sushidog

I have dual e-rams (a 120amp electric supercharger) on my 2.4l cobalt. After dynoing the car with them on and off I found they were only adding 6hp and 4tq - well below their rated gains. After measuring the voltage across the e-rams and subsequent conversations with the e-ram people, I found that my voltage was low - only 12.65 volts while in actual use. They require 13.8volts to obtain their rated performance (a 9%hp increase). The e-ram guys informed me that as the voltage drops, their performance decreases exponentially. If the voltage drop by as little as 1v, the e-ram's speed will drop by 4000rpm!

The solution I came up with was to add a 2v, 25ah Hawker, cyclon SLA battery to boost the e-rams voltage to a little over specs. It will just be wired to the e-rams and won't affect anything else. They warned me that going much over 14.5 volts could fry the e-rams (they spin at 25,000rpm, producing 3lbs of thrust and 1.7psi at 13.8v.)

Ok, here's the problem: What's the best way to keep it charged? Could I run a charging circuit from the car's alternator with a resistor, potentiometer and diode to drop the car’s charging voltage to the 2.37v-2.47v range needed? If so, what sizes/ratings would you guys recommend? Does anyone know where I can find a 2v battery charger? I did a search on the internet, but with no luck.

The e-rams only run at WOT, so I could get about 15-20, 1/4 mile runs from this battery before it would need recharging, sort of like n2o. So I wouldn't necessarily need to charge it while driving - maybe only once a month or so.

Thanks for your help.

c0baltic

i dunno man i always though those electric turbos.. were a joke.. i dunno maybe if you show us what it looks like

-drew

BlkSS4dr

yeah I would like to see

c0baltic

there is a cool video of someone on a dyno w/ a leaf blower on the intake and it added like 45hp lol funny as hell

-drew

sushidog

Yeah, you're right. Most are ****. The e-rams barely work - 5-9% hp gain depending if you're going with 1 or 2 units like I have. The problem with any electric supercharger to work, they must draw lots of power from your battery, and most batterys are not up to the task. Here's a picture of my top e-ram. The bottom one is on the end of the Injen CAI, so you can't see it.


Thomas Knight has a several electric centrifugal superchargers and at least one roots model that make anywhere from 5-12lbs of boost, but they require multiple batteries to work. I contacted Mr. Knight and he said that his esc-400 model ($1695) will make about 70hp on my cobalt using 24volts (with appropriate fuel management, of course). My super-erams cost $600 and only make 6hp so far... so there's much cheaper ways to make hp. Once I get them up to their rated power output, I think I'll see better gains, but they are a poor value right now.

I like the concept of electric supercharging for 2 reasons:
#1 It puts zero parasitic load on your engine, unlike belt driven supercharging does. Even a turbo obstructs the exhaust somewhat, producing a negative impact on hp.

#2 It only runs at WOT (like n2o)- which is the only time you truly need it. Therefore it doesnt affect engine realiability, longevity or gas mileage when not in use (unlike both turbo's and belt driven superchargers).

Yes, there are many negatives to the concept, that's why you rarely see them. It just depends on what you are looking for - how much you value fuel mileage, engine life and engine reliability versus price and sheer performance.

c0baltic

i dont know dude. i went to the site and checked it out, for $300 thats too much.. i dont see that much gain in it.. for that same price you can get 20x more hp with a small shot of n20

-drew

EmperorJJ1

iTrader: (5)

um im not 100% sure on how that would work right... but it seems like if what you need is a seperate 12v battery all together. or maybe a capacitor... but im stumped honestly... your best bet is to jump on a car audio forum and ask about that. also a good voltmeter would be very helpful

sushidog

Yes, you are absolutely correct. I plan on adding a n2o shot soon.

The real advantage of e-rams is that they make hp at all rpm - from idle to redline (try poping nitrous at 2k rpm and watch your intake explode). Plus, they add power on top of any other mods you have, including nitrous.

As I see it, there are 2 basic problems with nitrous.

1. It costs a few bucks every time you pop it, while my e-ram costs nothing to run as much as I want for the life of the car. If you use 1 bottle/month at $35/bottle = $420/yr + the cost of the n2o system = more that the total cost of buying and using dual e-rams for many years.

2. If the cops catch you using nitrous on the street they will tow your car and the fines, points and/or community service you receive will make you wish you hadn't.

Just be very careful using it on the street. Better yet, use a supercharger or turbo on the street and save nitrous for the track.

sushidog

Heres an update.

I installed my Hawker battery today. I now have a little over 14.5v at the e-rams under load. Boy the extra voltage really makes a difference in seat of the pants torque. This voltage increase will bump the e-ram's rpm from 20,400rpm to about 27,800rpm, so I should notice a nice improvement on the dyno. I'm expecting it to more than double my previous 6whp gain.

I can't wait to get her dyno'd again to see the actual whp gain. I'll post up the results, good, bad or ugly, when I do. I'll probably wait till I get my nitrous kit first, so I can dyno tune my n2o a/f ratio at the same time.

I think I'll just take the 2v battery off to charge it every month or so, unless anyone has any suggestions? I think I'll just wire up a simple voltage splitter (using a couple resistors or a high wattage potentiometer) connected to a 2amp, 6v battery charger for now.

I looked into a dc/dc converter for charging, and I may eventually get one, but it's about $70 for a 2 amp setup, which is a little more than I wanted to spend.