Harrop TVS86 Owners Thread

[FR-S2GT86]

So over the past two days, I have been in contact with Harrop and discovered the details of the CARB tune.

Requirements:

1) Completely stock engine and exhaust.
2) 95 mm pulley.
3) Another US$350+tax if you've previously purchased the supercharger before the CARB tune was approved. (I believe you can now get the price for the CARB tune included with purchase of the CARB-approved supercharger kit.)

What does this get you?

An EcuTek-based tune that needs no further calibrations to work properly and reliably, and a 50-State Legal CARB sticker for under your hood that remains valid ONLY if you leave everything else stock, making no further modifications to the engine, to the fuel, ignition, timing and emissions systems, to the exhaust system, or to the supercharger itself afterwards.

[Irace86.2.0]

Pretty standard stuff. I believe Edelbrock gave the CARB tune for free though and the stickers. Like OEM tunes, a catback is still legal and shouldn’t negatively or positively impact the tune or emissions. Frankly, lots of people want the CARB tune for smogging, but plan to run dirty in between smogs with headers, E85 and more boost.

Check out Edelbrock’s Executive Order:

https://ww3.arb.ca.gov/msprog/afterm...o/d-215-93.pdf

[FR-S2GT86]

Originally Posted by Irace86.2.0

Pretty standard stuff. I believe Edelbrock gave the CARB tune for free though and the stickers. Like OEM tunes, a catback is still legal and shouldn’t negatively or positively impact the tune or emissions. Frankly, lots of people want the CARB tune for smogging, but plan to run dirty in between smogs with headers, E85 and more boost.

Check out Edelbrock’s Executive Order:

https://ww3.arb.ca.gov/msprog/afterm...o/d-215-93.pdf

Yeah, I plan on staying completely stock after installing mine and affixing the sticker.

[morrisonmagic]

Originally Posted by morrisonmagic

The base line in this case is the Harrop carb tune verse Zacks custom via remote dyno tuning which had the results I asked for.

Unfortunately they did not dyno the car before. One of the reasons torque is a little lower is that I have equal length headers and I also was looking for a very smooth power delivery instead of max power. Lastly I want the car to last as long as possible so I like to tune on the conservative side when tuning. Way less problems in the long run. I will have the car at Road Atlanta next weekend for 2 days so I will have a good track report next week.

Well I am back from 2 days at Road Atlanta and the car ran flawlessly. I hit 128 on the back straightaway and the car pulled away from a BRZ with headers and tune on that long back straight easily. I could not be more pleased with this kit and for me to be able to have a kit that works as well on track is a big deal. Big thumbs up!

[FR-S2GT86]

Question: Does anybody know what the parasitic drag is on the engine using the 95 mm pulley? I may have an idea to reduce the parasitic loss to the engine as the RPM's increase, but I need the actual HP figures required by the supercharger at its different RPM's that it runs at in order to choose the equipment needed.

[Irace86.2.0]

Originally Posted by FR-S2GT86

Question: Does anybody know what the parasitic drag is on the engine using the 95 mm pulley? I may have an idea to reduce the parasitic loss to the engine as the RPM's increase, but I need the actual HP figures required by the supercharger at its different RPM's that it runs at in order to choose the equipment needed.

I have no idea. A person could drive at highway speeds on cruise control for a few hours and report their fuel economy and compare it to a person without a supercharger. Besides reverse calculating it that way, I don’t really know how someone could directly measure the parasitic effect.

The bypass valve should eliminate some losses, but I don’t know what else you have in mind. If you were thinking of having a clutch system on the pulley like the AC setup, I don’t know if that would work because air wouldn’t get past the supercharger lobes very well without them spinning, so you would need them to spin at a minimal level, which becomes complicated. Even a turbo has some parasitic loses, so any effort might only be for a few mpg improvement.

[FR-S2GT86]

Originally Posted by Irace86.2.0

I have no idea. A person could drive at highway speeds on cruise control for a few hours and report their fuel economy and compare it to a person without a supercharger. Besides reverse calculating it that way, I don’t really know how someone could directly measure the parasitic effect.

The bypass valve should eliminate some losses, but I don’t know what else you have in mind. If you were thinking of having a clutch system on the pulley like the AC setup, I don’t know if that would work because air wouldn’t get past the supercharger lobes very well without them spinning, so you would need them to spin at a minimal level, which becomes complicated. Even a turbo has some parasitic loses, so any effort might only be for a few mpg improvement.

I'll see if I can get my answers on Thursday (or at least ask them) when I visit Harrop-USA.

I think it could easily be calculated on a bench set-up environment, and the Harrop engineers have probably already calculated everything.

.....and no, it's not a magnetic clutch setup that I'm thinking of. I'll explain a bit more in time as I gather more information. I don't want to give my ideas away just yet.

[Kiske]

Originally Posted by FR-S2GT86

I'll see if I can get my answers on Thursday (or at least ask them) when I visit Harrop-USA.

Please take some pics of the shop if you can. I'm curious too see if the USA branch is a glorified distribution warehouse or if they are doing their own design/testing there.

[FR-S2GT86]

Originally Posted by Kiske

Please take some pics of the shop if you can. I'm curious too see if the USA branch is a glorified distribution warehouse or if they are doing their own design/testing there.

I will if they’ll allow me to.

[Calum]

Super charger input power came from here.
https://www.eaton.com/us/en-us/catal...fications.html

Crank pulley size came from here.
http://www.atiracing.com/products/da...dam-subaru.htm

Based on a 180mm crank pulley, and a 95mm SC pulley, the supercharger should be spinning at ~14krpm at 7400rpm crank speed. Based purely on assumption that's somewhere in the realm of 8psi? That would put the super charger at roughly 23kW input power at 7400rpm.

Someone with more knowledge on the subject please confirm or correct my numbers.

[FR-S2GT86]

Originally Posted by Calum

Super charger input power came from here.
https://www.eaton.com/us/en-us/catal...fications.html

Crank pulley size came from here.
http://www.atiracing.com/products/da...dam-subaru.htm

Based on a 180mm crank pulley, and a 95mm supercharger pulley, SC should be spinning at ~14krpm at 7400rpm crank speed. Based purely on assumption that's somewhere in the realm of 8psi? That would put the super charger at roughly 23kW input power at 7400rpm.

Someone with more knowledge on the subject please confirm or correct my numbers.

Thanks for posting that information. It helps me to make my calculations.

Actually, the stock crank pulley is 5.875 inches (or 149.2 mm). With the 95 mm (or 3.75 in.) supercharger pulley, this would make the drive ratio 1:1.57

So performing the calculations using online tools:

At an engine RPM of 7,400 (redline), the supercharger pulley should be spinning at 11,593 RPM with no belt slippage.

According to the published information from Eaton, the maximum input of the blower is 73 kW (or 97.9 HP) at the maximum of 20,000 RPM with a maximum pressure of 2.5 bar (or 36.3 PSI).

Since we have 73 kW at 20,000 RPM and we know our maximum supercharger pulley speed will be 11,593 RPM, then solving for X, where X = kW, would give us 42.3 kW under max conditions.

42.3 kW is equal to 56.7 HP, which should be the maximum parasitic draw of the supercharger with the 95 mm pulley.

[Calum]

Originally Posted by FR-S2GT86

Thanks for posting that information. It helps me to make my calculations.



Actually, the stock crank pulley is 5.875 inches (or 149.2 mm). With the 95 mm (or 3.75 in.) supercharger pulley, this would make the drive ratio 1:1.57



So performing the calculations using online tools:



At an engine RPM of 7,400 (redline), the supercharger pulley should be spinning at 11,593 RPM with no belt slippage.



According to the published information from Eaton, the maximum input of the blower is 73 kW (or 97.9 HP) at the maximum of 20,000 RPM with a maximum pressure of 2.5 bar (or 36.3 PSI).



Since we have 73 kW at 20,000 RPM and we know our maximum supercharger pulley speed will be 11,593 RPM, then solving for X, where X = kW, would give us 42.3 kW under max conditions.



42.3 kW is equal to 56.7 HP, which should be the maximum parasitic draw of the supercharger with the 95 mm pulley.

You've completely negated that drag (AFAIK) doesn't increase linearly, and that pressure ratio will effect input power.

Nevertheless, looking at the graph, at a pressure ratio of 1.7ish and an rpm of 12000ish you'd be at a little under 20kW.

[FR-S2GT86]

Originally Posted by Calum

You've completely negated that drag (AFAIK) doesn't increase linearly, and that pressure ratio will effect input power.

Nevertheless, looking at the graph, at a pressure ratio of 1.7ish and an rpm of 12000ish you'd be at a little under 20kW.

Okay forgive me, I'm new at this but bear with me here, I'll eventually figure it out. The first time, I was using algebraic ratio equations to figure out the ratio from Eaton's published maximum figures and now I'm understanding their graph on the bottom of their specifications page.

If the pressure ratio on the left side of the graph is the increase from atmospheric pressure, using bar figures, let's say a pressure ratio of 1 is 1 bar (14.5 psi), and we know at our maximum blower speed at an engine RPM of 7,400 will be 11,593 RPM. We know that at that RPM on our cars with that pulley, there is about an 8 psig increase according to manifold pressure readings, then the absolute pressure in psi would be 14.5 psi + 8 psi, or 22.5 psia total, which equals 1.55 bar.

1.55 would be our pressure ratio with the blower speed of about 11,600 RPM.

Plugging those values into the graph, that would give us a parasitic draw right at around 15.5 kW or 20.8 HP running at full throttle with a 95 mm pulley.

Does that look more accurate?

We can plug those numbers in to find out a kW (HP) parasitic draw at other RPM's as well, but right now, I'm mainly concerned with maximum parasitic values.

If someone else wants to calculate some of the smaller pulleys, they should be able to use this information to do that.

This is fun!

[Irace86.2.0]

Why maximum?