Harrop twin screw sc for s65

[Hujan]

Originally Posted by pbonsalb

The twinscrew this thread is about would definitely not keep the feeling of NA.

You mean in power band or throttle response. Or both?

Originally Posted by squartus

Exactly, either with this or the twin turbo N/A feel is gone. Which im rather fine with. This or the Gintani twin turbo both look like two of the only choices for low end torque, which is where this engine lacks.

Maybe pair an certi blower with a higher FD diff?

[M.Hagen]

Originally Posted by Serpico

if they are very similar, why does it take 14 psi to get 515hp on the RS4, yet 7.5psi on the m3 to get `550?

Where did you see a TVS1740 making 550 hp @ 7.5psi?

Originally Posted by Serpico

oddly, it looks like the tvs is running out of steam at 6800-ish rpms.. the same rpm that the original harrops dyno's only went to 7k rpms

A positive displacement supercharger is appropriately named as it feeds a fixed volume of air per revolution, in this case 1740cc of volume. This type of supercharger effectively mimics the powerband through the engine's natural VE curve. Assuming the mass air output from the blower is in the entropic sweet-spot of the efficiency map, the torque peak and horsepower peak should occur at the same engine speed as the N/A Powerband. There will be some variation to this as the thermal efficiency creates an effect on the charge density of the mass flow, but in generalities it is a safe assumption.

You can see that represented in the APR dynos, where peak power occurs at relatively the same RPM as the N/A curve.

Originally Posted by Serpico

And no one yet has told us what IATs are lookinig like. I dont care what "data" a business tries to promote, but 170+ IAT's is KILLING power. ask any tuner, any real tuner. Intercooled applications should be seeing roughly 30-40 * over ambient.

The Harrop kit is intercooled.

Is the 170F IAT's you referenced data from an M3 or RS4 with a TVS1740? That seems very high.

The TVS1900 superchargers found on the GM LSA motors usually have IAT's in the 120-130F range after multiple dyno pulls (heat soak pulls), and they run similar intercooler designs.

Originally Posted by Serpico

and ill say it again now, if we dont get a harrop dyno with a boost log, its meaningless.

I am curious why you think manifold pressure vs RPM is an important metric? If it is for comparison to other supercharger kits available for the S65, I think you have a misunderstanding of mass flow in relationship to manifold pressure.

8 psi on a TVS1740 is not the same mass flow as 8 psi on a Vortech V3 Si-Trim (VF-650 blower).

One system is a fixed volume per engine revolution, the other is a compressor. Power is made through mass flow consumed in the engine, not through manifold pressure.

I apologize in advance if your desire for manifold pressure logs is not to compare to other 'compressor style' superchargers.

[pbonsalb]

Originally Posted by Hujan

You mean in power band or throttle response. Or both?

?

Both.

[BPMSport]

Originally Posted by M.Hagen

Where did you see a TVS1740 making 550 hp @ 7.5psi?



A positive displacement supercharger is appropriately named as it feeds a fixed volume of air per revolution, in this case 1740cc of volume. This type of supercharger effectively mimics the powerband through the engine's natural VE curve. Assuming the mass air output from the blower is in the entropic sweet-spot of the efficiency map, the torque peak and horsepower peak should occur at the same engine speed as the N/A Powerband. There will be some variation to this as the thermal efficiency creates an effect on the charge density of the mass flow, but in generalities it is a safe assumption.

You can see that represented in the APR dynos, where peak power occurs at relatively the same RPM as the N/A curve.



The Harrop kit is intercooled.

Is the 170F IAT's you referenced data from an M3 or RS4 with a TVS1740? That seems very high.

The TVS1900 superchargers found on the GM LSA motors usually have IAT's in the 120-130F range after multiple dyno pulls (heat soak pulls), and they run similar intercooler designs.



I am curious why you think manifold pressure vs RPM is an important metric? If it is for comparison to other supercharger kits available for the S65, I think you have a misunderstanding of mass flow in relationship to manifold pressure.

8 psi on a TVS1740 is not the same mass flow as 8 psi on a Vortech V3 Si-Trim (VF-650 blower).

One system is a fixed volume per engine revolution, the other is a compressor. Power is made through mass flow consumed in the engine, not through manifold pressure.

I apologize in advance if your desire for manifold pressure logs is not to compare to other 'compressor style' superchargers.

Great post.

I am scheduled to dyno the car tomorrow, looking forward to it. I have never seen IAT's close to 170 with the pump on.

[Hujan]

Originally Posted by pbonsalb

Both.

I don't see why an S/C would affect throttle response. It's not like you have to wait for a waste gate to close in order to start spooling the compressor. It is belt fed from the engine and therefore spins when the engine spins. Thus, I wouldn't expect any S/C--roots or centrifugal--to alter the throttle response of an N/A motor.

Powerband might be a different story. One thing I do like about the ESS kits, for example, is that they retain the flat torque curve and constantly ascending power curve of the N/A motor, but shift them both up by a considerable margin. It's nice. The Harrop kit might alter that a bit, but my recollection from the dynos posted earlier is that the power band still more closely mimics a stock S65 than it does a turbo car (which is good, IMO).

[Verify]

Originally Posted by M.Hagen

Where did you see a TVS1740 making 550 hp @ 7.5psi?

we havent, we have only seen centris doing that. the TVS is only doing 515

A positive displacement supercharger is appropriately named as it feeds a fixed volume of air per revolution, in this case 1740cc of volume. This type of supercharger effectively mimics the powerband through the engine's natural VE curve. Assuming the mass air output from the blower is in the entropic sweet-spot of the efficiency map, the torque peak and horsepower peak should occur at the same engine speed as the N/A Powerband. There will be some variation to this as the thermal efficiency creates an effect on the charge density of the mass flow, but in generalities it is a safe assumption.

flow may be the same, but power potential from cooler air vs hotter air is not. Do we have a compressor map for the TVS?

You can see that represented in the APR dynos, where peak power occurs at relatively the same RPM as the N/A curve.

for the audi yes, but it also starts to heavily decrease tq and subsequent hp. obviously the VE efficiency of the S65 is allows for better high rpm hp, but again, can the TVS spin to 8400 efficiently? Thats the question we all are waiting to see.



The Harrop kit is intercooled.

Is the 170F IAT's you referenced data from an M3 or RS4 with a TVS1740? That seems very high.

We havent seen any. Its just a reference to what the ESS550 (non-intercooled) kit did in their tests. The A-W 625-650 kits are seeing about 40* above ambient and A-A are seeing about 30* above ambient. Given that we already estabished the centris are more efficent/cooler I was making atatement that the harrop has to be in that range to be acceptable. We' have also seen what 10* difference in heatsoak/performance between comparable kits

The TVS1900 superchargers found on the GM LSA motors usually have IAT's in the 120-130F range after multiple dyno pulls (heat soak pulls), and they run similar intercooler designs.

what is ambient though, 120-130 is ok if its in 100* weather, but not 60-70's. I think your actually strengthening my comments


I am curious why you think manifold pressure vs RPM is an important metric? If it is for comparison to other supercharger kits available for the S65, I think you have a misunderstanding of mass flow in relationship to manifold pressure.

manifold pressure is important, as well as CFM. centris flow 1100-1200 cfm vs the tvs "1740" correct? so in theory, the tvs should produce more poer per psi.. given all else equal. but theory also reverts us back to heat

8 psi on a TVS1740 is not the same mass flow as 8 psi on a Vortech V3 Si-Trim (VF-650 blower).

One system is a fixed volume per engine revolution, the other is a compressor. Power is made through mass flow consumed in the engine, not through manifold pressure.

yes, we get this. so lets see what psi the tvs needs to get XYZ HP

I apologize in advance if your desire for manifold pressure logs is not to compare to other 'compressor style' superchargers.

It is for comparison, for 2 reasons. 1- to educate us on what psi it needs to get X hp, and 2, because its using a wastegate style actuator to control boost, which is very interesting in itself.

In bold


@mike, if your dynoing tomorrow, get all the data you can, as well as realtime video like the rest do. not an edited video but one continuous recording. I think we would all appreciate that

[BPMSport]

Throttle response is pretty much the same as an NA car. There is a minimal amount of time for the electronic bypass to actuate, but that's about it. The car responds very quickly to changes in throttle.

Centri kits don't mimic the factory curves as much as this kit does because boost pressure is a factor of RPM. The Harrop kit shifts the entire torque curve up even at lower RPM ranges because boost is being produced much sooner in the RPM range. The boost pressure of the PD setup is not a function of how fast the crank is spinning. With the centri kits you will see the highest delta in the upper RPM ranges only.

I might not have explained this very well and it would be more well illustrated with graphs.. I'm on iPhone atm

[M.Hagen]

Thanks for the reply.

To preface the response, I hope this is being received as information and an attempt to get everyone "on the same page", not as hostile or argumentative There is not a lot of history with positive displacement superchargers on this forum, so I understand the back-and-forth.

Originally Posted by Serpico

we havent, we have only seen centris doing that. the TVS is only doing 515

Apples and oranges, for points already stated.

Originally Posted by Serpico

flow may be the same, but power potential from cooler air vs hotter air is not. Do we have a compressor map for the TVS?

Yes, a cooler charge air mass will make more power.

Harrop may volunteer the compressor map if they feel obligated and have release permission from Eaton. The TVS1900 is on the Eaton website, but the TVS1740 is not. We do know through what has already been published, that the TVS1740 can achieve 65% efficiency at 20,000 RPM (versus the TVS1900 max of 15,000 RPM for 65% efficiency), so I suspect the efficiency island will be a much different shape.

Originally Posted by Serpico

for the audi yes, but it also starts to heavily decrease tq and subsequent hp. obviously the VE efficiency of the S65 is allows for better high rpm hp, but again, can the TVS spin to 8400 efficiently? Thats the question we all are waiting to see.

Eaton has stated that the recommended max RPM on the TVS1740 is 20,000 (to keep efficiency above 65%), so the maximum pulley ratio is 2.38:1 if one were to obey the Eaton limit. However, we all know it is common to overdrive the TVS blowers, and they still do make power above the recommended limit, but with depreciating results, just like any other blower or compressor.

The maximum efficiency will be between 75% and 80%, comparable with the newest Vortech Si trim centrifugal units. Just like the centrifugal units, this maximum efficiency is near the 'middle' of the operating window. Where these blowers get used, efficiency is between 60% and 70%.

Originally Posted by Serpico

what is ambient though, 120-130 is ok if its in 100* weather, but not 60-70's. I think your actually strengthening my comments

Dyno bay was 88F.

It worth repeating that the maximum efficiency of the TVS units is equal to the maximum efficiency of the Vorteh Si-trim units (~78-79%). I would hesitate to automatically assume a TVS blower would run hot, unless it is ran way outside it's efficiency limit and and inadequate heat exchanger was being used.

Originally Posted by Serpico

manifold pressure is important, as well as CFM. centris flow 1100-1200 cfm vs the tvs "1740" correct? so in theory, the tvs should produce more poer per psi.. given all else equal. but theory also reverts us back to heat

The "value" associated with the Eaton TVS nomenclature is the volume of air swept with every revolution of the blower. In this case, the TVS1740 displaces 1740cc of air per revolution.

The CFM can't be exactly defined, as the compressor map is unavailable publicly. A TVS1900 at maximum efficiency (15,000 RPM) and a 2.0 PR is flowing 944 CFM. I would assume the TVS1740 will be less, seeing as it sweeps less volume per revolution. Best guess given the %-reduction of swept volume (8.5% reduction) would be 864 CFM.

Originally Posted by Serpico

It is for comparison, for 2 reasons. 1- to educate us on what psi it needs to get X hp, and 2, because its using a wastegate style actuator to control boost, which is very interesting in itself.

I think the only way to understand "the potential" of the kit is to know what RPM Harrop is turning the TVS1740 at. PSI is irrelevant to how much power the kit is capable of, since it is not a compressor.

For arguments sake, let's say the Harrop kit makes 550 rwhp with a pulley combination that results in 10psi on a stock M3 (aside from the blower and tune). If you installed a full catless exhaust, the power might jump to 600 rwhp, but your manifold pressure will decrease. So now you are making more power, with less boost, on the same blower and tune.

Maybe I am preaching to the choir, but the missing keys are (1) the TVS1740 compressor map and (2) the pulley diameters for the Harrop kit. Only those two pieces of information can dictate the power potential.

Originally Posted by Mike Benvo

Centri kits don't mimic the factory curves as much as this kit does because boost pressure is a factor of RPM. The Harrop kit shifts the entire torque curve up even at lower RPM ranges because boost is being produced much sooner in the RPM range. The boost pressure of the PD setup is not a function of how fast the crank is spinning. With the centri kits you will see the highest delta in the upper RPM ranges only.

I might not have explained this very well and it would be more well illustrated with graphs.. I'm on iPhone atm

That is exactly correct.

A positive displacement supercharger will have a boost curve that is the inverse of the VE curve, since manifold pressure is the excess air mass not consumed.

Typically boost will be at its highest at lower RPM, dip during peak torque (max VE), and either stay constant, or slightly decrease as the engine approaches peak HP.

[lsmkr01]

Originally Posted by M.Hagen

A positive displacement supercharger will have a boost curve that is the inverse of the VE curve, since manifold pressure is the excess air mass not consumed.

Typically boost will be at its highest at lower RPM, dip during peak torque (max VE), and either stay constant, or slightly decrease as the engine approaches peak HP.

This is the simplest way a PD blower can be explained. Good work

[Jonjt]

Originally Posted by Serpico

So, for us intelligent people, what psi levels are apr and others using on the factory boosted cars to get equivalent hp? Are these other cars DI or port injection?

M.Hagen said what I was going to say, so I wont add to it.


Edit: It was mentioned (I believe by you) that the RS4 TVS1740 kit makes the same power as the kit released for the M3. I do believe Harrop was claiming 500whp for this kit, no? APR claims 626hp for their RS4 and R8 kit. That's too large a delta to attribute to powertrain losses, alone. We need to know how fast the M3 kit is spinning. I was implying this before but, I'm going to say it explicitly now: I don't think Harrop kit has the blower spinning at it's maximum speed, for 65% efficiency.

[Jonjt]

Originally Posted by Mike Benvo

Throttle response is pretty much the same as an NA car. There is a minimal amount of time for the electronic bypass to actuate, but that's about it. The car responds very quickly to changes in throttle.

Centri kits don't mimic the factory curves as much as this kit does because boost pressure is a factor of RPM. The Harrop kit shifts the entire torque curve up even at lower RPM ranges because boost is being produced much sooner in the RPM range. The boost pressure of the PD setup is not a function of how fast the crank is spinning. With the centri kits you will see the highest delta in the upper RPM ranges only.

I might not have explained this very well and it would be more well illustrated with graphs.. I'm on iPhone atm

For the reasons mentioned, i'd say that neither kit mimics the factory torque curve, necessarily.

Edit: for the consideration of throttle response, wouldnt the blower be considered nothing more than a bit of additional inertia that the engine has to spin? We aren't talking about lag, after all.

[pbonsalb]

I would have guessed harrop is not going to run a PD blower at 10 psi on a 12:1 motor. A PD blower can make full boost in the knock window of peak VE, just like a turbo, so boost generally must be lower. The centrifugal actually works very well with high CR motors since it makes peak boost only at peak rpm and makes only the square root of peak boost at half peak rpm. For the same reason, I think we will see the Gintani turbo kit run lower boost than what has been used on centrifugal kits.

Hopefully we will see a dyno soon.

My view is that any forced induction takes away from NA throttle response. With a centrifugal or with a PD blower, you have something dragging on the crank when it is making power. The centrifugal mimics the stock power the best and has the most predictable power curve since boost is entirely rpm dependent. The PD blower significantly alters stock power by fattening up the low end. A turbo does not have any less than stock power; its just that the turbos must have sufficient exhaust gas energy to make more than stock power, which means that some lag can be noticed before more power is produced in certain circumstances. Small twin turbos on a 4.0L V8 should be pretty responsive -- that is what BMW, Audi and Mercedes use now. Mercedes switched from a PD blower to twin turbos and from the little reading I have done, no one seems to be complaining.

I think all forms of FI have their advantages and disadvantages. I have had a centrifugal and a turbo on the same car, and prefer the turbo. For the E90M3, I would choose a PD blower based on theory, so I look forward to seeing the dyno results and more real world driving reports and some quarter mile and runway experiences.

[M.Hagen]

Originally Posted by pbonsalb

I would have guessed harrop is not going to run a PD blower at 10 psi on a 12:1 motor. A PD blower can make full boost in the knock window of peak VE, just like a turbo, so boost generally must be lower. The centrifugal actually works very well with high CR motors since it makes peak boost only at peak rpm and makes only the square root of peak boost at half peak rpm. For the same reason, I think we will see the Gintani turbo kit run lower boost than what has been used on centrifugal kits.

My guess is the "boost control" wastgate on the Harrop blower plenum is to help "bleed" the excessive manifold pressure in the lower RPM, where knock is most likely to occur.

The ideal scenario would be run the TVS1740 to it's maximum 'efficient' RPM, whilst bleeding excessive manifold pressure and increasing valve overlap through VANOS tuning, where necessary, to achieve the broadest powerband without risk to engine.

My hunch is that could be what is taking so long to develop.

Looking forward to Mike's dyno results.

[Limey]

Originally Posted by Jonjt

For those of you asking about more power from this kit, I want to point out that APR is using this exact same pump on the 4.2L V8 in the R8, to great effect. Their kit is making something like 650hp on the R8. It goes to show that this pump can support higher mass flow rates. I would imagine it's just a matter of time, before Harrop (or someone else) fits a smaller pulley to this pump and produces an M3 with more power.

Look here.

Smaller pulley and revised tune is in the works for Stage 2 from what I was told.

[Limey]

Originally Posted by Alex07M3

+1

I was told they'll be making an official announcement once another kit is installed, (mine I guess so v. Soon), so probably best not to rely on anything you hear unless it comes direct from either Harrop or their official N American distributor(s).

[BPMSport]

Originally Posted by M.Hagen

That is exactly correct.

A positive displacement supercharger will have a boost curve that is the inverse of the VE curve, since manifold pressure is the excess air mass not consumed.

Exactly. You can change the amount of boost pressure in the plenum by altering the cam position but it doesn't necessarily cause an increase in output. Harrop has tested this pretty extensively. Looking forward to the dyno tomorrow.

[Alex07M3]

Originally Posted by Limey

I was told they'll be making an official announcement once another kit is installed, (mine I guess so v. Soon), so probably best not to rely on anything you hear unless it comes direct from either Harrop or their official N American distributor(s).

Congrats on the purchase!! I just can't wait to see this kit in action, you lucky...

[pbonsalb]

Originally Posted by M.Hagen

My guess is the "boost control" wastgate on the Harrop blower plenum is to help "bleed" the excessive manifold pressure in the lower RPM, where knock is most likely to occur.

The ideal scenario would be run the TVS1740 to it's maximum 'efficient' RPM, whilst bleeding excessive manifold pressure and increasing valve overlap through VANOS tuning, where necessary, to achieve the broadest powerband without risk to engine.

My hunch is that could be what is taking so long to develop.

Looking forward to Mike's dyno results.

That would be fancy. We see programmed boost on turbo cars but adjusting it through overlap on a PD blower car would be interesting.

[Jonjt]

Originally Posted by Limey

Smaller pulley and revised tune is in the works for Stage 2 from what I was told.

By Harrop?

[Verify]

i think we are just going to have to agree to disagree as we are repeating ourselves. Lets see what theory vs appllication actually pans out.

for anyone curious, here is a good read about the TVS (1900 ie bigger) on other platforms

http://www.audizine.com/forum/showth...-Supercharging

as well as this one listing the performance metrics of the different S/C types on the audi RS4's ie TVS Vs Vortech since everyone wants to drag in the Audi into the debate

http://audirevolution.net/forum/index.php?topic=499.0

from that, it looks like we are actually anticipating the TVS to be pushing 10-12psi to run the same MPH's as 8psi on a vortech

(APR 130mph trap. 104octane, weight reduction-14psi) (JMH 130mph trap 8psi 92 octane full weight)

[Limey]

Originally Posted by Jonjt

By Harrop?

and Aviva. Install underway. I should have it next Wed.

[Verify]

I guess Mikes dyno didnt go too well..