Official Harrop TVS1740 Supercharger Thread

[erics02wrx]

Before SC, I occasionally had problems with the 1-2 shift only if I was shifting super aggressively.

I found out it probably happened because I hadn't fully depressed the clutch pedal by the time I was trying to engage 2nd gear (transmission not completely disengaged). Now with more power I seem to short shift the 1-2 as 1st is somewhat traction limited and, if I slam second gear, traction control will kick in and pull power. So I found that the car is way quicker if I'm not aggressive in the 1-2 shift as the car doesn't get unsettled.

[averagejoe]

Interesting. When you guys talk about difficulty shifting into 2nd, do you mean synchro engagement, or drivetrain movement? 2nd is definitely slow to engage on mine as well, but I have trouble finding 3rd due to movement when I lift off at the top of 2nd gear. I replaced the engine mounts but did not do the transmission mounts. Are poly mounts worth it in this situation?

[erics02wrx]

Yes, mine is just a problem with 2nd synchro engagement...and just for info, I'm at 50k and only did engine mounts (Vibra-Technics) because I was getting RB done.

[averagejoe]

I've run poly engine mounts before, but that was on a time trial car that was still street legal, though it was not my daily driver - that thing was rough to drive, for that and other reasons. It was however an FD RX7 so totally different animal. Do you folks running poly mounts on this car feel like you can live with them? I see the Vibra-Technics use rubber, but are they on a similar level of stiffness? Thanks for the info everyone!

BTW I realize this is a bit off-topic w.r.t. the Harrop supercharger, so if you want me to start a separate thread, I can do so. Just thought it was somewhat Harrop-related because these symptoms only appeared with the extra 50% peak power the car is now making.

[DRLane]

RUG8RB8

Found this reference from FI Interchiller interesting when exploring upward vs downward discharge.

Not the exact Harrop blower as ours, but same principle regarding AIT sensor location.

Harrop 2300/2650 FDFI:
With the Harrop LS3 based blowers we have found flaws in the IAT2 sensor placement, it’s location as circled in the above picture is in the 2nd runner this is located right next to the cylinder head, in the supercharger housing so not only is the sensor absorbing engine heat it’s also absorbing blower case temperature and cylinder head temperature (3 heat source locations) we have found that we can have 10c (50f) fluid temps and that the IAT2 can be as high as 35-40c (95-104f). This poses a tuning issue, we need accurate temperatures or near enough accurate and we need them to swing in temperature when you go wide open throttle as example if the temp is 40c (104f) we need that temp to climb up to at least 70c (158f) for a window to tune ignition timing vs temperature. Luckily with blower spacer plates fitted and a thermal blanket this window for tuning does exist. However without blower spacers plates and thermal blanket no such window exists you could have 0c (32f) or 40c (104f) fluid temps and the IAT2 would be the same because the sensor itself is so heat soaked.

Remember back above to the LS9 example, that sensor was in the lid absorbing blower case temperatures, the sensor in the harrop blower is in the actual case, in the actual runner, right next to the cylinder head. In this particular case without blower spacer plates and a thermal blanket you have ZERO ability to tune for temperature. We were baffled when this blower was released and Harrop claimed their IAT only climbed by 10c (18f) on a dyno power run and that this was the best most efficient blower they had produced….it only climbed by 10c because the sensor was so heat soaked, once we installed a chiller again we see all of the flaws of that blowers design.

[RUG8RB8]

Originally Posted by DRLane

RUG8RB8

Found this reference from FI Interchiller interesting when exploring upward vs downward discharge.

Not the exact Harrop blower as ours, but same principle regarding AIT sensor location.

Harrop 2300/2650 FDFI:
With the Harrop LS3 based blowers we have found flaws in the IAT2 sensor placement, it’s location as circled in the above picture is in the 2nd runner this is located right next to the cylinder head, in the supercharger housing so not only is the sensor absorbing engine heat it’s also absorbing blower case temperature and cylinder head temperature (3 heat source locations) we have found that we can have 10c (50f) fluid temps and that the IAT2 can be as high as 35-40c (95-104f). This poses a tuning issue, we need accurate temperatures or near enough accurate and we need them to swing in temperature when you go wide open throttle as example if the temp is 40c (104f) we need that temp to climb up to at least 70c (158f) for a window to tune ignition timing vs temperature. Luckily with blower spacer plates fitted and a thermal blanket this window for tuning does exist. However without blower spacers plates and thermal blanket no such window exists you could have 0c (32f) or 40c (104f) fluid temps and the IAT2 would be the same because the sensor itself is so heat soaked.

Remember back above to the LS9 example, that sensor was in the lid absorbing blower case temperatures, the sensor in the harrop blower is in the actual case, in the actual runner, right next to the cylinder head. In this particular case without blower spacer plates [...]

I have read this and called and discussed with them. We have a very similar situation, sad but true. I have been so swamped lately, just had zero time to work on a solution.

[DRLane]

Originally Posted by RUG8RB8

I have read this and called and discussed with them. We have a very similar situation, sad but true. I have been so swamped lately, just had zero time to work on a solution.

Doesn’t seem like we have many viable alternatives for placement. Might experiment with better shielding the exterior of sensor from heat, as well as the bottom of the SC plenum.

[rotomoto712]

Not to thread hi-jack, but out of curiosity, what are some of the Harrop owners at higher altitudes seeing for boost? I've been working with the Harrop guys and BPM on trying to troubleshoot some boost issues i've been having (maxing out at 5.2), and I am curious to what extent altitude affects boost on these. I'm currently at 293M ~960 Ft, but there are many elevation changes where I am, though I don't think any are higher than 2000 ft.

[rotomoto712]

Originally Posted by DrFerry

rotomoto712 Lower boost from the Harrop blower at higher altitudes (>=5000 feet above sea level a.k.a. Denver Colorado etc.) has been an issue for a few members on this thread. Altitude is a well known negative power effect both with positive displacement blowers and turbos - as well as normally aspirated engines. You may want to do a quick web search for the mathematical formula used to calculate boost pressure loss as elevation increases. I think a rough rule of thumb is 0.5psi loss for every 1500 feet of elevation change.
https://www.corvetteforum.com/forums...rcharging.html

However, you stated you're blower is only making 5.2psi of boost at an estimated 1000ft to 2000ft above sea level. Since the Harrop makes ~6.5psi of boost max, I would expect the Harrop to make about 5.8 to 6.1psi at your stated altitudes. So 5.2 psi of max boost seems on the low side for your stated elevation. Do a smoke test to check for boost leaks at the throttle body boots and the plenum air box connection. Ensure the bypass valve actuator is properly closing. To do this, turn on the ignition, have a person floor the throttle pedal (WOT) to cycle the bypass valve actuator, then check with your hand the actuator rod has properly closed the actuator bypass valve by ensuring the actuator rod can not move any further towards the back of the car.

In summary, I don't think 1000 to 2000 feet of elevation change - above sea level - will cause all of the drop from the 6.5psi max boost (the Harrop is supposed to generate) down to 5.2psi. I would expect more like 5.8psi to 6.1psi at your stated elevations (altitude variances). Please verify your locations altitude with google earth - or similar source. Ensure no boost leaks are present at the throttle body boots by smoke test. Ensure the bypass valve actuator is closing properly at max boost (if not then adjust the actuator rod linkage). Please see the various posts on this thread about boost leaks and how to check the bypass valve actuator, and the actuator rod functioning.

Thank you for the tips!
I already did a smoke test , and there are no leaks and I also verified the boozt with a manual gauge. The bypass actuator appears to be working, at least with the engine off and responds to throttle position, but I'm not sure if it's closing properly at max boost. I'll have to check that next.

[rotomoto712]

I just tested the bypass again, and per you suggestions, i had my wife floor the throttle with the ignition on, and sure enough the rod was not fully closing. While she had the throttle depressed i pushed the bypass shaft and it moved an additional 1/8 -1/4 of an inch. Eaxh time she floored the throttle after that it went fully closed, but it would appear as though it's either occasionally binding or requires an adjustment as you mentioned. Next time i drive the car I will report back with my findings.

[rotomoto712]

Quick update:

I finally drove the car after ensuring that the actuator rod was fully opening, and on the first drive, I saw the boost get up to around 5 psi by 5.5K rpms and 6.2 at redline. However, each time I opened it up, I noticed the max boost gradually dipping lower and lower, until on the very last run, I only saw ~5.6 psi at redline. When I got home, and tested the actuator again, sure enough I noticed that the rod was not fully extending until I helped it along with my finger (this time only 1-2mm of extra movement). When I pushed the actuator rod by hand with the engine off, it moves freely for the first 75-80% of travel, but then binds in the last few mm of travel.

I am awaiting a response from Harrop at this point, as the connector to the bypass actuator was originally broken when I received the kit due to mishandling during shipping, so I think that there might be some internal damage to the actuator or the rod itself. I think it best to await their response at this point before I tweak anything.

[rotomoto712]

Nothing new to report yet. After speaking with Harrop, they determined the cause to be a faulty Bypass actuator. They will be sending out a replacement once they have them back in stock. I'll post an update once I get the new actuator.

[RUG8RB8]

I don’t think you need one, told me same thing, But I have a spare now. Just remove it pretty simple, clean and lubricate thoroughly. Worked perfectly after that and have nearly 35K miles since still steady at 6.5 psi.

[rotomoto712]

Out of curiousity how quickly do you hit 6.5 Psi, i.e. at what RPM?

[RUG8RB8]

Originally Posted by rotomoto712

Out of curiousity how quickly do you hit 6.5 Psi, i.e. at what RPM?

It is a positive displacement super charger, it happens extremely fast, matter of seconds and at nearly any rpm. I have posted logs on here somewhere and I don’t post much, so if you search you can see the excel file that will list everything. I am busy at work and don’t have time to search now.

[CamasM3e93]

Originally Posted by rotomoto712

Out of curiousity how quickly do you hit 6.5 Psi, i.e. at what RPM?

Building upon RUG8RB8 comments, it’s also a strong function of your traction control setting, wheel slip under acceleration, and how hard you press down on the accelerator, not just rpms. If you leave traction control on and throttle aggressively the wheels will spin and the car will cut throttle but it will feel like the kit is causing the motor to lurch or sputter. Subsequently you will struggle to see 6.5psi. Traction control completely off or a solid wheel and suspension setup and full throttle, you’ll get to 6.5 in a real hurry, my experience around 4-5k rpm. I tend to be light on the throttle in real world driving and won’t see it in those scenarios until 6-7k rpm.

My last coached track event the guy is like ‘full throttle, full throttle.’ Me: really? Uh, ok, here we go. Foot to floor, car accelerates from track speeds like gonzo as we approach the chicane. Coach: brake brake brake! He didn’t ask for full throttle again, lol. It’s a great kit but at 3600lb the e90 and e92 really demand other adjustments to wheels tires and other suspension to get the most out of it and reliably see those upper boost pressures unless you’re willing to drive around with traction control off. Strangely, when I had it on my 400 lb heavier e93 i was faster than with it on my sedan partly because the extra weight helped with wheel spin, even with all seasons on the e93 versus summer conti ecs on the e90.

[rotomoto712]

Since I have an E93 I've noticed that I too have had very little trouble with wheelspin, and I am also running Michelin AS/3s in the stock sizes. Not that it means much as I have never seen 6.5 psi lol. Interesting point about the traction control as well, though I typically never just slam on the gas pedal, but progressively feed in the throttle. Even with the malfunctioning bypass valve, I have observed that it shoots up to around 4.5 psi pretty quickly by around 4-5K rpms and slowly builds. The car is out of commission right now, as the rear differential just went out last week. I'm having one custom built right now by limitedslips .de, but I will try RUG8RB8's suggestion on cleaning and lubricating the bypass valve while I wait for the new diff, as it looks like it's going to be a while before I get the replacement bypass valve.

[RorosM3]

Originally Posted by BPMSport

We've got two kits left for anyone that is interested. Thanks for the feedback everyone. The Harrop is definitely second to none!

Are these kits still available? New account so I’m not able to PM, Thanks

[rotomoto712]

Originally Posted by DrFerry

rotomoto712 In my experience, when going wide open throttle (W.O.T) 6.5psi of boost is delivered at least by 3500 RPM - when the bypass valve has been fully closed by the bypass actuator.

Wow! That would make a massive difference in performance compared to what I've been seeing. What elevation are you at?

[rotomoto712]

I bought the kit new last year.

[M.Hagen]

Originally Posted by rotomoto712

Not to thread hi-jack, but out of curiosity, what are some of the Harrop owners at higher altitudes seeing for boost? I've been working with the Harrop guys and BPM on trying to troubleshoot some boost issues i've been having (maxing out at 5.2), and I am curious to what extent altitude affects boost on these. I'm currently at 293M ~960 Ft, but there are many elevation changes where I am, though I don't think any are higher than 2000 ft.

I was seeing between 3.0 and 3.4 PSI at my altitude (nominal 4,300ft).

TVS Superchargers are 'positive displacement' units, which means they pump the same volume of air for every revolution of the engine crankshaft. You will see lower observed manifold pressures at altitude, as the ambient pressure is much lower.

Here is the write-up and logs from my car when it had the Harrop kit installed. I don't have the original images linked anymore, so I apologize for the dead 'Photobucket' links.

https://www.m3post.com/forums/showthread.php?t=1357187

Cheers.

[rotomoto712]

Quick update: I received the new Actuator and ECU from Harrop in the mail yesterday, and after installation, I took it out for a drive and...

...Still not seeing 6.5 psi. However, the boost response is drastically improved. Between 3-4K it quickly shoots up to 5.2 psi and just crests 6.1 psi at redline in third gear. At that same rpm range, it shoots up to 5.5 psi and gets up to about 6.2 psi at redline in fourth gear. The area where I tested is ~1000 Ft in elevation. Seat of pants I can confirm the extra power, as I broke traction in third for the first time.