Moon Assad

I have one in my garage Ha Ha.

eviltwinkie

haa...i honestly dont know...these are fickle engines these are...it would be easy to say that the increased flow+porting+proper tuning could easily make that kinda power. however, its also easy to say that nothing about these engines is ever quite as it seems.

I for one think that reworking the rotor design itself would yeild better results. Given the bias of the housing design, and perhaps adding a bit of bias to the rotor to compliment that design would be a better approach.

redesign the rotor while your at it with a few well placed "scores" to increase combustion turbulence a bit while your at it...

eviltwinkie

Your offically now clumped w/ MM...

You greedy bastard!! haa haa...I hate you both...

eviltwinkie

Some of us are used to working with other people...unfortunately most others are not...

All I do for my day job is fix problems given to me by people who dont understand things themselves. Add the complexity of different cultures and languages along with limited to no solid information...and you learn real quick that arguing never gets anyone anywhere...shame others do not prescribe to the same principles...

Server outage apparently for maintinence...seems pretty consistent daily at 4am CST to about 5am CST...

california style

Am I right in thinking that the exhaust headers attach to these three ports in the picture?

eviltwinkie

Ya...thats where they mount up...

california style

so u r saying the transition from the ports above to the header is a 90 degree bend and therefore is causing flow/impact issues when overheated?

Because the ports fire directly out wards not raked back type thing.....

MazdaManiac

iTrader: (3)

The port flow issue is due to flow area. They are just too small.
The siamesed port does not revert because it is in a constant state of flow.
A flapper would be worse than useless - it would be a flow restriction.
Think about header design - the scavenging effect of sequential ports draws exhaust from the adjoining port. This is what happens at the siamesed port.

Heat retention happens at the port in the irons, not the outlet in the housing, so increased flow will not appreciably affect the port temps.

Then don't argue when you don't know what you are talking about. That is the main issue we have with your methodology.

BTW - isn't this a supercharger thread?

eviltwinkie

From the chamber...the energy is directed outwards...as it exits the chamber it immediately has to make an almost 90 degree turn which is currently performed by slamming the energy directly into the port and routed down into the header which then has yet another tight turn before being routed back. As the gas hits the walls for deflection, it will impart some of its energy on the walls...

or to simplify it...turn on a hair dryer and put your hand at 90 degrees in front of it...your hand will heat up in less time than if you held your hand at 45 degrees...

eviltwinkie

Right...so I think his idea was to try to increase the flow area by utilizing most of the volume of the siamesed port for each pulse...I think...

I am not sure I would say it was a constant state of flow. Its fed by timed pulses from each rotor and I think he's trying to do something mechanically as each side fires to increase the flow...

Again, agreed that retention happens at the port...but I think the running idea here is that the center siamese port is restrictive enough that those ports are not being utilized as much as they may possibly be. Additionally, by increasing the amount of flow by reducing the restrictions it may in turn operate cooler due to an increase in efficiency...how much is totally unknown as its all simply postulations obviously.

My bigger gripe is those tight turns...

california style

So this what u mean?

MazdaManiac

iTrader: (3)

All a flapper would do is keep the port flow area as small as it is before the blending point until it hits the header.

Its commendable that you guys are playing with this stuff, but you are way off base with regards to how the fluid dynamics work in the system as it stands.

Tight turns not withstanding, any progressive increases in actual flow surface are more important than any sort of flow "smoothness" with regards to fluid evacuation from the point of higher pressure.

eviltwinkie

Does classic header design apply w/ this engine?
Does a scavenging effect actually occur considering that they all dump to the same location?

EDIT: Answered by rotarygod..
How can we scavenge when we have no port overlap? Well, what if we have so much velocity from our wonderfully designed exhaust that the exhaust pulse actually pulls more air from the chamber than just the exhaust gasses? This would mean that it pulled the chamber into the negative pressure zone below ambient pressure.

Rotarygod probably knows better than I on that stuff...

The reason I ask is because I've never actually thought about it...glad you kinda brought that up actually...

=)

I think in discussing the whole port scrape issue that one thought was that perhaps the temps are increasing due the higher temps of FI as well as the inefficency of the ports as is.

Of course it could simply be the one of the other answers too

eviltwinkie

I'm not sure if his idea is translating properly. I had a bit of confusion about it myself. Let me restate it just to be sure that we are all on the same page and that your statement still holds true.

That siamese port insert...make it flat mentally and allow it move horizontally within that same space between chambers.

I think the toying idea is...due to the pressure inbound from the rotor the plate (insert) would be pushed back and forth giving each rotor as much port volume as possible during each pulse.

So theoretically...its as if each rotor would have the entire siamese port to itself as the space between the current insert and the port opening is tight and appears to be restrictive.

Hopefully I explained his idea correctly...

Right I think this statement is being driven by the whole hairdryer thing...I was simply stating that the tight turns allow the hot gas to smack amongst things and therefore heat them up in the process.

If the above stated idea is correct...then if we look at a single rotor as a thought experiment...and said...you can have the entire siamese port to yourself...would that not be an increase in the volume it could utilize and therefore increase flow?

eviltwinkie

Yep..amongst other turns after those points..

Rotarygod on exhaust...reading now..

https://www.rx8club.com/series-i-tech-garage-22/another-one-my-insanely-long-exhaust-tech-articles-73332/

Brettus

iTrader: (2)

Getting back to why these turbo motors failed ...... MM said that he didn't think the turbo choking the flow at high rpm was going to cause additional heat .
MM - Can you elaborate on what you did to check EGTs with the Greddy vs your larger turbo?

MazdaManiac

iTrader: (3)

I stuck a K-type thermocouple in the manifold right at where it enters the turbo and measured the EGTs under load at all RPM ranges and at cruise and its the same between the two, very different turbos.

rotarenvy

here is my predicted c30-94 engine demand if anyone is interested. flow rate is beeing exagerated by the way I calculated air mass

MazdaManiac

iTrader: (3)

Wow. Whatever turbo you are plotting there, it is WAY over-sized for what you are doing.
You need to run the boost up 12 PSI+ before that thing even starts to breathe.

rotarenvy

true, but it's indicative of the centrifugal sc's out there. maybe the expect you to run low compression high boost? adding the impeller speed dosn't seem to help. it gives more PR but at that PR the engine can flow more air and this compressor can't flow enough.

MazdaManiac

iTrader: (3)

Which is what makes the turbo superior - it will up its speed to meet the target boost in the ranges in which it is most efficient.

rotarenvy

yeah constant PR makes it much better.

tajabaho1

reading this thread has throughroughly convinced me to screw the petit supercharger and buy a damn turbo kit instead @.@

now I need to find that extra 4-5k for all the upgrades for the turbo kit before I install all of them @.@

sosonic

Maybe you are getting your superchargers confused. There are different types. A centrifugal supercharger and the twinscrew are different. Pettit is a twinscrew supercharger, not a centrifugal... Different superchargers will have different dyno chart, different overall HP, and give boost at different rpms.

kartweb

Just as we were getting comfy with understanding the powerband natures of various air pumps, it turns out a new turbo is in development that will change everything.

Details are a bit sketchy, but the new technology uses a valve & gate system that extends maintains the P/V factors for both the turbine and impeller over a range 4-5 times wider then simple system we have today.

Both Volvo and Smiths are working on gated systems independently, and both have already filed a few patents. Any Turbo wizards who are looking for a really cool job in Ashville NC need to look at Smiths.