I cut this from offroad80's and it's Graeme's reply to questions raided about his turbos, I'm sure he won't mind me doing that. I have one of his grunter2 turbo's and am wrapped in it.
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Other than the exhaust housing on some FT’s and a minor (1-1.5psi) increase in boost pressure between the 1HDT and the 1HDFT turbos, there isn’t another single difference. Some in Oz had 58020 (possible it was a replacement), some had 17010. All the European orders that I have done have 17010 housings on them. Their isn’t much difference between the two in any case.
Neither of the two differences referenced are a justification for a claim that one can handle more pressure reliably than the other.
What governs the turbos capability with boost is predominantly its airflow capability on compressor side, compressor design (max operating rpm) and the thrust bearing design. Obviously the turbine end needs to flow too, but it is less important when looking purely at boost capability.
I don’t need to look at a compressor map to determine the safe operating area of the turbo. In fact, I don’t use compressor maps for any of my designs. That’s not to say I don’t know what they can flow; its that I know how to calculate what they can flow, what their peak efficiency will be and what the max power I can expect at what rpm in what engine (IDI, low pressure DI or high pressure DI) based on comp wheel parameters.
Even for those that look at compressor maps to work out sizing etc, do they account for max operating level wrt sea level, max ambient air temp, max air temp into inlet manifold? I am sure some do, but you will always find some who are offering advise to others that don’t and its because they haven’t got a clue how to.
Here are some facts on the CT26 as fitted to both T and FT engines:
• They are limited in operating rpm to ~ 110,000 due to comp wheel design. This limits their maximum flow at choke to ~ 80% as if operating it at higher speed
• On an intercooled, big exhaust 1HDT and FT at around 14psi, this rpm limit is reached at ~ 2500 engine rpm (2400rpm on the FT). Of all the engines, the FT is the turboss are least safe at higher rpm due to the higher flow of the heads – some 15% improvement at 3500rpm.
• The turbo will boost higher than 14psi however the comp wheel will fatigue and eventually break in half. It is difficult to say when this will happen but it certainly does happen and I am happy to provide some photos. This will cause engine oil to feed into your engine which will cause it to run at very high engine speed (somewhere over 6k) until the engine is left without oil. Almost every time I have seen this it is followed with a comprehensive engine build.
• The thrust bearing on a CT26 will allow 20psi, but the life is reduced and this kills the front rear seal on the turbo, leading to smelly exhaust and engine getting contaminated with ash and other particulates that don’t burn when the oil gets into the cylinder. Replacing the thrust bearing with a 360 degrees version like available on eBay will help greatly, but your left with a low operating speed comp wheel ;-) so what is the point?
• The turbo on the Yanmar and Yamaha marinised T and FT engines IS NOT a CT26. It is a far larger frame turbo with a water cooled exhaust housing (pretty std on a marined disel) that doesn’t reach the operating pressure of 29-31psi until over 2500rpm. The thought that it was suggested that it is a CT26 is quite funny. The T and FT and have different pistons and injector nozzels to these engines, though that is another matter.
Bottom line is this. You can use your factory CT26 with an intercooler and other breathing mods (inlet manifold on a T, airbox, exhaust etc) at up to 14psi with limited rpm over 2500 safely and get a huge improvement in power. But keep within the limits for reliability. They are a nice turbo but they are not magical, they have limits.
All my turbos will run lower EGT’s than factory. As an example, when I tow a 4T caravan I’m at 27-30:1 AFR at ~ 100km/h 1900rpm on flat. Factory turbo will be at that driving by itself. When not towing I’m at 40:1 at 100km/h. All this means is that with a Gturbo the engine will be much cleaner and have lower EGT’s at all times. When towing I aim for not less than 22:1. I can be pegged at 26psi up hills towing my 4T van and my EGT’s are really terrific. For fun AFR of 18:1 is the lowest I am happy to see.
I recently posted some dyno results on IH8mud of stock CT, direct swap to mine and another of DTS kit and GT2860RS vs mine. You should check out the difference in AFR’s. Most tuners tune their 1HZ’s to 17:1 while mine from same tuner in Qld was at 20:1 and boost response was far superior.
As for photos of my turbos, to be honest, I have posted some turbos on some sites. I work a fulltime engineering job in town and do turbos as well. Plus I have a young family so I don’t have a lot of time to write on forums and argue with people or even pedal my wares much. But, if that’s a problem then I can post some photos. Also, when its 2am and I’m off to bed, I don’t always think of taking photos. I haven’t even got the website up yet but its happening slowly and obviously there needs to be photos on their right?
There is a new range out now with extended tip technology. Parts have arrived and I’m busy making them for people. I also change the turbines as well to my own design, the factory turbine is quite antiquated. Also, I have been redesigning the 1KD-FTV variable vane turbo that will push the 1KD past 200kW at crank in one guise and a 170kW at crank version with factory AFR’s for the average punter.
I guess what I am saying is, not much time for photos.[quote]
The entire tread over there is here
http://www.offroad80s.com/turbos-t9385.html" onclick="window.open(this.href);return false;
There is some fuel pump mod to do and he sends them to you and is very easy to talk to even in my layman's terms and some of my "dumb" questions where explained exactly what I needed do and how to do it.
I don't normally go into bat for a product but there is an exception because it IS a good one.
Graeme's gunna have to put me on the payroll soon.
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