The GReddy intercooler has definitely thrown off the balance of the car. It is fairly heavy & is mounted ahead of the front axle, so the weight distribution isn't 50/50 anymore.

Has anyone else noticed the car being a bit less stable & the front end more 'bouncy' when cornering at speed?

 

Put a subwoofer in your car! :p

 

Put a bag of sand in the trunk? Maybe some new springs or a set of coilovers are due for your car?

 

Front suspension not hard enough and damped to compensate for extra weight, a little off balance in weight distribution can be cured by slight change in driving style.

 

Just get the spare tire kit...at least that will be more useful than a bag of sand?

 

are you serious?

 

I think he is serious. Poster child for the anti-butt-dyno society.
Or, in this case, the anti-butt-lateal-accelerometer society.

The intercooler is NOT affecting your handlng. Not in any way you will notice, anyway.
A full, 90 lb. tank of gas will do more to your yaw moment than a 15 lb. intercooler, regardless of position.

 

Technically, the forces I am referring to are heave and yaw.

I think the intercooler weighs a good bit more than 15#, unless they added lead to the box. The gas tank is between the axles, whereas the intercooler is hanging out over the front axle, this also makes a difference. You must also concede that 'regardless of position' is specious, as having mass right on the axis of rotation would make it neutral.

If you plug & chug the equations, you'll see there's mathematical justification for my observation. So, yes, it is provable that there is an effect, and a noticeable one at that.

If you want to go crazy with the math, here's a link:

http://med.ee.nd.edu/MED7/med99/papers/MED188.pdf

Bon appetit!

 

Does anyone know the weight of this intercooler? I can't imagine that it is too heavy. I don't have this setup so I cannot really tell you if it actually does throw off the balance of the car, but it seems that it really shouldn't. On that logic, by putting luggage in the trunk, shouldn't you be creating the same effect? Obviously the weight is in a different part of the car, but it is on one extreme of the car as is the intercooler. I'm not too keen on the mathematics of this, but I'm sure there is a very complex way to figure this out, as well as a simple way to show the basics of what is going on. What if all of your fluids were low? Wouldn't that then also have some sort of similar effect, but help your handling? I'm talking out of my *** now, good night

 

Of course there is a calculatable effect, but I really doubt that you can perceive it. The intercooler probably weighs less than 20#. If you simplify the problem by treating the car as 3000# uniform bar, then the addition of a 20# intercooler a distance L/2 from the CG would add 2% to the rotational moment of inertia. If you went further and actually found the true moment of inertia taking into account that the mass is concentrated near the wheels, then it would add even less effect to the total moment.

You ain't feelin' it.

 

Just relocate your battery to the trunk or to the wiindshield wiper fluid holding tank.

 

I'll weigh it when I get home. I can't imagine it being that heavy, or really effecting the suspension. Seriously though, most of the people on here that have upgraded to the turbo, have taken care of other things first, like suspension, and transmision. So if you're all stock except for the turbo, maybe its time to upgrade to a decent suspension set up. But I really can't imagine a 15lb intercooler effecting your handling to that great an extent, over the front axle or not.

 

I'm putting on the turbo now, and my suspension consits of tein s techs, so I'll let yall know.

 

absolutely no effect on handling

of course I had tein coilovers and the RB sways - car handles like a dream.

 

Thank you for the good feedback.

I have the Mazdaspeed sway bars, but to cure the bouncy-bouncy problem, it sounds like I'll need to firm up the suspension.

I'm a bit leery of coilovers...don't they harsh the ride quality quite a bit?

 

If you get a good pair, you could mess around with the dampening. But if you are trying to get your car to handle better, you are probably going to have to get used to a harsh ride. Its a fair tradeoff.

 

^ Sapphonica, if it makes you feel better, there's a group buy potential on Hawker Odyssey PC680 mini-batteries. Lots of RX-7s run with those. They are lightweight and can be mounted before the front wheel line as oppose to the stock battery that is twice as heavy and mounted in front.

We're looking at about $125 shipped for PC680 w/ Metal Jacket & SAE Terminal and aluminum battery box.

 

Mathematically calculations will show a number - a number that is practically meaningless to actual performance.
As noted, a 90 lb mass between the rear wheels will have a greater lever arm than a 15 lb mass between the front wheels. Just look at the distance to the CG for these two and it will be obvious.
Add to that the fact that the fuel is a dynamic load (as opposed to the relatively static mass of the intercooler) and you will see that you are splitting hairs.

"Provable", yes. Noticeable, no.

 

You got a turbo and don't want to buy coilovers? Cmooon~ It'll make your RX-8 soooo much better with a nice set of coil overs. Sure it'll mess with your ride quality, but then there are controllers out there such as the TEIN EDFC and the Apex EDC.

 

I have AutoEXE springs in my car and they actually improved the ride quality. Very comfortable, especially for so much drop.

 

I do have to comment that every single RX-7 has had the gas tank behind the rear axle line and no one complains about weight shift differences. Alot of RX-7's are running around with large front mount intercoolers and no one complains about weight shift. Yes technically there would be an effect from adding weight here. The key though is how much and can you feel it? There are a few options in this case. 1 is to remove the intercooler and run with less power but better weight distribution. Of course there is a heavy turbo weighing down the right side of the engine although mounted much closer to the vehicle centerline and low in the chassis probably makes it's effect minimal. The 2nd is to do some suspension work to attempt to re-setup the car to a fairly neutral behavior although even with the intercooler it is probably still better than nearly every other car on the road. The 3rd option is to do a custom mount intercooler somewhere else inside the engine bay. On top of the engine is one option but then you shift more weight vertically. The last option is to just enjoy the added power and let your right foot steer the car through the corners! That's when it gets really fun!

 

Maybe you forgot to re-tighten your engine mount when you installed the damn thing. That would lead to a little "bouncy bouncy" during hard cornering!

 

Lets see if 1 gallon of gasoline equals 5.8 to 6.5 lbs. And our cars have a 15.9-gallon tank. So that’s 92.22- 103.35 lbs added to your car when you’re driving with a full tank. And then also If you're like the average male and you weigh about 180 lbs, that means that your car has about 283 lbs more to the back right side of your car, and that doesn’t affect you that much, so I don’t think a 15 lb intercooler will do that much.

 

Ok, just got done weighing the friggin intercooler, and it came in at a wopping 10.5lbs. The change in handling is in your mind.