be a good way of livening things up a bit !
I have done the dual manual boost controller mod, made my own FCD for about $20, and imported a water/methanol injection kit from USA for less than $300 to avoid having to bugger the front of the vehicle by fitting a bigger intercooler, and protect against detonation. Now set at 1.0 bar (by 2500rpm) for turbo 1 and 1.2 bar (17.6 psi) for both turbos. Performance improvement is VERY significant.
I guess I may destroy the stock turbos if I leave it at that level - anyone have any tips ?
Testing air charge temps today and the 50/50 water methanol injection which I have set to kick in at 8psi does a great job of cooling things down. The air fuel ratios are still very rich at higher boost using the stock ECU.
Monday, April 09, 2007 - 08:37 am, by: Ben Evans(Sbyder)
I know of numerous supras running 16psi on stock turbo's for years, so depending how you treat it, im sure the turbo's will last, just remember to keep good clean oil in it. Just remember that the sudden surge from 5ish psi to 17psi on the 2nd turbo at full noise can do damage to the 2nd turbo due to the kick it gets when the bypass valve opens.
Steve and Brad, try the TTC mod and see if you see the same boost levels when boost kicks in later on in the rev range (around 4800rpm). If there is something wrong with your sequential system, the TTC mod will bypass it.
Also check all vacuum lines are tight and make sure one hasn't come off either IACV solenoids. That has caused me 1st turbo boosting issues numerous times. A good indicator is heaps of compressor flutter on back-off.
Brad if the whineing noise you are hearing sounds more of a mechanical whir than a normal turbo spooling sound, it might pay to remove the compressor pipe and check if the compressor wheel has any play. Also check for bad oil condition and smoke when you boot it.
Monday, April 09, 2007 - 09:50 am, by: Steve England(Stevee)
Thanks Ben,
Yes, thought I had read elsewhere of stock turbos handling that sort of level. I am not usually very aggressive with the throttle, however I like to know its there - and make sure its there quite often. With timely application of the throttle you seem to be able to avoid the worst of that rush to turbo 2. I was mainly only trying to further improve the spool and boost at low RPM. This may have even been overdone, as when I am driving on winding hilly roads, I seem to be backing off all the time after the boots "flair" - but I like it.
Your ride looks great. I guess that grille is part of the kit, or can it be obtained on its own. (can only imagine the price tag). What is the noise level of that exhaust - any drone at cruise ?
Monday, April 09, 2007 - 10:26 am, by: Ben Evans(Sbyder)
The grill is actually part of the complete fibreglass bonnet. Its styled like Mercedes and I have not found anyone that knows what manufacturer makes the kit including front bar, rear bar, door pillows, skirts, wheel arch flares and bonnet.
The exhaust is super quiet, until it hits the 2nd turbo, and even then she's only marginally loud. I'd say -100DB at full noise.
Previous
Upload
