Harrop Supercharger Review: Dyno and 1/4 mile runs.

[ImmortalBimmer]

I’ve been looking at the Harrop for years and tried to get as much info as possible. There’s just not enough videos of the Harrop, dyno info, or ¼ mile times for the supercharger. So I’m writing this review to help others out there who want more info like me. As of right now, I have 113,300 miles on the car and planning to keep the car for a long time. The car also has Akrapovic Evo Exhaust with BPM Sport tune.

So I finally got my hands on used one (3,550 miles on kit) from a fellow member a month ago. When I finally received it, I got the guys at European Motor Gruppe in Houston to install it. While it was at the shop, I put in a fresh set of spark plugs and o2 sensors. They did a great job with awesome pricing, and I’m happy with their service. The first time I stomped on the gas I had a huge grin on my face. I very impress by the low end torque and the powerband in the midrange. It acts like a big block v8 now. The M3 was lacking that punch down low and now I have it. I can’t get enough of the power down low, I’m punching it everywhere I go now. Even with Michelin Pilot Sport 4s 295s in the rear, I was still losing traction off the line and chirping into second gear. I gave a lot of people rides in the car and every one of them love the pin to the seat 1st gear pull. One of the guy has a 1400 RWHP twin turbo Viper, and commented just how nice the car pulls and feels for the horsepower level. That’s a win in my book.

Everyday drivability is still the same which is great. During stop and go traffic, the temperature needle is slightly above 210F. I haven’t seen any issues so far. Overall, the kit is worth it in my opinion. If your chasing horsepower numbers then this won’t be the kit to get. If you want low end torque, then this is the kit for you. I’m happy and satisfied with the kit. Just waiting for stage 2 kit now!!!

On to performance: I use the Dragy App to measure my performance to get an idea of the changes.

With just Akraprovic exhaust and tune, I was able to run the ¼ mile in 13.26 @110.77 at 86F with DA 2276FT ¼ tank of gas. My 60 foot time is not that good. It’s just stomping on the gas. No launch control

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I was able to run a ¼ on the Dragy App with 12.54 @119.83 at 77F with DA of 1677ft 1/8th tank of gas. As like before, I’m just stomping on the gas with no launch control.

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Update with cooler weather run. I was able to run 12.26@122.44 at 68F with DA of 682FT with 1/4 tank of gas. Just like the other runs, no launch control was used.

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Here’s a vid of 1/4 mile runs with some driving at the end.

On the Dyno Jet, with just exhaust and tune it made 345.6rwhp and 252.71 torque SAE corrected on 93 octane. With the supercharger, the car dynoed 465.72 rwhp and 320.73 torque SAE corrected on 93 octane.

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[pbonsalb]

Picking up 10 mph in the quarter is serious business and shows a major power gain. I’d love to see a Stage 2 dyno but the upgrade path for the Harrop has been under development for years and it seems uncertain whether it will ever be offered. They are a challenge to tune and only one tuner is in the business.

[nycplumber]

Thanks for posting. Would love to see a 60-130 time

[BP709]

Thanks for the review! Definitely on my list of things I want to do. Fit and finish of the Harrop just seems so much better than other options. I'm in Houston as well. Would love to check it out sometime!

[pbonsalb]

ESS just posted some G1 centrifugal dynos in the General subforum. It looks like the positive displacement Harrop has a solid advantage below 4000 rpm, which is what you would expect. Beyond that, though, it appears to be at a disadvantage.

[M3R1]

Awesome set up! SC'd M3's are awesome!

[Ashley_rj]

Hey, I agree it's pretty hard to find data on the Harrop. I am very happy with mine. Here is my dynapack chart from Harrop in Melbourne with a stock exhaust.[IMG][/IMG]

[Jeef]

who tunes your harrop m3?

[amrazM]

Originally Posted by Jeef

who tunes your harrop m3?

mike benvo, bpm

[Jeef]

is he the only one who offers ots tunes for these? any other options for custom tuning?

[nycplumber]

Originally Posted by Jeef

is he the only one who offers ots tunes for these? any other options for custom tuning?

Rk does as well. Personally, when I buy this kit I will get it from BPM and use Mike's tune.

[Properstyle]

kinda under welming. Harrop looks good, sounds good, But out side of stop and go joy is at a clear disadvantage to every other maker.

IMO its just due to size. ESS,vf,gintani use over sized blowers. This means lower torque as blowers are not in their effeceny range at lower rpm. A v3 doesn't max out until 16psi yet its not even spun to half of that on ess kits.

the harrop is only a 1.7 so its smaller size allows it to be in max power out put early but runs out of breath early.

[pbonsalb]

Its more centrifugal versus positive displacement — totally different goes of superchargers. A centrifugal by design will make roughly the square root of peak boost at half peak rpm. In other words, a centrifugal that makes 9 psi at 8400 rpm will make only 3 psi at 4200 rpm. This law holds true whether you put a tiny centrifugal on the car or a giant one. The popular V3 Si trim is actually a pretty good match since for the S65 given that about the best anyone can do on pump gas is 600 rwhp SAE Dynojet and the blower would be maxed out probably before 700 rwhp.

The positive displacement, in contrast, will reach peak boost before the centrifugal is at 2 psi and maintain it all the way to redline unless it is undersized. I don’t think it is undersized. It is limited more by the fact that any more boost in the low to midrange would cause knock on pump gas. In that sense, the centrifugal that builds boost over rpm and does not make high boost (relatively speaking, from the S65 perspective) is better suited to the 12.0:1 compression S65 if more than a 50% power increase is desired.

[tlow98]

Originally Posted by Properstyle

kinda under welming. Harrop looks good, sounds good, But out side of stop and go joy is at a clear disadvantage to every other maker.

IMO its just due to size. ESS,vf,gintani use over sized blowers. This means lower torque as blowers are not in their effeceny range at lower rpm. A v3 doesn't max out until 16psi yet its not even spun to half of that on ess kits.

the harrop is only a 1.7 so its smaller size allows it to be in max power out put early but runs out of breath early.

Yeah see above about blower type.

“Outside of stop and go”? That’s where you spend 99% of your driving. Unless you have a race car and that’s all you use it for positive displacement super chargers are the way to go if you value throttle response and power that you use all the time instead of 5% of the time when you’re doing high rpm pulls.

Power under the curve is the biggest proof on the pudding... Positive displacement blowers do that. Everywhere.

[Properstyle]

Originally Posted by pbonsalb

Its more centrifugal versus positive displacement — totally different goes of superchargers. A centrifugal by design will make roughly the square root of peak boost at half peak rpm. In other words, a centrifugal that makes 9 psi at 8400 rpm will make only 3 psi at 4200 rpm. This law holds true whether you put a tiny centrifugal on the car or a giant one. The popular V3 Si trim is actually a pretty good match since for the S65 given that about the best anyone can do on pump gas is 600 rwhp SAE Dynojet and the blower would be maxed out probably before 700 rwhp.

The positive displacement, in contrast, will reach peak boost before the centrifugal is at 2 psi and maintain it all the way to redline unless it is undersized. I don’t think it is undersized. It is limited more by the fact that any more boost in the low to midrange would cause knock on pump gas. In that sense, the centrifugal that builds boost over rpm and does not make high boost (relatively speaking, from the S65 perspective) is better suited to the 12.0:1 compression S65 if more than a 50% power increase is desired.

The blower is actually very large for a s65. Being one of those who actually decided to say screw what the forums say and push the envolpe going full e85 12 psi ect. You really quickly on if the vortech v3 wasn't so large and was closer to the size of the rotrex 93 it would make a lot more tq sooner. Given my car is pulled down I actually generate more tq then a Harrop.

Case in point. Running 78mm pulley the vortech v3 basically cruises in boost. Making 7psi at the same rpm points that a 96mm pulley car only makes 2. What this means is tq very earlier. The problem is if I was no on e85 this would be too much boost for 93 octane at the top of thr rpm. The blower is so large that people think of it to be gutless sown low because in reality it's no in its Efficiency range.

If the Ess came with a blower the size compressor to the rotrex ce-93 you would see boost much sooner because of the size and actually get away with running more boost on 93.

It's not really a pd vs centri. The bore and stroke of a s65 is not designed to actually make tq down low. So you will
Never see that table top power band like you do on any other platform using a pd blower.

[Properstyle]

Originally Posted by tlow98

Yeah see above about blower type.

"Outside of stop and go"? That's where you spend 99% of your driving. Unless you have a race car and that's all you use it for positive displacement super chargers are the way to go if you value throttle response and power that you use all the time instead of 5% of the time when you're doing high rpm pulls.

Power under the curve is the biggest proof on the pudding... Positive displacement blowers do that. Everywhere.

I live in Texas my community isn't stop and go ah all lol. And in my case now I make more power than what is usable in stop an go to actually enjoy it. Right now I rarely have to go over 4-5k rpm. It's amazing what happens when you pulley a blower down to operate in its efficiency range as apposed to driving around in what would be compared to a over sized turbo car.

[tlow98]

Originally Posted by Properstyle

I live in Texas my community isn't stop and go ah all lol. And in my case now I make more power than what is usable in stop an go to actually enjoy it. Right now I rarely have to go over 4-5k rpm. It's amazing what happens when you pulley a blower down to operate in its efficiency range as apposed to driving around in what would be compared to a over sized turbo car.

cool, your car sounds awesome.

[pbonsalb]

Originally Posted by Properstyle

It's not really a pd vs centri. The bore and stroke of a s65 is not designed to actually make tq down low. So you will
Never see that table top power band like you do on any other platform using a pd blower.

It really is PD vs centrifugal. You are not understanding how either work and their respective boost curves. You cannot change centrifugal to make full boost at low rpm, apart from over spinning it and bleeding off boost at high rpm. Even a planetary gear drive centrifugal like ASA, Rotrex and HKS have the same centrifugal curve. They spin faster than the vortex so they reach the minimum centrifugal speed at which boost starts being created a little bit sooner. But it’s pretty minor. Study the AA Rotrex 600 rwhp dyno and compare to a similar power Vortech V3 Si dyno and you will see.

You are correct that an engine that makes leak power at 8400 rpm is not going to make much torque at low rpm. However, there is no disputing that the positive displacement makes full boost much much much sooner on this motor and has a dramatically better low end power curve. That is a function of how the PD blower works in contrast to how the centrifugal works.

The benefit of the PD is also it’s disadvantage on the high compression S65. It can’t be set up provide as much boost as it could due to concerns about knock and rods that are present at the higher VE levels that exist in the low to mid range. If you installed stronger rods and ran higher octane and let it boost to 8 psi like the typical high power centrifugal kit, any advantage the centrifugal still had due to higher efficiency would show up at much higher rpm rather than the entire 2nd half of the power band.

From 2000-4000, the PD wins every time. From 4000-8000, the centrifugal wins. Any all out race the centrifugal wins because you are under 4000 only during the launch. Honestly, I find the torque of my modded NA E90M3 to be perfectly fine for lazy low rpm daily driving around town. I’d rather add top end power for the occasions when I hot rod around. The only situation where I would want more low end is highway cruising in 5th or 6th, where I wanted to be lazy and not downshift. The PD blower would be nice there. With the centrifugal I would still be downshifting. My car is 6MT; those of you with DCT can do tremendous downshifts with zero effort. My next car will be auto or DCT and turbo

[Properstyle]

Originally Posted by pbonsalb

It really is PD vs centrifugal. You are not understanding how either work and their respective boost curves. You cannot change centrifugal to make full boost at low rpm, apart from over spinning it and bleeding off boost at high rpm. Even a planetary gear drive centrifugal like ASA, Rotrex and HKS have the same centrifugal curve. They spin faster than the vortex so they reach the minimum centrifugal speed at which boost starts being created a little bit sooner. But it's pretty minor. Study the AA Rotrex 600 rwhp dyno and compare to a similar power Vortech V3 Si dyno and you will see.

You are correct that an engine that makes leak power at 8400 rpm is not going to make much torque at low rpm. However, there is no disputing that the positive displacement makes full boost much much much sooner on this motor and has a dramatically better low end power curve. That is a function of how the PD blower works in contrast to how the centrifugal works.

The benefit of the PD is also it's disadvantage on the high compression S65. It can't be set up provide as much boost as it could due to concerns about knock and rods that are present at the higher VE levels that exist in the low to mid range. If you installed stronger rods and ran higher octane and let it boost to 8 psi like the typical high power centrifugal kit, any advantage the centrifugal still had due to higher efficiency would show up at much higher rpm rather than the entire 2nd half of the power band.

From 2000-4000, the PD wins every time. From 4000-8000, the centrifugal wins. Any all out race the centrifugal wins because you are under 4000 only during the launch. Honestly, I find the torque of my modded NA E90M3 to be perfectly fine for lazy low rpm daily driving around town. I'd rather add top end power for the occasions when I hot rod around. The only situation where I would want more low end is highway cruising in 5th or 6th, where I wanted to be lazy and not downshift. The PD blower would be nice there. With the centrifugal I would still be downshifting. My car is 6MT; those of you with DCT can do tremendous downshifts with zero effort. My next car will be auto or DCT and turbo

I fully understand how both work but it's clear you don't understand what I said.
I never said or anything about making max tq in a centrifugal at lower rpm.

Due to the size or rather over all output of thr vortech v3 you can not run a pulley small enough to allow it to work in its Effiency range in the lower rpm on pump gas because when it is in the higher rpm it will move to much air for 93 octane to use with out basically taking all timing out of the car.

A smaller blower can operate in its Effeicny range sooner. This same aspect is with turbos as wells. There is always a trade off, smaller blower less top end big blower lacking lower end. While a centrifugal will not make max boost in lower rpm by its design the amount of air flow drastically changes at each rpm based on thr speed of drive section. So as I stated again. Dropping in pulley as small as I've run being and being e85, stomping on the car in thr Lower rpm in stop in go traffic is completely unusable.

There are people running more than 7 psi on thr harrop but the blower is just too small to keep up with the turn over rate of a s65. Thr blower is maxed out using an upper pulley as it is sent out the box which is why you can only do lower pulley to up boost. It's just too small of a blower. A 2.1 would have been better suited for a s65 to continue to make power with in thr upper rpm range.

Personally I would never spend 10k just for increases tq to use in moderate traffic I'd keep the car Na and Learn how to drive it then try to make a small bore and stroke car operate like a detuned Amg. Which is why I said a PD blower on this car will never have a table top tq curve like you get in a 6.2 ls car with the same. A centrifugal will never make the same tq curve.

[Properstyle]

Now in comparison the ops car actually made less wtq at 3-4K then this vortech v3 is at 9psi. Then in over all tq is made quite a bit less. Even on the 93 octane run which is in the graph. So again if the Ess car came with a smaller blower you wouldn't need to pulley it down so much to move the boost curve over. Number do not lie here. All people have to do is drop pulley an thr whole band changes after appropriate tune. If the harrop was bigger it wouldn't be a companions but as I said before the blower is just too small.

[Properstyle]

Graph

[drwankel]

Question about your tire setup. I just installed a harrop supercharger on my 2012 e92, with stock zcp wheels and suspension (no spacers). Currently running stock size PS4s tires, (245s and 265s). I obviously need way more rubber on the back, and need to change the fronts up to keep the balance correct.

You mentioned that you are running 295 PS4s tires on the rear, and it sounds like you are on stock zcp suspension and without spacers as well.

What is the total tire setup you are running? Do you have any issues with the wider setup? No rubbing? Handles well? In other threads i've seen people comment that 295s on the rear and anything wider than 255s on the front dont give enough sidewall support. However, I've never actually found anybody running this setup specifically on the PS4S tires and am curious how its working out for you.