Review for Harrop SC

[Sered]

I compared it to a 620 kit and the Harrop was still making more power down low. Most 620 kits dyno in the 515rwhp range from what I've seen. That's a huge power difference under the curve. The torque curve is especially interesting as it seems it would still have made great power below 2k rpms.

Can't wait to see what they do on stage 2.

[Sered]

Originally Posted by C|3R1C

See above. Please let me know if there is something I should change or if you have better info.

Well I know from experience that the manual cars fall out of the centri powerband. The gear spacing is especially bad but it really becomes apparent in 2nd through 4th gear. While I think the DCT would still reign supreme, having the rpms drop to ~4k after a short shift from 1st to 2nd due to traction wouldn't be such a big deal on the Harrop kit.

Even though it is a different platform, the manual vs DCT comparisons on the F8x show them running much more closely together (mainly because of the turbo powerband but also because BMW put a better gearbox in that car).

[C|3R1C]

Originally Posted by Sered

Well I know from experience that the manual cars fall out of the centri powerband. The gear spacing is especially bad but it really becomes apparent in 2nd through 4th gear. While I think the DCT would still reign supreme, having the rpms drop to ~4k after a short shift from 1st to 2nd due to traction wouldn't be such a big deal on the Harrop kit.

Even though it is a different platform, the manual vs DCT comparisons on the F8x show them running much more closely together (mainly because of the turbo powerband but also because BMW put a better gearbox in that car).

I just meant the comparison between the centri and screw type but I see what you mean between dct and mt

[Pro-AM3]

Originally Posted by C|3R1C

From what I understand, it's the way the blowers produce power. The centri kits keep making boost to redline, while this screw type makes full boost halfway through. The trade off is the power isnt as high at the top but you get more area under the curve. I attached this overlay with a 585. It is a VERY VERY rough comparison, as the new kit is a 595 and the dyno is like 2 years old, but I feel is shows a good representation of how each of the kits work. I did a light search for these graphs, so this is a mere representation. If someone has more accurate or correct info, which Im sure a lot of people do, by all means correct me. I would never want to misrepresent something.

Boost at redline is boost at redline and it should make equal power unless something is forcing the DME to pull timing.. aka Heat

[C|3R1C]

Originally Posted by BossManE90

Boost at redline is boost at redline and it should make equal power unless something is forcing the DME to pull timing.. aka Heat

After quite a bit of googling because Im curious to this as well, Ive settled on the fact that roots type superchargers generate more heat at the top of the engine range vs centri. To add some say (for roots in general) that it takes more engine power to turn at the top of the RPM vs centri. That I can see considering the two roots lobes compared to the impeller. More heat up top + more energy require to turn I would speculate is to why it does not make as much peak HP, though I think I would place more emphasis on the energy required over the heat since it only starts to lose power power in comparison to the centri at around 7.25k rpm. As for why is makes more torque, I would venture to say it draws in more air, maybe?? I dont really know. This is my guess.

In regards to heat soak, there are two intercoolers in the manifold.

Thoughts?

[Shredicus]

Damn I love these kits

[ashtaron14]

Originally Posted by C|3R1C

After quite a bit of googling because Im curious to this as well, Ive settled on the fact that roots type superchargers generate more heat at the top of the engine range vs centri. To add some say (for roots in general) that it takes more engine power to turn at the top of the RPM vs centri. That I can see considering the two roots lobes compared to the impeller. More heat up top + more energy require to turn I would speculate is to why it does not make as much peak HP, though I think I would place more emphasis on the energy required over the heat since it only starts to lose power power in comparison to the centri at around 7.25k rpm. As for why is makes more torque, I would venture to say it draws in more air, maybe?? I dont really know. This is my guess.

In regards to heat soak, there are two intercoolers in the manifold.

Thoughts?

You're on the right track. In the old days the Roots type blower are more prone to heat soak, because the twist of the screws or lobes are less, and usually have nylon end tips that would actually come in contact with the other lobes while working. With the lobes in the Harrop (Eaton), they are twisted 160 degrees and don't touch one another (more twist means more compressed air).

Centri, on the other hand, runs a gearing system. For example, with a 4:1 ratio. the gear outside the compressor turns once, the turbine turns 4 times. Like a turbo, a centri will need to spool. It's not like a Roots or Twin Screw, but the advantage is more boost.

For our Harrop kit, there's an electronic bypass (like a throttle body). When you start the motor, the bypass is open, letting the engine breathe normally. When you step on it, the bypass is closed, forcing the air to go though the lobes. An example of this technology is used on the Audi S4's 3.0T.

References:
http://www.audi-technology-portal.de...n/supercharger
http://www.eaton.com/Eaton/OurCompan...Audi/index.htm

[Sered]

Originally Posted by BossManE90

Boost at redline is boost at redline and it should make equal power unless something is forcing the DME to pull timing.. aka Heat

A roots type is not as efficient as a centri unit; so at the same boost levels it may be making less power if the IATs aren't handled as well. Either way, this graph shows a tremendous gain on power under the curve which will make a significant difference when it comes to acceleration (especially on the manual cars). Even in regular driving, there will be a huge net gain here.

Mercedes uses a clutched pulley to achieve a similar result to the bypass that Harrop is using.

[M.Hagen]

OP - Can you please measure the snout pulley diameter? I am curious what RPM the Stage-1 setup is turning the TVS1740. Thanks.

Originally Posted by BossManE90

Boost at redline is boost at redline and it should make equal power unless something is forcing the DME to pull timing.. aka Heat

10psi on a Eaton TVS1740 is not the same mass airflow as a Vortech V3-Si at 10psi nor a Rotrex C38-91 at 10psi. Even when all else is the same, these three compressors will all make different power at the exact some pressure ratio on an S65.

While in most cases increasing boost increases mass airflow, the proportionality of that relationship is dependent on the compressor map.

[regular guy]

Originally Posted by Sered

Well I know from experience that the manual cars fall out of the centri powerband. The gear spacing is especially bad but it really becomes apparent in 2nd through 4th gear. While I think the DCT would still reign supreme, having the rpms drop to ~4k after a short shift from 1st to 2nd due to traction wouldn't be such a big deal on the Harrop kit.

Here's the DCT RPM drop table per gear.

Gear	RPM	Speed	Target RPM	Drop
1	8300	43.20568719
2	8300	70.37289958	5095.813953	3204.186047
3	8300	95.84118705	6094.405594	2205.594406
4	8300	122.9778898	6468.494898	1831.505102
5	8300	148.9411242	6853.154162	1446.845838
6	8300	171.493343	7208.509142	1091.490858
7			6895.384615	1404.615385

Here's the 6MT RPM drop table per gear.

Gear	RPM	Speed	Target RPM	Drop
1	8300	41.70702915
2	8300	71.41685114	4847.152127	3452.847873
3	8300	106.930857	5543.393939	2756.606061
4	8300	141.8636941	6256.189213	2043.810787
5	8300	169.1451738	6961.290323	1338.709677
6			7240.425532	1059.574468

[C|3R1C]

Originally Posted by M.Hagen

OP - Can you please measure the snout pulley diameter? I am curious what RPM the Stage-1 setup is turning the TVS1740. Thanks.



10psi on a Eaton TVS1740 is not the same mass airflow as a Vortech V3-Si at 10psi nor a Rotrex C38-91 at 10psi. Even when all else is the same, these three compressors will all make different power at the exact some pressure ratio on an S65.

While in most cases increasing boost increases mass airflow, the proportionality of that relationship is dependent on the compressor map.

Yes I will get to that tonight. And ty for the information. That was exactly what I was looking for.

[C|3R1C]

Originally Posted by Sered

Well I know from experience that the manual cars fall out of the centri powerband. The gear spacing is especially bad but it really becomes apparent in 2nd through 4th gear. While I think the DCT would still reign supreme, having the rpms drop to ~4k after a short shift from 1st to 2nd due to traction wouldn't be such a big deal on the Harrop kit.

Even though it is a different platform, the manual vs DCT comparisons on the F8x show them running much more closely together (mainly because of the turbo powerband but also because BMW put a better gearbox in that car).

When Mike gave me a test drive in his car he had to short shift 1st for traction, I think around 7k rpm IIRC. It still hauled like a beast.

[Sered]

Originally Posted by regular guy

Here's the DCT RPM drop table per gear.




Here's the 6MT RPM drop table per gear.

Thanks dude! That 1st to 2nd to 3rd is srs bsns

[regular guy]

Originally Posted by Sered

Thanks dude! That 1st to 2nd to 3rd is srs bsns

2nd to 3rd is pretty bad too. You were right, the DCT has much better spacing until you hit 7th. But at that point, who cares?

[Sered]

Originally Posted by regular guy

2nd to 3rd is pretty bad too. You were right, the DCT has much better spacing until you hit 7th. But at that point, who cares?

Yeah, already at "go-directly-to-jail" speeds lol.

[C|3R1C]

Originally Posted by Sered

Yeah, already at "go-directly-to-jail" speeds lol.

Those speeds come up really fast

[Pro-AM3]

I think its safe to say your correct on both, its taking more power to run it, and the heat generated is pulling timing. I think this blower would benefit greatly, even more so than centri kits, from a larger ice tank, and also methanol pre S/C. As long as the lobes are coated to be safe from corrosion.

thats the trick in the domestic crowd with these kinds. Spray some meth on it and you get the benefits of cooling the most, because anything not atomized and still in liquid form will make contact with the lobes and reduce temps as well.

I think you could get away with a very very small nozzle to start and very very minimal methanol content as to not interfere with AFR too much, just use water..

AND THEN.. you can do it even better! use a larger ice tank AND ice in the methanol injection kit

[Shredicus]

Originally Posted by BossManE90

I think its safe to say your correct on both, its taking more power to run it, and the heat generated is pulling timing. I think this blower would benefit greatly, even more so than centri kits, from a larger ice tank, and also methanol pre S/C. As long as the lobes are coated to be safe from corrosion.

thats the trick in the domestic crowd with these kinds. Spray some meth on it and you get the benefits of cooling the most, because anything not atomized and still in liquid form will make contact with the lobes and reduce temps as well.

I think you could get away with a very very small nozzle to start and very very minimal methanol content as to not interfere with AFR too much, just use water..

AND THEN.. you can do it even better! use a larger ice tank AND ice in the methanol injection kit

I'm inclined to agree. The synergy between a TVS unit and WMI is pretty awesome, and I'm sure the gains will be significant across the powerband.

[Pro-AM3]

Originally Posted by C|3R1C

Yes I will get to that tonight. And ty for the information. That was exactly what I was looking for.

Ever get a chance to measure for us?

[rayyan1127]

Harrop SC kit is just fantastic

[rayyan1127]

find the video from youtube about ESS 625 M3 compare to Harrop M3
do not believe everyone can always get 180mph everyday...

[pbonsalb]

The two cars looked pretty close in the video. Surprising given the supposed power difference.