Does anyone have dyno results for things like stock clutch fan versus efan ? Stock water pump versus electric water pump ? A/C on versus off ? Power steering versus manual ? And any other peripheral parasitic things I have missed ?

 

Hey David. It would interesting to see. However i'm not sure if any of these add versus more of freeing up available Hp. Of course you could be asking how much
Hp drain do these cause. rx7doctor

 

It's an act of faith to say there is a power difference. The problem is the difference which you can theoritically measure is only in the 2-5hp range. Dyno readings are so variable that these differences are within normal statistical error so could possibly show up as a loss rather than a gain.

It really comes down to a decision as to whether the hp increase is worth the cost. For example if you go efan and have 2 more rwhp was the cost worth it.

 

yesturday I was at a red light and some guy pulled next to me in a cavalier. It has crome rims and a really loud system as well as a loud exhaust. He teased; at a light that I have been known to count with my eye closed; I stomped on the gas dumbed the clutch and sped out like a wildman. I left him in the dust. As I took off I felt a serge of power and all the ideot lights came on. It seems that the belt for the water pump and alternator snaped. My eninge was idleing at 1000. I quick went home and shut the car off before it over heated.

I learned 2 things.
1 there is some power to be gained by adding a electric water pump.
2 don't do upid street raceing when your buget is close to none.

 

Electric water pump? These exist?

I make sure my belts are fresh and adjusted, so I should be ok there.

As for whether there is a performance gain, I think it's minimal. The main advantages of things like the e-fan is not the huge hp gain, but rather how it cleans up the engine bay and upgrades an old technology (like the clutching system, which in many of our cars has just locked in the "engaged" position after all these years).

Though I kinda like the idea of the electric water pump... it would be cool to have only ONE belt, for the alt. People would look at it like "WTF? only one belt?"

But I'm not ready to trust my engine's cooling to an electrical water pump. Don't ask me why I'm more comfortable with an e-fan but not an e-pump, I'm just weird that way.

Jon

 

electric water pumps will go out after so many hours of use.

 

Everything will go out after so many hours use. We will die after so many hours use. I know what you mean, though

Actually, there are electric water pumps that are efficient, look good, and will stay with you for a good while ( like a good fuel pump ). I like the billet pumps that pump in the 40+ GPH range. See Summit racing Meziere 100 Series Electric Water Pumps 43 GPM, Billet Aluminum, Black Anodized, LT1, LT4, Buick/ Chevy/ Pontiac, 199.00 Each

 

doesn't matter. Never saw one for a '84 13B rotary yet so I don't have to make that choice. Definitely going e-fan soon though. I removed my A/C and air pump and when the difference is minimal, there's less to wind up on acceleration, less weight, and less to maintain.

 

You will never find one specifically for an RX-7, but if you have a place for it and 12 volts to it and the gpm's are up to snuff, then you can plumb it inline and use it.

 

The motor will wind up faster, most notably in 1st and 2nd gear.

 

but the more electrical stuff you have the harder the alternator is going to have to work.....is it worth it? do it and find out. i did an efan conversion and noticed no power gain. the only thing i did notice is it winds up faster

 

I'll take winding up faster !

 

Winding up faster = power gain.

The advantage to the efan is that it is not on all the time. While the fan is on, there may be no difference between efan and no efan, but when you shut it off, the load on the alt goes away, and more ponies are available to turn your wheels.

 

yeah but the power you get is miniscule. converting to a cone filter i noticed a lot more power gain, and what is that probably +5hp.....if that. and with the increased electrical load i was refering more towards an electrical water pump

 

Turning the mechanical fan and efan at a constant rate take about the same amount of power, I will not argue with that. The advantage of the efan is that the engine can accelerate independent of the fan speed, therefor the inertia of the fan does not hold back the engine from accelerating, because the fan itself is not accelerating. That is why you gain power when doing the conversion, because you no longer have to accelrate it.

-Marques

 

but don't 7's have a clutch fan and stop spinning faster at a certain rpm?

 

ya and it engages when it's feeling hot and locks on hench the clutch till it cools to a certain temp. so if you lauch when your fan is going its gonna go whirrrrrrr faster like an isuzu till it cools down. but it's all that inertia of the big fan that your having to turn while you accelerate vs a one speed electric fan. so thats the power savings

 

I used to have some engine dyno sheets that showed the difference on an engine dyno (its a lot more accurate than a chassis dyno, as differences of as little as a 1/5 hpo are easily noticeable. i couldn't find them for this posting but will continue to look, but for the time being consider this:


average tuners now days ignore the little things, remember the little things add up, The Efan by itself is only XX, but the efan with xxx + other mods = ZZZ and etc.

How many of you know how to index a spark plug? While it doens't apply itself to rotaries very well with 2, 3, and 4 prong plugs , for a piston engine people use to index the plugs, by marking them so that they knew when the open face was facing the combustion chamber, why? because it propogated a better flame front. While it might only add on 1 HP for that piston, add 7 more for a v-8 and damn that little bit became 8 hp. put an underdrive pulley on the water pump, and alternator and theres another 2~5 hp take the fan off and theres another 2~3 hpfine tune your carb, or your timing, theres another 3 or 4 hp, eventually all of those little things make 15~20 hp and thats a noticeable difference . Its the same for any engine, its those little things that give you a winning edge.

how many of you thought to run a lower profile tire? not cause it looks cool, but because it changes the final drive ratio on your drivline? simply going down one aspect ratio on a tire can shave a tenth of a second. Once again we are talking when it all adds up.

now days people are so used to slapping a computer chip in, or a bigger turbine or what not that they forget the little things that could make it even faster.

so even though I don't have a copy of my old engine dyno sheets that show the differences, I know they are there, and regardless of what some people think, I will continue to add those ponies up, 1 pony at a time.

I think what we need to look at is the culmulitive (sp) hp that you end up with from all of the little things.

 

mezzire does make a water pump specifically for 13b rx7's.

look your summit mags some more in the import section. they have had one for years and years and years.

 

And with efan motor will warm up faster because it has a thermostat and is OFF. Mechanical fan still turns and moves air when motor cold.

 

Also if one were to run a E-fan and E h20 pump combo it could eliminate any possible hotspots in the motor after shut off since htye can run on their own. Now i dont know how much of hot spot problems are in rotaries, but i know in some piston engines hot spots can lead to short gasket/seal life.

 

I'll post the water pump info when I get home... (I'm at work), but there is a water pump that will fit (with an adaptor)