A> ddunbar wrote:
Hello Paul,
On the 15-5-2003 you posted a 13B curve showing the benefit of the
dynamic effect on the normal aspirated engine. What is the length
where the valve opening is placed.
Do you have a curve on the turbo engine as the primary runners are at
around 21" which has no valve to give a shorter length.
The secondary has the valve and the length is 14".
My question is how much variation in the curve would there be on the
turbo engine.
--
Best regards,
ddunbar mailto:ddunbar@echidna.id.au
A> If I gave the impression the dynamic effect was beneficial for our use I gave the wrong
A> impression. It is not.
A> To answer your question Mazda did not say in the SAE paper.
A> No on the turbo HP curve availability but the 21 inch length with the dynamic effect
A> was chosen to improve the car engine torque at 2500-3000 RPM under modest boost levels
A> and to improve the BSFC at those same car cruise RPM levels. Total effective
A> runner length becomes 42 inches in that case.
A> My turbo system will use the 17 to 20 inch length WITH OUT
A> the dynamic effect to improve the BSFC under modest boost
A> levels during aircraft cruise around 5000 to 5500 RPM.
A> Paul Lamar
Hi again Paul,
I was aware of what you had posted and that is was for the non turbo
engine, I have trouble expressing myself in writing.
I was inquiring to why Mazda have the valve in the secondary runner
which is at 14" of the length.
--
Best regards,
ddunbar mailto:ddunbar@echidna.id.au
A> It gets really complicated when they have two different lengths in series.
A> One section is tuned at the 21 inch length and twice the 21 inch length.
A> The next section is tuned at the 14 inch length and twice the 14 inch length.
A> so you wind up with a series of humps in the torque curve all the
A> way up to max RPM and beyond in some cases :)
A> Mazda's biggest problem with the rotary in car use is low RPM torque.
A> It makes a better aircraft engine by far. I think they should forget
A> all the dynamic chamber mess and just use an electrically controlled
A> and de clutched super charger and be done with it. They will wind
A> up with more car type useful HP in the bargain.
A> Paul Lamar
Paul I found a copy of the curve that I was looking for, it was posted
30-5-2001.
It does show the difference between the non turbo and the turbo
engine.
I think you are right with the car exercise. Volvo uses this system on
many of their diesel engines.
Thanks for your help
--
Best regards,
ddunbar mailto:ddunbar@echidna.id.au
A> Please email that jpg to me as I don't recall which one it is.
A> Paul Lamar
Attached is the file I was talking about.
--
Best regards,
ddunbar mailto:ddunbar@echidna.id.au
A> OK that one. You will get more boost (about 3 psi more ) and power as that one
A> had the muffler on.
A> You can really see the hump in the torque curve of the six port NA
A> engine dynamic chamber effect at 2500 to 4000 RPM. That old six port
A> really falls flat at the higher RPMs.
A> It also looks like the turbo engine would benefit greatly
A> from a bit of street porting. Either that or the waste gate is
A> opening too soon. Probably the latter.
A> Since you are running a post 93 engine with the much larger
A> intake ports and the good 91 turbo charger you should get
A> a lot more power than 200 horses.
A> Paul Lamar
Paul I have a dyno sheet of a street car with the same work done to
the engine and turbo as mine which got 220 hp at the back wheels but
it seems a bit high to me.
I will scan it latter today and send it.
I am still trying to decide on a propeller.
--
Best regards,
ddunbar mailto:ddunbar@echidna.id.au
220 HP is very doable with the stock 91 turbo and your engine.
Paul Lamar
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