Old & New

Mark, I've seen a couple new water pumps on eBay lately. Search for "928 laso".

mark kibort

Since the axial compressor has a pretty distinct pressure curve vs air flow.(very similar to a torque HP curve.) the net gains are pretty close to the same from small engines up to 3.2 liter engines. when you get to 4.7 liter, and as long as the HP is still under 240 at the rears, the gains are still in the 5-6% range. Not coincidentially, we measure a 1psi net change in the intake. (.5" Hg relieved in the air box, and 1/2psi pressure added, for a net of 1psi)

cool thing about the eRAM testing, is that you can turn it off or even pull it off of an intake during a dyno run and watch the curve drop 3-6%.

Scots car was a great candidate at the 215hp rear wheel range. but, we were running out of fuel and spark (battery was going real dead) but, during the max torque area, it gained the 10ftlbs of torque.
We also did the dyno runs at Devek with all to see. my 84 at the time was about 232 at the wheels, and with the eRAM on gained about 8hp.

Mk

m21sniper

Was that with a double e-ram unit, or a single?

I've emailed the company a couple times and had some discussions with them.

As i've always said since i first heard of it, the theory is completely sound.

If i was gonna use E-ram i'd want four of them, two for each inlet(2psi of boost correct?). I guess my battery would be dead in 10 seconds though, lol.

m21sniper

Thanx for the link sharkskin.

mark kibort

It was with two in parallel. (so that drives the cost up on our cars!)
on the 911 3.2 liter , it was just one unit, but it had 200rear wheel hp before and 210hp after.

they did some vets with 4 eRAMs (two in series, one on each side of a dual throttle body set up) dont know it would be a full 2psi, but probably in the 1.3-1.5 psi net range. parallel doesnt increase pressure, but it does double flow. because our engines require a specific mass flow at certain rpms, the pressure goes up vs 1 due to you being at a different point on the presssure curve due to double the flow. axial flow compressors are great at making flow, but bad at making pressure. but if you do it right, it can do the task. in the old airliners, they used to use a axial flow compressor, dual rotors, to compress the cabin air. so, the concept is sound, its just not a match for the "real" turbos or superchargers. Just a good bolt on device for a reasonable cost.
think of it like having 200mph ram effect, at the stoplight.

MK

m21sniper

If you're doubling flow volume into an enclosed space doesn't it follow that you're also in effect roughly doubling pressure?

How much is one of the eram doubles going for nowadays?
What results did they get from the quad eram vette setups?

Thanx.

mark kibort

Not really, and this is because "flow" (ie CFM) is measured with no resistance, and then resistance to gerate a pressure curve. at no flow, or little flow, just before stall, max pressure is achieved, and its the same for one fan in parallel as it is for 2. however, in series. back to back, the fans pressure is close to doubled. one thing that parallel flow fans do as well, is that because the flow is doubled to the fixed volume flow (the engine requirements) the point on the pressure curve is slightly different and higer based on the pressure of 500cfm required vs 1000cfm or 2000cfm produced in free air. at 500cfm required, the pressure at generated by a 1000cfm free air blower is X. at 2000cfm the pressure is slightly more, but not double.

if you draw a graph of 0 flow, 1psi for a data point and 1000cfm vs 0psi as another data point and draw a line, you can see if we keep the 1psi constant, at 0flow, and just draw the line to 2000cfm and 0 pressure, you see the gains in pressure is not as great as in series.. this means if one fan can meet the air flow needs, 4 fans all in series may produce the most gains. But yes, thats close to 200amps.

mk

m21sniper

"But yes, thats close to 200amps."

Too bad no one makes a high output alternator for 928s, sounds like you could get some pretty serious power gains from using four of them, though by that point you're spending pretty serious money.

Say la vie.

mark kibort

Its not as bad as it first seems. i ran a 100 amp system on my first 5 liter part euro racer, even did a couple of speed gt races in it in 2001. used the little 13lb oddessy battery too!! its only used for the wide open throttle periods, and on the off throttle its charging at the max capacity of the alternator. (in our case 80-90 amps i would imagine) it lasted an entire race season with no problems. im sure for drag racings its not an issue. Heck, the starter runs 300 to 400amps sometimes, and only for 5-10 seconds on a cold day
Mk

m21sniper

IIRC our 928 alternators are rated at 95 amps.

I use a little drycell battery too, mine is 14lbs IIRC. Waaaaaay lighter than the 42lb factory anchor.

Did you ever see the dyno results from the quad unit vette runs?

Were they seeing gains roughly double vs a twin eram setup?

I like the concept of these things, and think that they show a lot of potential in the future as rpm potential is increased via revised designs.

If they can ever get that thing to 50,000rpm for a comparable draw, they'll REALLY have something.

mark kibort

then we will have perpetual motion devices too!! ha ha. actually, the compressors follow many of the same rules at turbos and belt driven superchargers. its all about efficiency. 50,000rpm would be the power ^2. (squared) 800watts now, vs 64,000watts!!!!(or about 8hp) generally, its about 1hp per 1psi at 400cfm or so. (ball park power required) even at 100% efficiency of the electric motor, and fan, that day will never happen. However, there are versions coming now with better pressure vs flow charateristics. (more of a turbine like impeller) i think the key thing is to get the motors to handle the increased current, without burning out and keeping the size small.

with the right design, 400amps may drive a true 3-4 psi compressor for intermittant use. actually as you get higher in the pressure range, the centrifugal superchargers with motors are better, but they cost much much more, and require separate batteries. the eRAM is and probably always will be a modest bolt on device for that $300 price tag. (compared to intake mods, cams, chips, etc)

never saw that vets dyno run, although the guys said they were happy. it was on some open road speed competitor vet.
the eRAM also has found its way to nascar for downforce aids on the craftsman truck series., and for disposible qualifying brake cooling on some nascar teams.

mk

SharkSkin

Interesting... so by it's nature(volume bias rather than pressure) it's going to do about the same for any car up to a certain displacement... it will either stall to some extent or run out of breath as you range from small to large engine.... with no real difference till it runs out of breath.

mark kibort

well, since i had to change the water anyway from the radiator leak from the SCCA race puncture, i started to dig into the water pump area to see if i could spin it and feel any issues. by the time you pull covers back, you are almost apart anyway, so i just dug into it and pulled the pump that was suspect. it made a light growling noise when hand spun, but not much different than a stock pump. also, the bearing was loose a little, about twice the loosness of when i changed the timing belt last year after it missed a few teath at Speed GT Laguna qulifying. the real angry rattleing sound under higher rpms 3k , or so, made me worry , even though there was not any detectable noise without a stethascope. so, got the new pump in yesterday evening and today finished up. got it all together and then found one large washer!!!!!!! AHHHHHH, "where does this go?" i asked, knowing exactly where it goes and for a second considering not worrying about it. it was the washer that mates to the little spring on the tensioner and the little plastic insulating pad that separates the little plunger that fits into the tensioner roller arm.

Was it really needed?? who knows, but i pulled everything back off, (thankfully, i didnt mount the fans or fill the radiator at that point) , except for the console alternator /ps pump and was able to get the tensioner out without removing the harmonic balancer. put the washer back in and re-assembled everything. cost me another hour at least.

anyway, timed the engine and filled with distilled water, waterwetter and a little antifreeze. (mabe a quart or so)

drove it around today, running like it aways did, and its got a brandnew waterpump. I hate spending that much time for something that doesnt make the car go faster!! the pump had some play in the bearing, but not much. sure sounded bad in the stethascope, but it wasnt that bad, or you could have heard it.

anyway, its done now and the pump bearing feels much tighter.

Mk

dr bob

That's one of those washers you really don't want to leave out. Without it, the spring will quickly eat through the plastic insulator. The reduction in length will allow the belt to loosen, but with the spring now in contact with the elctrical connector for the tension light, you'd never see the loose belt warning. Good idea putting it back in there, IMHO.

Keep up the good work!

Chuck Schreiber

Hey Mark

How bout going from Holbert Car to Holbert Kibort Car to Kibort Car??

Kind of like the John Cougar to John Cougar Melencamph to John Melencamp gig

Just a thought.