I have seen the dyno results of the CLR beveling on an IT engine on the dyno. It works, the question is can you afford it?

 

cmon sureshot i wanna hear about how ur engine runs get that thing in there and let us know

 

and? how much power did the motor make without the bevels and how much with them? was this NA or turbo? what did the port timing look like? where is the dyno sheet?! what makes you think we will belive you instead of 88integraLS without a dynosheet? this is exactly how the rumors start, first its thrown out there, then people add thier own numbers and then everyone does it, then all the rotors are busted and you cant find any used stock ones. its like the drink pepsi become a president ad. on tv.

 

^^ thats a bunch of crap. it is intuitively obvious that it works, the question is just how much. dont get me wrong, i'd love to see some hard evidence too, but that doesnt mean im gonna say it wont work otherwise. obvoiusly more flow and more timing will result, meaning more power.

 

watch what you say.
" it is intuitively obvious that it works"
and who's intuition should i trust here?
"obvoiusly more flow and more timing will result, meaning more power"
how do you know this without testing? i am not denying that it may work, i never said that, i just want to see some sort of proof. the easiest thing to do would be to have a before and after dyno sheet with no other changes. more timing doesnt mean it will make more power in fact it is just as easy to have negative results as it is to have positive ones.
so far in this thread i have seen not even one evidence that shows any modification to the engine have made anymore power then stock. am i wrong?

 

Kahren, Our (mine now) Dyno is an older Stuska 800 Waterbrake. As much as I wish I had the gonzo bells and whistles automatic load control and data collection system; I dont, so I take the readings manually. I have added a Video Cam to record the control panel for runs to aid in data collection. I need to go back and review the notes on that particuliar engine.
But if memory serves me correctly we had a 16HP increase with the CLR Bevels on a IT class engine, SDJ 13B header, and class legal carb.

 

How hard does this get to explain. A dyno shows what one motor can do at one time. Thats it. Alot of this "proof" crap sounds like personal feuds. It also irritating that so many will ask for "proof" of how this modification makes more power, yet those asking can't seem to fathom the common knowledge that in order to have an accurate comparison between a internally modified engine and a non-modified engine, all other possible variables will have to be controlled. You would have to have the same amount of tire tread on the rear wheels just to yeild the exact same power, not to mention numerous other variables. This is not possible without some serious $$$ for a possible marginal hp difference. The idea of rotor beveling is simple: Allow air to enter the combustion chamber with minimal turbulence. Rotor beveling, smooths out the transition between the port and combustion chamber. At the extreme bevel, there is also a weight reduction, so how would one tell whether the hp increase was attributed to the actually beveling or the weight reduction???

 

sorry, didnt mean anything personal.

what i mean is that generally as far as flow is concerned, you can get a good idea whether you are helping or not by eyeballing things. flow dynamics is really simple. the complicated part is trying to mathematically quantify the flows. it is rarely very hard to look at two parts and say 'this one is better' but if you want to know how many percent better, thats a major undertaking.

hence it is pretty obvious that the charge will flow around the beveled edge of the rotor better than it will flow around the corner on the stock one.

as far as timing, yes you can have too much, but as far as duration goes on a rotary, more is better within reason. if he bevels the edge 5mm, then that adds 3.x mm more duration (like one degree or something), which is not far from the difference between a bridgeport and a large streetport.

pat

 

Sureshot I love that beveling. I believe the wheight you removed was minor, but, re-balancing is always plus. I will probably copy, if you don,t mind.

I have some questions though. Is your engine a turbo. I'm particularly wondering if the early opening would fly on the turbo.

I ask this because I think your exaust is conservitive. Which, I think, is good for a street turbo. I think I would bump it till the you could see no "edge" when looking in from the outside. Not much more. Just a little.

 

Not necessarily...


-Ted

 

so not to interrupt the lil camp fire thats goin here but how much do the goddamn bevelled rotors that started this shitshow cost??

 

does this mean that after adding a header, and bevels and a carb the total gain was 16hp? or does that mean that the engine previously had both the header and the carb and then the bevels were added?
so did you just take the motor apprt and add the belvels on the rotors? and nothign else beign changed other then that? what was the total hp output? whp or fwhp?

 

wow that's sweet, have to try that on some toasted rotors!

 

How does it delay the closing when the side seal is what closes of the port? Does the bevel basically just lower the turbulance around the rotors square edge before the port closes?

 

The chamber is effectively closed by the edge of the rotor, not the side seal. Very little air flows though a 0.004" crack.

That's why you can get an engine to run without the side seals installed.
It won't run well (no idle, very low power), but it will run.

I can say this b/c I have witnessed porting errors where the intake port was opened very large and not bevelled. All of the side seals on both the front and rear secondary secondary ports ate themselves when their leading edge caught the port and compressed longetudinally. The engine made very low, yet still readable compression. It would not idle below 2000 rpm, and was very hard to start.
The poor running condition was due to the leakdown of compression. No engine will run at all if the ports(or valves) never don't close.

 

Bored at work and nothing else to do...

Seriously though, comparing dyno graphs is not a big deal for me.
Although the absolute numbers might not mean much, it's the curve of the plot that interests me.

Even with a few vacuum hoses loose, you can still tell the chracteristic of the curve.
Changing "timing" does not automatically raises the entire curve upwards.
In fact, I'd be very surprised if the entire curve does that.
It's most likely certain sections (mostly the tail end) would go up.

But, like I said, the offer is still there...
I've got about $700 sitting in my PayPal account, so I'm still waiting for him to accept...


-Ted

 

You know as soon as I typed that question, I thought about it some more and forgot how tight the side clearance of the rotor and side plates were. Duhhh!

 

Yeah, I kind of jumped on that one since I have seen it argued before.

Mazda's timing specs on the ports are also inline with the rotor edge and not the side seal for both opening and closing of the side ports.

 

Engine was dyno'd in Race form with stock rotors, in race trim.

Engine was disassembled, Beveled rotors were installed. Only change to engine was the beveled rotors and the rotating assembly balanced.

I dont have the data sheet here in Wiliston with me, its packed away with Stans stuff.

 

so..umm......yea...nobody has the price huh im gunna have to PICK UP THE PHONE....cand call CLR......ok....ok....hell ill dyno my stock T2! hook it up ted! rent me some champfered rotors and a rebuild and ill dyno that hoe! lmao but it looks like nobody acually knows the price to those damn things..i dont doubt those CLR ones make a difference but a DIY champfer job...im skeptical at best until i see dyno results befores and afters...sorry i like looking at numbers and solid lines myself...

 

IIRC the cost of lightening and beveling the rotors was $650, put that was well over a year ago.

 

I just spent considerable effort cleaning this thread. It would hate to have to delete the thread, but if it happens again, then I see no choice as obviously people are unable to discuss this topic in a calm, rational and mature mannor.

 

Early opening is a big power plus on ALL rotaries.
The trick is not letting corner & side seals get jammed in the hole.

Late closing is more beneficial with boosted motors.
NA’s gain some high end – more with the S5 VDI.
Extreme late closing under boost is what a "Miller cycle" is about.

Any porting will diminish idle smoothness.

My specific port job is still untested, so you should compare it with others until I get some results.
Like I said earlier - In 6 months it will look either brilliant or stupid.
I am hoping for more high end, and expecting some idle lope.

 

do you remember roughly how much power this motor made?

 

It is well established that the earlier than stock opening intake ports make more power!

In the "streetport" only classes they had to keep making rules to limit the early opeing ports. Now the junction of the leading apex seal end and corner seal must not be able to be seen from inside the port (it is on the side housing at all times).

Beveling the rotors was a trick from way back in these classes as well to get early opening without violating the porting rules.

Beveling the rotors is also very nice because it opens and or closes the port ealier WITHOUT having to increase the port volume at the face so it keeps the velocity up in the port. This is nice on NAs to keep the lower rpm power up without sacrificing top end power.

The stock ports are expanding in volume for 32 deg before the intake opens sucking in exhaust gasses since the exhaust port is open. Opening the intake ports ealier decreases the amount of exhaust sucked into the intake stroke so more room for air/fuel charge. S5 RX-7 primary opened the intake even later to suck in more exhaust and so were able to simplify the EGR system and still keep the EGTs down at low load.

In the upper rpms the increased overlap of early opening means an enhanced scavenging effect if the system is set up for scavenging (tuned headers decreasing exhaust pressure in an NA or intake pressure above exhaust backpressure in a turbo).

Think about it; with an early opening streetport and beveled rotor one can get to P-port race port timing without the excess overlap and poor flow dynamics of a bridgeport (smaller runner leading to large port area, bridge portion of the port has no outside radius to guide flow).