it must be the infamous batwing style port

 

Thanks, I couldn't recall the name of them. I didn't mean to imply that NACA ducts were knew, but my point is that it was a functional design that may not have been R&D'd on a combustion application. If Round and Square are what has been implemented thus far, who knows what could be hiding behind that tape.

Reading a wiki on NACA ports can shed some insight on the purpose and benefits of that style ducting, I was just giving a theory onto why it might be tight lipped and hidden. Because why would it be so secretive if it was a run of the mill round/square port job?...or perhaps it's rotary shaped for aesthetics...and it will shoot out rotary shaped flames

 

The new 2008-2011 Mazda6 has a cd of .27 Nice to see progress is made with engineering focus from a wind tunnel. Though go with the 2011 as it has double wishbone up front vs the MacPherson in prior years...I didn't catch that difference until I already picked up the 2010.

 

Yea and when i posted that i got some BS run around about ppl trying to make a living. Howard has put out **** tons of useful information and maybe he will post pics of the ports who knows. I have PM'ed many "top dogs" on here with zero reply what so ever. I guess i haven't earned there "respect". Howard always will answer any questions and try to help out as best he can.

 

i do apologise for the thread at 378 posts and not yet on the dyno. people are reading this thread to learn more comparatively about turbos and not about my porting which i choose to keep to myself.

i do want to respond to the aero stuff.

CD of course is multiplied by frontal area so while the Maz 6 may have a .27 number it has a much larger frontal area V the FD. i don't want readers to think that it takes less hp to push it through the air as it doesn't. that said, kudos to Mazda for the .27

another point re post 378... the earlier Maz 6 (i own one) does have a double A arm suspension. it is a trick design that is sort of hybrid but does deliver negative camber gain on bump so do take a closer look.

speaking of my Mazda 6... it is kind of unique as it is a 6 rotor!


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But don't you think porting is intricately tied into turbo selection just as Cam selection is in Piston applications? It's not exactly something to brush off, not to mention the wheel can only be invented so many times...

 

Improperly ported exhaust can also cause the apex seal wear that Howard experienced.

As far as aerodynamics, Cd also does not tell the whole story- CdA is a better measure as it include frontal area.

Progress.... 1935 Tatra T77A Cd = 2.12

 

True...porting does have a lot to do with how quickely the motor can intake or discard exhaust. BUT it really doesn't matter in the case because all the turbo's will be tested on Howards motor, so the port stays as a constant in this experiment. As well as his whole set-up, which is what this thread is all about. "Turbo performance." and seperating fiction from reality!

 

Howard,

Do you think placing the BOV on the pipe up stream of the IC will have the same effect at place the BOV on the pipe from the IC to the elbow?

I like the idea of placing the BOV off the IC end tanks, but the picture I had seen of your set up use a long bent tube. Do you think that bend and length helps or hurts the pressure in the IC?

I have a v-mount set up and I will need to look at tanks and will see if I can place a similar set up as you with the BOV place in between the Rad and the IC on the tank leading to the elbow pipe. My thinking is that the cool air from the IC being released by the BOV will allow for extra cool air to pass the IC and Radiator.

You input is always great.

 

That's impressively awful, considering that a barn door's Cd is 1.

 

HC can ignore the port, but the turbo which wins this test may not be the best choice for someone with different ports. It's always about the combo...

 

Their has become too much **** talk in this thread Howard can't wait to see final results with all the different turbos from what I have seen a well ported engine works well with most turbos and will show similar patterns of power delivery I'm sure Howard has a handle on his porting styles etc

 

Why would anyone care at this point what these turbos do in comparison if we have no idea what the port design is?

Howard himself made this comment about port design, "...port design as well as turbo configuration play a huge role in determing midrange hp on a turbo'd motor..."

I guess my next question is what is the actual point of this thread and what are the majority of people who run stock/street ported motors supposed learn from secret port designs and dyno hype that has yet to happen?

 

Don't let the perfect be the enemy of the good!

Though I concur that porting has an performance effect (perhaps on the margin), HC's work here has substatial goodness in assessing overall turbo selection. The value of this is more than I've seen anywhere else on this forum with the possible exception of Sean's myriad posts.

Keep your eyes on the prize HC... and THANKS!

 

"Do you think placing the BOV on the pipe up stream of the IC will have the same effect at place the BOV on the pipe from the IC to the elbow?"

there are two issues to consider re your question... the first is the actual performance of the BOV... being closer or further from the turbo. lots has been written re reaction time, efficacy etc and i don't believe anyone has conclusively demonstrated that location is significantly important as to BOV function.

the other issue is aero flow and here i do have a strong opinion. Greddy and Mazda spent time crafting well reasoned elbows to help make the 90 degree turn and set up for the triangular positioned butterflies.

in the non turbo NA world flow benches rule. since engines are just air pumps you want to get as much air into and out of the engine. NA motors don't have a mechanical pump (turbo) ramming the air in so they really have to spend time on flow.

we have a pump so we can if we choose be lazy. we will still get lots of air into the motor. that does not mean we should be lazy. every CFM counts and it is no different w a turbo. my entire system of manifolding is designed w flow in mind. and that includes BOV placement.

IMO the worst place you can have your BOV is on the outside of any bend and the number one worst place is the elbow, just before making the all important turn towards the throttle plates. and yes i know Greddy does make an elbow w a BOV boss in just this place. (i am sure the engineers at Greddy weren't happy about that... probably a marketing/convenience driven decision).

as i see the pressure side of the turbo'd rotary, the needs are...

a large efficient non restrictive (at 1000 CFM) air filter so the compressor is not penalised w incoming drag. (my manifolding accomodates a 9 X 7 filter w less than 1.5 inches of water drag at over 1000 CFM).

engine compartment air is 150 degrees. outside air is a must

short straight delivery to IC

tube volume minimized.

efficient, large IC. remember rotaries need 1.3 times the air that piston engines need to make one hp so airflow is V important. your IC should remove over 130 F temp from the charge air w modest restriction.

after the IC you are on "final approach" w the goods. you want smooth surfaces heading towards the 90 degree turn to the motor and you want the flow to be shape-changed to conform to the triangular shaped throttle body.

the last thing you want is some big disruptive 2 inch diameter BOV hole.

again going back to the NA guys who know their stuff on flow... put it on a flow bench and you would barf.

the tubing from the IC to the throttle body should receive lots of love.



"I like the idea of placing the BOV off the IC end tanks, but the picture I had seen of your set up use a long bent tube. Do you think that bend and length helps or hurts the pressure in the IC?"

the single reason my BOV is on the extension tube is to fit the IC fan. i don't think it is an issue but if i didn't run the fan it would be bolted directly to the IC.

"a barn door's Cd is 1."

depends whether it is zipped or not.

"a well ported engine works well with most turbos and will show similar patterns of power delivery"

absolutely.

when finished, this project will provide alot more than top tick SAE hp numbers. it will provide spool curves, BSFC differences, EGT differences, EMP (pre turbo back pressure) differences and a (most important) horsepower under the curve Index.

under the curve?

w the semi dreadful (for performance) gear spacing on the stock FD trans guess where you are after shifting at 7800?

2nd is 4512 RPM
3rd is 5384
4th is 5607
5th is 5608

and that doesn't give any additional RPM deduction for acceleration drop-off between gears.

you are interested in going fast... how much time have you spent looking at your power at 5500? 4500?

it is relevant and turbo output characteristics play a large role. we will nail it down w the HP under the Curve Index.

porting plays a huge role here BTW.

rotary porting is far more complex than most believe. it starts w a degree wheel. i raced/built piston engines for many years before switching in 83. i designed/raced my own cams in conjunction w Competition Cams for a number of years. rotaries, while somewhat different, are more similar to piston engines than you might suspect. as such, it wouldn't hurt to do some time reading on cam timing.


sure, your results will differ. i could name 25 items on my setup that will be different than your setup. some items on your FD could be better some worse than my setup.

the key is i will be trying hard to keep my setup constant so the turbo differences can be isolated.

i am doing this project for one reason... to satisfy my own curiosity. i will say it has become even more tantalising w the intro of a few new potentially amazing turbos so i can assure you i am more anxious than you are to get rolling.

 

That's impressively awful, considering that a barn door's Cd is 1.

ya, sorry typo-

Progress.... 1935 Tatra T77A Cd = .212

 

Thanks for the reply Howard.

 

Any update on this?

 

Ah, but are the sleeves in place, or were the ports enlarged to sleeveless spec, or were the exhaust port openings kept small and smaller diameter sleeves fitted?

I forget where I saw it, but just crushing stock sleeves to eliminate the rapid area change was worth a 30+ percent increase in flow. Also a large increase in noise. Higher flow with smaller size means higher velocity, which I assume is something a turbine would want. (That's not facetious. I keep seeing engineering evidence to the contrary!)

 

my motor will be back at Beyond Redline (otherwise known as Titletown-- you know, Green Bay and all that) by this next Friday Feb 18.

i bought a new Datalogit from Ari and i asked him if it really could run 8 auxilliaries... after a pause, he said he didn't know. my old DL would only run 4. the DL site says 8. i emailed them and they said 8.

that's really exciting because i have not been able to log everything i wished.

currently i log AFR, Fuel Pressure, EGT and EMP (Exhaust manifold Pressure.... "backpressure" preturbo). since that's 4 i haven't been able to log both EGTs. i guess i will be able to w the new unit.

let's hope all works proforma as i am really interested in evaluating the turbos.

howard

 

I have a power fc with old type commander and no datalogit but my tuner has one (I don't know if it logs 4 or 8 auxilliaries but I'm assuming it does 4 only).

I am getting bungs welded on each runner to connect dual egt with my single turbo set-up. I know dual egt is recommended but would it be an overkill in my situation? Should I just go for single egt?

 

proper tuning is a 3 legged stool.

EGT, along w knock and AFR, will dial you in. all need to be logged. a single digital logged EGT is all you need.

howard

 

Howard, have you considered dropping the PFC in favor of a more sophisticated ECU? I am currently looking into the newest Wolf, it seems to be a much more powerful option.

 

Haltech FTW!

 

It would be best to do the test with the most used and known ECU for these cars, the PFC, as to be comparable to what most owners can achieve with it.

Then repeat with AEM, Haltech, Microtech, Motec, Wolf, etc and note the advantages and disadvantages, similarities and differences from them all... but it would take forever! and a large bank account!