BHR new header and midpipe
11-25-2014, 11:51 AM
#301
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The exact science isn't 100% known. If it was public knowledge, than there would have been a header this successful before now.
Charles has indicated that there have been many iterations, and that each change he made to it produced a change in the output, including a few times he has noted that "one change made produced as much more gain as other popular headers have in total." Presumably this one change is not the length of the header, though it may be.
I doubt that Charles will publish the exact R+D he spent his time and money on, so you may never get a straight answer as it is unlikely that anyone else will take the time, trouble, and cost to figure it out and then publish free of charge.
Charles has indicated that there have been many iterations, and that each change he made to it produced a change in the output, including a few times he has noted that "one change made produced as much more gain as other popular headers have in total." Presumably this one change is not the length of the header, though it may be.
I doubt that Charles will publish the exact R+D he spent his time and money on, so you may never get a straight answer as it is unlikely that anyone else will take the time, trouble, and cost to figure it out and then publish free of charge.
The exact science isn't 100% known. If it was public knowledge, than there would have been a header this successful before now.
Charles has indicated that there have been many iterations, and that each change he made to it produced a change in the output, including a few times he has noted that "one change made produced as much more gain as other popular headers have in total." Presumably this one change is not the length of the header, though it may be.
I doubt that Charles will publish the exact R+D he spent his time and money on, so you may never get a straight answer as it is unlikely that anyone else will take the time, trouble, and cost to figure it out and then publish free of charge.
Charles has indicated that there have been many iterations, and that each change he made to it produced a change in the output, including a few times he has noted that "one change made produced as much more gain as other popular headers have in total." Presumably this one change is not the length of the header, though it may be.
I doubt that Charles will publish the exact R+D he spent his time and money on, so you may never get a straight answer as it is unlikely that anyone else will take the time, trouble, and cost to figure it out and then publish free of charge.
Last edited by pistonhater; 12-03-2014 at 10:10 PM.
11-25-2014, 02:45 PM
#303
The Racing Beat uses 1 3/4" primaries, the BHR uses 1 7/8" primaries so it is a little bigger. I wonder if larger pipe would allow even further gains. Usually increasing pipe diameter increases peak hp at the cost of low-mid range torque (for pistons engines anyway).
11-25-2014, 06:33 PM
#305
rev it up
I wonder if we get to see a dyno comparison with a RB header.
I have spent a lot on my current header by getting it ceramic coated inside and out however, I appreciate the science that larger diameter pipes will lead to better exhaust flow thus more top end power.
On my supercharged car the benefits will be a lot greater compared to stock.
I have spent a lot on my current header by getting it ceramic coated inside and out however, I appreciate the science that larger diameter pipes will lead to better exhaust flow thus more top end power.
On my supercharged car the benefits will be a lot greater compared to stock.
11-25-2014, 10:40 PM
#306
I agree, I posted a question about heat further up. With the amount of heat a rotary puts out, I can imagine the tunnel getting quite warm. Even with my RB midpipe my whole center console is heated .....
11-26-2014, 02:14 AM
#308
This isn't directly about the BHR header, but while on Charles's site I noticed the Dyno slip had a max WHP of 155 with the header. I might be crazy, but shouldn't the rx8 be putting down at least 180 WHP stock, and therefore maybe 200 with the header? I know the test car is currently in a unspecified level of disrepair but is that 30 WHP gap really all up to air filters and spark plugs (or whatever was worn out... i dont really remember). If I'm totally off base please correct me bc I'm genuinely curious.
11-26-2014, 04:57 AM
#309
11-26-2014, 04:58 AM
#310
This isn't directly about the BHR header, but while on Charles's site I noticed the Dyno slip had a max WHP of 155 with the header. I might be crazy, but shouldn't the rx8 be putting down at least 180 WHP stock, and therefore maybe 200 with the header? I know the test car is currently in a unspecified level of disrepair but is that 30 WHP gap really all up to air filters and spark plugs (or whatever was worn out... i dont really remember). If I'm totally off base please correct me bc I'm genuinely curious.
11-26-2014, 12:13 PM
#312
We are often asked about "heat wrapping" a header as a method to reduce heat in the engine bay. We do not recommend wrapping the header. Even though RX8 exhaust temperatures are not as high as other rotary applications, wrapping a stainless steel header will accelerate fatigue in the metal. A better answer is to use heat shields that do not reduce airflow around the header.
11-26-2014, 12:28 PM
#313
You gonna eat that?
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Heat wrapping rotary exhaust can be trouble, it's just too hot. From Racing Beat ...
We are often asked about "heat wrapping" a header as a method to reduce heat in the engine bay. We do not recommend wrapping the header. Even though RX8 exhaust temperatures are not as high as other rotary applications, wrapping a stainless steel header will accelerate fatigue in the metal. A better answer is to use heat shields that do not reduce airflow around the header.
We are often asked about "heat wrapping" a header as a method to reduce heat in the engine bay. We do not recommend wrapping the header. Even though RX8 exhaust temperatures are not as high as other rotary applications, wrapping a stainless steel header will accelerate fatigue in the metal. A better answer is to use heat shields that do not reduce airflow around the header.
Thanks for the heads up.
11-26-2014, 03:00 PM
#314
Registered
It has been stated several times that there was no tunning involved whatsoever. It was a Low mile 2008. The car had a BHR ignition kit installed several months prior. But I doubt that counts as "engine tuning."
12-07-2014, 10:34 AM
#316
You gonna eat that?
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I can only speak for myself, but I was waiting for someone to report on sound quality.
I imagine most people like me who don't race are waiting for others to buy it and relate their experience.
It's a sizable investment for everyday drivers.
Plus, it's Winter, so many are storing there 8s until Spring.
If I choose to get one, it will be then.
I imagine most people like me who don't race are waiting for others to buy it and relate their experience.
It's a sizable investment for everyday drivers.
Plus, it's Winter, so many are storing there 8s until Spring.
If I choose to get one, it will be then.
12-09-2014, 09:30 PM
#318
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I can only speak for myself, but I was waiting for someone to report on sound quality.
I imagine most people like me who don't race are waiting for others to buy it and relate their experience.
It's a sizable investment for everyday drivers.
Plus, it's Winter, so many are storing there 8s until Spring.
If I choose to get one, it will be then.
I imagine most people like me who don't race are waiting for others to buy it and relate their experience.
It's a sizable investment for everyday drivers.
Plus, it's Winter, so many are storing there 8s until Spring.
If I choose to get one, it will be then.
However, the hp gains are quite significant, so I'm sure daily drivers would have lots of fun with it anyway
12-10-2014, 01:12 AM
#319
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I can only speak for myself, but I was waiting for someone to report on sound quality.
I imagine most people like me who don't race are waiting for others to buy it and relate their experience.
It's a sizable investment for everyday drivers.
Plus, it's Winter, so many are storing there 8s until Spring.
If I choose to get one, it will be then.
I imagine most people like me who don't race are waiting for others to buy it and relate their experience.
It's a sizable investment for everyday drivers.
Plus, it's Winter, so many are storing there 8s until Spring.
If I choose to get one, it will be then.
I was going to help out one of the field testers with a sound video, DB readings as some tracks have DB limits.
Unfortunately it didn't happen maybe in a month or two once their car is sorted we can do a few videos for everyone.
12-11-2014, 05:12 AM
#320
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I know I'm wading in at the end of this conversation, so you'll have to forgive me for skim reading and cherry picking the discussion, but our long tube, offset branch header made a back to back (with associated fuel and timing tweaks) 16bhp gain on the dyno vs a standard manifold.
I talked about it with some guys on here who were looking at doing systems a few years back via PM, I don't know if they're still on here but they'll confirm it for you.
I don't mind stating it publicly now as we have gone away from the Renesis as our race motor anyway, and similar designs are starting to filter through to the aftermarket it seems, but a lot of people on here seem to believe that no overlap means you can't benefit from pulse tuning, I don't know where that comes from, it reduces the benefit, yes, but it certainly doesn't remove it, so using long headers with an offset centre branch allows you both to keep the velocity up and use the stronger harmonics to help make up for the loss that no overlap gives.
I talked about it with some guys on here who were looking at doing systems a few years back via PM, I don't know if they're still on here but they'll confirm it for you.
I don't mind stating it publicly now as we have gone away from the Renesis as our race motor anyway, and similar designs are starting to filter through to the aftermarket it seems, but a lot of people on here seem to believe that no overlap means you can't benefit from pulse tuning, I don't know where that comes from, it reduces the benefit, yes, but it certainly doesn't remove it, so using long headers with an offset centre branch allows you both to keep the velocity up and use the stronger harmonics to help make up for the loss that no overlap gives.
Last edited by PhillipM; 12-11-2014 at 05:16 AM.
12-11-2014, 10:16 AM
#321
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That makes sense to me. Leveraging something that critically changed in the exhaust behavior from the REW to the MSP to produce different results from similar attempts with RX-7s.
12-11-2014, 10:47 AM
#322
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Well, we know mazda deliberately designed the ports and header to prevent the last bit of charge from leaving the chambers due to emissions regs (as the last bit of charge by the apex seal is still fuel heavy and full of unburnt HC's - they'd rather hold that charge and have it go back through again, like built in EGR) - for power, you don't want that though, so you can use both the pulse tuning and the higher port velocity with the long-branch tubular to encourage flow through the port orifice - not only to remove that last bit of charge but also create a partial vacuum which helps with filling when the intake port opens.
Now, okay, it's not a lot compared to what switching from a log manifold to a tubular can do with proper overlap on other engines, but given the difficulty of finding more ponies on these engines, then a 16 horsepower increase isn't to be sniffed at on a Renny (although our back to back was manifolds only, so a full system change from stock and cat delete might see more horses) and I would assume BHR has extracted similar amounts?
I'll be interested to see what they make when people are testing anyway, your manifold is straighter than ours so I'd expect most people would gain that or more? Although we had more room by the port exits to play with.
As for not being on for a while - I'm afraid I've gone to the dark side and fitted an S2000 engine (cue pitchforks)
Now, okay, it's not a lot compared to what switching from a log manifold to a tubular can do with proper overlap on other engines, but given the difficulty of finding more ponies on these engines, then a 16 horsepower increase isn't to be sniffed at on a Renny (although our back to back was manifolds only, so a full system change from stock and cat delete might see more horses) and I would assume BHR has extracted similar amounts?
I'll be interested to see what they make when people are testing anyway, your manifold is straighter than ours so I'd expect most people would gain that or more? Although we had more room by the port exits to play with.
As for not being on for a while - I'm afraid I've gone to the dark side and fitted an S2000 engine
(cue pitchforks)
Last edited by PhillipM; 12-11-2014 at 10:57 AM.
12-11-2014, 12:06 PM
#323
12-12-2014, 02:27 PM
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To be honest, I still love the Renny, and I'm tempted to build another motor but running ceramics and re-coated side housings (we had a lot of wear issues, shock load may have contributed though) - but it'd go in the daily driver to be proven out before it went back in the racer....