RyanFox

I tried searching the forums for some answers, admittedly not as proficiently as I could have. There are a few things about my Rx7 that I'm not sure about and I'm too lazy and dumb to use search bars. (I did try for a bit but came up short on answers for some questions)


For one, my 5th gear makes this whining sound when I step on the throttle. Its only in 5th gear and the guy I bought the car from said this was a normal thing with the car.

Manual says to use 10w40 guy I bought it from suggests 20w50. opinions?

From what I've heard, K&B filter in the stock cold air compartment is better than just putting a cone on. thoughts?

Best options for exhaust?

Tips for maintaining the car?

EDIT: OH and this damn alternator, how do I go about upgrading this thing?

Thanks guys!!

Sgtblue

iTrader: (16)

Tips?
*State the year and sub-model (i.e. TII etc.) in your posts or signature while in this section.
*Don't be lazy. I wasn't when I went bothered to search your profile to find out you have a 87, or S4.
*Yes, IMO a good flowing filter in the stock air-box sourcing ambient air is usually better than a cone filter sucking in hot under hood air. Admittedly not racing looking, but effective. Rather than a K & N which uses an oiled cotton media that might dirty up your MAS, you might want to search for what others recommend. I'm a FD guy and we have a MAP system which is unaffected.
*Not sure about the whining sound in 5th, but it wouldn't hurt to change out the gear oil since the car is new to you. I recommend a good synthetic 75w90. While your at it, change out ALL the fluids, including and maybe especially coolant. Downloadable copies of the Factory Service Manual are available to help.
*Exhaust is often a trade-off between emissions, noise and performance. But I suspect a header on a NA car is probably the biggest bang for your buck in that area regardless of the cat-back.
*As to oil viscosity, I doubt it makes any difference. And when in doubt, stick with what your manual says. Know that with a rotary, I would make oil change intervals a little closer than what your used to in a piston engine. And when check the oil level, also check it for fuel dilution over time.

RyanFox

Thanks for taking the time to help me out, I'll definitely remember to include the sub-model next time. The previous owner just had all the fluids changed out so I'm not in a hurry to do that again, although he did not mention the gear oil so I will definitely get that done. I've heard the racing beat exhaust system is a good one for this car, full set up is $1200 though which isn't cheap.

Evil Aviator

As stated above, synthetic gear oil typically fixes whining noises, but if it doesn't then there are more serious problems that need to be fixed by a professional ASAP, otherwise the transmission my soon turn to complete junk and possibly ruin other expensive parts when it fails. I prefer Red Line MT-90 synthetic oil (available online at Jeg's, Racer Parts Wholesale, Summit Racing, etc.), but other common brands include Royal Purple, Idemitsu, Neo, and Amsoil. Personally, I'm not a fan of Mobil 1 because they are shady about the content of their supposed "synthetic" oil, and it has been known to eat RX-7 transmission synchros.

Use the manual to select the correct oil grade for the weather in your region. Back in the late 70s and early 80s, multi-viscosity oils with a very wide range (10W-40, 10W-50, etc.) were not very stable, so sports car owners tended to avoid them. Modern multi-viscosity oil is much more stable now, so there is no reason to avoid them. Most RX-7 owners have found good results with Castrol GTX (non-synthetic) oil.

Yes, a standard drop-in filter works just fine up to about 200hp. Contrary to internet propaganda from K&N's competitors, a properly-oiled K&N filter will NOT adversely affect any of your car's components.

Racing Beat for the street, custom 321 stainless steel exhaust system for the track. Headers help the most, but they are not legal in all US states. Also, if the cat is original, then it is probably clogged up, so changing to a new cat sometimes helps a lot. A "catback" exhaust system will only yield marginal gains, so it isn't really worth bothering with it unless your current system needs to be replaced.

- Follow the maintenance schedule at the front of the factory service manual. If you like to drive aggressively, then follow the "Unique Driving Conditions" schedule.
- The secondary injectors kick in around 3,800 rpm. If you drive like a grandma and never get past 3,800 rpm then the secondary injectors will clog up, then that one time you need to step on the gas pedal to pass a car the engine will blow due to an extreme lean condition. No, I am not kidding. Therefore, be sure to accelerate the engine up in the rpms on a regular basis. Note that this does not mean to redline the engine on a regular basis, which is a common misconception.
- Mix the coolant with distilled water, not tap water. You can buy distilled water from most drug stores for a little over $1 per gallon.
- Whenever I buy a used RX-7, one of the first things I do is replace the two O-rings under the oil filter pedestal. This is because they crack over time, causing oil to drip on the heater hose which will eventually develop an intermittent pinhole leak that will drive you nuts.
- Check all of the rubber fuel lines, as most of them are cracked and scary at this age.
- If the stereo surround is cracked, consider replacing it with a Series 5 surround that is more rubbery and less prone to cracking. Note that this also requires changing the associated heater vents to Series 5.
- Pulsation Damper