performance degradation
 

the 0-60 and 1/4 times are posted for new 7s. how much does the performance decline as the car gets older, assuming good maintainence. i'm looking into buying one, and while i don't need the fastest car on the block, it'd be nice to know how well a 7 holds its performance as it gets older and the car racks up miles. for long time owners have you notice this? thanks.

Good question. I believe RX-7's hold less performance as they get older compared to Supras, NSXs etc. Mainly because of the boost and suspension problems.

A long term test by Car and Driver magazine showed no drop in performance after 30,000 miles. Automobile Magazine purchased a '95 RX-7 from the Mazda press fleet and found the engine revving more freely as they racked up the miles. That has also been my experience with the FD I've owned. In fact, when I bought my '95 new, I thought something might be wrong. The engine felt too tight. It wasn't as rev happy as the previous generation 7's I've owned. But now that it has had time to break in, it feels like it's spinning freely.
The apex seals are spring loaded so they maintain contact with the inside of the walls of the rotor housing. This should seal off the combustion chamber and maintain its integrity, unlike a piston engine in which the valves and rings can wear and leak.

I went and looked it up. The long term test was reported in the June 1993 issue of Car and Driver. Here are some of the results:

..... new .........................35,000 miles

0-60 5.2 sec ........................5.2 sec

street
start
5mph-60 6.4 sec. ................ 6.2 sec

1/4 mi. 13.9 sec .............. 13.9 sec.

Top speed 152 mph ............ 163 mph


The big difference in the top speed result could be due to that loosening up I was talking about in my previous post.

what about after 35k? like as the car reaches 60, 70, 80k? what about performance after rebuilding the engine?

Sorry, I don't have any tests for higher mileages. As, I said, the design of the apex seal works to keep the combustion chamber sealed, unlike the wear of a piston engine which can increase the leakage of blow by gases.

I've seen some rotor housings coated with carbon deposits, so that may cause some leakage, but my experience with rotary engines is that they remain strong and seem to rev more freely until they suddenly pop. (An apex seal breaks or the water seals start leaking.) Actually, I've never had a rotary engine fail on me. But then I've sold my cars before they went over 150k miles.

I found an interesting comparison. We've seen how Car and Driver's long term test found no performance degradation of a '93 RX-7 at 35,000 miles.
In the December 1991 issue, they retested a Mitsubishi 3000GT VR 4 they had for a long term test. Here are some of the comparison figures they found:

___________NEW________________30,000 miles____
0-60mph____5.2 sec______________5.6 sec______
1/4 mile_____13.9 sec_____________14.2 sec_____
0-100mph___14.2 sec_____________14.9 sec____
street
start
5-60mph____6.8 sec______________7.1 sec_____

top speed___152 mph____________154 mph_____

we already knew the 3000GT VR 4 is the worst of the import super car :p: