[JoeAyalaM]

Throttle modulation comes to mind as a solution to smoking tires, would it be possible?

[LesBaer]

Guys, I'm just curious - why would anyone go with the LT4 over the Heartbeat? Weight? I'm not an expert on these things, but I've done my homework and decided on the Heartbeat already. What significant advantages does the LT4 have?

It just seems like the LT4 was designed by GM to be able to fit into the multiple applications of the LT1, with each application having it's own unique circumstances - so what's the lowest common denominator? I'm almost thinking the C7's heat issues could have influenced the decision to go smaller. Maybe it was emissions or mpg...I'm not sure. I'm not one of these people who's going to sit here and say the Heartbeat is better because that's what I have. I'm just trying to think about it logically. If I'm wrong, I'm wrong.

ADM sells both and I realize that it's hard for a vendor to talk about these things considering their supplier relationships. However on the Corvette side, Vengeance appears to have done a pretty good comparison. What do you guys think?

http://www.chevyboost.com/content.ph...pgrade-results

[Mr. Wyndham]

Originally Posted by LesBaer

Guys, I'm just curious - why would anyone go with the LT4 over the Heartbeat? Weight? I'm not an expert on these things, but I've done my homework and decided on the Heartbeat already. What significant advantages does the LT4 have?

It just seems like the LT4 was designed by GM to be able to fit into the multiple applications of the LT1, with each application having it's own unique circumstances - so what's the lowest common denominator? I'm almost thinking the C7's heat issues could have influenced the decision to go smaller. Maybe it was emissions or mpg...I'm not sure. I'm not one of these people who's going to sit here and say the Heartbeat is better because that's what I have. I'm just trying to think about it logically. If I'm wrong, I'm wrong.

ADM sells both and I realize that it's hard for a vendor to talk about these things considering their supplier relationships. However on the Corvette side, Vengeance appears to have done a pretty good comparison. What do you guys think?

http://www.chevyboost.com/content.ph...pgrade-results

The LT4 (the engine) features many internal upgrades to handle the power than an LT1 just doesn't have. This is why they're able to sell a 650hp engine with a full manufacturer powertrain warranty.

Some upgrades to the engine includes higher flow fuel pump, injectors, and rail...larger combustion chambers (lower - but still high - compression ratio), solid titanium intake valves, longer duration camshaft, stainless steel exhaust manifold (vs cast iron), forged steel crank with tungsten balancing inserts, aluminum damper, flat-top forged aluminum pistons, higher-strength lighter weight connecting rods, and diamond-coated wrist pins.

They seem to have opted for a smaller rotor supercharger so they could save weight, improve packaging into the Stingray, and then rev them higher to create the boost they needed. The LT4 (the whole engine) only weighs 75 lbs more than the LT1. The supercharger assembly itself is 20lbs lighter than the LS9's supercharger...which used TVS 2300 rotors, like the aftermarket systems.

[LesBaer]

Originally Posted by Mr. Wyndham

The LT4 (the engine) features many internal upgrades to handle the power than an LT1 just doesn't have. This is why they're able to sell a 650hp engine with a full manufacturer powertrain warranty.

Some upgrades to the engine includes higher flow fuel pump, injectors, and rail...larger combustion chambers (lower - but still high - compression ratio), solid titanium intake valves, longer duration camshaft, stainless steel exhaust manifold (vs cast iron), forged steel crank with tungsten balancing inserts, aluminum damper, flat-top forged aluminum pistons, higher-strength lighter weight connecting rods, and diamond-coated wrist pins.

They seem to have opted for a smaller rotor supercharger so they could save weight, improve packaging into the Stingray, and then rev them higher to create the boost they needed. The LT4 (the whole engine) only weighs 75 lbs more than the LT1. The supercharger assembly itself is 20lbs lighter than the LS9's supercharger...which used TVS 2300 rotors, like the aftermarket systems.

Sorry, I should clarify - I meant the LT4 SC.

[Mr. Wyndham]

Originally Posted by LesBaer

Sorry, I should clarify - I meant the LT4 SC.

Oh, well...then this is all that applies from that post...my mistake!

They seem to have opted for a smaller rotor supercharger so they could save weight, improve packaging into the Stingray, and then rev them higher to create the boost they needed. The supercharger assembly itself is 20lbs lighter than the LS9's supercharger...which used TVS 2300 rotors, like the aftermarket systems.

[LesBaer]

Originally Posted by Mr. Wyndham

Oh, well...then this is all that applies from that post...my mistake!

They seem to have opted for a smaller rotor supercharger so they could save weight, improve packaging into the Stingray, and then rev them higher to create the boost they needed. The supercharger assembly itself is 20lbs lighter than the LS9's supercharger...which used TVS 2300 rotors, like the aftermarket systems.

Thanks man, I appreciate any info I can get from you!

[Tr6]

Thank you Mr. Wyndham for the info! We should all be really glad for having a camaro especially when it comes to SC install as we do have the option to go with the LT4 SC and not have to get an entire hood with it! Ei: Non- C7 Zo6, C7s the roots lt4 SC won't fit on the stock hood so you have to get the C7 ZO6 hood too lol. Or just get a procharger and not worry about it.

Another positive thing is that it is a GM SC. It's used for quite a bit now, OEM durability and quality. Please do note that I am NOT saying aftermarket ones are crap, just noting an aspect of the OEM SC to give you that extra piece of mind.

[Mr. Wyndham]

Originally Posted by Tr6

Thank you Mr. Wyndham for the info! We should all be really glad for having a camaro especially when it comes to SC install as we do have the option to go with the LT4 SC and not have to get an entire hood with it!

You're welcome!

I think that extends to a lot of the aftermarket units, too...

I do believe that the last generation CTS-V and Corvette ZR1 started the "inverted supercharger" trend...which allowed for smoother airflow, better cooling, and flatter packaging of supercharger systems. The aftermarket quickly caught on and now everyone's doing it...tons of benefits.

[jessrayo]

Originally Posted by LesBaer

Sorry, I should clarify - I meant the LT4 SC.

I have run 3 different superchargers on my ZL1 and currently I'm back to the 1.9 LSA supercharger vs. the 2.3's I had at one time. I don't have a lot of hard data but I can tell you what I found out through personal experience.

First off superchargers have a limited rpm range. The stock LS9 ZR1 corvette 2.3 supercharger was running at about 15,000 rpm at peak engine rpm. The LT4 supercharger is running at about 20,000 rpm at peak engine rpm. Mathematically if you take 2.3 (supercharger size) and multiply by 15,000 (supercharger rpm) you get air volume in liters per minute. In this example the LT4 will move about 34,000 liters of air per minute and the LS9 will move about 34,500. The LT4 takes 500 less liters of air and converts it to a little more horsepower as the engines are both 6.2's rated at 638 and 650 respectively. The smaller supercharger takes less power to spin as long as you don't run out of usable supercharger rpm.

If you dyno the engine with different superchargers on the car and look at the power to the tires, at an equal amount of power to the tires the bigger supercharger will always have to provide a little more air than the smaller one because it is not as efficient.

All superchargers have a maximum rpm. The 2.3's limits are pretty hard at 23,000 rpm. When the supercharger hits this rpm the heat it generates is greater than the cooling system can possibly cope with and it will rapidly lose power as the boost observed will be caused by increasing air temp rather than increased air molecules. This is what Vengance racing did with the heartbeat in the article you posted. Vengance took the supercharger to its max rpm and logged the power on the dyno. And just a note they had 826 whp, my ZL1 made an absolute max of 836 whp on a 2.3 because that is all the air that thing will possibly pump. As they noted in their article, this is over 90 more hp than LT4 supercharger could make at it's max speed. If I do a few calculations I find that the LT4 makes 89.22% of the power the heatbeat does so if it had the exact same efficiency and the heartbeat was spinning at 23,000 then that LT4 would be spinning at a little less than 28,000 rpm. I haven't actually worked with the 1.7 but that seems like a lot of supercharger rpm.

So after all of this, I would answer your original question by saying that if someone was not looking for the absolute most horsepower possible through the supercharger, the smaller supercharger would be more efficient. This means the smaller supercharger will get better mpg because air/fuel ratios are constant and the smaller supercharger needs less air and fuel to make similar power.
Also your engine would have a little less stress over the life of the engine because the 1.7 might take 20 hp (very crude estimate) to drive and the 2.3 might take 40 hp. The stress of spinning that supercharger at speed is in the pistons rods and crank but doesn't make it to the tires.

I don't have the exact figures available on the LT4 supercharger but because it is mass produced by GM I suspect the cost of the system is a little less.

Oh, and one more thing, the smaller supercharger generally generates less heat than the big one. The heartbeat has way more cooling capacity than the LT4 but it needs it because it makes more heat all of the time. Kind of a by product of the lack of efficiency. So if you significantly upgrade the supercharging cooling accessories and run a smaller supercharger it will have even better overall results at the track.

[oldman]

Originally Posted by jessrayo

I have run 3 different superchargers on my ZL1 and currently I'm back to the 1.9 LSA supercharger vs. the 2.3's I had at one time. I don't have a lot of hard data but I can tell you what I found out through personal experience.

First off superchargers have a limited rpm range. The stock LS9 ZR1 corvette 2.3 supercharger was running at about 15,000 rpm at peak engine rpm. The LT4 supercharger is running at about 20,000 rpm at peak engine rpm. Mathematically if you take 2.3 (supercharger size) and multiply by 15,000 (supercharger rpm) you get air volume in liters per minute. In this example the LT4 will move about 34,000 liters of air per minute and the LS9 will move about 34,500. The LT4 takes 500 less liters of air and converts it to a little more horsepower as the engines are both 6.2's rated at 638 and 650 respectively. The smaller supercharger takes less power to spin as long as you don't run out of usable supercharger rpm.

If you dyno the engine with different superchargers on the car and look at the power to the tires, at an equal amount of power to the tires the bigger supercharger will always have to provide a little more air than the smaller one because it is not as efficient.

All superchargers have a maximum rpm. The 2.3's limits are pretty hard at 23,000 rpm. When the supercharger hits this rpm the heat it generates is greater than the cooling system can possibly cope with and it will rapidly lose power as the boost observed will be caused by increasing air temp rather than increased air molecules. This is what Vengance racing did with the heartbeat in the article you posted. Vengance took the supercharger to its max rpm and logged the power on the dyno. And just a note they had 826 whp, my ZL1 made an absolute max of 836 whp on a 2.3 because that is all the air that thing will possibly pump. As they noted in their article, this is over 90 more hp than LT4 supercharger could make at it's max speed. If I do a few calculations I find that the LT4 makes 89.22% of the power the heatbeat does so if it had the exact same efficiency and the heartbeat was spinning at 23,000 then that LT4 would be spinning at a little less than 28,000 rpm. I haven't actually worked with the 1.7 but that seems like a lot of supercharger rpm.

So after all of this, I would answer your original question by saying that if someone was not looking for the absolute most horsepower possible through the supercharger, the smaller supercharger would be more efficient. This means the smaller supercharger will get better mpg because air/fuel ratios are constant and the smaller supercharger needs less air and fuel to make similar power.
Also your engine would have a little less stress over the life of the engine because the 1.7 might take 20 hp (very crude estimate) to drive and the 2.3 might take 40 hp. The stress of spinning that supercharger at speed is in the pistons rods and crank but doesn't make it to the tires.

I don't have the exact figures available on the LT4 supercharger but because it is mass produced by GM I suspect the cost of the system is a little less.

Oh, and one more thing, the smaller supercharger generally generates less heat than the big one. The heartbeat has way more cooling capacity than the LT4 but it needs it because it makes more heat all of the time. Kind of a by product of the lack of efficiency. So if you significantly upgrade the supercharging cooling accessories and run a smaller supercharger it will have even better overall results at the track.

This should be a sticky...

[Tr6]

Originally Posted by jessrayo

I have run 3 different superchargers on my ZL1 and currently I'm back to the 1.9 LSA supercharger vs. the 2.3's I had at one time. I don't have a lot of hard data but I can tell you what I found out through personal experience.

First off superchargers have a limited rpm range. The stock LS9 ZR1 corvette 2.3 supercharger was running at about 15,000 rpm at peak engine rpm. The LT4 supercharger is running at about 20,000 rpm at peak engine rpm. Mathematically if you take 2.3 (supercharger size) and multiply by 15,000 (supercharger rpm) you get air volume in liters per minute. In this example the LT4 will move about 34,000 liters of air per minute and the LS9 will move about 34,500. The LT4 takes 500 less liters of air and converts it to a little more horsepower as the engines are both 6.2's rated at 638 and 650 respectively. The smaller supercharger takes less power to spin as long as you don't run out of usable supercharger rpm.

If you dyno the engine with different superchargers on the car and look at the power to the tires, at an equal amount of power to the tires the bigger supercharger will always have to provide a little more air than the smaller one because it is not as efficient.

All superchargers have a maximum rpm. The 2.3's limits are pretty hard at 23,000 rpm. When the supercharger hits this rpm the heat it generates is greater than the cooling system can possibly cope with and it will rapidly lose power as the boost observed will be caused by increasing air temp rather than increased air molecules. This is what Vengance racing did with the heartbeat in the article you posted. Vengance took the supercharger to its max rpm and logged the power on the dyno. And just a note they had 826 whp, my ZL1 made an absolute max of 836 whp on a 2.3 because that is all the air that thing will possibly pump. As they noted in their article, this is over 90 more hp than LT4 supercharger could make at it's max speed. If I do a few calculations I find that the LT4 makes 89.22% of the power the heatbeat does so if it had the exact same efficiency and the heartbeat was spinning at 23,000 then that LT4 would be spinning at a little less than 28,000 rpm. I haven't actually worked with the 1.7 but that seems like a lot of supercharger rpm.

So after all of this, I would answer your original question by saying that if someone was not looking for the absolute most horsepower possible through the supercharger, the smaller supercharger would be more efficient. This means the smaller supercharger will get better mpg because air/fuel ratios are constant and the smaller supercharger needs less air and fuel to make similar power.
Also your engine would have a little less stress over the life of the engine because the 1.7 might take 20 hp (very crude estimate) to drive and the 2.3 might take 40 hp. The stress of spinning that supercharger at speed is in the pistons rods and crank but doesn't make it to the tires.

I don't have the exact figures available on the LT4 supercharger but because it is mass produced by GM I suspect the cost of the system is a little less.

Oh, and one more thing, the smaller supercharger generally generates less heat than the big one. The heartbeat has way more cooling capacity than the LT4 but it needs it because it makes more heat all of the time. Kind of a by product of the lack of efficiency. So if you significantly upgrade the supercharging cooling accessories and run a smaller supercharger it will have even better overall results at the track.

Jessrayo, I gotta say... Thanks a mill for a FANTASTIC write up!!!

Originally Posted by oldman

This should be a sticky...

+1 To this.

[toohighpsi]

Originally Posted by jessrayo

I have run 3 different superchargers on my ZL1 and currently I'm back to the 1.9 LSA supercharger vs. the 2.3's I had at one time. I don't have a lot of hard data but I can tell you what I found out through personal experience.

First off superchargers have a limited rpm range. The stock LS9 ZR1 corvette 2.3 supercharger was running at about 15,000 rpm at peak engine rpm. The LT4 supercharger is running at about 20,000 rpm at peak engine rpm. Mathematically if you take 2.3 (supercharger size) and multiply by 15,000 (supercharger rpm) you get air volume in liters per minute. In this example the LT4 will move about 34,000 liters of air per minute and the LS9 will move about 34,500. The LT4 takes 500 less liters of air and converts it to a little more horsepower as the engines are both 6.2's rated at 638 and 650 respectively. The smaller supercharger takes less power to spin as long as you don't run out of usable supercharger rpm.

If you dyno the engine with different superchargers on the car and look at the power to the tires, at an equal amount of power to the tires the bigger supercharger will always have to provide a little more air than the smaller one because it is not as efficient.

All superchargers have a maximum rpm. The 2.3's limits are pretty hard at 23,000 rpm. When the supercharger hits this rpm the heat it generates is greater than the cooling system can possibly cope with and it will rapidly lose power as the boost observed will be caused by increasing air temp rather than increased air molecules. This is what Vengance racing did with the heartbeat in the article you posted. Vengance took the supercharger to its max rpm and logged the power on the dyno. And just a note they had 826 whp, my ZL1 made an absolute max of 836 whp on a 2.3 because that is all the air that thing will possibly pump. As they noted in their article, this is over 90 more hp than LT4 supercharger could make at it's max speed. If I do a few calculations I find that the LT4 makes 89.22% of the power the heatbeat does so if it had the exact same efficiency and the heartbeat was spinning at 23,000 then that LT4 would be spinning at a little less than 28,000 rpm. I haven't actually worked with the 1.7 but that seems like a lot of supercharger rpm.

So after all of this, I would answer your original question by saying that if someone was not looking for the absolute most horsepower possible through the supercharger, the smaller supercharger would be more efficient. This means the smaller supercharger will get better mpg because air/fuel ratios are constant and the smaller supercharger needs less air and fuel to make similar power.
Also your engine would have a little less stress over the life of the engine because the 1.7 might take 20 hp (very crude estimate) to drive and the 2.3 might take 40 hp. The stress of spinning that supercharger at speed is in the pistons rods and crank but doesn't make it to the tires.

I don't have the exact figures available on the LT4 supercharger but because it is mass produced by GM I suspect the cost of the system is a little less.

Oh, and one more thing, the smaller supercharger generally generates less heat than the big one. The heartbeat has way more cooling capacity than the LT4 but it needs it because it makes more heat all of the time. Kind of a by product of the lack of efficiency. So if you significantly upgrade the supercharging cooling accessories and run a smaller supercharger it will have even better overall results at the track.

Great discussion points and observations! It can be difficult to make direct comparisons between a specific SC performance because the application and surrounding hardware can dramatically affect the SC's performance.

When looking at the generic SC map data, between the R1740 and R2300, we find they are quite similar in all aspects except flow. Since the 2300 rotor has a slightly lower L/D (length over diameter) along with higher displacement it is actually a slightly better performer in "specific" terms. (R1900 is my favorite blower due to it's L/D)

For example, at 1.8 PR (~12 psi boost) the peak adiabatic efficiency occurs at 10K RPM on both superchargers, with the 2300 having a 1% benefit. This 1% benefit for the 2300 is shown across the RPM range of the SC.

When it come to input power between the ZR1 and C7Z06, the R1740 generic at 20,000 RPM and 1.8 PR has a mass flow of ~2200 kg/hr. If we want to reach the exact same point with an R2300 it needs to be turned 16,000 RPM and requires 6.2KW less input power than the R1740 spinning at 20,000 RPM.

Now again these are generic SC map comparisons, restrictions in the system such as air filters, inlets, throttle bodies, intercoolers, ports, calibration, etc. all influence to total performance of the system. Most probably the discrepancy between the ZR1 and C7Z06 as noted by jessrayo

The stock LT1 that I have on the engine dynamometer is equipped with a TVS 2300 Heartbeat and makes 630 ft-lbs of torque and 670 flywheel HP with 7.5psi boost on 100 octane unleaded, it's the same setup and calibration that ran 10.8s @ 129 in the 2016 Camaro (610RWHP). My Z06 LT4 runs 10 PSI of boost from an R1740 to make 650 ft-lbs and 650 flywheel HP. In this case the blower requires more boost to make a similar output (I think the stock LT4 could make 670HP with 100 octane) but has a higher torque value due to the increased speed of the blower reaching a higher volumetric efficiency at a lower engine speed.

It's important to realize that at the OEM level there are no Kudos to making more power that the vehicle is specified for. The Z06 was known to have 650HP long before the engine development began (same for CTSV2 and ZR1). If the engine makes more power than the specification, there isn't a big celebration by the engineers (well maybe a small one , who doesn't love power!) but then they have to figure out how to get the performance down to the desired level.

As for peak possible power from a 2300? That will depend on the application, there are 2 credible sources listed above that seem pretty realistic in their application. I've been over at Kenny Duttweiler's (that guy is just awesome) shop and watched him make about 1100 HP on an LS engine with a 2300 with which should yield well over 900 RWHP. Everything in the system must be addressed, especially all areas on the inlet of the SC, they are the most important as the final limiting speed feature of a TVS SC is the inlet area, once the rotor speed exceeds the ability of the inlet port to fill the rotor chambers it's all down hill from there as noted by the examples in the original post.

[MIAMI2SSRS]

Thank you jessrayo and toohighpsi. I will be reading your posts again and again to make sure that i am clear in the concepts. Great way to explain it in layman terms. I appreciate it!!!

[LesBaer]

Thank you both from me as well. Superchargers and DI are new to me, so I'm trying to absorb as much as I can right now. I'm going to keep my boost conservative at 6psi since we don't the same forged engine as the Z06. I also won't have wider wheels and Pilot Super Sports for at least another month.