Is porting for power a myth?

Any form of normally aspirated power mods.
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Re: Is porting for power a myth?

Post by PeteH » Tue Nov 13, 2018 3:23 pm

Which is fine, but it assumes you know exactly what your mass air flow really is. I think the first thing good tuners do is to calibrate the MAF sensor, because it's know to be pants. I could easily make one read something different just by putting it in a different tube, or taking out the screens, or spraying a bit of oil on it, or changing the battery voltage (probably, I'm guessing). MAFs are fun to look at, but I'm not sure they are a reliable alternative to a dyno.

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Re: Is porting for power a myth?

Post by V8 Power » Tue Nov 13, 2018 3:25 pm

Carl Ryan stated that my engine was now flowing 282g/s which was as good as he had seen from a N/A Renesis. I would like to find out how that translates into actual power though.
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Re: Is porting for power a myth?

Post by PeteH » Tue Nov 13, 2018 3:38 pm

Theoretically, a 231 uses 213g/s at 8200rpm.

A straightforward pro-rata increase to 282g/s would equate to 306bhp at the fly (say 245whp).

C'mon, get it on the dyno.... :twisted: :thumleft:
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Re: Is porting for power a myth?

Post by 13Black » Tue Nov 13, 2018 3:46 pm

Well yh, assuming the same intake and that no one has scaled it to buggery etc, but I'm not that stupid :P the latter would produce the same voltage anyway.

And no one said anything about it being an alternative to a dyno, just another metric that could be useful.
I believe they're rather accurate/repeatable from what I've seen, which is reassuring given its job.

Who needs fancy theoretical stuff when you have datalogs from several different engines of various porting configurations :P
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Re: Is porting for power a myth?

Post by RobinPZ72 » Tue Nov 13, 2018 5:19 pm

I don't know if this is true, but if the RX8 doesn't have the 4 wheels rolling within reason the ECU gets upset and reduces outputs! If that's the case you could have a well tuned car that will or could go like a bag of spanners!

Also if it's good on a dyno it could be a pup ready to chuck it's toys out on the road!

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Re: Is porting for power a myth?

Post by PeteH » Tue Nov 13, 2018 5:24 pm

You have to disable the traction control, otherwise it cuts power and tries to brake the rear wheels when you run it on a 2-wheel dyno. There was a rumour that the RX-8 knew when it was on a dyno, and deliberately restricted power, but we have seen no evidence to support this, and it appears to be one of those urban myths.
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RobinPZ72 (Tue Nov 13, 2018 6:23 pm)

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Re: Is porting for power a myth?

Post by V8 Power » Tue Nov 13, 2018 5:42 pm

Maybe we should blindfold them so they don’t know they are on a Dyno?
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13Black (Tue Nov 13, 2018 5:46 pm)
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Re: Is porting for power a myth?

Post by cib24 » Tue Nov 13, 2018 6:26 pm

Just book a club day at Santa Pod. The 1/4 mile trap speed never lies about the power you are making even if your ET sucks.
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RobinPZ72 (Tue Nov 13, 2018 6:44 pm)
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Re: Is porting for power a myth?

Post by RobinPZ72 » Tue Nov 13, 2018 7:09 pm

1/4 mile more interesting and sorts the men from the boys LOL!!!!!!


Santa pod a bit far! Elvington maybe!

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Re: Is porting for power a myth?

Post by 13Black » Tue Nov 13, 2018 7:24 pm

With my 2nd gear synchro, I fear that a 3-cyl Micra would beat me at Pod.
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Re: Is porting for power a myth?

Post by 350matt » Tue Nov 13, 2018 7:55 pm

reading through that FD power comparison it showed a street port was rather beneficial, however this is all at 350+ bhp levels of airflow

forced induction is the only way chaps.....

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Re: Is porting for power a myth?

Post by V8 Power » Wed Nov 14, 2018 8:06 am

PeteH wrote:
Tue Nov 13, 2018 3:38 pm
Theoretically, a 231 uses 213g/s at 8200rpm.

A straightforward pro-rata increase to 282g/s would equate to 306bhp at the fly (say 245whp).

C'mon, get it on the dyno.... :twisted: :thumleft:
I can’t believe it is that high.
Only one way to find out though.
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Re: Is porting for power a myth?

Post by Conan » Wed Nov 14, 2018 5:09 pm

V8 Power wrote:
Wed Nov 14, 2018 8:06 am
PeteH wrote:
Tue Nov 13, 2018 3:38 pm
Theoretically, a 231 uses 213g/s at 8200rpm.

A straightforward pro-rata increase to 282g/s would equate to 306bhp at the fly (say 245whp).

C'mon, get it on the dyno.... :twisted: :thumleft:
I can’t believe it is that high.
Only one way to find out though.
Are we going to run a book on this :lol:
My guess is 200-205 at the hubs
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Re: Is porting for power a myth?

Post by cib24 » Wed Nov 14, 2018 5:11 pm

V8 Power wrote:
PeteH wrote:
Tue Nov 13, 2018 3:38 pm
Theoretically, a 231 uses 213g/s at 8200rpm.

A straightforward pro-rata increase to 282g/s would equate to 306bhp at the fly (say 245whp).

C'mon, get it on the dyno.... :twisted: :thumleft:
I can’t believe it is that high.
Only one way to find out though.
It is peripheral intake and exhaust ported? So, essentially not a Renesis but an older 13b N/A motor highly modified?

Has it been mapped at all?

On the stock ECU maybe 200-230. On a standalone and mapped well then 280-320.
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Re: Is porting for power a myth?

Post by Conan » Wed Nov 14, 2018 5:15 pm

Perhaps we should make some competition rules :)
Guesses should have a maximum 5 HP span otherwise we could all get it right ;)
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Re: Is porting for power a myth?

Post by 350matt » Wed Nov 14, 2018 9:47 pm

cib24 wrote:
Wed Nov 14, 2018 5:11 pm
V8 Power wrote:
PeteH wrote:
Tue Nov 13, 2018 3:38 pm
Theoretically, a 231 uses 213g/s at 8200rpm.

A straightforward pro-rata increase to 282g/s would equate to 306bhp at the fly (say 245whp).

C'mon, get it on the dyno.... :twisted: :thumleft:
I can’t believe it is that high.
Only one way to find out though.
It is peripheral intake and exhaust ported? So, essentially not a Renesis but an older 13b N/A motor highly modified?

Has it been mapped at all?

On the stock ECU maybe 200-230. On a standalone and mapped well then 280-320.
I think its a hybrid so side intakes but peripheral exhausts
and why would an aftermarket ECU release so much more power? you can map these things well enough with Mazda edit and the stock ECU
or am I missing something?

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Re: Is porting for power a myth?

Post by V8 Power » Thu Nov 15, 2018 7:02 am

It is Peripheral intake and exhaust.
Tuned by Karl Ryan with standard ECU. He reckons there is potentially more power to be had by going with larger injectors and tuning accordingly.
For now it is set up well and safe.
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Re: Is porting for power a myth?

Post by 350matt » Thu Nov 15, 2018 6:42 pm

Why would going up in injector flow rate give more power? unless its being throttled back currently as the current injectors are maxed out?

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Re: Is porting for power a myth?

Post by V8 Power » Thu Nov 15, 2018 6:53 pm

When Karl first got it to tune it was running lean at the top end.
He richened it up to be safe within capacity for the current injectors. However he believes it may benefit from larger injectors due to its ability to shift air.
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Re: Is porting for power a myth?

Post by warpc0il » Thu Nov 15, 2018 8:50 pm

I'm surprised that the original injectors are maxing out, unless they need a good clean.

Some low pressure fi installations have been happy with oem injectors

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Re: Is porting for power a myth?

Post by 350matt » Thu Nov 15, 2018 10:15 pm

unless your injectors are up to 80%+ duty cycle then there's no need to change them and 90% of the time you want the injector to be 'just' big enough to give you the best control of the pulse width at high speed
and the stock RX8 injectors are 400cc / min? which should give injector cover up to 400bhp ( treating it like a 6 cylinder engine)

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Re: Is porting for power a myth?

Post by Dr. FrankenRex » Fri Nov 23, 2018 10:51 am

Having been out in Graham's car, it shifts a lot more air than you might expect... I'd certainly say larger injectors would be of benefit to it given the sheer size of the porting and the RPM it's hitting up top.
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Re: Is porting for power a myth?

Post by RobinPZ72 » Fri Nov 30, 2018 10:29 am

A quickie! When porting what measures are taken to insure balance between the ported ports volume?
How would you know if let’s say the exhaust ports all have the same volume or do, we rely on the PCM to sort out differences! You could do some very simple measurement with fluids just to make sure handy work done are as similar as possible!

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Re: Is porting for power a myth?

Post by ChrisHolmes » Fri Nov 30, 2018 10:43 am

Ooh! That would be fun with liquid in the auxilliary ports, not to mention trying to balance the combustion chamber volumes!
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Re: Is porting for power a myth?

Post by RobinPZ72 » Fri Nov 30, 2018 10:47 am

Yeah I did the Aux ports with and without the cylinder valve that’s when I notice that the back valve had a different cut out!! Yes I know I could of just looked at it, but hey tiz me!!!

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