wozzoom

I hit the dyno with my 86 and I finally got to play with my RPM actuated 6-ports. This is what I found:

http://wozzoo.tripod.com/Mazda/Pictures/JeffsDynoRun4.jpg

(If the link doesn't work, copy it into a browser)

The blue run shows my 6-ports opening at 4200 RPM, the red run has them opening at 5200 RPM. During the blue run, I lost about 9 RWHP and 13-14 Ft/lbs of torque.

If we assume that the HP curve is mostly linear, then that would be about a 10 HP loss all the way to idle! Screw that! Just thought you should know.

Jeff Wozniak
My Mods: http://wozzoo.tripod.com/stable.htm

Icemark

It appears to me, that the opening of the ports on either case is a little late, and particularly that the opening of the ports at 4200 there must be some explanation of a clear drop in HP. Perhaps since the stock fuel map opens the secondaries around 3800 RPM.

Also if I am reading the chart correctly it appears that the torque curve of your motor is not very linear when comparied to a stock motor, suggesting that perhaps the Apexi Super AFC is not set up correctly and you are running too rich.

SoloIIdrift

Looks nice! I have high hopes now for my N/A.

jacobcartmill

iTrader: (6)

thats interesting, i thought that 6pi just increased hp, how did it cause a loss at 4200? i thought they werent supposed to come on til like 5500

Icemark

VDI comes on at 5500, 5th/6th ports start opening around 3800

wozzoom

The 6 ports do open around 3800 stock. But then again my car isn't very stock. I'm running an S5 Street Ported engine with high flow exhuast/headers.

Opening of the 6 ports any earlier on my car posted similar results on every run. The best compromise was to have them open at 5200 RPM with the VDI.

I hear what Icemark is saying about my torque curve. My problem was it was very hard to tune the AFC because my ignition was breaking up above 5000 RPM. (IE: The wideband was all over the place above 5000 RPM) I need to make some changes to the ignition before I can attempt to tune again

DaleClark

iTrader: (55)

I'd be interested to see a comparison graph with the 6-ports closed through the whole pull overlaid with the 6-ports open for the whole pull. The sudden opening of the 6-port sleeves might have caused a hiccup or the like in the EFI, causing it to pull timing/enrich fuel/who knows what.

Anyhow, interesting results!

As far as the wideband breaking up at high RPM, how are you getting the RPM pickup? If it's a clamp-on pickup, it might not be able to lock on to the spark pulses that are coming that quickly.

Dale

slvr7

iTrader: (1)

Just to add a thought to Dale's comment - I was recently on a dynojet, and they used two clamp-on pick ups for the RPM - one on the leading and one on the trailing. Did they use two for yours?

Curtis
'86 GXL autox'r

wozzoom

Yep. The pickups for the RPM came from the two clamps on the trailing plug wires.

The wideband was a seperate unit that was not connected to the Dyno. The wideband had no idea what RPM the car was at. When my car would misfire at high RPMs, the wideband would show instant rich. The numbers would bounce between 12 and 15 all the way up to 7500 RPM.

I guess next time I run, I'll need to do some pulls with the 6 ports open and closed for the whole run... Then I will know the exact RPM to open them...

peejay

This is something I plan on doing if I ever get my 6P running

And then eliminate the pressure-controlled actuators for an electric solenoid or two, with an RPM activated switch.

Of course, the "crossover" point in the two HP curves might vary depending on throttle position, in which case things get much more complex!

rxseven

On the exhaust activated 6-ports the ports don't open suddenly at a fixed rpm. So I am not sure if the sudden changes in flow characteristics has anything to do with the dip. On my 85 SE, they start to open just under 3K and are fully open by 4K. I agree with icemark, seems a little late to open the aux ports. I would love to see a comparison with the sleeves removed totally. You are bound to see a greater increase in max HP without them.

wozzoom

I'll argue that point. Have you ever seen the side housing without the port sleeve installed? The aux port transition is horrilbe for air flow. (It's about 3/16" of an inch deep!) The air will hit the bottom of the port and have to bouce over a 3/16" inch lip before it gets SUCKED into the engine. This kills velocity. Unless something is done to smooth the transion of the aux port, then you'll loose power compared to the 6-port sleeves.

Also, the whole point of this post is to show that you loose HP and Torque by opening the 6 ports early! The dyno graph clearly shows that. Removing the sleeves will make the loss even greater down low. Do you really want to loose 10-15 HP and ft/lbs of torque to gain "X" amount on the very top? For a street driven car, keep the port sleeves.

Icemark

Or the added turbulence might help... I can't help but think at some point Mazda had tried pineapple style actuated ports, and for some reason decided not to go with them, despite the HP advantage.

Quote:

Also, the whole point of this post is to show that you loose HP and Torque by opening the 6 ports early! The dyno graph clearly shows that. Removing the sleeves will make the loss even greater down low. Do you really want to loose 10-15 HP and ft/lbs of torque to gain "X" amount on the very top? For a street driven car, keep the port sleeves.

Yes I agree, since you mention that your motor is street ported, the much higher than normal opening is probably helping, while opening too low appears to be cooling the combustion too well. From a overly rich mixture at mid RPM perhaps???

SoloIIdrift

Oh wait this is a streetported motor? Very interesting, I'm running almost the exact same setup but no exhaust yet.

Who did the streetport? Is it a huge one or templates from racing beat?

wozzoom

I did the street port myself.

The intake porting is mild. I extended the primary port by 1-2 degrees and widened it outward. I extended the aux ports by about 3 degrees upward. I then port matched all the intake manifold pieces.

the exhaust ports have the NA diffusers removed and replaced with Turbo II sleeves. The exhast ports were widened about 3/8" of an inch total. The exhaust port was also extended up and down by 1 degree for a total of 2 degrees.

I did not use Racing Beat templates. They were home made templates.

wozzoom

Total speculation. Mazda didn't install pineapple type sleeves because of the cost... If the sleeves cost $20 bucks per set, that would add up to a huge cost over the life of the car.

IE: $20 x 200,000+ cars = about $4 million! Do you think Mazda is going to spend 4 million dollars to equip every NA RX-7 with contoured 6 port sleeves? The bean counters say: "NO Freakin way!" Its called economics...

There is no way that adding turbulance to the intake is going to help give you more power!!! Why the hell do we port and polish our intakes then??? I guess all those flow benches out there are worthless...

SoloIIdrift

I assume you are using the S4 TPS/ fuel injectors and stock ECU.

What are your Apexi-AFC settings?

Basically I'm wondering if I'm running lean right now with stock exhaust, but same motor as you.

wozzoom

you assume correctly. S4 ECU and TPS.

My AFC settings are odd... Turns out I needed more fuel.
1000-5000 = + 5
6000 = +6
7000 = +7

Anything under +5 gave a very high 15 reading on the wideband. Almost 16... MY CAR is the Exception...every other NA I've seen has made more power leaning things out. Only way to set the AFC is to go to a dyno...

RacerXtreme7

iTrader: (2)

Heres a thought, your STOCK ecu turns on the secondaries around 3500-4000 RPM as usual, but guess what? YOUR PORTS ARE CLOSED, weres the fuel go???? hmmmm maybe it falls out of suspension and turns into little pools in your intake, then when they open (late as hell I might add) your engine ingest RAW un-atomised (fuel really doesnt atomize, it just floats suspended in air as small dropplets) fuel puddles for several thousand revolutions. Juat a theory.............. Could also be you described you raised the upper portion of the port, effectivly making the port close later then stock. 6 Ports have a really LATE intake port closing as it is stock, infact Racing Beat and Mazda Factory RACE Peri Ports close earlier then 6 ports. Maybe this extra intake duration is too much at those RPM's you've indicated and your getting your intake charge being squeshed back into the intake (reversion), thus loosing HP / torque. Just more theory.... Good luck with your project. Best way to end this debate is with ports closed and TUNED for an entire run, them run with the ports open and TUNED the entire run.

rxseven

Quick question wozzoom: How much could you widen the port without the threat of the corner seal dropping of into the port?

Roy James

I been kinda wondering the same thing. Im going to attempt a SP on this TII block i have, but im not sure exactly how much i can go before its "too far". I was thinking about getting some templates from racing beat or somewhere simliar. Anyone know if the templates are worth it? Thanks

wozzoom

That makes no sense. Do you know what happens to the primary injectors when the secondaries kick in???

When the secondaries come online, the primaries drop down there duty cycle by 50%. The secondaries come online at 50%. There is no extra fuel when the secondaries come online...

wozzoom

You can do one of two things:

1) Get the templates from racing beat/mazdatrix
or
2) Use the rotor as your porting guide...

I did the number 2 option. When making my template, I I started with the rear iron. I left the rear stationary gear attached and layed the rear rotor on top of the housing. In this position, I could rotate the rotor around the housing and see where the seals were in relation to the ports.

I would pass the rotor over the port and then move the rotor just past the port. I would then scribe a line on the iron for my extended port location.

peejay

Interesting. But totally wrong.

The lower port is never closed. Air flows through it to the rotor any time the secondary throttle blades (both sets if you still have both sets) are open. The sleeves only close off the upper ports.