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05-28-2026LAST POST
I have been absent for a long time, my apologies been crazy busy with work and traveling. I was looking on here to see if any new items have popped up concerning active E-85 real time adjustments based on measured (FF sensor) ethanol content. Lo and behold, on the BPM site, I see that Mike now offers a new software upgrade in conjunction with the APE flex fuel sensor, and the Harrop is an option not just the ESS and VF Engineering. I am curious if anybody has opted for this yet? If not, I have already sent out an email through my friend Brandon at Performance Technique. If this is a real option now, I will order and keep everyone posted about results.

https://www.bpmsport.com/ape-e85-flexfuel-m3.html

https://www.bpmsport.com/cars/bmw/m3/e9x-m3-s65/sc-revision.html


Heat soak, I think we must get the type of sensor and location replaced. Seriously, think that is a must. However, I daily drive my M3 still, quite heavy actually, have nearly 60K on the car post S/C. Yes, Mark I am past due on S/C oil change and still cant find good instructions on how it can be accomplished safely in the car. That being said the car runs flawlessly both in heavy CA traffic and on open road mountain twisties. It has literally, Never had a hiccup.
I do not mean to derail the thread in any manner. I did want to build on the previous post and say that is BPM is working in conjunction with APE to provide true flex fuel capabilities for this platform, then I think many supercharged M3 owners (whether it be harrop, ESS, AA etc.) will want to utilize this.

I know in the northeast it is hard for me to obtain E85 consistently, and then it has to be drained and replaced with 93 octane once the weather gets cold and the ethanol content drops for the winter blend.
Considering the Harrop kit... Was also about to pull the trigger on the Infinity Auto Design Intake System. Will the intake port of the Supercharger 'Plenum' match with the intake? At first it looks like it might but I don't think it will.

Does any intake system (Dinan, AFE, MS, Eventuri, etc....) match up to the Harrop Plenum Inlet?

Thank you!
I cannot say for the other options that you mentioned, but I was able to make the Technocraft intake system fit quite well. I was not able to get the elbow to fit, however, but I’m quite happy with the end result.
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Has anyone ever looked into porting? Corvette guys get over 50whp from it.
We’ve finally got kit allocations! - It’s been a long time since kits have been available. Will be posting more info in the next couple days. Stay tuned!
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Mike, thanks for update! Are there more updates?
Question I have had in the back of my mind for a little while. The installation process of the harrop requires you to remove one of the engine support hooks.

If you had to do some work that required using an engine brace to support the engine because you needed to drop the subframe, like rod bearings, oil pan replacement, or engine mount replacement, is there anyway to support the engine without removing the supercharger and temporarily reinstalling the hook?
Iyzmi wrote
If I'm giving it half to three quarter throttle consistently from low RPM to high RPM without shifting it will sometimes "hesitate" until about 4k. It's hard to describe, but you can feel a noticeable step in power delivery. I thought it was transitioning VANOS profiles in a non-linear way but Mike's fueling explanation also makes sense. It's not a consistent issue and only occurs under partial throttle.
Did you find a fix for this. I'm having the exact same issue on a new install
DBE wrote
Did you find a fix for this. I'm having the exact same issue on a new install
I went from an ESS tune with included injectors to a BPM tune with green giant injectors and that cleared it up.
Iyzmi wrote
I went from an ESS tune with included injectors to a BPM tune with green giant injectors and that cleared it up.
Im confused. You were running ESS tune with the harrop kit?
My problem is Harrop kit with the included BPM tune. I might reach out to Mike directly for help
DBE wrote
Im confused. You were running ESS tune with the harrop kit?
My problem is Harrop kit with the included BPM tune. I might reach out to Mike directly for help
No, I was running an ESS kit with ESS tune, but having the symptoms reported by Harrop users.
Iyzmi wrote
No, I was running an ESS kit with ESS tune, but having the symptoms reported by Harrop users.
Ok thanks for clarifying
DBE wrote
Did you find a fix for this. I'm having the exact same issue on a new install
My car was doing something similar and when it would act like that I could see the air fuel ratio go insanely rich on my P3 gauge and the car would bog a little. Donut gaskets between the header and the xpipe were leaking causing the oxygen sensor readings to be thrown off. New OE gaskets never had the issue again.
I know we've discussed interchillers a few times on here, and personally I dont understand how it could work without impacting cabin a/c performance.

Was at cars and coffee yesterday, and there was someone there with a heavily built chevy SS. Twin turbo, fully built engine. Has a water to air intercooler system like the harrop kit and other supercharger kits.

He had an interchiller setup (he personally installed it as well as built the entire car) and he absolutely swears by it. Said absolutely no impact on cabin a/c performance, and said his IAT is are so cold sometimes that it messes with his tuning.

Someone needs to give this a try and up my confidence in running this with the harrop. Tempting.
drwankel wrote
I know we've discussed interchillers a few times on here, and personally I dont understand how it could work without impacting cabin a/c performance.

Was at cars and coffee yesterday, and there was someone there with a heavily built chevy SS. Twin turbo, fully built engine. Has a water to air intercooler system like the harrop kit and other supercharger kits.

He had an interchiller setup (he personally installed it as well as built the entire car) and he absolutely swears by it. Said absolutely no impact on cabin a/c performance, and said his IAT is are so cold sometimes that it messes with his tuning.

Someone needs to give this a try and up my confidence in running this with the harrop. Tempting.
It’s not a particularly difficult install, go for it!
I'll do it when I have time. I built a garage with a lift but I have so many jobs going on I barely drive any of my cars. Stage 2, interchiller and 3.62 have been on my list of things to do asap
I’m also working on an interchiller but not one that is purchased from a vendor. I’m using parts from an EV. I’m pretty sure I have everything I need for install besides that I’ll have to fab/make a bracket to hold the “chiller”. Going for a pretty simple and clean install that doesn’t look like a rats nest of hoses and plumbing all over the place. Just need to find a Saturday where I can get away from the family and spend the day at the shop installing it. It’ll be a win for me if I can bring IAT back to ambient or obviously lower as it’s hot here in Houston.
Dealing with some strange stuff. In the lower gears it only seems to hit 3 psi but in the higher gears from 100-170 it's around 6psi. Boost is building like a centrifugal at times as well. Has anyone dealt with this?
DrFerry wrote
The bypass valve actuator controller (computer box) maybe malfunctioning. If a transistor on its printed circuit board is going out, funky things can happen with the actuator bypass valve. Very early on in my Harrop ownership experience, something similar happened with mine and Mike B' sent me a new actuator controller box. And that fixed it.
What's weird is it seems to fully open and close with ignition on. Did yours do the same?
I did the recalibration a few times already and no luck. Thanks a lot for the insight!!
BP709 wrote
I’m also working on an interchiller but not one that is purchased from a vendor. I’m using parts from an EV. I’m pretty sure I have everything I need for install besides that I’ll have to fab/make a bracket to hold the “chiller”. Going for a pretty simple and clean install that doesn’t look like a rats nest of hoses and plumbing all over the place. Just need to find a Saturday where I can get away from the family and spend the day at the shop installing it. It’ll be a win for me if I can bring IAT back to ambient or obviously lower as it’s hot here in Houston.
We're you able to install it yet? I'm quite curious since I live in Houston too. I would head this route to if it works for you.