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I'm not really loving the slack or the lack of straight up mark on the intake cam though. Don't remember if that's a VVT thing or not, i try to avoid those motors.
.... No..... that's in time. You can't physically put the tool low enough between the gears to get it to the marks on the timing plate.
Yeah, it looks right to me, assuming that the tensioner has been released and the motor spun around a couple times (if it were a new timing belt install).
To note, the FM tool does not work well with the VVT motor. When the tool is in place, the intake cam will want to snap back clockwise once it is free. If you time the motor like this, by the time you re-tension the belt & turn it around a couple times, the teeth will be off. You basically have to time the intake one tooth retarded then check it post-tensioning to confirm that the engine is timed properly.
To note, the FM tool does not work well with the VVT motor. When the tool is in place, the intake cam will want to snap back clockwise once it is free. If you time the motor like this, by the time you re-tension the belt & turn it around a couple times, the teeth will be off. You basically have to time the intake one tooth retarded then check it post-tensioning to confirm that the engine is timed properly.
Ask me how I know!!!
The problem isn't with the FM tool. What's going on is that if you leave equal amounts of slack on both sides of the belt, when the tensioner takes it up it will effectively shorten the belt on the intake side relative to the exhaust side and stuff will be off. You need to put it on with as much of the slack on the intake side as you can get -- this is true no matter what method you use to keep stuff aligned while installing the belt.
I've been kind of lethargic lately working on my car but I finished up my timing belt job. I timed it exactly as it should and I made a new mark to correspond to the vvt gear in a completely vertical position to match the exhaust gear. I also tensioned the belt correctly. The car is back together and started right up. Unfortunately, I don't have any data to post yet but I did note that my crank trigger offset changed again not that the car is all back together and the current crank trigger offset to get a fixed 10 degrees to an actual 10 degrees is 0 degrees in either direction.
OP chiming in. Unfortunately, I can barely work on my own engine, much less a VVT. I definitely recommend indexing tdc at the crank, and verifying with the screwdriver in cylinder 1 trick. Follow factory instructions, and any supplemental miata forum instructions for the timing belt install. turn it over a few times to make sure it stays in spec. Get a good dyno tune, with the new configuration.
As for my big bump in power, I'm fairly certain that the exhaust was off too, and I've added the mazdaspeed intake cam while I was doing the work. The head was decked during the initial rebuild. I too was surprised by the dyno results.
Again, big thanks to the forum. sixshooter and friends have been a big help.
I don’t know what did it but I replaced the belt and miscellaneous seals. With the new belt properly tensioned and me playing with street tuning some more I managed to get this dyno plot.
That's right in line with what an untouched VVT engine on a stock header, K&N intake, and any sort of aftermarket exhaust should do. Some optimization of the I/H/E and either bowl or compression bumps can get you around 150hp. Emilio claims that 150hp number with an untouched VVT and I/H/E, but that's still the entire Racing Beat catalog, a really nice VVT motor, and a really good tune. I haven't been able to breach high 140s with that setup, Emilio's saying 150s possible, but that's splitting hairs at that point.
That's right in line with what an untouched VVT engine on a stock header, K&N intake, and any sort of aftermarket exhaust should do. Some optimization of the I/H/E and either bowl or compression bumps can get you around 150hp. Emilio claims that 150hp number with an untouched VVT and I/H/E, but that's still the entire Racing Beat catalog, a really nice VVT motor, and a really good tune. I haven't been able to breach high 140s with that setup, Emilio's saying 150s possible, but that's splitting hairs at that point.
I hear that the nb2 header is pretty efficient at doing exhaust things. I am running a JR header which at its smallest size after the collector seems to be somewhere between 1.75 and 2 inches in diameter. Also my cat is a magnaflow which is only 2 inches on interior diameter. I am sure that those two variables contribute to me not make what Emilio with the whole RB catalogue makes. My goal right now is to maximize my toque and see if I can get closer to 120/125 torque and call it a day for naturally aspirated stuff.
A large portion of my HP gains seems to be from adding more vvt from 6k and up.
The blue line was using this new VVT table and red line was running I think the tune I had before the belt was changed. But before the belt was changed my dyno plots seemed rather non-responsive to vvt changes.
The problem isn't with the FM tool. What's going on is that if you leave equal amounts of slack on both sides of the belt, when the tensioner takes it up it will effectively shorten the belt on the intake side relative to the exhaust side and stuff will be off. You need to put it on with as much of the slack on the intake side as you can get -- this is true no matter what method you use to keep stuff aligned while installing the belt.
--Ian
This is correct. Thanks!
RE: VVT advance,
That's really odd that you're gaining power from adding advance up top. Most maps I've seen make max hp with close to full retard on the intake cam up there.
Andy, you are very close to my virtual dyno chart, VVT + Boltons and a squaretop. I was expecting a bit more but I expect I will need to pay for a dyno tune for that. I should just boost my damn car already.
I think there is something not quite right with the VD graphs you guys have provided. I have about 200 dyno runs and have seen countless other N/A unmolested VVT engine dynos and all of them ramp down and stay ramping down once they pass the 6K mark on the torque side. Both of those graphs have the torque regaining momentum. That's not right.
I think it's time for both of you guys to hit an actual dyno and get real results. If your tune is anywhere near decent, your engine is in proper working order, and your engine ancillaries are not choking it, you should be seeing 120 wtq and 130 whp on an unmolested VVT engine on gasoline. With a good tune, a square top with a good air intake, a long tube header with a free flowing exhaust, you should get 125 wtq and 145 whp on gasoline.
I believe both of you will be pleasantly surprised by actual dyno results. The torque numbers on your VD are way low in my experience.
It seems like my 134 run was a false positive. I did some extensive testing last night adding and removing ignition timing and adding and removing vvt timing. All my tests were 3rd gear, roughly the same time on the same road.Blue line here was with the same ignition and vvt table as my previous best run. I have to double-check that my afr table was exactly the same too, I just realized I might have changed that. The blue run here was me adding more advance to igntion timing. Adding or removing timing in either vvt or ignition reduced my vd plot.
Edit: Double checked, appears to be the same afr table.
What does your timing table look like? Here's my timing and intake table. No advance before 3k RPM as my advance at 1600 rpm caused the car to buck around that RPM Range.
07-09-2019, 03:08 PM
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