Originally posted by chaz805
ok, getting ready to order a remanufactured motor....is it worth the extra money to have 3mm apex seals put in? my goal is about 225-250 WHP eventually.

If the engine was suffering from detonation then it was obviously not tuned properly. And in any case, be they 2mm or 3mm seals detonation will break both of them.

The 2mm seals we use are factory Mazda, nothing special there. We have also used these seals in circuit racing applications with no dramas at all.

In the drag car we are running a MoTeC and know that it is tuned nice and safe so no detonation occurs at all.

In an RX-4 street car we built, using a std compression (9.4:1) RX-4 engine, running 18psi on 96 octane unleaded we were making 430+hp and the car ran 10.91@124.8mph over the 1/4 on M&H street tyres, full exhaust, driven to and from the track. We never had any dramas with apex seals or anything else, but once again we know the car was tuned properly.

Many people over hear have found that the 2mm apex seals are definitely easier on the rotor housings, and seal better than the 3mm seals, and with correct tuning reliability is not an issue.

The reason for keeping the 2mm in the new engine is because it'll be running at a higher rpm range then the previous rotary engines. At higher rpms rotary apex seals have a greater tendency to "chatter" therefore the 3mm seals will be heavier and have more tendency to "chatter" at high rpms then the 2mm seal.

About the 2 mm vs. 3 mm apex seal controversy, two quick points:

1. Technical papers have shown that thinner apex seals seal better because, roughly speaking, they don't "bounce" or "stick" as much as thicker seals. I could cite several papers, but that would be overkill.

2. Racing Beat, which has been involved with Mazda rotaries since Mazda came to the US and has long offered competition parts and service, does not recommend changing 2 mm seals to 3 mm. They should know. See their technical manual. Certain rebuilders advocate changing the seals, but many (not all) have a poor reputation in the field for building rotaries that last just until the warranty period expires.

Originally posted by J-Rat
They do provide some resistance to detonation, which is a good thing.

Jarrett

Originally posted by chaz805
it is starting to sound like 3mm seals are more of a hassle than they are worth. I think after listening to you guys I will probably just order a stock rebuild and spend the 3 or 4 hundred $$ on having my injectors blueprinted, maybe a S-AFC and a good A/F gauge!!