Date: Tue, 21 Oct 2003 22:42:17 +0300 From: Antti Rauramo To: dtlc@helios.net Subject: [DTLC] 2H and 12H-T again... Reply-To: dtlc@helios.net Hey, I was doing a little off-road today with our ol' buddy Philippe Trottier, and of course we discussed all things Land Cruiser. And the said that there are things about the 12H-T that make it more suited for road than for off-road: - the valve timing is such that the valve doesn't stay closed enough to provide much torque in the very low rpms (600rpm or so, very useful off-road as we all know) but allows it to run better at higher revs - the injection is not diaphragm (sp?) controlled, so it doesn't adjust power like H or 2H or B or 3B when running slowly with varying load, but you have to use the gas pedal Made me want the 12H-T a little less (which may be good for my sanity). Then again, as I presented him the choices between H+T, 2H+T and 12H-T, his choice was 12H-T with the cam from a 2H. And another thing was that 2H really doesn't have piston skirt cooling jets. The thing that was lost after 1983 is sleeves. So turboing an H isn't actually any more evil than turboing a 2H. Comments? -- Antti Rauramo 1978 HJ-45LP Helsinki, Finland Date: Tue, 21 Oct 2003 14:36:40 -0600 From: wayne@crushersrule.com Subject: Re: [DTLC] 2H and 12H-T again... To: dtlc@helios.net Reply-To: dtlc@helios.net ----- Original Message ----- From: "Antti Rauramo" To: Sent: Tuesday, October 21, 2003 1:42 PM Subject: [DTLC] 2H and 12H-T again... > Hey, I was doing a little off-road today with our ol' buddy Philippe > Trottier, and of course we discussed all things Land Cruiser. And the > said that there are things about the 12H-T that make it more suited for > road than for off-road: > - the valve timing is such that the valve doesn't stay closed enough to > provide much torque in the very low rpms (600rpm or so, very useful > off-road as we all know) but allows it to run better at higher revs > - the injection is not diaphragm (sp?) controlled, so it doesn't adjust > power like H or 2H or B or 3B when running slowly with varying load, but > you have to use the gas pedal > > Made me want the 12H-T a little less (which may be good for my sanity). > Then again, as I presented him the choices between H+T, 2H+T and 12H-T, > his choice was 12H-T with the cam from a 2H. > > And another thing was that 2H really doesn't have piston skirt cooling > jets. The thing that was lost after 1983 is sleeves. So turboing an H > isn't actually any more evil than turboing a 2H. > > Comments? > > -- > Antti Rauramo > 1978 HJ-45LP > Helsinki, Finland not really true, the 12HT lugs down to 600 quite easily, 400 and it likes to balk. the only thing i don't like about the 12HT is the touchy pedal with the standard but with the auto it is very nice... Wayne www.crushersrule.com http://www.luxuryimports.ca/index.html have you laughed 8^)) at a jeep, lately? Calgary Alberta Canada From: w.j.markerink@a1.nl To: dtlc@helios.net Date: Wed, 22 Oct 2003 04:41:05 +0200 Subject: Re: [DTLC] 2H and 12H-T again... Reply-To: dtlc@helios.net On 21 Oct 2003 at 14:36, wayne@crushersrule.com wrote: > not really true, the 12HT lugs down to 600 quite easily, 400 and it > likes to balk. the only thing i don't like about the 12HT is the > touchy pedal with the standard but with the auto it is very nice... The touchy pedal can be solved, seems to be a mis-configured 'arm-of- leverage' or 'actuator-ratio'....too little pedal-travel for too much cable-travel, but only at the start of the pedal travel: http://www.a1.nl/phomepag/markerink/12H-T_throttle-response.txt (start is German, essential text on the bottom is English) -- Bye, Willem-Jan Markerink The desire to understand is sometimes far less intelligent than the inability to understand [note: 'a-one' & 'en-el'!] Date: Wed, 22 Oct 2003 09:44:17 +0300 From: Antti Rauramo To: dtlc@helios.net Subject: Re: [DTLC] 2H and 12H-T again... Reply-To: dtlc@helios.net wayne@crushersrule.com wrote: >----- Original Message ----- >From: "Antti Rauramo" > > >>- the injection is not diaphragm (sp?) controlled, so it doesn't adjust >>power like H or 2H or B or 3B when running slowly with varying load, but >>you have to use the gas pedal >> >> > >not really true, the 12HT lugs down to 600 quite easily, 400 and it likes to >balk. the only thing i don't like about the 12HT is the touchy pedal with >the standard but with the auto it is very nice... > > But that is besides the point; let me rephrase the question: If I, with a 12H-T, set the hand throttle so that the engine runs at, say, 1000rpm, and then ease off the clutch and start crawling over an obstacle, will the 12H-T stay at about 1000rpm, or will the rpm drop when the load increases? -- Antti Rauramo 1978 HJ-45LP Helsinki, Finland Date: Wed, 22 Oct 2003 16:00:15 +0900 To: dtlc@helios.net, dtlc@helios.net From: stedman@ans.kobe-u.ac.jp Subject: Re: [DTLC] 2H and 12H-T again... Reply-To: dtlc@helios.net At 09:44 03/10/22 +0300, Antti Rauramo wrote: >If I, with a 12H-T, set the hand throttle so that the engine runs at, say >1000rpm, and then ease off the clutch and start crawling over an obstacle, >will the 12H-T stay at about 1000rpm, or will the rpm drop when the load >increases? There is a full mechanical governor available for the 12H-T that will maintain a set RPM essentially until you stall the engine. This is a stock OEM Toyota part and was normally found on any of the engines that saw fire service work. Sorry that does not address your question but it does add something to think about. Dave Stedman Kakogawa Japan N 34=B0 45' 45.2" E 134=B0 52'22.3" stedman@ans.kobe-u.ac.jp stedman@canada.com Date: Thu, 23 Oct 2003 08:32:59 +1000 From: "Greg Goulden" Subject: Re: [DTLC] 2H and 12H-T again... To: dtlc@helios.net Reply-To: dtlc@helios.net > -----Original Message----- > From: dtlc-owner@helios.net [mailto:dtlc-owner@helios.net]On Behalf Of > Antti Rauramo > But that is besides the point; let me rephrase the question: > > If I, with a 12H-T, set the hand throttle so that the engine runs at, > say, 1000rpm, and then ease off the clutch and start crawling over an > obstacle, will the 12H-T stay at about 1000rpm, or will the rpm drop > when the load increases? Antti, I think we are all reading too much into this. Both engines use a load/speed governor as part of the injection pump, it's the engines characteristics. I believe what you are feeling is the difference in low rpm torque between the 12HT and 2H. As the 2H has a compression ratio of around 22:1 (off the top of my head), it's going to have more very low rpm torque than the 12HT at only 17 or 18:1. At those low rpm's, the turbo simply isn't going to be making boost to make up for the lower compression ratio. Also, another thing to consider (which I don't think is applicable to the earlier engines) is that Toyota also fit a heavier flywheel to the 1HZ's in the HZJ105's, than they do on the TD's (eg. 1HD-FTE), which would also add to your low rpm performance. Regards, Greg Goulden 2000 HDJ105 Melb. AU.