slalom29

I was looking into purchasing these headers, I just wanted to get your opinions about the piece and the company. You can see them at I-m-racing.com?

Sanguine_Dark

I've got an email into the guys over at bulletproof automotive about these. I'm interested in more specs on them as there is little information available. If you find out anything I'd love to hear it. If I get a response I'll post what info the provide.

v300

iTrader: (1)

RE-Amemiya is one of the top Japanese rotary tuners. Their RX-7 recently won the Japan GTC300 class. Not too sure about their header though. You might want to ask "Rotarygod" or Racing Beat.

rotarygod

Conventional header designs are not yielding any noticeable improvements on the Renesis. The siamesed center port really cancels out any benefits of tuning since they themselves (center exhaust ports) are collected at the engine. Racing Beat has only found about a 4 peak hp gain with conventional headers. 4 hp isn't noticable anywhere unless you are driving an 8 hp car. 4 hp is even worse when it is only at the peak power spot. This means that it isn't really any better anywhere else in the usable powerband. Everyone making power only at peak rpm isn't doing anything for real world everyday performance. But it does look better on a dyno. As we all know higher peak numbers help sell product from a marketing standpoint but it is average power that wins races and makes you faster. Everyone always likes to ask "How much power does it make?". They always fail to specify where though. If you say that product A makes 200 hp and product B makes 210 hp then obviously product B is the better product, or is it? What isn't obvious is that product B may make less power in most of the usable rpm range or at the very least no gains except peak. See the flaw in the system?

As long as headers are being made for the Renesis that are of equal length over all 3 runners, there aren't going to be any serious gains. The center port needs special attention. The first header I see that has the outer ports 1 length and the center port an entirely different length and collected at a different location as the other ports will peak my interest and be worth a look. Until then we will probably see several different headers hit the market for several hundreds of dollars and claim only a few hp gain. The important thing to see is where it makes more power. I personally feel the RE-Amemiya header ($1400 !!!!) to be a waste of time and money. Don't buy the first thing that becomes available. Wait until you have a choice and can actually find one that works as would be expected of a header.

Sanguine_Dark

Rotarygod...

Good points. Thanx for the input on this. No one else seems to know anything about a lot of the 'stuff' floating around out there.

Japan8

Thanks for the thoughts Rotarygod. I had been wondering about the RE Amemiya header as well.

Jt-Imports

On RE-Amemiyas webpage it even says the gains are very low. I havent seen a car ever if you put headers on it, it gives you 500hp come on.........

I dont think its a good idea to buy it though either, but if you plan on being N/A forever and not getting one of the kits coming out soon, then it might be an alternative idea.

rotarygod

The way I see it you get about (near) 4 hp for $1400. That is $350 per hp. That gain is also only at the very top part of the rpm range. Basically peak power but nothing really usable. ECU upgrade will get around 20 hp and probably more. We'll just use that number anyways. Canzoomer wants something like $600 for his. That is $30 per hp. His gain is noticable from about 5000 rpm all the way up. I don't know why anyone anywhere would ever buy that header especially for the price. That is exotic supercar pricing.

No one believes a header will give you 500 hp. Well maybe the ricers do! 10-15 would be nice though. None of the current ones will do that though. When someone designs one properly for this engine we'll probably see it.

bassoon811

Do to the center exaust port being collected before it hits the exaust manifold a conventional header will only be efficent on the outer two exaust ports. I remember seeing a design where the center port had a tube running down from that port around a foot, I don't remember the reason but this would produce the largest HP gain. Due to space this design would be hard to impliment.

rotarygod

Actually I posted that picture. The center port runner was done differently to help fool the siamesed port into thinking everything was working the same as if it were seperate. It's a neat acoustic trick and the way that I personally feel it should be dealt with. Since I haven't actually tried it I can't say with absolute certainty that it will work as predicted but it is an example of the lengths that should be thought of to deal with the siamesed runner.

bassoon811

Ok, I had done a search but there were like 150 threads with the word "headers" in the replys and I wasn't going to look through all of them, even thoe you haven't tried them do you think there would be a HP gain, and if so how much. IMO a header in a highly tuned engion, like ours, should get at least 5-7 in the power band.

rotarygod

Supposedly RE-Amemiya claims 7-10 gain from their header. Racing Beat however tested it and only found about 4 peak. 7-10 is nice but I want to know where in the powerband. I assume it is only up top and I don't want a gain there. I want an average gain lower in the powerband. Regardless, 7-10 for $1400 is a bit extreme. Even Paul Yaw has claimed little gain from headers regardless of length. I wish I had a damn RX-8 so I could try some things out. I don't see why we couldn't get 10+ hp over a broad range though.

david borla

Aren't Racing Beat and RE-Amemiya competitors? If they are I would suggest getting a second opinion from a non-biased source.

If you feel that you would be able to "get 10+ hp over a broad range" why are you so skeptical of RE-Amemiya's claim of 7-10?

rotarygod

I still have the issue with the simesed center port messing up tuning. I still feel that there is a better way to do it but I haven't seen anyone try it yet. Paul Yaw, who is very honest and has no desire to disprove other people's claims, stated in the past that the Renesis was "unresponsive" to various headers. Paul doesn't care if someone buys another product or not, even if he has one available. He merely tries something and tells it like it is whether it is good news or not. Paul is the single most knowledgeable rotary person that I know of and if he can verify others claims then I believe him. Everybody in the import world claims a 7-10 hp gain from headers. How many actually get it and where is the gain usually at?

How is your design coming David? We've been anxiously waiting for your results or some pictures. You have always been one of the few exhaust people that I trust. I definitely agree with your past statements that ask why people buy something because it is shiny rather than made better. I've always wondered this myself.

david borla

I would have to agree that the center port holds the most potential for power gains. We have experimented with 3 different header designs for the RX8 however none were satisfactory. We have come up with a new design that we will be testing in the next two weeks. I don't want to get into the specifics of our design for obvious reasons but I can tell you that there is a potential for improvement with the center port. There has been a delay in the development of this header because we have had a Ford GT and Lamborghini Gallardo in our facility for the last two weeks and all other projects were put on hold as these vehicles are rare and very difficult to find (and no, we haven't raced them). We have another RX8 coming in at the end of next week and we will resume development of the exhaust manifold. Thanks for your interest.

rotarygod

I wish I had a chance to play with a GT and a Gallardo. I'm lucky if I ever get to touch one!

Your testing seems to reinforce what I've been saying here for a while. Good to know. We'll be waiting!

AMUSE

i have get the one from fujita few days to go to be arrive..

Charles R. Hill

iTrader: (7)

Since I am lucky enough to have a friend in the fabrication biz he and I are working on a header design, the likes of which I have never heard of being used on a car, much less a rotary. I think one of the major problems with getting more power via the exhaust system is becuase the rotor leaves little, or no, area with which a vacuum may be developed in the housing. What I am wondering, which may help my design, is the nature of the port timing between the outer and center exhaust ports. Anyone care to enlighten me? Thanks.

CRH

rotarygod

The lack of intake/exhaust port overlap (6 degrees of dwell) does limit the potential gains compared to the older engines. You are correct in that we can not pull air into the engine from good scavenging during overlap since we don't have it.

The port timing between the outer and center ports is identical. The 6 port and 4 port engines are different from each other though. The exhaust port timing on the 6 port engine is:

Exhaust opens: 50 degrees BBDC
Exhaust closes: 3 degrees BTDC

It is the same for all of the exhaust ports.

The 4 port engine is slightly different :

Exhaust opens: 40 degrees BBDC
Exhaust closes: 3 degrees BTDC

Again this is the same for all exhaust ports.

The primary intake ports on each engine don't begin to open until 3 degrees ATDC and the secondary kicks in a 12 degrees ATDC.

Hope that helps.

I have been wanting to try several combinations from deadleg pipes to a complete triple exhaust, to stepped pipes, to a valve actuated system that varies backpressure with rpm and load. I just need a car, the proper facilities, and the time and money to do it.

shawnio

speaking of no overlap ...

would it be possible to have variable exhaust valve timing?

although rotary engines have had variable intake timing and manifold length and what not, why not variable exhaust valve timing?

too complex?

draco067

Perhaps because there aren't any exhaust valves...

The exhaust ports are built-in to the sides of the combustion chamber, there's nothing to vary.

rotarygod

I think he is asking if it is possible to do a rotating valve assembly like the auxillary intake ports but also on the exhaust. Yes it is possible. The issue will be with the rotating vavles themselves. It will take a very special material to withstand the extreme temperatures of the rotary exhaust. Variable exhaust tuning is possible and is something Ferrari has done on several of their cars. Mercedes even has variable tuning with the new SLR. Both companies rely on small dual exhaust tips (or quad). One tip has an actuator that opens and closes depending on engine load and rpm. This alters the exhaust tuning. It can be done but is alot of money in research.

neit_jnf

I've seen a header (Amemiya?) that incorporates a center divider into the center port but is still 3 pipes. How about doing this but really dividing the exhaust into 4 pipes and then tuning the respective lenghts to the different airflow? The two outer pipes would be bigger than the center ones in diameter and shorter in lenght? It could be a 4-2-1 design or even a true dual independent exhaust. Anyone?

rotarygod

It would be preferred to keep the ports seperate. This is the whole problem in the first place. They wouldn't necessarily need to be of a different length though. There are many things that can be tried. Some may work well. Others may not.

Omicron

Personally, I'd wait for the Borla header. I think RE Amemiya rushed theirs to market without full development. Borla, on the other hand, is clearly taking their time and doing it right. Just my 2 cents.