BiTurbo228

Neat! How close can you get the colours to that teal colour you get in old evacuated tube digital displays? My main gripe with aftermarket gauges is how modern they look, so something that could pass for 80s is ideal...

Interesting to see the weight of the powertrain. So maybe 184kg for the engine and 'box as-is, ~3kg apiece for inlet and exhaust manifolds (give or take), 10kg flywheel(?), 4kg starter (if it's one of the gear reduction types) and maybe 7kg for the clutch. So 211kg or so all-in. Not bad going! For reference my 2.5l Triumph OHC and OD gearbox was 269.5kg, and my AJ6 4.0l and 5-speed was a whopping 324.6! both with PS pumps, and the Jag with aircon.

Yeah I think they're more about mitigating transient losses in oil pressure. Like little flutters of starvation that might not be an issue at 1500rpm but would cause havoc at 7000. I suppose it's a (comparatively) cheap bit of insurance if your race engine cost 10k to build...

I wouldn't be so concerned about the gearbox crossmember height (unless they're particularly ruthless in NZ). A lot of modern cars have ~150mm ground clearance, so raising the gearbox crossmember by 20mm should be plenty. Useful to know the crossmember's 180mm though. I've had to drop mine by 10mm of so but that's still plenty (though the rack sticks out below that...).

That's basically what Ford did for the Sierra in Group A racing. They were homologated with Weber engine management and changed to Bosch motronic in '87. In the first race of the WTCC they were disqualified for not matching homologation, but for race 2 they stuck a big 'Ford' sticker over the Bosch logo and passed

I don't know how visible this forum is in the grand scheme of NZ motoring society, but a non-standard e-throttle being picked up by tech inspection is dependant on the tech inspector knowing what the standard throttle was. Is it non-standard to the car that's not allowed, or non-standard to the engine? As the 4GR has an e-throttle as standard, could an argument be made that you're retaining the standard setup for the engine...

Wiring loom looks good so far. Making me wonder if I should do mine at some point, mainly for weight reduction! They carry around a lot of unnecessary copper... Any idea what the new one weighs compared to the old one?

I seem to remember applying valve lift via rocker ratio and it got even weirder, what with it changing over the course of their motion due to where they contact the valve moving around relative to the pivot point (both the follower and the rocker finger). I don't think it ended up changing things enough to align with the advertised specs, but I'm not sure he actually measured valve movement directly. The thread's here if people fancy a look. Edit: found the thread on rocker ratios too

There was a chappy called oldtuckunder in the Triumph world who did a fair bit of investigation of various aftermarket cams for the 2.5 OHC before he passed away. His main conclusion was that the advertised specifications of a cam (not just duration, but also the four timing numbers) didn't match anything at all on the actual cam grinds. He reckoned their main goal was to sound flashy so they sold cams, and make it so if someone went to a cam grinder and asked them to grind those specs they'd end up with scrap. Not sure if that's something peculiar to Triumph/UK cam manufacturers or whether they're all at it. His setup was pretty simple. Popped the cam on a lathe and attached a dial indicator and degree wheel, then turned the cam through its rotation and marked lift every degree or so. Not really accurate enough to reproduce a cam from (there's odd stuff that happens with where the radius of the dial indicator nose sits relative to the angle), but enough to get a decent comparison between cams. It's simple enough to do with a flat surface and vee blocks as well. I did it to demonstrate what everyone knew already: that the Rover 2600 in the SD1 was detuned with a weedy little bumpstick by comparing it to the M20B25.

That was my thought. Surely more flow at part throttle just means you have to close the throttle more to restrict the power to the level you need to cruise. Unless it promotes more efficient combustion or something like that...

Love that your 'midrange' is about 5000-8000rpm

I'd be tempted to pop an idler pulley on just to justify your hacking off of the timing mark. See, it was all planned out right from the start

Yeah a lot of people think the 155 DTM engine is a Busso and it's got nothing to do with it at all. The homologation is for a PRV (IIRC) that came in the Lancia Thema V6 via that Fiat/Saab/Lancia/Alfa joint big saloon project that gave us the 164 and the Saab 9000.

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! 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.

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...

@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!

No worries lighter pistons does the trick for the long rod. 3.1 tons at 10k rpm, compared to 3.2 for the short rod with the same pistons (3137kg vs 3186kg, so not quite as big as the rounding suggests). Was 3353kg with the heavier pistons and long rods.

@kpr Just added those numbers in and you're right. Although the long rod pull 150g less at 10k rpm that's offset by the added weight of pistons and rods: 3.2 tons for the short rod and 3.35 tons for the long rod. @Roman Man those pistons are superlight! Carillo reckon their rods weigh 383g, though I'm never sure if they include the rod bolts with their weights. Even so, that's about 2.2 tons at 10,000rpm which is sort of middling factory figures for a lot of engines. It takes 12,000rpm to get to the same 3.2 tons as kpr's 4AGE. If the V6 doesn't work out like you'd hoped I vote try and get a 1NZ to rev to the moon I reckon your deconstructed piston was the piston itself tearing apart due to g forces. People think about rods a lot but pistons can be quite happy to chuck their crowns off at high speeds too!

Yeah definitely goes to show how the actual thing that matters is weight. Can't find rod length for the short-stroke R, but if it's the same as the non-R then it hits 9000g at 16500rpm Found some piston weights for it though. It's all marketing gumph rather than a bloke with some scales and oily bits so I'm a little skeptical, but they mentioned 'saving 5g/2% on the R piston' which would put it at 250g for the non-R and 245g for the R. No idea on conrods, but I know they're Ti so if they're anything like the 375g rods of the 1299R then that puts it at about 4.4 tons. Still very much up there, but comparable to the 1299R at 12000rpm. Amazing what lightweight spinny bits and a short stroke can do (though there's a hell of a lot of guesswork in those numbers).

Thought you'd never ask Yeah I know practically nothing about bearing speeds and oil shear, other than that it happens and this thread mentioned a chappy trying to rev a Mazda K8-DE to 10,000rpm and killing bearings due to oil shear (he'd tapped the block to measure pressure at each main bearing which never dropped, but was still wiping bearings). I'm assuming they meant he killed main bearings, but it's possible he was killing big ends. There's also a thing when you're spinning high rpm that the oil pressure isn't great enough to force itself from the outside of the main bearings 'upwards' towards the centre of the crank, starving the big ends. That's why you get things like nose-fed cranks in high end motorsport. Either way it's caused by the diameter of the main bearings and how fast the crank's spinning. Yeah the trade-off of having big bearings from it being a 2.5l version of an engine designed as 3.5l is that the crank should be pretty strong. Even with the smaller big ends of the 4GR it still has generous crankpin overlap which is a good indicator of rigidity. It might be a big V6, but V6 cranks are inherently short anyway. All bodes well for avoiding torsional resonance and other nastyness. I think I'd got some numbers for kpr's pistons and rods. Not sure if it was from here or just online, but plugging those in to 10k rpm gives roughly 3.2 tons of peak force on the crankpin (fudged a little as I don't actually know the weight of the little end so it's an approximation). That's definitely going some! Although I've just done a cursory look into bike engines and they're something else entirely. Went for a Ducati Panigale V-twin as there's more info out there than the V4 and they've actually got car-sized cylinder volumes. 11k rpm on a 60.8mm stroke and 116mm bore 5272g and 4.2 tons. Highest I've come across for a production engine by some 13%. Very true on the valvetrain! Might be worth running with no bonnet for the first few high rpm pulls

Just catching up on the first posts of your thread, and the 4GR does seem like quite a good base design for high revs (bar the smallish valves). I've plugged the basic dimensions in to my little engine internal forces database to see how different rpm ranges compare to other engines/setups. Mean piston speed is a halfway decent way of working out how high an engine might rev, but the thing that kills rods and pistons is maximum acceleration at TDC (the piston screaming up to the top of the stroke then doing a full 180 in a fraction of a second to come back down the bore). At 10k rpm the 4GR is pulling 5449g which...is up there. No production engines have that high forces, and only a tiny handful of tuned ones. Your 1NZ is one of them at 5016g at 9000rpm. There was a bloke with a billet-cranked stroker S54 that was 5975g at his 9000rpm redline. K20a's at 9000rpm are 5131g. If you take F20a's to 9200rpm which they can do that's 5088g. That's it that I've come across, though I started it to look at long stroke I6s and torsional resonance so it's probably missing a fair few high-revving V6s. If you take the 4GR down to 9000rpm then that's 4413g which is far more common for a lot of high revving stuff. High revving big-bore Alfa V6s hit 4608g at 9k rpm and they're far less built for revs than the 4GR. The factory redline for an S52B32 is 4137g, and are happy up to 4352g. Stock K20a limiter is 4685g, and F20C is 4655g. @kpr's 9k rpm short-rod 4AGE is 4616g. All depends a bit on the piston and rod weight though, which I can't find online for the 4GR. 5000g with a 300g piston is going to be a lot less load than even 3000g with a 600g piston. Journal/bearing surface speeds are up there as well. At 10k rpm they're 10.17m/s for the mains and 8.0 m/s for the big ends. I've only come across folks racing Jag V12s that are higher. 9k rpm again is more acceptable (though still high) at 9.15 and 7.2m/s respectively. The 993 GT3 3.8 is about there at 9.0 and 7.8 m/s, but that's pretty much it that I've come across. Not sure if they like to eat bearings like S54s or if they're ok. Big bearings and small stroke does make for a stiff crank though, so hopefully torsional vibrations would be less of an issue.

Ah I hadn't thought about it as 3 separate 3-cylinders. I was more thinking about linking it up like a straight 6 with a 6-3-1 pairing 1 and 6, 2 and 5, and 3 and 4 together.

@Rhyscar Interesting. As usual the 2-stoke folks are well ahead of everyone else in exhaust design. Shame it seems tricky to do on a 3-1 merge as V6s could probably do with that design much more than other engine designs, given that it's not practical in the slightest to pair the correct cylinders together for pulse tuning. I do still think dividing one of the three pipes in half so you've got 1.5 pipes merging together would work, the question is how to fabricate it. Suppose you could cut one of the collector pipes in half to weld along the inside and then stitch it back together again.

Do you have to be concerned about bleeding air from the system? Mainly asking as it looks like a bit of an air trap popping down into the sump plate, up into the filter and then back down again. Edit: on second thoughts, probably not. I had the lines for my X1/9 oil cooler loop up and over the engine before being connected to a cooler under the boot. Never seemed to have oiling issues.

Do you need to pair them as whole pipes? Could you merge 1.5 pipes together on each side then merge those two together afterwards...