How do I increase engine torque?
 

Hi,

I recently bought an 82 RX7 in near mind condition. The car has most of its original parts, and it runs great. I was wondering if you could give me some advice on how to increase engine torque.

I don't want to go overboard; however, I'd like to know what aftermarket components I could add to increase its torque.

Thanks,
Mel

Free up the exhaust with a header and a good system. That alone is going to make a huge difference as the stock exhaust is very restrictive.

You won't gain a lot by swapping carbs unless you go to something more radical and that is goin to increase top end, not low/midrange.

A properly tuned fuel injection system would be the next best thing without opening up the engine.

welcome to the board, Mel. :)

I think the first question to get out of the way would be: what do you have in mind? how much of an increase are you looking for?

I completely agree with everything Aaron said, but i hope you realize that you need to be realistic as your 12A will NEVER pull from idle or even close to it. pretty much, no matter what you do to it, it will never pull like a V8 or an Audi 2.7TT.

I'm not looking for a ridiculous increase in horsepower, just more than it has now basically. In addition to swapping out the exhaust, would installing a cold air intake work?

Yes, a "cold air" intake will usually add about 1%, which sounds like the small increase that you are looking for. See the "Mazda Comp Manual" on this website for the proper dimensions for the cold air intake:
Foxed.ca - Mazda RX-7 Manuals

You didn't state the reason that you want torque. If it is for racing, then you need to keep the engine in the higher rpm range. Peak torque is typically around 3500rpm. You should not pull a trailer with your RX-7, so I hope that is not why you are asking.

One thing that is important to understand is that the rotary engine is a "high-rpm" engine, which means that it has very little torque, so in order to make a lot of horsepower it does so due to higher rpm. Otherwise, forced induction is used to increase torque and hp. Being upset at the rotary engine's torque is like being upset that a turbocharged engine has lag or that a diesel engine only runs on diesel fuel. If you don't like it, then you should sell it and get a car that you like better as opposed to spending a lot of time and money attempting to make it into something that it isn't.

I'm definitely not looking to race. I'd just like to soup-up the car a bit. I would be fine with installing a cold air intake, header and exhaust system.

Would this 12A be able to handle these three upgrades? Thanks for everyone's suggestions so far.

If you are not racing, then a "cold air" intake is mostly a waste of time and money, although you can install one if you like. I would just install the header and exhaust. Racing Beat makes some very nice exhaust systems.

Do these cars handle intake, exhaust, and headers well? Or should I say, is the money spent on these types of mods worth the hp increase you get out of it?

I'm new to rotaries so please excuse me if this is a noob question.

It depends on the year of the RX-7. The 79-92 models benefit quite a bit from more efficient exhaust systems. The carbureted 79-85 models benefit from a proper cold air intake, but this will require a custom carb hat and huge intake tube, so it is not really that practical for a street car. A better intake solution for the 79-85 carb models is to install an aftermarket intake manifold with an aftermarket carburetor or an EFI throttle body, although this can get rather complicated and pricey. The 84-92 EFI models come from the factory with a cold air intake that is good up to about 200hp before it starts to become a noticeable restriction, and most novice attempts to improve on it end up being a "hot air intake".

The carb models may require some retuning when a performance exhaust is installed. The EFI models have an airflow meter that will help compensate for minor changes, although radical changes to the engine's airflow rate will require an aftermarket fuel computer, reflashed ECU, or standalone engine management system. The 93-on models have a speed-density engine management system that is easily upset if too many modifications are made to affect the engine's volumetric efficiency, so you need to be more careful with these later models.

This is the noob section of the forum, so that goes without saying. ;)

As long as it is not a question like" are round tires better than flat tire?,because lately my car doesn't seem to drive well."
LOL!
Up here all Questions are Good Questions!.
Some are repetitive though and for that it is highly advised to do a fast search before posting a question.(FAQ's up top in this section.).Repetitive/all ready answered questions just bog up the visibility of newly composed threads that need to be answered in a timely fashion.

It seems like everyone needs their question answered Pronto here..for some reason!,so we try to keep the FAQ's out of the Loop and the New threads up.

Don't worry about your intake. The exhaust is where the joy is found. If you have no smog inspection to worry about removal of the cats is the single biggest gain you can realize. If you're gonna do that you may as well add a header. Adding the header adds noise. A Racing Beat presilencer attached to the header tempers the noise somewhat.
Now the stock muffler is the remaining bottle neck. Replace with Racing Beat $$$$, or use a borla, 99 bucks Amazon.

Once your exhaust is done, an intake change/upgrade is feasible, but will not show the dramatic improvement the exhaust upgrade does. I'd spend that money on a steel flywheel, were I in your shoes. But that's down the road.

Attachment 500857
20 dollar intake improvement. Does nothing but increase noise, if you like that kinda thing. I only use it during adjustment time, as it makes access easier than the quieter stock can.

I think I'm going to go with this one.

Thanks for everyone's advise. This is the first time I've had a rotary engine, and I was a bit leery of what performance upgrades it could take.

I remember back when I first bought my 81 new, a friend who tracked his already old 240Z explained to me what a 'momentum car' was. Just because it doesn't make your eyes bleed from a stop doesn't mean it's not fast.