I think he suggested you go outside and play a game of “hide and go fook yourself”.
Who the fook is this guy?? Lol another ms Jackson account probably
This is absolutely 100% correct and what I've been saying from the beginning. When octane limited, the key to performance and reliability is to maximize BMEP while keeping Pmax and compression temperature and pressure in check. Octane does not inherently limit hp or torque/cid. If it did, we wouldn't see factory-stock, reliable, production engines making significantly more hp and torque/cid than supercharged Coyotes. Think about this: if you were to limit peak cylinder pressure (Pmax) to the stock level, but somehow retain higher pressure as the piston travels down the bore on the power stroke, then you get more power with no more chance of detonation or stress on the piston, rings, valves, rod, etc. This is one of the positive effects of lowering compression ratio. The pressure degrades slower on the power stroke so average torque applied to the crank is higher.
Another interesting data point was my prior vehicle, a 2015 F150 5.0 with a Whipple kit. I had the 3.5 pulley on it, which showed about 15 psi on gauge. This was on the Whipple cal and I always ran it on Shell 93 with no octane booster. I sold the truck with about 30k miles on it. The current owner beats on it mercilessly and is at around 80k miles now. It's melted cats twice but the engine is still in perfect condition. He even did a compression check recently and it was all good. I can't help but wonder if the reliability of that one was enhanced by the fact that the truck motors were half a number lower compression than the Mustang (10.5 vs 11). Guess we'll never know for sure...
Which ones?
Let's assume for a minute that a pump gasoline supercharged coyote makes about 600 ftlb at the crank, or about 2 ftlb/cid.
I will be the first to admit that I did not see the "per cubic inch" statement. So I guess ill give you that. I will also add that honestly I don't really care for torque. A lot of people in the coyote world are obsessed with it. I also don't really care for the whole "hp/ci". At the end of the day, unless you pay a lot out of pocket you are unlikely to see a car from factory that can match the Hp at the wheels that a coyote puts out at 10psi.
I find it useful because it gives you access to a much larger data set and you can learn from those successfully making more. What’s better than 3.5 hp/cid from 122 cid? 3.5 hp/cid from 302 cid of course...
I agree completely, which is why it’s what I have! I’m into mine for 15k less than a hellcat and it’s faster, but not as reliable. I figure if the engine goes I can build a stout lower compression short-block for it and still be ahead on money and power.
In looking at the specific graphs you posted above, something didn't look right to me. In Chapter 17, he claimed low compression and boost made more than double the power vs high compression and no boost assuming the same Pmax. In Chapter 19, Figure 20, he showed that the low compression motor only had a ~10% power and torque advantage over high compression with the same Pmax. Secondly, starting with the basic "motoring" (unfired) curve, the pressures peaked much higher in Chapter 19 Figures 21-23 than they did in Chapter 5 Figure 7. Chapter 19 did not seem to specify the manifold pressure used for each compression ratio. One might mistakenly assume the low compression ratio engine ran higher manifold pressure, but this is not the case. I ran the combination through my own thermodynamic kinematic FEA model to figure out what was going on and see if I could replicate it. It turns out, they assumed the same manifold pressure for all three compression ratios, and a rather high one at that. In Figures 21-23, they used the same manifold pressure of 1.5 bar (~22 psi boost) on all three. One doesn't even need an elaborate engine simulator FEA to determine this your yourself, as the pressure-volume ratio formula is provided and is accurate. This revelation is especially interesting since Figure 20 shows that low compression still had a 10% power and torque advantage over high compression even at the same boost level and Pmax. Something else interesting is that our models both agree that the air charge prior to spark is 200-250 deg F cooler at the lower compression ratio with the same boost but more power. Therefore, the low compression engine is further from detonation and has room to increase manifold pressure, thereby growing its power advantage while maintaining knock safety margin.
You think this is true regardless of ignition timing? What I’m saying is that with 22 psi boost and 12/1 compression the ignition had to be retarded so severely that the net change in power was negative.
Yes, overly retarded ignition timing will affect the coyote in the same way as any other gasoline SI engine.
the only 10% advantage thats mentioned is for high compression, at low RPM. High RPM is only slightly toward low CR, nothing that can be seen in the graphs.
I don't agree with the motored traces in the graph I posted, they have those wrong or on a different scale not shown. Detonation has little to do with pre spark temperature. Peak cylinder pressure is what causes it, this is post spark, and what this chapter was comparing. The lower compression engine could not increase its boost more, as you seem to think, It would run into detonation if 80 bar was that threshold. This is why I said, dont let your IATs get out of control when running a high CR engine with boost. You don't seem to understand this, detonation is in the end gases, its different from pre-ignition. Pre-ignition is the engine is out of the ECU's control, luckily with EFI and well designed combustion chambers its very rare.
I dont agree with the motoring, but I do believe the double peak.
Figures 24 and 25 are for low RPM. Its confusing because they switched from showing low med high CR to, high then Low CR graphs, you need to look at descriptions. Again the goal was peak cylinder pressure as a representation when both would be detonation limited. Manifold pressure would not be able to be increased in either motor.