I dont see whats so extreme about it. When people has issues with vac lines coming off people spike to 20+ psi. Obviously the turbos are capable of providing much more than stock boost levels, so i just dont see why you would want your turbo spooling to 20-30psi causing excessive wear, when you only want 10 psi.

I have seen some extreme turbo drag cars running no wastegate and controlling boost via a pop off valve. But they are operating within a different criteria where longevity is of little concern. Other than that, superchargers are the only other instance where I see them used, and that is due to them needing them in order to keep boost at a level below what the blower would produce at max engine rpm.

 

That's why there is a hard fuel cut programmed into the computer. It will stop an overboost better than anything else. Pop off valves are an imprecise "last resort" method of boost control.

 

Hey arghx, it's my understanding that the stock ECU cuts fuel on just one rotor in the event of a 'minor' overboost, then cuts both rotors if the MAP signal goes above a certain voltage. Have you seen any info that might confirm or deny this?

 

I do not think this is valid however I'm curious to see if anyone else has heard of this. I just don't think its something Mazda would do.

 

oh, and I would just like to say it was the local forum that can take credit for producing the retard that though up DEI.

 

I don't know about "minor" vs "major" overboost but here is what the Service Highlights says:



It looks like the fuel cut logic is pretty sophisticated. I am pretty sure the 2nd gens cut fuel to only the rear rotor during overboost as well. The overboost fuel cut boost pressure on the FD stock ECU depends on rpm:

 

Damn arghx, you must have that damn book memorized by now. Everytime I see you post you back your info with that ****. I love it, we need more people willing to do the research then comment rather then the other way around. Keep it up man!!

 

I understand what he is saying. He is wanting some sort of device installed on the intake side to bleed off excess pressure over the levels he wants to run... since the stock wastegate in the exhaust doesn't cut it. Seems like a logical thought process, but here is the downside:

Once your intake device is just bleeding air, your exhaust wastegate will think its doing its job, and will still not be diverting enough exhaust gas away from the turbos. At this point, your wastegate could actually end up closing off all the way and leaving your intake air bleeding device (??) to do all the work. What this does is forces your turbos to spin at the maximum the engine can make them spin. I' sure its going to kill their longevity and also heat up the intake charge drastically. Basically, damage your turbos thoroughly.

 

Here's a hint. Manufacturers tend to organize their documentation in the same way, whether it is a workshop manual, technical guide, or wiring diagram. So my FD service highlights is organized the same basic way as my FB service highlights. Same goes with service manuals--an STi service manual looks like a Legacy service manual, and so do the wiring diagrams. As another example, Ford, GM, and Alldata usually organize their electronic resources in the same way.

SAE engine papers (a paper about a specific production engine) are generally organized in a similar way. Lab-testing papers are all organized the same way. I have put together an electronic library of car reference material. Usually it takes 5 minutes max for me to find this kind of stuff.

Thanks. I wrote a lot of papers in college...

 

Please understand that it was not my intention to argue with the "veterans" but I wasn't given any evidence to back up their statements. I wanted reasons why I should not use a pov and hadn't gotten one. The last few posts have been what I expect from a forum like this and I appreciate the solid info. Had I gotten an answer like these the first time we wouldn't have gone through all the bullshit to get to an answer I can accept.

Again, thanks for the solid answers and reasons to back them up

 

I understand what you're saying, but keep in mind that the reason you had to go through all the 'bullshit' is because you were calling a pop off valve a wastegate, which is completely incorrect terminology in the RX-7 world--- I don't care what some random piston-engined company calls it.

You've already been given numerous opinions, and it seems that you really want to run a POV. So, fire it up

My advice is to either induce a little exhaust restriction, or dump the twins altogether and run a single turbo with a proper Tial external wastegate.

 

No. The reason we went through all the bullshit was because there were two people who couldnt get past a simple gramatical error. The people who provided me with the best answers and the reasons and proof to back them up were the people who understood what i was trying to convey instead of bein stuck on one simple word. Its that simple. Being a rotary or a piston engine makes no difference. My idea had nothing to do with engine design.

Given the answers i was from Kai, arghx, and monkman, its clear that my idea isnt the best one there is. They are the reason why i consult forums like these. They were honest, complete, and non-judgemental. The several others who decided to try and make the "noob" look like an idiot were no help at all. People like that are what ruin forums like these instead of bein a helpful resource like theyre intended.

Again, thanks to those who took the time to correct and look past a one word error, ill end up taking off the turbos and porting the factory wastegate. Im not buying a single kit when it will be useless to me in the future. The motor is going to stay, for the most part, stock until it gets replaced. 10lbs is already more than enough to walk a corvette or anything else around here, minus my best friends tt 350Z at 500+rwhp. And thats just a matter of time...

 

dude just sell your car...

this wasn't a grammatical error again you didn't even know what the f you were talking about. You knew that a wastegate controlled boost but you had zero idea of the concept. Otherwise you wouldn't have suggested to put it on the ic. Remember you called them BOTH wastegates (the pov and the actal wg) so if you were at least mediocre on your knowledge a red flag would have gone off. The best part wasq when the answers that came weren't to your liking you got pissy. Even though the advice you got was SOUND.

Nevermind that one of us ******** even provided you with a how to pics. So instead of acting like a whiny kid that got yelled at, man up and thank the one person who gave the most detailed and best answer to solve your problem.

 

Man... Listen, I appreciate the pics. I don't appreciate your attitude. You have no idea what my knowledge level is. Both devices bleed off air, in almost the same exact fashion even. One is on the exhaust manifold, one is in a pipe. Big goddammit deal. Lose your high horse attitude and either be helpful and understanding, or go bother somebody else. I never said I was right in my idea, and as a matter of fact I did say I understand why it won't work, no thanks to you. If ya wanna be an ***, pick on somebody that'll take your ****. I, however, don't intend to. Ya might be one of the beat builders in the country, or ya might be a wannabe. Either way ya don't need an attitude toward a guy that wanted to learn somethin and made a slip up in the process. Don't tell me you haven't ever made a mistake...

The answers I got were sound, yes. They were very definite no doubt. What they lacked was any reason that made them correct. The only reason you gave me was because I was trying to use the wrong part in the right place. Had you looked past that maybe you could have given me the reasons I couldn't use the right part in the right place, but you were, and still are, stuck on the fact that i made a simple error. Get past it man. It was corrected and the conversation continued without you in a much more productive fashion.

Youre right. Here's my thank you to the most detailed answer about the question I asked. Monkman, thank you for giving me a logical answer why I shouldn't do what I wanted. That's exactly the answer I was looking for.

 

YOU came here for explanations. If you don't like how you receive your explanations then go elsewhere for them. If you'd have done any decent amount of research whatsoever on here then you'd have realized that every question asked here renders very similar results - people picking on the person asking questions. People gave you answers - if you want explanations for those answers then start another thread or, here's a novel idea, do the research yourself.

 

I'd say this thread has about served it's purpose......