He is one of the TOP tuners, and without a 2nd thought, the top 1MZ person.
I truely think Tony taking his time to write this up for us all, can be a HUGE benifit to the community.
Anyway, like all supercharged 1MZ setups, or any other supercharged setup that is non-intercooled, the key player is air intake temps. Besides that, I've read the thread and all the guys on there still doesn't have a full grasp on the relationships between power and octane.
To cover some basics, HP is just torque at a given RPM, and nobody mentioned anything about torque on the forums. Torque is the measure of energy and force inside the combustion chamber, which is similar to dynamic compression. Dynamic compression is a peak pressure rating, but torque is the average force throughout the entire power stroke over a 180deg crank rotation.
Dynamic compression is "static", meaning it is just a measurement of "peak force" inside the cylinders. Just like torque, it is just a force measurement, but we like to look at torque because it is the average force, and that lets us know if we are getting close to knock on certain octane and certain compression raio. HP is work done, and equals to the amount of force exerted versus time, so HP doesn't mean too much because you can make more HP with the same torque at higher RPM's. Given some basic calculations, with the 230-280 lbft of torque that our S/C'd 1MZ-FE's are putting out, we are within acceptable limits of 91 octane. In similar comparisons, like an IS300 2JZ-GE which is also 10.5:1 CR and the same redline (6200-6500RPM), these motors have pushed well over 300 lbft of torque on 91 oct and have proven to live for years, well tuned of course. The usual number is not to exceed 100 lbft per 1.0L of engine displacement (300 lbft for 3.0L, 200 lbft for 2.0L, etc..) when dealing with 10+ compression ratios from my findings. It really applies to all sorts of high compression motors too, ranging from a B18C5 Type-R engine with 10.6:1 CR, as they try not to exceed 180 lbft of torque on the stock 1.8L or bad things happen. The same applies to E46 BMW M3's when their stock 10.5:1 CR 3.2L motor likes to blow up when touching near 350 lbft of torque (see HPF turbo kits for M3's for data).
What supercharged engine differs is that your torque curve is mostly flat. Compare a stock N/A 1MZ-FE dyno and a TRD SC 1MZ and you will find a totally different type of torque curve. Roots supercharger works this way because airfflow is determined by the supercharger, and supercharger airflow is a linear curve based on engine RPM. Whenever you have a linear airflow curve, it results in a linear HP curve because airflow is HP. To get a linear HP curve, must come with a flat torque curve.
So with that being explained, the most important area which you want to focus on whenever tuning a supercharged engine is the highest RPM which torque peaks. Not exactly where the engine makes peak torque, but where the torque peak is held the longest and just before it really starts falling. On your dyno, Adam, that is 4500-5000RPM. The reason why your engine is doing well, comes from the fact that your air/fuel ratios is also nice and rich in that area. It is rich where it is needed; that is when the most cylinder pressures occur, and at the highest RPM which is it happening. Highest torque at highest RPM at peak = most heat and highest tendency to knock and blow up pistons.
On the other hand, all the dyno's I have seen on a few supercharged Solaras, they start to lean out at torque peak and peak RPM. On some member's post, their air/fuel curve is 12.0:1 AFR across the board, but that means the engine is either running unnecessarily rich at redline, or of it is perfect at redline, then it is too lean at 4500-5000RPM. From other forum member's posts, they let the sucker lean out around 4500-5000RPM, but they still think its safe because it becomes rich at redline. Most tuners do not understand this, so they kinda follow the usual thing --tune the engine rich when the most boost is made, and richer at high RPM's. This applies to many common motors like a Honda, or a more performance-oriented motor, as well as turbo motors. But this does not apply to a supercharged 1MZ-FE, or any roots supercharger engine that does not breathe well from the factory (cars with naturally heavy falling torque curves N/A).. For turbo, whenever full boost is reached, peak torque is reached. And if the motor is efficient, it carries power to redline. .Our SC'd 1MZ's don't like to knock at redline due to the way our engines are designed. People are blowing motors due to an issue with tuning obviously.
For an SC setup, it can be well tuned on the dyno; but once you go on the road, air intake temps can soar up and skyrocket. You could be sitting in traffic for 30 mins, and then once traffic opens up, you go nuts and do a 0-100 mph pull. Do that a few times and I can guarantee blown pistons. Octane requirements will greatly change depending on supporting mods as well. If you have a free flow exhaust, no cat, and a nice and fat cold air intake (3.5" pipe or bigger), all these mods will lower IAT's and keep it cool a lot longer. If you have a short ram, a 5spd transmission in which the RPM's always stay higher than an A/T, or a restrictive exhaust, this will keep the heat inside the motor and increase the tendency for knock. And what do you know, although it is the same PSI pulley, same supercharger and relatively the same power, one is more likely to knock then the other. Which again, the entire thread has failed to mentioned this.
For your Camry, remember when we were on the dyno, I did 3 consecutive full dyno pulls? You probably thought I was nuts, but it was to check for heatsoak and consistency. I figured that if I couldn't make the engine knock with your current tune after 3 hard runs on the dyno back-to-back with limited airflow cooling from the dyno fans, each pull being about 15 secs long, you will never run into knock unless you REALLY kill the car in the middle of summer. To me, your setup was safe. Now the other guy on the forum with the same boost pulley could knock, because his exhaust may be more restrictive, or his tune was off. This immediately puts everything in a different perspective. Your engine with a good tune and stress tested on the dyno will run for years or more, while the other guy could ruin the motor on a spirited highway trip in a month.
But IMO, if you are looking to truly bullet proof your setup, you can still do more. Switch to 9 heat-range plugs, like an NGK BKR9EIX, or Denso IK27's. It may seem cold, but not exactly too cold if you imagine your supercharger being heatsoaked, and on the borderline of knock. If you baby your car for a month and drive like a grandma, then these plugs could foul up. But if you drive it hard on a regular basis, I can guarantee you these plugs will last just as long, and you won't even feel a difference in gas mileage. The other upgrade you can do is water/meth injection, sprayed before the blower. This will pretty much give you more power and being safer at the same time.
You can directly post this on the forums if you wish.. I would have posted, but I couldn't log in. If you can look into this problem for me, that would be great.
- SolaraGuy Street Racer
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