Justin, I'm just going to wade into this gently, but I believe what he was getting at is that the 1320 requires more horsepower to spin. So, within the relative boost range that the 900 and 1320 can make, the 900 will make its boost with less strain on the engine.

Think of it this way, the supercharger is a power adder, yes? But it takes power to make power.

So (and I'm going to use fake numbers here, for the sake of argument), say ...

Your BRZ NA makes 200bhp.
With a blower, your BRZ makes 300bhp.
You're using the 900 blower
The 900 takes 30bhp to make enough boost to put you at 300bhp.

That means the engine is doing the work of 330bhp, thus the rods are taking the strain of the resultant torque. But you lose 30bhp by the time that power gets to the flywheel because the blower is slowing the crank down.

Now, same power for NA and boosted
You're using the 1320 blower
The 1320 takes 50bhp to make enough boost to put you at 300bhp.

So now the engine is doing the work of 350bhp.

And again, these are made up numbers, but I've actually heard numbers close to this before for blowers, so I don't think I'm far off the mark.

This is why these blowers are rated for larger engines, they naturally make more power, so relative to their overall power output, the blower is, as a percentage of power, a smaller parasitic loss / increase in load.

The point about the compressor map vs after cooler efficiency is that, if the smaller blower can make enough air to flow the desired CFM, and you can cool that air enough to keep IAT down and ignition inside the engine controlled, you will make the desired power with less strain on the engine - because the blower requires less horsepower to spin it. The 900 with a good cooler really is better matched to a STOCK motor on this vehicle than the 1320. That said, Harrop made their kit to be flexible and allow for it to be used with built motors without needing much modification - so there is far more headroom and potential with their kit over the Cosworth, as is evidenced by their in house race car.

Does that make more sense?

I get that. I was more interested in this part of his statement:

He said it’ll never generate as much heat, probably meaning IATs.

Usually there are not linear hp gains with progressive smaller pulleys because a charger will hit efficiency and spin/max limits. I’m curious where this kit hits its stride. Is it between 10-20psi? Is it 15-30psi? Is it 20-25psi?

I think as far as "where it hits its stride" is defined by the compressor maps, I don't have that info. But yes, the point is, if the blower isn't working as hard, it will generate less heat via better adiabatic efficiency. And this is why if you have a cooler that can combat that additional heat, the 900 is a better blower for a stock engine. The engine, driving the blower, will work less to make the same power since the aftercooler can bring the IAT back down into the desired range for the given power level.

Cosworth designed their kit to be an OEM level power adder. Harrop designed their kit to allow for dramatic growth.

That’s why I posted the compressor map hoping someone could read it and figure it out. It would be cool to know.

I found this thread on page three. So sad.

I just got my 2020 registration renewal for my 2013 BRZ. No need for a smog this year. At this point I don’t think Harrop will be getting CARB certification. Hopefully I can enjoy the kit for a few more years before smogging will be necessary then I’ll either be swapping to a JRSC or selling the car. We will see what happens then.

You bought the car new? I thought CA just changed it from 6 to 7 years for a new car but that would mean yours should be due this year. Harrop is most definitely getting CARB approval very soon! I don’t think you’d be very happy going to a rotrex after driving a TVS1320 on ethanol. I recommend the Harrop kit to everyone over everything else and I had both a Jackson and Edelbrock kit.

I doubt they are going to get CARB approved. Why? This car is at the end of its production run. The talk is the motor will be getting updated for the second gen in 2021 anyways. Are you privileged to information that they are still trying to get CARB approved because that would be cool? I know they are based in Australia, but they seem to be taking forever. Other companies have released MY17+ CARB kits/updages and/or have updates like how JRSC has released a CARB C38 SC alongside the C30. It just seems that Harrop isn't working at all on CARB approval.

From what I understand, the smog law changed from 6 to 8 years, so if I understand this correctly the 2013-14-15-16-17-18-19-20 years of my car will not require smog. In the fall of 2020, my registration for 2021 should include a notice to smog the car, so I have one more year to enjoy this kit.

I agree that moving to the JRSC might be a step back from the Harrop, but I am not a fan of the Edelbrock kit, even though it uses the same Eaton TVS 1320 SC. The JRSC seems to have better reliability/less issues, unless I am mistaken, and there are no issues with the Edelbrock kit.

Wouldn't hold your breath. From the source via their contact forum over THIS weekend.

Confirm with Neal at The Racer's Line. He was one of the 1st Harrop dealers for this platform in the US. My understanding is the 13-16MY should have CARB approval any day now. Neal just picked up a brand new 2019 to work directly with Harrop on getting CARB approval on the 17' and newer cars. It took Edelbrock a LONG time to get CARB approval and they have done it so many times. Again, check with Neal but I still have faith that Harrop will get CARB approval soon (not that it matters to me, don't think I'll ever have another Subaru boxer).

Crossing fingers

I wanted to expand on this topic. Just some rough timelines:

Jackson Racing SC
Mentioned Here: Spring 2013
Released for sale: Fall 2013
CARB approved: November 21st 2013

https://ww3.arb.ca.gov/msprog/afterm...eo/d-700-2.pdf

Works Turbo
Mentioned Here: Stage 1 Fall 2014, Stage 2 Spring 2015
Released for sale: Stage 2 Spring 2015
CARB approved: Summer 2015

https://arb.parts/Executive-Order/D-748


Edelbrock SC
Mentioned here: Winter 2014
Released for sale: Fall 2015
CARB approved: July 29th 2016

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

Harrop SC
Mentioned here: Winter 2014
Released for sale: Summer 2015
AU Emission approved: Spring 2016
CARB approved: .........Pending.................

https://www.harrop.com.au/blog/lates...sions-approved

Just saying. After four years since the release date and over three years since gettin emissions approved in Australia, yet still nothing here, I'm not holding my breath that this will happen. I hope they prove me wrong. :popcorn:

To be fair, the other 3 companies are based in the US, making it dramatically easier to achieve. But I agree with you, it's been far too long -- they should have taken it more seriously.

Pure speculation on my part, but these two items might be related.

Advertising should be close to the expectation, and the expectation should be close to the outcome. If someone says CARB pending then that should reflect a timeline consistent with the word pending. It creates an expectation that the CARB tune is finalized, the testing might even be finalized, that they are just pending the outcome of the analysis or waiting for official documents stating the car passed. Maybe this is the case, and the process is taking three years, but I believe a more appropriate description would have been to say that the company was working on development of a CARB kit, so as not to lead the consumer into a false expectation.

Imagine buying something online and then, instead of the order status moving from processed to delayed-at-port or backordered, clearly describing the situation, it just said pending shipping... forever. Your patience could wear thin. I’m getting there. I’m just fortunate that California extended the smog requirement two more years.