I have a 94 Rx7 with apexi intake, PF catback, power pulleys and double friction clutch. 54K w/ original engine.
Im thinking of getting a downpipe and a radiator next.
People say that I will need a new ECU to put a downpipe in it but is it really essential? Also, members have been saying radiator and downpipe are important reliability mods due to all the heat in the engine bay. Is this a fact or an opinion? Please help me with your expert suggestions. Thanks guys

 

The downpipe IMHO should be everyone's first mod. It might be cutting it a little close with the catback and intake, but people have gotten away with more. It is up to you, but if you do it, be really careful on cold nights.

 

Well, read through this:

http://www.scuderiaciriani.com/rx7/reliability.html

As far as an ECU? The ECU is really needed when you begin to boost OVER stock boost levels. Normal boost pattern is around 10-8-10 (from the 3rd gear boost test).

When you start getting boost levels higher than 10 PSI, the stock ECU will not be able to compensate for the extra air into the Air/Fuel ratio. Therefore, you need an upgraded ECU to help add more fuel to help even back out the Air/Fuel ratio at higher boost levels.

Basically, you can add the downpipe and you will be fine as long as you keep the boost level at/around stock boost levels.

 

The M2 ECUs, are they reliable? How much powergain should i expect from a downpipe and a M2 ecu ? Thanks

 

You can get a used urgraded ecu for 300-400 bucks. The cold night thing is because when it is cold outside it makes your intake charge cooler and thus denser. You run more boost and at lower temperatures. It's like running an upgraded intercooler. Just keep the boost at stock levels and you *should* be alright.

 

M2's are really good from what I hear, however, I choose Pettit. Here's an example, depending on your mods what you can expect from something like a Pettit ECU:

https://www.rx7club.com/forum/showth...threadid=97425

 

Stock boost = all good. keep it at 10-11 psi and you should be fine. If it goes 13+psi you will need an ECU. Iam not sure it will be stock when you put the DP on. The intake with exhuast is the thing that really wants to make that boost creep.

 

Does ECU tuning count towards reliability mod?
Wouldn't it shorten the life of my engine if to much power is added? Thanks for all the quick responses.

 

ECU tunning is the most potent factor in reliability. Stick with the plug and plays until you buff up on standalone units. Its a rareity to here a blown engine on re-programmed ECU's. More power always shortens engine life, its up to the tunning to say how much damage will be incurred. Rich=little hp loss, leanER= more hp less room for error. Also timing plays a factor.

 

If done right, it shouldn't shorten the life of the engine. However, running higher levels of boost will probably shorten the life of the turbos. The turbos are designed to operate at certain levels. Increasing that level will surely decrease it's lifespan. Nothing is made to last forever.

 

It will shorten the life of your engine if not enough fuel is added. When you put in an uprgraded ecu you can turn the boost up some too.

 

So more power means more heat right? so do you recommend getting a radiator at the same time? Or can i getaway withit? (I've never had overheating problems)
I live in the Northeast coast where I have full four seasons. Thanks

 

It really depends on the amount of boost you will be running. The radiator is a good reliability mod, however I've seen a some heavily modified FD's still using the stock radiator. The main problem with the stock radiator is the plastic parts that tend to crack from heat, not so much it's cooling ability.

 

OK then I've set my mind on M2 Downpipe and M2 Remapped ECU. Any suggestions on this ?

 

Sounds like a good plan.

I think M2 are a little more conservative than Pettit ECU's but you should notice a nice gain when you get them both hooked up.

 

Thanks for all the kind advice!

 

The M2 is more conservative than the Pettit because it's tuned to run on 91 octane, which is the highest commonly available in California.