WesBrooks Posted February 8, 2016 Share Posted February 8, 2016 Morning! I've seen that the 4.6 converter is larger than the 3.9 and locks up earlier. On my 3.9 at least I'm looking to mega squirt (after run in), do a mild tune on a 3.9, and port the heads a little while keeping the valves the same size. General aim is to improve efficiency and bring BHP up to around 200 ish. At most I'd be swapping to an early serpentine cross bolted 4.6 ('95 ish?) on to the original box. Given there's hopefully a general increase in torque across the rev range I'd like to go a size up on the torque converter. Is it a straight swap or will it physically not swap? Not yet got as far as checking if ratios in the box change for the standard 4.6 too. As an aside which are your favorite reads for V8 tuning that don't mainly focus on tuning for light vehicle/fast road use? Thanks, Wes. Quote Link to comment Share on other sites More sharing options...
daslandroverman Posted February 8, 2016 Share Posted February 8, 2016 According to ashcroft the bigger converter won't fit a 4HP22, and needs a different backplate and centre boss. Read here, about half way down: Clicky Quote Link to comment Share on other sites More sharing options...
WesBrooks Posted February 8, 2016 Author Share Posted February 8, 2016 Thanks, I'd had a flash through that a few months back but missed that. Quote Link to comment Share on other sites More sharing options...
zim Posted February 8, 2016 Share Posted February 8, 2016 Don't worry about the converter, we run a cam'd 4.6 that likes to rev through a 4.2's converter. The 4.6 doesn't fit. G Quote Link to comment Share on other sites More sharing options...
Carloz Posted February 8, 2016 Share Posted February 8, 2016 There is a early "big" 4.6 Torque Converter and a later "middle" 4.6 TC. The big one was fitted to early 4.6's and have a 15mm longer bellhousing. Quote Link to comment Share on other sites More sharing options...
=jon= Posted February 9, 2016 Share Posted February 9, 2016 Don't worry about the converter, we run a cam'd 4.6 that likes to rev through a 4.2's converter. The 4.6 doesn't fit. G Out of interest, is that in front of a standard 4HP22? Ashcroft seem to suggest that for a 4.6 or larger you need uprated box internals - but I think that may be them covering themselves for someone using it in an 'extreme' fashion, rather than normal usage... I'm considering sticking a 4.6 in and not having to uprate the gearbox internals would save me a fortune Quote Link to comment Share on other sites More sharing options...
Bowie69 Posted February 9, 2016 Share Posted February 9, 2016 I wouldn't bother upgrading.... HHP22 cope fine with that amount of power. Quote Link to comment Share on other sites More sharing options...
WesBrooks Posted February 9, 2016 Author Share Posted February 9, 2016 Thanks again for the information just building up pieces of the puzzle while I'm building pennies for the next stage! Would the mid sized converter fit with only replacing bolt on parts between the crank and gearbox - or is it the same as used on the 95 3.9? Edit: While the converter is slipping I did read something about a torque multiplication. Does this mean that the slipping converter isn't all bad as is the case with clutch slip under load? I just like the idea of a lower lock if I've gone to the effort of making it breathe easier throughout the rev range! Quote Link to comment Share on other sites More sharing options...
Bowie69 Posted February 9, 2016 Share Posted February 9, 2016 Indeed, the 'slip' allows the engine to come up into the power band, for an RV8 around 2K, rather than having to bimble around at 1K finding you are running out of torque. Makes fast launches up a hill very easy, and crawling over large lumps a lot less hard on things, especially the drivetrain. Quote Link to comment Share on other sites More sharing options...
WesBrooks Posted February 9, 2016 Author Share Posted February 9, 2016 https://en.wikipedia.org/wiki/Torque_converter#Efficiency_and_torque_multiplication That's a good read. So 3.9 converter with a tuned 3.9 or 4.6 would generally mean hotter oil if you really push it - easily monitored with a seperate guage and dropped with the auxilary oil cooler (rusty hedgehog on the D1s). The lock up clutch in either isn't liable to slip unless worn out or the engine is seriously tuned? Quote Link to comment Share on other sites More sharing options...
Bowie69 Posted February 9, 2016 Share Posted February 9, 2016 Exactly As you say a cooler is a good idea -in fact a cooler autobox is a happier box anyways, so I would budget for something better than a bogbrush off a D1. Some info: http://www.digi-panel.com/trannyoil.htm These are handy to monitor, though expect they can be found cheaper at RS etc: http://www.ashcroft-transmissions.co.uk/temperature-strip.html Quote Link to comment Share on other sites More sharing options...
=jon= Posted February 9, 2016 Share Posted February 9, 2016 Gr I wouldn't bother upgrading.... HHP22 cope fine with that amount of power. Great....I guess I'd need to swap to the medium sized torque converter though? Just need to source a decent 4.6 now! Quote Link to comment Share on other sites More sharing options...
WesBrooks Posted February 9, 2016 Author Share Posted February 9, 2016 Great....I guess I'd need to swap to the medium sized torque converter though? Just need to source a decent 4.6 now! This was the bit I missed on the Ashcroft site: "Small" is used on the 300 Tdi, P38 diesel and the TD5. "Medium" is used on the 3.9, 4.0 and the later 4.6 P38. "Large" is used on the early 4.6 P38"s. Note the large converter can only be used with the stage 2 as it will only fit the 4HP24 front end. So large not needed for mild tunes. Medium is standard for V8s. What sort of mileage life do you get out of the medium converters? I don't think my truck saw much off-road work as it's transfer box lever was frozen. It did have a toe-hook though... So for the ironies if looking for a donor 4.6 engine & box I'd want a 95 or later for cross bolting & thor inlet or earlier for a better block and bigger converter! Any idea on the rough year for the larger converters? I presume all of the more fancy electronic controlled boxes (eg D2) are medium converters? Edit: Noddy mistake there. 4.6 engines started in 1996 so all cross bolted? Wouldn't this mean all serpentine belts? https://en.wikipedia.org/wiki/Rover_V8_engine#3.9.2F4.0 Quote Link to comment Share on other sites More sharing options...
zim Posted February 9, 2016 Share Posted February 9, 2016 Out of interest, is that in front of a standard 4HP22? Ashcroft seem to suggest that for a 4.6 or larger you need uprated box internals - but I think that may be them covering themselves for someone using it in an 'extreme' fashion, rather than normal usage... I'm considering sticking a 4.6 in and not having to uprate the gearbox internals would save me a fortune I run a 4hp22 from an LSE. Thinking back, my converter might actually be out of a 4.0 RR P38. I had to swap a few bits over so i could run my MS off the standard crank sensor. But either way, i'm definately not running the 4.6 TC, it's still sat on the shelf. I run a big P38 oil cooler on my gearbox, but even when i had the 4.2 in it - could quite often see temperatures of 140 C. On paper thats not good, but touch wood it's not died yet. Hydraulic winches being driven whilst in bogs aren't nice on auto boxes if you ask me ! G Quote Link to comment Share on other sites More sharing options...
zim Posted February 9, 2016 Share Posted February 9, 2016 Here's a picture for you : Left - 4.2 LSE Middle - 4.0 P38 Right - 4.6 P38 1996 Gems Quote Link to comment Share on other sites More sharing options...
Carloz Posted February 14, 2016 Share Posted February 14, 2016 Indeed, the 'slip' allows the engine to come up into the power band, for an RV8 around 2K, rather than having to bimble around at 1K finding you are running out of torque. Makes fast launches up a hill very easy, and crawling over large lumps a lot less hard on things, especially the drivetrain. Not only the engine can make more revs! The Torque Converter, the name already says something, can multiply the torque from the crank up to two times depending on type. The lesser the rpm difference between crank and autobox inputshaft the smaller the torque multiplying effect, which is logical of course. Quote Link to comment Share on other sites More sharing options...
Bowie69 Posted February 14, 2016 Share Posted February 14, 2016 Yup I agree ^ Quote Link to comment Share on other sites More sharing options...
=jon= Posted March 4, 2016 Share Posted March 4, 2016 Out of interest, which converter is normally used when doing an auto conversion on a 3.5? Ashcroft say : "Small" is used on the 300 Tdi, P38 diesel and the TD5. "Medium" is used on the 3.9, 4.0 and the later 4.6 P38. "Large" is used on the early 4.6 P38"s. Note the large converter can only be used with the stage 2 as it will only fit the 4HP24 front end. So it's either going to be a small or a medium. If HoSS can't remember which he used when he did the conversion, is there any way to tell without pulling it all apart? Quote Link to comment Share on other sites More sharing options...
WesBrooks Posted March 5, 2016 Author Share Posted March 5, 2016 I think the large completely locks up at lower revs? If you acurately watched speed against revs that might help. I don't have the figures. Quote Link to comment Share on other sites More sharing options...
=jon= Posted March 5, 2016 Share Posted March 5, 2016 Apparently Ashcroft supplied all the bits, so they should know what they normally supply - I'd imagine it was a medium.. New engine has a large already attached typically which is of no use to me!! Quote Link to comment Share on other sites More sharing options...
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