Roman Posted July 16, 2023 Author Share Posted July 16, 2023 Yeah I dont think roller bearings will work for anything. As roller bearings on a crank are usually where the crank gets pressed together around the bearings I think? The rockers have roller bearings on them. Could always be made lighter though. Ceramic pistons is definitely not gonna happen but lighter/stronger rods and pistons should be easily achievable. Alright so ol mate @chris r was a GC and noticed a K series engine at Pickapart over the weekend. (I didnt think there would be anything K powered there! But late model liteace or whatever with a 7K) So he was kind enough to message me and ask if I wanted him to grab me the oil filter housing. I dont have it yet, but he took a measurement for me so I could scale the flange from a square on gasket drawing that I've got. So it's looking pretty good for fitting. Oil gallery drill holes are in red. The threaded holes for the flange have enough wall thickness away from the main pipes too. In terms of fitting it looks ideal, however I am a little concerned about oil feed pipe size. The 4GR oil pump outlet/inlet is 18mm dia, but the inlet on the K filter is 11mm. So it ends up around half of the cross sectional area. This motor runs all of the oil through the filter, no bypass. Then has 4x vvti pulleys, 6 oil squirters then all the other usual stuff to supply. So I'm a little concerned that it might be a bit of a restriction, but does anyone know if that's likely going to be an actual problem? I will go pull apart the standard 4GR filter assembly and see if it's got any bottlenecks in the filter housing. Since the plate the sump will be cut from is fairly spendy I'm not overly keen on getting this wrong. 4K setup is looking like an awesome solution so long as it will flow enough. 1 Quote Link to comment Share on other sites More sharing options...
HighLUX Posted July 17, 2023 Share Posted July 17, 2023 A 3Y filter housing looks similar to a K series. I wonder if it would have bigger oil galleries Quote Link to comment Share on other sites More sharing options...
mjrstar Posted July 17, 2023 Share Posted July 17, 2023 19 hours ago, h4nd said: Any option to do what the 2T goons do I was thinking about the 2 stroke thing, does this reduce stresses on the piston compared to a 4 stroke, in my head when the piston goes up on the compression stroke it won't fly in half at TDC because pressure on the top to help hold it together... But on the exhaust stroke at the top you don't have lots of pressure on the top of the piston so that's when it'll fly apart. Maybe @Roman and @BiTurbo228 can get together and graph this idea to tell me how wrong I am. Quote Link to comment Share on other sites More sharing options...
BiTurbo228 Posted July 17, 2023 Share Posted July 17, 2023 @Roman Is the oil gallery hole expandable at all? From the gasket it looks like you could bring it outwards a little to better overlap the gallery in the sump. Depends what the structure's like above it I suppose. Also, I stumbled upon this thread while trying to find out how high a 2GR could rev before shitting the bed and a guy on there mentioned revving the solid lifters until they gave up (but helpfully didn't mention what revs that was). He's also on MR2OC here, but I can't see how to DM people on there which is helpful. He also talked bout running a 5GR crank and rods with 2GR pistons ion a 2GR block. That gives you a short-stroke 2.9l with space for bigger valves in its 94mm bore, and access to 2GR aftermarket forged pistons (468g with ballparked pins and rings). If the 5GR rods weigh the same as the 2GR ones (which they shouldn't) then that's 3.2 tons at 10,000rpm which is about what kpr's 4AGE is pulling. @mjrstar You're spot on that the compression cushions the piston/rod at TDC, and the peak tension loading is during the exhaust stroke. I'd guess you're right too in that it'd help a s stroke rev a little higher, but I've no idea how much it helps cushion things. I suppose you could work out how much pressure is exerted at TDC by the compression (and ignition too if that's already started) and minus it from the upward forces. Peak ignition forces are huge, so if some of that's already happening at TDC then it'd be a noticeable effect. Edit: This site (which doesn't site sources, but is an old Flash website which does increase my faith in the info a little) suggests ~2/3rd of peak combustion pressure occurs at TDC (probably depending a lot on ignition timing), and that peak pressures are around 1000psi-1500psi at full chat. With that we're probably looking at anywhere upwards of 2 tons of 'cushioning' which is plenty enough to help pistons stay together on a 2-stroke. I bet exciting things happen if there's a misfire at max rpm though! 1 Quote Link to comment Share on other sites More sharing options...
GARDRB Posted July 18, 2023 Share Posted July 18, 2023 On 15/07/2023 at 23:48, shrike said: Any valvetrain conversion options if it's the limiting factor? 3 Quote Link to comment Share on other sites More sharing options...
keltik Posted July 18, 2023 Share Posted July 18, 2023 T58 conversion if this doesn't work. Then you can run 19,000rpm all day 1 Quote Link to comment Share on other sites More sharing options...
Roman Posted July 18, 2023 Author Share Posted July 18, 2023 21 hours ago, BiTurbo228 said: Also, I stumbled upon this thread while trying to find out how high a 2GR could rev before shitting the bed and a guy on there mentioned revving the solid lifters until they gave up (but helpfully didn't mention what revs that was). He's also on MR2OC here, but I can't see how to DM people on there which is helpful. He also talked bout running a 5GR crank and rods with 2GR pistons ion a 2GR block. That gives you a short-stroke 2.9l with space for bigger valves in its 94mm bore, and access to 2GR aftermarket forged pistons (468g with ballparked pins and rings). If the 5GR rods weigh the same as the 2GR ones (which they shouldn't) then that's 3.2 tons at 10,000rpm which is about what kpr's 4AGE is pulling. That or even a standard 5GR sounds good, however that also blows the budget (and engine replacement budget) completely to smithereens. 4GR = $700 replacement engine 2GR = $4000 replacement engine 5GR = $$$$$???? replacement engine or crank (only available in China) If the 5GR was more easily available, it would make sense as the best base to start from. Quote Link to comment Share on other sites More sharing options...
GARDRB Posted July 18, 2023 Share Posted July 18, 2023 5gr from Aliexpress? 2 1 Quote Link to comment Share on other sites More sharing options...
BiTurbo228 Posted July 18, 2023 Share Posted July 18, 2023 Ah. Those are some persuasive numbers yeah, let's see how high the 4GR will rev as-is! Found a video of a 9000rpm 2GR Lotus Exige so someone's sorted the valvetrain. Interestingly, if they're using forged pistons about the same weight as the JUBU ones and rods similar to MWR's then 9000rpm is about 3.2 tons as well... 2 1 Quote Link to comment Share on other sites More sharing options...
Truenotch Posted July 18, 2023 Share Posted July 18, 2023 10 hours ago, BiTurbo228 said: 9000rpm 2GR Lotus Exige Wow, that thing is cool! 1 Quote Link to comment Share on other sites More sharing options...
Roman Posted July 19, 2023 Author Share Posted July 19, 2023 @BiTurbo228 could you plz run the numbers on the 2mzfe and vq25hr ? Quote Link to comment Share on other sites More sharing options...
ajg193 Posted July 19, 2023 Share Posted July 19, 2023 On 17/07/2023 at 12:15, HighLUX said: A 3Y filter housing looks similar to a K series. I wonder if it would have bigger oil galleries 3Y only takes smaller diameter filters, or at least my one does - no idea on gallery size Should be able to get away with drilling out the 4K one a little though 1 Quote Link to comment Share on other sites More sharing options...
Roman Posted July 19, 2023 Author Share Posted July 19, 2023 Found another option today. Suzuki swift. 3 bolt flange with bigger galleries and just an o-ring. Will compare options in a few days when back where car is. 1 Quote Link to comment Share on other sites More sharing options...
xsspeed Posted July 19, 2023 Share Posted July 19, 2023 2 hours ago, Roman said: @BiTurbo228 could you plz run the numbers on the 2mzfe and vq25hr ? cheeky request for rb20det comparing stock crank/rods with rb26 crank/rods, stock vs aftermarket piston would be lush too - at 78/79mm I'm hoping low mass means can rev to the moon even without as good a rod ratio as roman's 4gr 1 Quote Link to comment Share on other sites More sharing options...
flyingbrick Posted July 19, 2023 Share Posted July 19, 2023 Wow you guys are all really smart. My contribution: 4 3 Quote Link to comment Share on other sites More sharing options...
BiTurbo228 Posted July 19, 2023 Share Posted July 19, 2023 8 hours ago, Roman said: @BiTurbo228 could you plz run the numbers on the 2mzfe and vq25hr ? Man those are hard engines to find info about! 2MZ-FE looks pretty similar to the 5GR from what I can find out. Same bore and stroke, and the 1MZ is pretty similar to the 2GR (same stroke, similar bore, same conrod length, same bearing diameters). Makes me wonder whether they re-used a lot of the tooling/base components between the engines. I can't find the conrod length for the 2MZ anywhere online for anything further than that. If I could find compression height of the pistons I could work it out as I've got the rod length and compression height of the 1MZ (provided the deck heights are the same). If it's anything like the 5GR then it's probably got a pants rod/stroke ratio as well so might be a bit weak on power. VQ25 I can at least find conrod lengths. 5131g at 10,000rpm and 4156g at 9000rpm, compared to 5449g and 4413g for the 4GR. Slightly bigger piston, but offset by smaller stroke. Main bearings on the VQ are a little smaller so surface speed is better (9.99m/s at 10,000rpm), but big ends are bigger so likely heavier (offset a little by the shorter crank). Rod/stroke is on the high end of acceptable at 2.02. I chucked some ballpark numbers for the piston and rod weights in and if the VQ pistons are 40g heavier than the 4GR with rods the same then they come out with the same figures. So yeah, the 2MZ and VQ25 are probably a little more likely to be able to hit 10,000rpm from a bottom end perspective, but the differences are a set of forged pistons away from each other (if that, depending on how much the stockers actually weigh). If anyone's got a set knocking around then we can get a little further! 6 hours ago, xsspeed said: cheeky request for rb20det comparing stock crank/rods with rb26 crank/rods, stock vs aftermarket piston would be lush too - at 78/79mm I'm hoping low mass means can rev to the moon even without as good a rod ratio as roman's 4gr I've got a decent amount of info on RB26s, but again RB20s are proving a little trickier to find info for. I've got conrod weight from the FIA historic database, but can't find stock piston weight. If you fancy measuring one I'll plug the numbers in! RB26s are an interesting one. People quite happily zing them up to their 8k rpm redline, but then there's been lots of people nuke oil pumps at 7500rpm which says crankshaft resonance to me. If you buzz through resonance quickly enough you can avoid it damaging things, which is easy enough in lower gears with boost. If you loiter around the wrong rpm for too long though then stuff starts going majorly wrong (oil pumps exploding, flywheel bolts backing out, valvetrain damage as motion is transferred through the chain/belt, timing scattering as the trigger wheel is out of sync with cylinder 6). This is much more of an issue for I6s with their long noodley cranks than it is for I4s and V6s (one of the reasons I think the 'I6s are the best engine configuration bar none' crowd need to go do some proper research). But still, 8250rpm is the 'max rated rpm' for the RB26 from Nissan and that's 2.6 tons. I've found weights for supertech pistons and stock rods for the RB20, and at the same 2.6 tons you'd be spinning 9500rpm. Shorter throw crank should be stiffer and lower inertia for resonant frequency too which is good, but I can't find anyone online talking about experiencing issues at a certain rpm that would point towards crank resonance so what rpm that occurs at is a bit of an unknown. Most high-revving I6s seem to top out around 3 tons, for what it's worth. Lower than high revving I4s and V6s, which I assume is thanks to the noodley cranks. You do get some over that on standard cranks, but you start getting comments like 'they start marking bearings' or 'oil pump exploded' which I don't really count as 'being able to rev that high'. Still, suggests the RB20 bottom end might have some headroom above 9500rpm. I've certainly seen some videos of 10k rpm racers, but you never know how stock their cranks actually are when there's been a lot of money thrown at them. Will watch the video when I get back home and see if they hint at how much work's been done. 3 Quote Link to comment Share on other sites More sharing options...
xsspeed Posted July 19, 2023 Share Posted July 19, 2023 Cheers, yep should have some loose pistons around to measure. I was originally thinking add a couple hundred ccs through a 26 crank and slightly bigger pistons to aid low down torque and boost creation but will be interesting how much of a max rpm penalty that would create Mostly I just wanted to talk about rfbs on Roman's page again 2 2 2 Quote Link to comment Share on other sites More sharing options...
yoeddynz Posted July 20, 2023 Share Posted July 20, 2023 On 20/07/2023 at 08:08, xsspeed said: Mostly I just wanted to talk about nissans on Roman's page again Nice one 1 1 1 Quote Link to comment Share on other sites More sharing options...
Roman Posted July 21, 2023 Author Share Posted July 21, 2023 Yeah that's fine, 4GR chat is a safe space to discuss shitty engines from other manufacturers too 1 1 5 Quote Link to comment Share on other sites More sharing options...
Bling Posted July 22, 2023 Share Posted July 22, 2023 Pretty detailed video that may be of use. 1 1 Quote Link to comment Share on other sites More sharing options...
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