3.0 16V engine mods, etc

[blade7]

Love my KW V3's too -- but disappointed to hear yours need rebuilding at 65k. Congrats on 3k miles in a month! I put 3k on mine in the last couple years I bet... (Mental note: must drive that car more!)

My KW's have done around 25k miles in the past 15 years. I had to change both of the front springs recently, as they had snapped in the same place close to the bottom. KW certainly know how to charge for new springs too.

[Thom]

Perhaps it's just me but every time I go back to the 951 for a short drive, recently for a very sedate A to B drive to carry engine parts in the back for another car, it reminds how special it is. I have been playing with fancy exotic cars for a while and the "humble" 944 turbo, when fitted with a powertrain worthy of its brilliant chassis, is nothing to sneer at... and I am not aware of any 2 door performance car with a similar power to weight ratio that can carry that much junk in the back without quibbling.

[Jay Wellwood]

Thom....curious as to which GTX Turbo you have?

[Thom]

Jay, the turbo is a Garrett GTX3576R Gen 1 with a Tial 0.82 turbine housing.

Interesting that you ask about the turbo as I have been toying with the idea of trying a slightly larger one. The mid range thrust is massive but when reaching the higher end of the rev range in 4th and 5th it seems the turbo is slightly running out of breathe as boost tails off from 23 psi to 20-ish and adjusting the boost settings does not help. I suspect the compressor is very slightly undersized and cannot support every last cfm that the top end allows - good for reliability and I do not "need" to push the engine that high with all the meat available between 4-6k rpm, especially on the road, but but but... Upgrade to a Gen 1 GTX3582R to fill up the little corner of the top end left and lose 500 rpm in spool or break the bank and try a new G35-900 ?
I thought I was done modifying this car as it is now a superbly balanced package that works in all weather and I can't help thinking that attempting to go any further may be a futile and costly exercise...

[gruhsy]

How about trying the GTX3584RS Turbocharger?

And the G-Series G35-900 62mm?

I am curious how it will work on our cars especially with your 16V setup.

[Thom]

Well yes, the G35-900 seems a good candidate. It has the same wheels sizes as the GTX3582R whilst in terms of product range evolution it seems to replace the GTX3576R whilst the G35-1050 replaces the GTX3582R.
The GTX3584RS seems to have been an interim model using a then new design of turbine wheel that probably morphed into the turbine wheel design of the now new G series, but it seems a very large and already obsolete beast that may not even physically fit. I seem to remember that Duke/Gustaf gave it a try a while back, and though not being bad per se it did not seem remarkable or revolutionary either.
The GTX3582R Gen 1 would be the lazy choice as I could just reuse my Tial turbine housing, whereas a G35-900 would need not only a new turbine housing but also adapting work with the exhaust, but at least it would certainly fit down there as its seems as compact as my GTX3576R.

I always check what the Supra guys are doing when new turbos are launched as the 2JZ-GTE is similar to a 3L 16V engine like mine - same capacity, similar "total" head flow. The G35-900 seems to work well there but also on smaller engines... Decisions, decisions.

[Thom]

Been digging through older log files. Here is an instance where boost holds up to 23 psi (250 kPa) all the way beyond 6k rpm in 4th gear. Not sure what I was thinking with the turbo presumably running out of breathe, perhaps the car is doing that old 944T trick of making someone always crave for more.

log.jpg (71.25 KiB) Viewed 1006 times

Note : high IATs as that was in mid July during the heatwave. IIRC ambient temp that morning was above 25°C.

[SirLapsalot]

Nice, that's impressive it holds that to redline no problem. Duty cycle flat at 50% the whole time. I don't think 39C would be considered high in most peoples books. Especially a for a 951!

I think it already came up in this thread previously, but man, those EGT's would be quite concerning for me. Especially considering the life of the turbo! The rate at which it's climbing right through the 934C you show there is definitely not good. Maybe you could confirm that sensor/conditioner is still reading correctly or calibrated correctly? If that's real reading you might want to consider measuring your backpressure and begin investigating what you can do to reduce those temps.

[Thom]

They have always been liked that. They are just a little higher now when cruising than with the previous engine, but under load they actually climb up less quickly than with the 8V engine that was running at 18 psi. There is nothing to be done, and believe me, I have tried. That's just where they are with the probe in the cross over port.

Yes that turbo is proving great now that it can run in its comfort zone with pressures like 23 psi rather than 18 psi on the 8V engine. On that log it even spikes to 27 psi when reopening the throttle whilst entering 4th gear. I will try again to turn up the boost, not that the engine needs it but for the sake of science.

[SirLapsalot]

Copy that, some things just are what they are I suppose. I've never experienced a build like yours so I'm sure there are some things that just can't be avoided considering the physical characteristics of a given setup and calibration.

Just curious though, when trying to reduce those temps, what all did you try?