[JSH]

Originally Posted by ZL1Atlanta

A couple years ago I made a spreadsheet of all the stock A10 ZL1 dyno numbers... That said, 1400 x 84% = 1,176 RWHP available to you.

King and I kicked around A10 power loss here a few months back and I was at 15% and he was closer to 10%. That's why I use 1200 and 1250. In summary, there's probably at least a hundred more wheel horsepower left in the engine

[ZL1Atlanta]

Originally Posted by JSH

King and I kicked around A10 power loss here a few months back and I was at 15% and he was closer to 10%. That's why I use 1200 and 1250. In summary, there's probably at least a hundred more wheel horsepower left in it

Not sure where you are considering the power it takes to turn the supercharger in your estimates with only 1400 HP (estimated) available to you, but right on. I’m just sharing my experience. Sometimes walking the line of breaking stuff is part of the fun.

[radz28]

Originally Posted by ZL1Atlanta

A couple years ago I made a spreadsheet of all the stock A10 ZL1 dyno numbers I could find and averaged them out. The number was 15 I believe and the average drivetrain loss was 16% (assuming every engine actually made 650 HP). That isn’t exact science, but gives an idea. That said, 1400 x 84% = 1,176 RWHP available to you. Naturally parasitic loss has to be removed from the power the engine is experiencing, so you’d take some number away from the 1400 and then do your x 84% if you’re trying to back in what is safely left for you at the wheels. Maybe TooHighPSI will chime in as I’m sure he has a pretty good idea of what parasitic loss is from his days at Magnuson developing the blower. I know it is more than 50 HP at these levels.

None of these guidelines are exact with possible factory flaws in blocks, pistons, rods, how hard it is being ran, tuning, etc. But all of those uncertainties are why I didn’t want to sleeve a stock block when trying to max out the 2650. It gave me maybe an extra 2-300 HP and we had just dyno’d over 1300 RWHP when the stock cylinder wall cracked. That said, we ran my car at ~1,100 RWHP for over a year and 100+ passes with no issues using LME’s 1400 HP offering.

Edit: In this video he is talking about a test Kenne Bell did between one of their blowers and a 2650 on an engine/blower dyno stand. At 22 psi the 2650 took over 200 HP. Much higher than I thought!

https://youtu.be/AvJ1nLRYteE?t=485

Didn't one of the C7 ZR1 engineers make a comment about how the 2650 consumed around 150-or-something HP to turn (at OEM power level), too? He tried to make it sound like an LT5 made similar numbers to the Demon or something by saying something to the effect, "... if you consider the power it takes to drive the 2650, it makes similar power to a Demon...", or something like that? Now I have to find that...

EDIT: Here's the article/quote:
https://www.lsxmag.com/news/2019-cor...n-development/

The supercharger actually spins slower than the one on the LT4: 15,860 rpm versus 21,000 rpm. The boost is 13.9 psi at peak.

We wanted to slow the supercharger speed down to introduce a lot less heat, said Lee. So running slower is more efficient.

Nonetheless, the LT5’s supercharger is drawing 110 hp to keep it spinning. That’s so much that it needs an 11-rib drive belt to accommodate the extra energy required to spin it. The LT4 only needs eight ribs on its drive belt. So effectively, this engine’s making 865 hp according to Lee.”

So - around 110-HP at stock LT5-levels, so I bet you guys can't be far off in your estimates (I wasn't questioning them - just trying to support them with this info ).

[ZL1Atlanta]

Originally Posted by radz28

Didn't one of the C7 ZR1 engineers make a comment about how the 2650 consumed around 150-or-something HP to turn (at OEM power level), too? He tried to make it sound like an LT5 made similar numbers to the Demon or something by saying something to the effect, "... if you consider the power it takes to drive the 2650, it makes similar power to a Demon...", or something like that? Now I have to find that...

I do seem to remember something like that. That video I shared references a 2650 at 22 psi, which is a good bit higher than an LT5 stock, so more resistance eating more power. Even at 150 though, it is 1400 - 150 x 86% = 1050 RWHP estimated to be safely available, or 1,125 RWHP if you use only 10% drivetrain loss. It’s just an unfortunate fact for blower cars.

Edit - saw that you updated the post to say it is 110 HP at stock levels and ~15k RPM. I can’t say for sure, but I’d be willing to bet we are talking much closer to 200 HP at above 20 psi.

[radz28]

Originally Posted by ZL1Atlanta

I do seem to remember something like that. That video I shared references a 2650 at 22 psi, which is a good bit higher than an LT5 stock, so more resistance eating more power. Even at 150 though, it is 1400 - 150 x 86% = 1050 RWHP estimated to be safely available, or 1,125 RWHP if you use only 10% drivetrain loss. It’s just an unfortunate fact for blower cars.

Edit - saw that you updated the post to say it is 110 HP at stock levels and ~15k RPM. I can’t say for sure, but I’d be willing to bet we are talking much close to 200 HP at above 20 psi.

And no doubt you (and many others here) know and or have seen how, sometimes, pulley'ing down BRINGS power back up, because at that point, the rotors are just beating/heating the air and efficiency drops. I think CSP or LMP (or both) posted a video or two showing that. I think Andrew was pushing TREEL1 to near 1000-WHP SAE and pulley'd down a bit and it got happier, but everything you're saying makes sense, and it seems to me, you're posting information people can learn from (obviously - Josh' and King' are always sharing their wealth of experience, too ).

Thanks to you all for taking time to share

[ZL1Atlanta]

Originally Posted by radz28

And no doubt you (and many others here) know and or have seen how, sometimes, pulley'ing down BRINGS power back up, because at that point, the rotors are just beating/heating the air and efficiency drops. I think CSP or LMP (or both) posted a video or two showing that. I think Andrew was pushing TREEL1 to near 1000-WHP SAE and pulley'd down a bit and it got happier, but everything you're saying makes sense, and it seems to me, you're posting information people can learn from (obviously - Josh' and King' are always sharing their wealth of experience, too ).

Thanks to you all for taking time to share

The balance of the combo is important for sure. We keep spinning it faster because the temps don’t go up while the power does, but everything has been done to optimize a 2650 (engine size, cam choice, head porting, cooling routing, cooling bricks, exhaust, etc). You can definitely plateau much earlier without thinking everything through and more pulley might just hurt more than it helps.

Happy to help where I think I can!

[JSH]

Originally Posted by ZL1Atlanta

Not sure where you are considering the power it takes to turn the supercharger in your estimates with only 1400 HP (estimated) available to you, but right on. I’m just sharing my experience. Sometimes walking the line of breaking stuff is part of the fun.

I should add that when an engine builder publishes a max number you can bet it's less than the failure number, e.g., 1400 is conservative. Everyone here knows that the stock short block will survive close to twice its published number.

I pullied my down last week from 2.625 to 2.75, and considered going to 3.00".

After all of the above, it seems more likely that I've got enough boost available but the engine can't flow it. It's making the same boost now that the OEM block had. Meth is looking better and better.

[ZL1Atlanta]

Originally Posted by JSH

I should add that when an engine builder publishes a max number you can bet it's less than the failure number, e.g., 1400 is conservative. Everyone here knows that the stock short block will survive close to twice its published number.

Well, I took the bet and was told “we told you so” by LME when mine cracked and that I need sleeved, iron or billet to make the power we wanted. But, have it if you want. Sometimes it is more fun to learn from doing.

[JSH]

Originally Posted by ZL1Atlanta

Well, I took the bet and was told “we told you so” by LME when mine cracked and that I need sleeved, iron or billet to make the power we wanted. But, have it if you want. Sometimes it is more fun to learn from doing.

They've already said that their iron block is the next stop for me

[toohighpsi]

Originally Posted by ZL1Atlanta

I do seem to remember something like that. That video I shared references a 2650 at 22 psi, which is a good bit higher than an LT5 stock, so more resistance eating more power. Even at 150 though, it is 1400 - 150 x 86% = 1050 RWHP estimated to be safely available, or 1,125 RWHP if you use only 10% drivetrain loss. It’s just an unfortunate fact for blower cars.

TVS superchargers are only mapped to 20psi as that's the maximum design pressure they were engineered for. Mapping a supercharger requires the unit to stabilize at each point before the data point is taken which can take up to a couple minutes so map data isn't available above these points.

Now that being said I don't think you're numbers are far off, but the calculation for RWHP doesn't work like that, it's just not that simple - although the turbo manufacturers would like you to think that... below is a note that a wrote a while back relating to the LS9 SC, same principals still apply to the 2650.

It is important to note that this input power requirement should not be confused with the parasitic power requirement of the supercharger. This always seems to be topics of discussion around different type of boosting devices and is normally completely misunderstood.

First of all the isentropic (or adiabatic, or thermal) efficiency drives the power requirement of the compressor excluding mechanical efficiency. In other words, any type of compressor that has an equivalent efficiency will have the same input power requirement (including exhaust driven devices). No device is free from mechanical losses and most are quite similar so this aspect can normally be overlooked for comparison purposes.

Parasitic power is simply defined as “power that is being consumed without any useful return”. In other words, pretty much anything that exists has a potential for being subject to parasitic power. If a supercharger is working to provide increased manifold pressure for the engine, that is not parasitic power, it’s work is providing a useful result – increased manifold pressure.

To understand parasitic power of a particular boosting device you need to look at the entire boosting system including it's interaction with the engine.

At vehicle cruise conditions for any boosted engine, increased manifold pressure is normally not required so any consumption of power from the boosting device is considered parasitic. In the particular case of the LS9, the parasitic power consumption of the supercharger under cruise conditions @ 70MPH would be approximately 0.86 HP. For exhaust driven devices the parasitic power is calculated from negative pressure differential across the engine (increased exhaust backpressure - which normally results in about the same value).

At WOT the parasitic power calculation is a summation of the frictional power requirement of the supercharger (which is a function of SC speed), system pressure losses (normally driven by packaging), and the isentropic efficiency of the compressor - this calculation applies to all types of boosting devices, including exhaust driven devices. As a side note, the R2300 supercharger at peak power on the LS9 has a frictional power requirement of 1.2 HP which is defines as the losses through the bearings, seals, gears, and oil.

For a mechanically driven supercharged application, many people seem to quickly point out the amount of power required to drive the device. This is primarily because it is easy to measure and is normally published information - but this is not the amount of power that needs to be paid for by the engine. Mechanical supercharging places the engine at WOT under what is referred to as a "positive pressure differential" - the intake manifold pressure is always higher than the exhaust pressure. This is an important factor as the engine, in simplest terms, can be considered a positive displacement compressor. When a positive displacement compressor [engine] is subject to a higher pressure at the inlet than the outlet, it becomes a motor that is capable of providing power. This is the condition that the boosted engine operates under with a mechanical drive supercharger, and when properly optimized, the positive pressure differential will provide a certain amount power output from the engine - this can then subtracted from the required input power.

As for peak power numbers, the highest I've see for a TVS 2650 was right around 1490 RWHP on a Patterson Elite built 427 LS, that car went 6.7s at well over 200MPH.



Displacement and RPM are your friend, Not sure how high they spun that 427, but since it was based off a COPO and they are rumored to spin over 10K rpm, I can only guess it was spinning pretty good also. COPOs are believed to be just under 1400 RWHP running 7.8s at nearly 180 MPH with a weight of 3500.

Hope that helps.

[radz28]

Good Lord - that was an awesome read!!!

I think the highest WHP I'd noticed, and was a similar head unit to your example, was around a hundred WHP less. That was LMP's 5th Gen.

[ZL1Atlanta]

Originally Posted by toohighpsi

TVS superchargers are only mapped to 20psi as that's the maximum design pressure they were engineered for. Mapping a supercharger requires the unit to stabilize at each point before the data point is taken which can take up to a couple minutes so map data isn't available above these points.

Now that being said I don't think you're numbers are far off, but the calculation for RWHP doesn't work like that, it's just not that simple - although the turbo manufacturers would like you to think that... below is a note that a wrote a while back relating to the LS9 SC, same principals still apply to the 2650.

It is important to note that this input power requirement should not be confused with the parasitic power requirement of the supercharger. This always seems to be topics of discussion around different type of boosting devices and is normally completely misunderstood.

First of all the isentropic (or adiabatic, or thermal) efficiency drives the power requirement of the compressor excluding mechanical efficiency. In other words, any type of compressor that has an equivalent efficiency will have the same input power requirement (including exhaust driven devices). No device is free from mechanical losses and most are quite similar so this aspect can normally be overlooked for comparison purposes.

Parasitic power is simply defined as “power that is being consumed without any useful return”. In other words, pretty much anything that exists has a potential for being subject to parasitic power. If a supercharger is working to provide increased manifold pressure for the engine, that is not parasitic power, it’s work is providing a useful result – increased manifold pressure.

To understand parasitic power of a particular boosting device you need to look at the entire boosting system including it's interaction with the engine.

At vehicle cruise conditions for any boosted engine, increased manifold pressure is normally not required so any consumption of power from the boosting device is considered parasitic. In the particular case of the LS9, the parasitic power consumption of the supercharger under cruise conditions @ 70MPH would be approximately 0.86 HP. For exhaust driven devices the parasitic power is calculated from negative pressure differential across the engine (increased exhaust backpressure - which normally results in about the same value).

At WOT the parasitic power calculation is a summation of the frictional power requirement of the supercharger (which is a function of SC speed), system pressure losses (normally driven by packaging), and the isentropic efficiency of the compressor - this calculation applies to all types of boosting devices, including exhaust driven devices. As a side note, the R2300 supercharger at peak power on the LS9 has a frictional power requirement of 1.2 HP which is defines as the losses through the bearings, seals, gears, and oil.

For a mechanically driven supercharged application, many people seem to quickly point out the amount of power required to drive the device. This is primarily because it is easy to measure and is normally published information - but this is not the amount of power that needs to be paid for by the engine. Mechanical supercharging places the engine at WOT under what is referred to as a "positive pressure differential" - the intake manifold pressure is always higher than the exhaust pressure. This is an important factor as the engine, in simplest terms, can be considered a positive displacement compressor. When a positive displacement compressor [engine] is subject to a higher pressure at the inlet than the outlet, it becomes a motor that is capable of providing power. This is the condition that the boosted engine operates under with a mechanical drive supercharger, and when properly optimized, the positive pressure differential will provide a certain amount power output from the engine - this can then subtracted from the required input power.

As for peak power numbers, the highest I've see for a TVS 2650 was right around 1490 RWHP on a Patterson Elite built 427 LS, that car went 6.7s at well over 200MPH.



Displacement and RPM are your friend, Not sure how high they spun that 427, but since it was based off a COPO and they are rumored to spin over 10K rpm, I can only guess it was spinning pretty good also. COPOs are believed to be just under 1400 RWHP running 7.8s at nearly 180 MPH with a weight of 3500.

Hope that helps.

Thanks for the input as always, Mike! I figured it wasn’t anywhere near as simple of a calculation as I was making it for the discussion, especially on high spun blowers at over 20 psi where efficiency is certainly not the same as it was at say 10 psi.

I’m pretty confident that once we fix an electronics issue I’m having with shifting my 10L90, we’ll show that the DI 2650 is making over 1400 in trap speed to weight. If you believe 60-130 to WHP formula’s, it’s already there.

[toohighpsi]

Originally Posted by ZL1Atlanta

I’m pretty confident that once we fix an electronics issue I’m having with shifting my 10L90, we’ll show that the DI 2650 is making over 1400 in trap speed to weight. If you believe 60-130 to WHP formula’s, it’s already there.

Will be looking forward to it, just give me a yell if I can help with anything!

[toohighpsi]

Originally Posted by radz28

I think the highest WHP I'd noticed, and was a similar head unit to your example, was around a hundred WHP less. That was LMP's 5th Gen.

Had to go look that up - as didn't remember that one, super nice nice car making some serious power!