RX8 Renesis Rotary eSC

I'm looking at doing something like this into my mx5 nd that i engine swapped in a 3.6l LFX, Trying to get my head around all the calculation etc lol
 
Update : Fitted water/meth kit . Just a single nozzle to the volute. Has dropped IATs by at least 20C and improved midrange but no difference in peak power. I suspect boost is actually dropping even more than before ( IE cooler air but same power at lower boost ) due to batteries unable to keep up. It has been suggested to me that a capacitor would fix this. I have no idea ...but imagine I'd need a HUGE capacitor to affect the top end and keep the voltage up as the engine gulps in all that cool air.
 
brettus8 said:
Update : Fitted water/meth kit . Just a single nozzle to the volute. Has dropped IATs by at least 20C and improved midrange but no difference in peak power. I suspect boost is actually dropping even more than before ( IE cooler air but same power at lower boost ) due to batteries unable to keep up. It has been suggested to me that a capacitor would fix this. I have no idea ...but imagine I'd need a HUGE capacitor to affect the top end and keep the voltage up as the engine gulps in all that cool air.
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Water/meth injection moves power making potential up quite a bit. It cleans the combustion chambers, smooths the combustion process and raises the octane level but it will not provide more power beyond the ~1% gain for every 10 deg drop in intake temps. You must increase ignition timing to take advantage of water/meth injection with all else the same if there's still room to do that.
 
I guess I was hoping for some extra after seeing what happened with Alex's meth injection setup. Would have thought it was more than 1% for 10C?
 
brettus8 said:
I guess I was hoping for some extra after seeing what happened with Alex's meth injection setup. Would have thought it was more than 1% for 10C?
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That spec is in Fahrenheit and yes that's about it. That temp drop only condenses the air charge slightly and a number of dyno tests have been conducted to validate that water/meth injection alone doesn't add more power in the absence of increasing the ignition advance to take advantage of the increased knock resistance. Pure methanol injection will chill things down a bit more but ultimately the temp drop has to be significant for gains to be significant. This is why the greatest benefit to water/meth injection is with boost where several degrees of heat are removed but most importantly boost can be turned up substantially.
 
Did some messing with Matchbot and came up with 6% for the 20C drop in temps I'm seeing which is equivalent to around 15whp. I think the logs would show something if I was getting that much but I still think there are other factors in play as mentioned above.
 
Update , a month or so back I decided to make a small change to the wiring. Wanted to have the charging wire such that it could be isolated with flick of a switch instead of constantly connected to the batteries. In the process of making this change I managed to short the batteries to ground for an instant. I initially I saw no damage done in the battery box so reassembled it all. It was only when I set the charger to 'charge' that I found I'd blown the charger. :mad:
Faced with having to buy another $400 charger I had a rethink. Spend $400 and live with a system that works but with high maintenance/high risk batteries that aren't quite doing the business up top. Or ..........start again with new batteries/charging system etc.
I chose the latter
So I've purchased a new charger, BMS, and batteries and will now mount the batteries/charger in the boot.
Went for 20x 2.3v prismatic 20Ah LTOs which are 0.52Kg each. Should end up with less than an extra 15kg in the boot which I don't think will upset the balance of the car by much.
Also purchased a 150,000 microfarad capacitor to mount up front with the ESC
Have everything except the batteries at this point.
 
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brettus8 said:
Update , a month or so back I decided to make a small change to the wiring. Wanted to have the charging wire such that it could be isolated with flick of a switch instead of constantly connected to the batteries. In the process of making this change I managed to short the batteries to ground for an instant. I initially I saw no damage done in the battery box so reassembled it all. It was only when I set the charger to 'charge' that I found I'd blown the charger. :mad:
Faced with having to buy another $400 charger I had a rethink. Spend $400 and live with a system that works but with high maintenance/high risk batteries that aren't quite doing the business up top. Or ..........start again with new batteries/charging system etc.
I chose the latter
So I've purchased a new charger, BMS, and batteries and will now mount the batteries/charger in the boot.
Went for 20x 2.3v prismatic 20Ah LTOs which are 0.52Kg each. Should end up with less than an extra 15kg in the boot which I don't think will upset the balance of the car by much.
Also purchased a 200,000 microfarad capacitor to mount up front with the ESC
Have everything except the batteries at this point.
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The weight gain is minor when considering the weight burden of a traditional turbo outfit. Every time you carry a passenger you'll be adding far greater weight than the batteries add. 100 lbs of batteries are acceptable as far as I'm concerned relative to the efficiency of the system, especially if they carry the car for an entire day or two before a recharge is needed.
 
brettus8 said:
So I've purchased a new charger, BMS, and batteries and will now mount the batteries/charger in the boot.
Went for 20x 2.3v prismatic 20Ah LTOs which are 0.52Kg each. Should end up with less than an extra 15kg in the boot which I don't think will upset the balance of the car by much.
Also purchased a 200,000 microfarad capacitor to mount up front with the ESC
Have everything except the batteries at this point.
Click to expand...
What BMS are you using? And the capacitor up front seems like a good idea. I am planning a second alternator just to charge the batteries. I am replacing the power steering pump with an electric one from a volvo and will mount the second alternator in the original ones place.
 
r.brown.bayliss said:
What BMS are you using? And the capacitor up front seems like a good idea. I am planning a second alternator just to charge the batteries.
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Just one I found on Aliexpress for LTOs 'ANT smart BMS' rated for 220A (550A peak) . I have no idea about these .... but am hoping it wont be too much of a mission to hook up - doesn't look too hard. I found my stock 100A alternator could easily manage the 35A charger I had previously. The new charger can do 35A or 70A .... If I need to go to 70A I will probably just get a high output alternator.
 
brettus8 said:
Did some messing with Matchbot and came up with 6% for the 20C drop in temps I'm seeing which is equivalent to around 15whp. I think the logs would show something if I was getting that much but I still think there are other factors in play as mentioned above.
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In one of my Turbocharging books (Maximum Boost probably) or some other literature I read over the years, for every 10 deg drop in motor inlet air temp you can expect a 1% bump in power. As it relates to rpm, for every gram of weight reduction in the valve train or rotating assembly that is actually contributory to the stress loads, you can gain about 30-40 rpm more above your redline. So lighter valves, retainer components, rocker ends, connecting rods, pistons, etc... can help raise the revs, don't forget flywheels and balancers, even if the rev limit remains the same, the time needed to reach it is reduced.
 
Upgraded batteries/BMS/Charger installed and operational. Over the moon with how well it all works. Some numbers from the BMS show 10kw at high rpm which lines up pretty well with what I was expecting.

full load on bms.jpg
 
With some help from an EE I managed to sort out the issues with the capacitor. Saw definite improvements but overall it's only marginally quicker than it was with the Lipos . But sooooo much more practical now with the LTOs vs the Lipos.!
 
brettus8 said:
With some help from an EE I managed to sort out the issues with the capacitor. Saw definite improvements but overall it's only marginally quicker than it was with the Lipos . But sooooo much more practical now with the LTOs vs the Lipos.!
Click to expand...
What was the issue, were the caps drawing too much current when charging?

My project has hit pause, I decided I needed to buy a "sensible daily driver", then I decided it needed new wheels (these are the old factory wheels), then I decided to flush the fluids and replace them and the filters, and this week it's getting lowering springs... So the Nissan is on hold for a bit 🤣

1747346005169.png
 
1000hp is tough to be up against. Roll racing at Mere Mere is a new concept for me. My main goal here is to get my 1850kg Nissan Fuga (Infiniti M45 for the Americans) down the track in under 12.63 seconds, that being the time my son set on his motorbike. No boost it does 13.9-14.1ish last time I went to Mere Mere

I have the Maserati all lowered and except for a minor cosmetic mod I am done messing about with that so back onto the main project car and the electric supercharger
 
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