Ok I've tried to search for this info. I understand that the max rpm's in the Cosmo where lower because of the auto but, what can be done to the 20b engine to allow it to safely rev as high as a 13b? Is the e-shaft the problem, or the additional rotating mass? Would balancing really help? Just asking a few questions before hand before the engine eventually gets rebuilt.

 

the 20b can rev safely up to 8k without a problem ,i think 9 is no problem either

 

factory fuel cut on the 20b is like 7200ish

 

But how much of that was due to the auto tranny?

 

Rotarys are made to rev. I want my 20b to be able to consistantly rev to 9k rpm's underload without fear of the something breaking. Currently I can't fully enjoy the performance of my stock 13brew because the factory ecu cuts boost at 7k rpms. I can't stand the loss of power when this happens. I'm like what the hell....I still have 2k rpm's left!

Why should the RX8 guys get all the high reving fun!

 

Uh, why


-Ted

 

lol

I'll be happy with 7k untill I rebuild my 20B. Then I'll be good for uh what, like 8k or something?

 

It's just personal preferance thats all. I don't want to have to back off the throttle at around 7k rpm's if there is 2k more to go. Our cars are geared for acceleration. With the power of a 20b, 7k rpms would come way to fast.

 

Bling owns all. Engine life and actual acceleration times are inconsequential compared to bling.

 

It sounds more like bragging rights.
Most of these engines do not make power up that high.
At a certain point, the excessive wear&tear is not worth bragging you can rev that high.

If the motor is revving so fast you're unable to shift and react, I would worry more about you not being able to control the vehicle...


-Ted

 

To each his own! There are specific reasons why I want my engine to be able to rev that high. Just because you 2 may think it's unnecessary doesn't mean it is. I personally wouldn't mind a little over rev projection for my engine. So do me a favor and stop "ASSUMING" I'm looking for braggin rights or the "BLING" factor.

 

Well what exactly do you plan on accomplishing, and how are you going to do?

 

Well just like metioned above, I currently hate the way my 13brew looses power at 7k rpm's because of the stock program of the ecu. There are occasions that I will go to the drag strip and will have to shift at 7k to keep the power. I know guys here on the forum that have the pfc are able to hold boost past that. This enables them to hold a particular gear for a little bit longer due to having more hp over the "entire" rpm range and gives them a slight advantage at the strip. I want this same benefit for my 20b.


Now as to the question "how"........Thats why I'm asking what needs to be done to allow for the engine to safetly rev a little higher without going snap,crackel, and pop.

 

How high do you want it to rev?
Stock, matted to our factory 5-spd up to 8,000-8,500 rpm.

 

To be honest, if it is built correctly, I don't see how anyone can hold it for that long in the rpm range; unless they are straight out drag racing.

With my car, I haven't been able to control over 5200rpm on the street. Keep in mind, that in 1 second it goes ZIIIIIIIIP and it is done.

With my small turbo and instant spool combination, in the 4k rpm band, I go from 300 rwhp (4,092 RPM) to 570 rwhp (4950 RPM). That is quite a lot of power, and do not forget the torque!

 

T-von, the thing is the 13brew stops making power in high rpms isn't the stock ECU, its the stock ports. If you want to make high upper-rpm power you're going to have to port it accordingly, and likely sacrifice low end power.

Performance wise, in the end it really dosen't matter how high you rev, its more of a question of the usable powerband and the gearing of the tranny.

 

Red I would only drive the car to limits at the strip not on the street.


John from what I understand the stock ecu starts cutting boost at 7k rpm's. The stock pattern is 10-8-10 then back down to 8psi at 7k. People who have an after market ecu and non seq twins can rev higher(even with stock ports). It's been proven.

 

If a "modded" 20b can safetly rev to that level and stay together, then I'll be happy. I just want to take extra precausions to allow for that level of safetly. Anyone know if balancing will make a big differance?

Overall you just don't really hear anything about the 20b's reving capabilities.

 

Oops....What I meant to say was people who have stock ports and an after market ecu with non seq twins can hold 10psi all the way to red line without engine damage or power loss.

 

I agree. Of course bolt ons like EMS, fuel system, turbos, etc must be changed to allow higher rpms, but even with a 100% stock core 8.0-8.5k is totally safe.

It can't hurt to balance the assembly, if you have that extra money to put into it, but in all likelyhood it wouldn't be necessary.

A modded 20B can rev. pretty high - I've heard up to 11,000 for drag applications. Depends how much money you want to spend.

 

Thx Bob Those are the answers I'm looking for. Once I get everything built, now I know that I can safetly set my rev lilmiter to about 8.5k without worrys.

 

You have no idea what you're talking about.


-Ted

 

There is nothing wrong with bling or bragging rights. I think you need to re-assess yourself. Either that, or you do not understand that simply hardening the engine to operate at higher rpm's is not going to yield any more power. The reason some race engines operate at higher rpm's is that their peripheral porting, intake, exhaust, and other modifications are better suited for higher rpm's.

LOL, if he did, then he would not have bothered to post this thread.

 

i agree.

von; you need to look at a couple 20b dyno charts

 

Guys, I've seen several 20b charts. I have always noticed that a 20b usually makes it peak power near the 6k rpm range. Whats the reason behind this? Also what could be done to move the hp peak a little higher up in the rpm band?


Ted you already stated that most 20b's don't make any hp that high but, you never gave a reason why. Please explain.

Overall guys, there is a reason why this forum is hear. So lets help each other and stop giving each other a hard time. If you don't have any usefull info to give out backed with a detailed explanation of why certain things work the way they do, then by all means please don't post.