[JimGnitecki]

I realize that the Magnuson 2650 kit for the LT1, and the ZL1 OEM setup, SHOULD get differing results, because both the hardware and the tunes are different. Still I was curious how the net "horsepower under the curve" outcomes looked when compared side by side.

The comparison below, between my 2022 LT1 with the Magnuson 2650 kit and the Magnuson tune, and the OEM ZL1 blower and tune, is imperfect for a couple of reasons:

- The ZL1 dyno chart was generated by Hennessey performance using STD correction, whereas my dyno chart was generated by Davenport Motorsports using SAE correction, so the ZL1 chart reads a little higher than it would have with SAE correction

- My LT1 was dynoed at 3567 feet of elevation, and so its dyno chart accuracy depends upon how accurate the SAE correction actually is for high altitudes, despite its theoretical accuracy

- Hennessey started their dyno run at 3500 rpm, which required extrapolating the power curve down to 2500 where my dyno chart began. I did that extrapolation using TWO lines: one assumes a rather optimistic extrapolation, and the other assumes a more likely extrapolation. But I used the optimistic extrapolation to give the OEM ZL1 setup the benefit of any doubt, and as you will see, even with that optimistic extrapolation, the 2 dyno charts do show a clear difference in tuning objectives.

You can see that although the total "area under the power curve" is remarkably identical, the EMPHASIS is clearly different. The ZL1 hardware and tune favours higher rpm operation. The Magnuson 2650 kit with the provided (unaltered) Magnuson tune favours low rpm operation. This is evident even with the optimistic ZL1 extrapolation, and is notably larger if you assume the more realistic extrapolation (The 2500 and 3000 rpm ratios of ZL1 to Magnuson 2650 become 0.73 and 0.90 respectively).

For a driver seeking maximum acceleration capability, and NOT wanting to modify EITHER the Magnuson or ZL1 tune, the ZL1 setup is superior, especially with the 10speed automatic, as the automatic will immediately put, and keep, the engine at high rpm as soon as a lot of throttle is applied.

For a driver seeking a wider powerband, the Magnuson kit and tune seem superior, as the power available at 2500 and 3000 rpm is higher, especially if you assume the more realistic extrapolation.

For a driver wanting to use either setup as merely a "starting point", I suspect that the Magnuson kit has higher power potential than the OEM setup, BUT the Magnuson kit also requires first some costly fuel system upgrades to go higher in power (which the ZL1 already has), and then also the forged internal engine pieces (which the ZL1 also already has). So, the ideal "starting point" for a really high power output would appear to be a ZL1 to which a Magnuson kit has been transplanted to replace the OEM blower.

Am I missing anything in this analysis?

Jim G

[SATINSTEEL1LE]

Just remember the LT1 has higher compression vs the LT4. So like for like, the LT1 will always make more power due to that.

[SATINSTEEL1LE]

Oh and let me tell you about the magnuson tune. Its HOT GARBAGE. I started with that on my completely stock ZL1 with maggie kit. Car made 590hp. On the same dyno, same 93 tank of gas, my car made 670hp with the JRE tune. Only difference was the tune.

The maggie tune was pig rich commanding 11.0 AFR and Ted's tune was asking for .82lambda which is like 12.10afr. Still safe, but closer to what you'd want to see for 93 at sea level.

[JimGnitecki]

Originally Posted by SATINSTEEL1LE

Oh and let me tell you about the magnuson tune. Its HOT GARBAGE. I started with that on my completely stock ZL1 with maggie kit. Car made 590hp. On the same dyno, same 93 tank of gas, my car made 670hp with the JRE tune. Only difference was the tune.

The maggie tune was pig rich commanding 11.0 AFR and Ted's tune was asking for .82lambda which is like 12.10afr. Still safe, but closer to what you'd want to see for 93 at sea level.

WHEN was your Magnuson tune installed? I am asking because the Magnuson tune installed on my LT1, which was received from Magnuson just over 2 weeks ago, which has not been altered in any way, produces an AFR trace that was AFR = 12 right across the rpm range.

I know that the Magnuson tune is conservative (as is the OEM ZL1 tune), but I am happy with it for 2 reasons:

1. It preserves the warranty that Magnuson includes with their kit if you run their tune unchanged

2. With the OEM 245/40 run flat tires, my car's traction control is active on the entire acceleration run when accelerating from 15 to 20 mph to 90 mph, so I could not use any extra power anyway unless I make the change to Nitto 555R2 tires at some point. I am hesitating on doing that until after I make a long drive from Canada to Southern California to visit My Son, as the trip would consume a good portion of the 555R2 tires' tread life just on the one trip, and thus waste a good part of their purchase cost ($1240 in Canada installed!).

Jim G

[JimGnitecki]

Originally Posted by SATINSTEEL1LE

Just remember the LT1 has higher compression vs the LT4. So like for like, the LT1 will always make more power due to that.

But the higher compression ratio in the LT1 forces a more conservative tune too.

Jim G

[SATINSTEEL1LE]

I got my tune from Magnuson exactly one month ago.

[JimGnitecki]

Originally Posted by SATINSTEEL1LE

I got my tune from Magnuson exactly one month ago.

I wonder why your tune from Magnuson for your ZL1 was so rich compared to my Magnuson tune for my LT1? If anything, I would think that my LT1's higher compression ratio and weaker engine innards would call for MY tune to be a bit richer than a ZL1 tune.

Curuous: How much power did your ZL1 show on the dyno, SAE corrected (not STD corrected) when it was completely stock (i.e. before the Magnuson kit replaced the OEM blower)? I am wondering how much power the Magnuson kit added over the OEM blower and tune, before your tuner improved it further.

Jim G

[toohighpsi]

Originally Posted by JimGnitecki

I
You can see that although the total "area under the power curve" is remarkably identical, the EMPHASIS is clearly different. The ZL1 hardware and tune favors higher rpm operation. The Magnuson 2650 kit with the provided (unaltered) Magnuson tune favors low rpm operation. This is evident even with the optimistic ZL1 extrapolation, and is notably larger if you assume the more realistic extrapolation

Am I missing anything in this analysis?

Jim G

Jim, it's not really a Magnuson SC or tune choice, it's the engine that deems this behavior. The LT1 with 11.5:1 compression ratio cannot run the higher blower speed (boost) or timing at lower RPMs that the LT4 can with its 10:1 compression ratio. So the LT4, by design, is going to have a nice wide full throttle torque curve - at the cost of fuel efficiency.

Since you're enjoying looking over power curves, here a couple more for you. Scenarios of the same car, on the same dyno, with the same corrections (STD) with the different blowers - all running at the limit that the engine is capable of on 91 octane (each run is the average of 3 back to back runs). Each run (except stock) is tuned for the fuel - all else on the vehicle is stock - including airbox and filter.

This first one is an LT4 Z06 M7, lowest line is the TVS1740 on stock cal, next is the TVS2300, and finally the TVS 2650. Notice the peak torque are is pretty limited by the fuel (91 octane) at higher RPM is where the gains can be found due to shorter piston TDC dwell times allowing increased timing (and increased cooling on the 2650)



Then this plot is the LT1 - Camaro SS A8 running 91 octane fuel. Lowest line is stock LT1 naturally aspirated, middle line TVS 2300 on 91 with standard pulley (98mm) then TVS 2650 with delivered pulley (I think it was a 110mm)



I will note that the canned cals are very difficult.

If you have everything on the car completely stock it will be pretty good although a bit conservative (as yours is). If you even change the air filter in the stock airbox (to say a K&N) it will offset the calibration. So many people already have an aftermarket CAI (which is normally a completely different MAF meter) and a variety of other bolt ons that custom cals will be required to achieve great performance.

[JimGnitecki]

Thanks, Toohighpsi! Your explanations for the 2 dyno charts are very helpful. But, I am confused when you say:

"Jim, it's not really a Magnuson SC or tune choice, it's the engine that deems this behavior. The LT1 with 11.5:1 compression ratio cannot run the higher blower speed (boost) or timing at lower RPMs that the LT4 can with its 10:1 compression ratio. So the LT4, by design, is going to have a nice wide full throttle torque curve - at the cost of fuel efficiency."

This SEEMS to be saying that the LT4 (ZL1) engine should have the broader torque curve (more torque and thus power at lower rpm), but my charts and table earlier show that the LT1 with the 2650 has better power at lower rpm than the LT4. Did I misunderstand what you said?

Jim G

[toohighpsi]

Originally Posted by JimGnitecki

This SEEMS to be saying that the LT4 (ZL1) engine should have the broader torque curve (more torque and thus power at lower rpm), but my charts and table earlier show that the LT1 with the 2650 has better power at lower rpm than the LT4. Did I misunderstand what you said?
Jim G

That is correct, generally the LT4 with smaller intake cam duration, lower compression, and small 1740SC spinning at higher speed will deliver higher low speed torque (and power) and a flatter overall curve than a 2650 on the LT1.
This is exactly the reason I really like the 2650 on LT engines (1 or 4) it is just the perfect balance of a fairly strong low speed torque and pulls hard right to redline.

[Katech_Zach]

Two different dynos, i would not compare data from two different dynos even if they claim to have the same correction factor.

[JimGnitecki]

Originally Posted by Katech_Zach

Two different dynos, i would not compare data from two different dynos even if they claim to have the same correction factor.

The whole point of correction factors is to enable comparisons even though runs were made on different physically located dynos.

I realize that because different dyno manufacturers use different methods of measuring raw torque and power, and so their results are not always comparable, and not always properly compatible with the SAE and STD formulas. But both of these dyno charts being compared are from DynoJet dynos. Assuming both dynos have been properly calibrated and maintained, the results are comparable, which is why I chose charts from Davenport Motorsports and Hennessey, and not from an unknown shop whose reputation for proper maintenance and integrity has not been proven.

Perfection might or might not be attainable, but in today's world at least, these two are as comparable as I could find.

Jim G

[Idaho2018GTPremium]

Interesting analysis, but since these are different dynos, different days, different cars, different elevations, different corrections, etc., one can't directly compare the two specific results, though we can look at trends between the two curves. That said, average or total hp under a curve is good, however, even that isn't fool proof. If two cars have the same average or total hp under the curve from 3500 to 6500 rpm, but one has more hp at the top end (say, 4500 and up as in this case), and the other has more hp at the lower end, the car with more hp at the top end will be quicker, because racing mostly happens from around 4800 or 5000 through 6500 rpm, esp. in modern automatics. The gears are spaced closely together and thus, during a race, will never drop down to the lower rpm range where the other engine makes more torque.

[JimGnitecki]

Originally Posted by Idaho2018GTPremium

. . . average or total hp under a curve is good, however, even that isn't fool proof. If two cars have the same average or total hp under the curve from 3500 to 6500 rpm, but one has more hp at the top end (say, 4500 and up as in this case), and the other has more hp at the lower end, the car with more hp at the top end will be quicker, because racing mostly happens from around 4800 or 5000 through 6500 rpm, esp. in modern automatics. The gears are spaced closely together and thus, during a race, will never drop down to the lower rpm range where the other engine makes more torque.

That's true, for minimizing time to a given high speed (and I think I said that above). But which car is going to be more pleasant to drive 95% of the time on the street, when the driver is NOT trying to accelerate at the highest possible rate?

I've driven cars with really peaky engines (the Honda S2000 for an example of an extreme). They are not fun to drive on normal roads and especailly in traffic.

Jim G