Harrop Supercharger Stage 5 vs 6

[Sam86]

Hi, hard to find info on the Harrop as I believe most people just go for the Elderbrock kit as that's local to the US but I'd like to see if anyone with the Harrop can give a little insight to me about their power claims.


Looking at their Stage 5 vs Stage 6 claimed flywheel power it's hard to believe the significance when the changes between the two kits seem very minor.

Stage 5 claims 250kw with the following
250 kW / 375 Nm (Standard 147 kW / 205 Nm)
Harrop Flex Fuel Kit
4 into 1 Headers
Harrop TVS1320 Supercharger Kit
Harrop ECU Recalibration

Where as Stage 6 claims a massive 305kw with
305kW / 420Nm (Standard 147 kW / 205 Nm)
Supercharger boost upgrade
85mm Supercharger Pulley - 10psi
2.5" Catback Exhaust System and 4 into 1 Headers
Harrop Flex Fuel Kit
Harrop TVS1320 Supercharger Kit
Harrop ECU Recalibration

Am I misunderstanding something because I don't see how a slightly bigger pulley and a catback exhaust is giving an additional 55kw over Stage 5 when the entirety of stage 5 (Supercharger, E85 and Headers which are the biggest power components only offer 45kw over stock)
Is the difference in the tune or are they exaggerating? Anyone with the kit able to offer some insight on what you got (ie did you get any of the stages or did you buy the SC on its own. The kit is like 9-14000 AUD which is ridiculous however I have most of the components aside from the SC and a Flex fuel kit.

Also any better alternatives that can be recommended however I do live in Australia and the Harrop factory is local which is my reason for looking at this kit (As I believe their prices include install and a dyno tune specific to your car). So whilst something like the Elderbrock or the Sprintex does interest me, the currency conversion and shipping cost and the fact i'm RHD might make those options more difficult

[tomm.brz]

that much intake boost the smaller pulley will set, will provide a big boost of power if using the flex kit and you fill with pure E85
Less %gain if you use petrol of course

Also the free (i suppose) catback will give a power bump at high rpm

Seems legit

[e30cabrio]

E85 (and its tune) on its own gave me a nice boost. I don't have an SC so on that front no clue.

[Irace86.2.0]

Originally Posted by Sam86

Hi, hard to find info on the Harrop as I believe most people just go for the Elderbrock kit as that's local to the US but I'd like to see if anyone with the Harrop can give a little insight to me about their power claims.


Looking at their Stage 5 vs Stage 6 claimed flywheel power it's hard to believe the significance when the changes between the two kits seem very minor.

Stage 5 claims 250kw with the following
250 kW / 375 Nm (Standard 147 kW / 205 Nm)
Harrop Flex Fuel Kit
4 into 1 Headers
Harrop TVS1320 Supercharger Kit
Harrop ECU Recalibration

Where as Stage 6 claims a massive 305kw with
305kW / 420Nm (Standard 147 kW / 205 Nm)
Supercharger boost upgrade
85mm Supercharger Pulley - 10psi
2.5" Catback Exhaust System and 4 into 1 Headers
Harrop Flex Fuel Kit
Harrop TVS1320 Supercharger Kit
Harrop ECU Recalibration

Am I misunderstanding something because I don't see how a slightly bigger pulley and a catback exhaust is giving an additional 55kw over Stage 5 when the entirety of stage 5 (Supercharger, E85 and Headers which are the biggest power components only offer 45kw over stock)
Is the difference in the tune or are they exaggerating? Anyone with the kit able to offer some insight on what you got (ie did you get any of the stages or did you buy the SC on its own. The kit is like 9-14000 AUD which is ridiculous however I have most of the components aside from the SC and a Flex fuel kit.

Also any better alternatives that can be recommended however I do live in Australia and the Harrop factory is local which is my reason for looking at this kit (As I believe their prices include install and a dyno tune specific to your car). So whilst something like the Elderbrock or the Sprintex does interest me, the currency conversion and shipping cost and the fact i'm RHD might make those options more difficult

I think you meant a smaller pulley. The smaller the pulley, the more boost.

I went from the 95mm to the 85mm, and there was some gains, but the difference between NA to 95mm was about the same feeling as 95 to 85mm + E85; ie, adding E85 is huge. The difference between 95mm and 85mm without E85 was small because of the need to avoid knock by retarding timing, so most of the gains and then some come from E85. Adding a header is another big gain that is almost as significant as the difference of going from 95mm to 85mm without E85. A catback exhaust will do almost nothing, but maybe 5-10hp if it is a restriction, so that is mostly about sound and maximizing the gains and eliminating any top end back pressure.

You can always buy the headers, catback, flex fuel or any other small items from anywhere and do a remote tune from anywhere like CSG, Delicious Tuning, FT86, etc. The supercharger is worth getting local because of shipping and problems you could have with damage from shipping. Plus, the Harrop kit is nicer.

[CSG Mike]

The pulley and ethanol is where the bump comes from.

Ethanol makes a HUGE difference.

[Sam86]

Originally Posted by CSG Mike

The pulley and ethanol is where the bump comes from.

Ethanol makes a HUGE difference.

But the Ethanol is already present in the Stage 5 kit so the only difference in the stage 6 is the pulley which is why I'm having a hard time believing a pully and catback is adding 55kw between 5 and 6

[Sam86]

Originally Posted by Irace86.2.0

I think you meant a smaller pulley. The smaller the pulley, the more boost.

I went from the 95mm to the 85mm, and there was some gains, but the difference between NA to 95mm was about the same feeling as 95 to 85mm + E85; ie, adding E85 is huge. The difference between 95mm and 85mm without E85 was small because of the need to avoid knock by retarding timing, so most of the gains and then some come from E85. Adding a header is another big gain that is almost as significant as the difference of going from 95mm to 85mm without E85. A catback exhaust will do almost nothing, but maybe 5-10hp if it is a restriction, so that is mostly about sound and maximizing the gains and eliminating any top end back pressure.

You can always buy the headers, catback, flex fuel or any other small items from anywhere and do a remote tune from anywhere like CSG, Delicious Tuning, FT86, etc. The supercharger is worth getting local because of shipping and problems you could have with damage from shipping. Plus, the Harrop kit is nicer.

The reason for my confusion though is that the difference isn't the e85. The flex fuel kit is present in both Stage 5 and 6, so the difference between 6 is only in the 2.5in catback and the pulley. Both stages are already on e85 that's why I don't see how they can possibly claim a pulley and catback is a 55kw increase.

And yea I already have a headerback exhaust- just with Harrops site listing, there doesn't seem to be any standalone product where they offer the upgraded pulley/ specified tune on its own.
If you don't buy one of their 'stage' kits you can only buy the flexfuel kit and supercharger separately- supercharger either without a tune or with a OTS tune for stock setups (so not for me and my aftermarket headers).
If I could buy their components separately then yea i'd just individually buy their SC, Pulley and then Take it to them for a tune but I don't know currently if I can (yet to hear back from their sales rep)

[CSG Mike]

Originally Posted by Sam86

But the Ethanol is already present in the Stage 5 kit so the only difference in the stage 6 is the pulley which is why I'm having a hard time believing a pully and catback is adding 55kw between 5 and 6

Ah, I didn't see that in the stage 5; reading comprehension failure on my part.

I would speculate that stage 5 is intentionally detuned to work with a stock clutch, whereas 6 requires an aftermarket clutch, just based on the output numbers.

[FR-S2GT86]

Originally Posted by Sam86

The reason for my confusion though is that the difference isn't the e85. The flex fuel kit is present in both Stage 5 and 6, so the difference between 6 is only in the 2.5in catback and the pulley. Both stages are already on e85 that's why I don't see how they can possibly claim a pulley and catback is a 55kw increase.

And yea I already have a headerback exhaust- just with Harrops site listing, there doesn't seem to be any standalone product where they offer the upgraded pulley/ specified tune on its own.
If you don't buy one of their 'stage' kits you can only buy the flexfuel kit and supercharger separately- supercharger either without a tune or with a OTS tune for stock setups (so not for me and my aftermarket headers).
If I could buy their components separately then yea i'd just individually buy their SC, Pulley and then Take it to them for a tune but I don't know currently if I can (yet to hear back from their sales rep)

Just purchase what you want, install it yourself, have Zack at CSG remote tune it for you and then get it on the dyno to see how much power and torque you've gained. Easy peasy.

[Irace86.2.0]

Originally Posted by Sam86

The reason for my confusion though is that the difference isn't the e85. The flex fuel kit is present in both Stage 5 and 6, so the difference between 6 is only in the 2.5in catback and the pulley. Both stages are already on e85 that's why I don't see how they can possibly claim a pulley and catback is a 55kw increase.

And yea I already have a headerback exhaust- just with Harrops site listing, there doesn't seem to be any standalone product where they offer the upgraded pulley/ specified tune on its own.
If you don't buy one of their 'stage' kits you can only buy the flexfuel kit and supercharger separately- supercharger either without a tune or with a OTS tune for stock setups (so not for me and my aftermarket headers).
If I could buy their components separately then yea i'd just individually buy their SC, Pulley and then Take it to them for a tune but I don't know currently if I can (yet to hear back from their sales rep)

Aww, I too didn’t read carefully enough. So these are flywheel estimates so whp will be less, so maybe 45 extra hp going from 8 psi to 11.5 psi according to them with a pulley change and a catback. 305 kW = 410 hp. Assuming a 15-20% drivetrain loss, that is 328-348whp, but probably closer to the lower numbers. That is probably possible on the 85mm pulley on E85 with an aggressive tune, but it is a little high for a conservative tune. I think those numbers would come more from the 75mm pulley. This is a forum member with the 75mm pulley with E85, and I believe he said it was a conservative tune, but I can’t remember, yet he is making 360whp, which a decent amount more than the numbers they gave as an estimate for a 85mm tune, which might be aggressive. The more boost, the more headers and exhausts will make a difference too, as there is more potential for a restriction.

[PulsarBeeerz]

Originally Posted by Irace86.2.0

Aww, I too didn’t read carefully enough. So these are flywheel estimates so whp will be less, so maybe 45 extra hp going from 8 psi to 11.5 psi. 305 kW = 410 hp. Assuming a 15-20% drivetrain loss, that is 328-348whp. That is probably possible on the 85mm pulley on E85 with an aggressive tune, but it is a little high for a conservative tune. I think those numbers would come more from the 75mm pulley. This is a forum member with the 75mm pulley with E85, and I believe he said it was a conservative tune, but I can’t remember:

I kinda had my heart set on a K24 swap but this makes a great case for half the price. lol

[grumpysnapper]

Originally Posted by Sam86

The reason for my confusion though is that the difference isn't the e85. The flex fuel kit is present in both Stage 5 and 6, so the difference between 6 is only in the 2.5in catback and the pulley. Both stages are already on e85 that's why I don't see how they can possibly claim a pulley and catback is a 55kw increase.

And yea I already have a headerback exhaust- just with Harrops site listing, there doesn't seem to be any standalone product where they offer the upgraded pulley/ specified tune on its own.
If you don't buy one of their 'stage' kits you can only buy the flexfuel kit and supercharger separately- supercharger either without a tune or with a OTS tune for stock setups (so not for me and my aftermarket headers).
If I could buy their components separately then yea i'd just individually buy their SC, Pulley and then Take it to them for a tune but I don't know currently if I can (yet to hear back from their sales rep)

Yeah I don't quite understand those figures either...
I'm at 346whp with E85 with the 65mm pulley (305whp on crap Australian 98ron) and 401NM and 360Nm respectively...with no cat, custom built 2.5 exhaust, ACE headers, injectors etc etc.
But it is a low compression built block...and its on a Motec, and while its not a super aggressive tune chasing every last hp, I'd still be very surprised at getting that power on an 85mm pulley.

[Irace86.2.0]

Originally Posted by grumpysnapper

Yeah I don't quite understand those figures either...
I'm at 346whp with E85 with the 65mm pulley (305whp on crap Australian 98ron) and 401NM and 360Nm respectively...with no cat, custom built 2.5 exhaust, ACE headers, injectors etc etc.
But it is a low compression built block...and its on a Motec, and while its not a super aggressive tune chasing every last hp, I'd still be very surprised at getting that power on an 85mm pulley.

Stage 6 claims 305kW at the flywheel, so that is 410hp, and assuming a 20% drivetrain loss, that is 328whp. The dyno above was from a 75mm pulley, and they made 360whp, which is about 450hp at the flywheel or 335kW. Here is the same car on a hot 100F day by the same tuner on the same dyno, but with the 85mm pulley. The difference between 315whp below and 328whp claimed when considering tuners, weather conditions, cars, altitudes, dynos, ethanol content, calculations and rounding errors, etc. isn't significant enough to call foul on Harrop for false advertising. Also, the gains from going from 85mm to 75mm was 45whp or 55hp at the flywheel or 41kW, which is less that the 55kw claimed going from 95mm to 85mm by Harrop, but I wouldn't be surprised if the gains from 95mm to 85mm are more significant than 85mm to 75mm, and it would be even less going from 75mm to 65mm, if heat and efficiency worsen.

Brandon/byun
- Harrop w/85mm pulley
- E60
- 13psi
- Ace A350 header and Ace front pipe, stock catback
- Very Hot day, 100f in the shop. Tuner: Zach CSG

Your low compression build isn't as relevant, but you are still putting down around 435hp at the flywheel or 324kW. What is your compression ratio?

[86TOYO2k17]

Originally Posted by Irace86.2.0

Your low compression build isn't as relevant, but you are still putting down around 435hp at the flywheel or 324kW. What is your compression ratio?

Dropping compression when not being knock limited will drop power a lot. Especially true with ethanol almost to the point of losing power proportionately to the percent of drop, IE 12.5 to 10 will drop power 20% unless you can make up for that drop with lots of timing/boost (turbo) it’s pointless with a supercharger on ethanol. Perfect example is the few people who went sprintex 335 on E85 with 10:1 compression on small pulley made same power as everyone else on sprintex 210 E85 same pulley. Even though they making way more boost. Or in his case on harrop ethanol 65mm pulley. Maybe arguments for safety margin on track or when ethanol isn’t available. But its a big power sacrifice when sub 20psi on ethanol. Maybe a minor 12:1 or maybe 11.5:1 drop tops.