Roman Posted December 8, 2021 Author Share Posted December 8, 2021 Here's some afternoon diagrams to go with the morning graphs @yoeddynz So while I was trying to figure out the VVTI situation, I was trying to think if the crank being offset in the block helps give piston clearance for vvti (piston accellerates away from TDC faster?) The crank sits 11mm further towards intake side of the engine, relative to the centreline of the bore. I just finished some of the drawings to take some measurements from to try understand whats going on with this. So there's some weird shit that goes on as the piston accellerates at different rates depending on if its coming down or going up. (when rotated clockwise) When the crank is laying flat at 90 or 270 deg, the piston is a different distance up the bore for each. On the way up, it's 6.962mm higher by that time, than the way back down. Then also, the crank angle at which the rod is perpendicular to the crank, happens at an earlier time on the combustion stroke than compression stroke. It happens at 21 degrees above horizontal instead of 12.44 degrees. Maybe there's a better gas expansion ratio at this point, of the gas expanding relative to the combustion chamber volume expanding. So more force can apply on the crank. Or something else dunno. Either way it's weird shit. Also some weird shit happens around 90 deg of crank travel on the combustion stroke. Where the rate of accel does weird stuff. I'm guessing this is also something to do with having the piston exert more force on the crank at that position. 8 Quote Link to comment Share on other sites More sharing options...
yoeddynz Posted December 8, 2021 Share Posted December 8, 2021 Designed so the when at maximum expansion force from the burning mixture does not coincide with the point of most leverage on the crank, thus smoothing the forces out somewhat on the crank making for a more linear rod force to crank ratio line? Hard to explain when typed out but you probably get it. 3 1 Quote Link to comment Share on other sites More sharing options...
Roman Posted December 8, 2021 Author Share Posted December 8, 2021 Yeah! Must something like that. Says in toyota stuff that it's done for sake of more torque. Also some of the above stuff is incorrect because I just read its got a 12mm offset not 11. D'oh. Will be the same but more exaggerated I guess. Also, gash expansion is an interesting typo to make 1 Quote Link to comment Share on other sites More sharing options...
cletus Posted December 8, 2021 Share Posted December 8, 2021 I wonder if that's why you had problems with the crank pulley coming loose? Having pistons and rods doing weird things with angles and speeds must make for interesting harmonics? 2 Quote Link to comment Share on other sites More sharing options...
Roman Posted December 8, 2021 Author Share Posted December 8, 2021 Yeah, good point! Although, to be fair I've stopped having problems with the crank bolt coming undone since doing it up tighter, and using some loctite haha. If the crank had a keyway in it, I bet I never would have had problems in the first place. Just a cheaper shittier design this way. It's quite smooth at high rpm though, it doesnt feel like it's going to explode into a billion pieces. Like I cant quite explain it, but some motors happily do high rpm but dont sound happy about it. It quite happily revs out and feels/sounds like it wants to keep going. Not a particularly scientific conclusion but there you go. haha 3 1 Quote Link to comment Share on other sites More sharing options...
xsspeed Posted December 8, 2021 Share Posted December 8, 2021 ken to see 10k even without the power to justify, just want to hear it 2 Quote Link to comment Share on other sites More sharing options...
Popular Post Roman Posted December 8, 2021 Author Popular Post Share Posted December 8, 2021 Due to overwhelming peer pressure I decided to set the rev limited to 9100rpm and see what happens Horsepower has peaked earlier but its still worth holding the gear so you drop down closer to peak HP Keep in mind fuel, ignition and vvti angles have fallen off the end of all of the tables haha. So not optimized. Let me explain what it sounds like: fucking excellent. I've added a 9k rpm column to my fuel table, and then adjusted VE values to suit results. It's not falling right on its face, at 8500rpm showing 107.5% VE, now at 105.2% So once stronger rods are in I cant see any good reason not to keep going even past that 14 4 Quote Link to comment Share on other sites More sharing options...
Spencer Posted December 8, 2021 Share Posted December 8, 2021 What a beast. 1 Quote Link to comment Share on other sites More sharing options...
ajg193 Posted December 8, 2021 Share Posted December 8, 2021 I wonder how long rings last at 10,000 rpm. Those earlier graphs of piston location vs angle are quite interesting. They make it ideally suited to long duration cam, can get quite deep into the compression stroke with open valve before it pumps much air back out. Quote Link to comment Share on other sites More sharing options...
Popular Post cletus Posted December 8, 2021 Popular Post Share Posted December 8, 2021 7 2 16 1 Quote Link to comment Share on other sites More sharing options...
Yowzer Posted December 8, 2021 Share Posted December 8, 2021 I can't see the video of it pulling 9k with open trumpets 8 Quote Link to comment Share on other sites More sharing options...
kpr Posted December 8, 2021 Share Posted December 8, 2021 Looks like it's hanging on really well! Quote Link to comment Share on other sites More sharing options...
keltik Posted December 8, 2021 Share Posted December 8, 2021 No matter what the actual RPM is, being able to get the tacho needle off the dial is immensely satisfying. Making power is just a bonus Edit: Does the 1NZFXE have asymmetric rods to go with the offset crank? I'm remembering the Subaru EZ36 which dropped the crank 20mm and had pork chop rods to help make everything fit / reduce geometry issues 2 Quote Link to comment Share on other sites More sharing options...
RUNAMUCK Posted December 8, 2021 Share Posted December 8, 2021 Balancing is an absolute must.* *really should do. Granted factory stuff is pretty well made these days. But those chinesium rods, who knows? I tried to balance my own rods once. But the scale was so sensitive I couldnt get it to repeat. Plus you really need a jig to do it right. Spending money building engines takes the shine off pulling 987654321 RPMs after the 2nd or third engine goes bye bye. Not to mention the opportunity cost of doing that, instead of squeezing power by doing (or experimenting with) other things. Also, have your crank, flywheel, pressure plate, and front pulley all balanced together too. (You can easily upgrade to a puck disc later if the neck snapping, pantie dropping torque gets too much for the organic unit) I've made a career out of taking shortcuts. And learned the hard way...... 1 2 Quote Link to comment Share on other sites More sharing options...
Roman Posted December 8, 2021 Author Share Posted December 8, 2021 14 hours ago, keltik said: No matter what the actual RPM is, being able to get the tacho needle off the dial is immensely satisfying. Making power is just a bonus Edit: Does the 1NZFXE have asymmetric rods to go with the offset crank? I'm remembering the Subaru EZ36 which dropped the crank 20mm and had pork chop rods to help make everything fit / reduce geometry issues It doesnt even have a tacho Nah the rods are straight, but on one side of the block they come reeeeaaallll close - most aftermarket rods you need to grind the block to make them fit. JUN conrods are actually a bit banana shaped so they fit without needing this. But those are like 4x as much so yep, die grinder it is. haha 6 1 2 Quote Link to comment Share on other sites More sharing options...
Popular Post Roman Posted December 16, 2021 Author Popular Post Share Posted December 16, 2021 After what seemed like an infinity amount of hours doing some exploratory porting on my spare head, and getting comfortable with the various dremel tools and when best to use each shaped bit. I've decided I'm ready to do some porting on the proper head. One problem I needed to address first though. Has been that each time I have needed to get the valve springs fitted, the local engine shop has had to do it. And it's taken then weeks to get it done each time. Buying a generic valve compressor tool probably works fine, but I dont have any budget for that currently. So I did some measuring and printed a tool to work with a G clamp. Works good! I can get those son of a bitch tiny valve retainers in place by my self now. Time to pull things apart. Since I've done this all a few times now, it's pretty quick to get the head off. Quick inspection - No signs of detonation on the pistons, and the really nasty residue buildup from when I first got the motor isnt there anymore. The pistons look quite dark compared to before, not sure why. Perhaps just a bit of regular old carbon build up. Something funny I noticed while pulling things apart to get the head off. The alternator was only hanging on by the tensioner bolt. The main bracket had both of the bolts had come completely out. I'd noticed in the logs from the drags that the motor had been dropping battery voltage with more rpm, and it was worst in first gear. So it was obviously belt slip. I've bought some threaded rod so I'll wind some studs in and loctite them into the block. Then use some spring washers on the nuts. Hopefully that'll fix it. So progress on porting the actual head has been much faster than expected. Everything I've read about porting has said "Do one small part on one cylinder, then move to the others instead of doing 1 port all at once" I thought this would be massively tedious but it actually speeds things up a whole bunch. Because you get your technique good for that area then apply it 3x more. Then figure out how to do the next part. The main issue I need to avoid on this good head, is damaging the valve seat. I absolutely 100% want to avoid needing to get the seat remachined. Because of the time factor involved with getting someone to fix it. So I took 4x valves from my spare engine, and ground the faces down to be just about level with the valve seat. Then put these valves in place while I worked on each combustion chamber. This also made progress massively faster in this area, as I could get stuck in with a higher tool speed, without worrying about critical damage. I'm reasonably convinced that removing the lip around the seats in the combustion chamber, and the bowl area will be responsible for any/all improvements. Which is interesting because I'm pretty sure that most CNC porting jobs I've seen look like they're just hogging out the port from the port end. Rather than doing anything in the chamber. (wild assumption) I'm 50/50 on whether downsizing the injector boss will help much, seeing how it's a bit further up the port. However this is possibly laziness talking as it's quite time consuming. Will do it anyway while this is all apart. Here's some cross sections showing changes made in the chamber. Red is standard shape and green modified. Basically I gave up on trying to be stingy with material removal, and opted to do what I think will maximize flow at low lift for both intake and exhaust. Apart from the combustion chamber changes the exhaust side looks like it will definitely benefit from reshaping the roof at the transition of the machining to the casting in the bowl area, as it was quite gross. All that's left to do now is tidying up the ports from the port sides. Then spend a bit of time polishing the modified combustion chamber faces so there's hopefully no surfaces which will induce knock. Hopefully not too long and I'll have this all back together. Also good news, with Auckland travel restrictions lifting. I'm able to start getting my Hoist in place, in the shed. Once this is done, I will make a start on a better exhaust. 20 1 Quote Link to comment Share on other sites More sharing options...
ajg193 Posted December 16, 2021 Share Posted December 16, 2021 What grade of threaded rod are you using for the studs? 1 Quote Link to comment Share on other sites More sharing options...
Roman Posted December 16, 2021 Author Share Posted December 16, 2021 Thats a good point its likely grade 4.6 rod. It didnt shear the bolts though, they just came out from vibrations. Quote Link to comment Share on other sites More sharing options...
deankdx Posted December 17, 2021 Share Posted December 17, 2021 did you happen to measure the chamber volume before the work there? (or will you measure the other head if same and compare?) would be interesting to see how much compression ratio has changed, assuming not much. 1 Quote Link to comment Share on other sites More sharing options...
Roman Posted December 17, 2021 Author Share Posted December 17, 2021 If I do some calcs for how much I've removed, being on the generous side at each step of the way it's something like 0.015cc per valve. Then maybe some extra off the bridge parts so lets say 0.1cc total per chamber or even double it to 0.2cc per chamber Then it's still only lost say 0.1 CR absolute max. So I'm still waaayyyy ahead of where I would be if I had to use the 13:1 pistons to get VVTI working. Or If I had to dig some valve reliefs into the pistons. So if it can breath only fractionally better at high rpm it's well worth the trade. 2 1 Quote Link to comment Share on other sites More sharing options...
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