Liquid Anarchy

iTrader: (2)

After talking to someone semi-knowlagable on the subject, I'm getting kindof nervous about my aux-bridge project on my S5 N/A.

So far, my plan was to harden on the e-shaft, and stationary gears, and do all the nessasairy (sp) oil modifications. I wasn't going to do race clearancing, or anything like that, as I'd only see the redline breifly while drag racing.

Also, I'm converting to Mechanical OMP, 12A Dizzy, and a Megasquirt for fuel; I planned on using the stock manifold (ported, polished, and beadblasted from TB to the Keg), and also, keeping a working 5/6th port system, cutting slots in the sleeves where the bridge's port openings would be (effectively closing the bridge until the ports opened)

Does anyone have experience w/ this, or see any flaws in my thinking? I remember Ito having some stuff to say about it... but his inboxes, always full.

I'm iffy about it now that I hear it "won't" work, and would just like to eb 100% sure before I start on it later this month.

drago86

Ito made 2 i think, as i remember, the s4 one worked alot better, i think because of the manifold, and i think they had a slight brap at idle, but were still pretty driveable. All this is stuff ive picked up indirectly from the other forum.

drago86

DP

88IntegraLS

You might know this already but Mazdaspeed7 just built an Aux bridge S5 engine and found that the stock computer couldn't keep up with the airflow, but you say that you will be using a megasquirt (not too familiar with it) so perhaps you will be ditching your maf sensor.

Remember that the runner splits before the secondary / aux rendering any kind of pressure wave tuning effect pointless. Mazdaspeed7 is working on making a custom intake manilfold but doesn't post here much. Check out the other rotary forum . . . he posts there quite a bit.

KNONFS

iTrader: (14)

Not to be an ***, but he also said:

-That he had a 14 sec car and never showed proof!
-True duals was the way to go, yet he changed after a couple of years
-Convert from the oem afm to a mustang maf

I would rather go with Itos experience!

Liquid Anarchy

iTrader: (2)

MS was the person who told me that it "can't be done". I intend to do anyway, but would like more info about it.

Now, about the S4 being better than the S5. It's proven that the S5's length is tuned better for high-RPM, correct?

My thought is, the intake (and opening point of the 5/6th ports and VDI) was designed to work best with the stock ports. Aftermarket ports should warrant aftermarket actuation points, correct? Just a thought.

$65 for 3 base pulls on a Dyno. 1st, 5/6 & VDI closed, 2 5/6 Open & VDI closed, 3 5/6 & VDI Open. Where the lines cross are the new, optimum opening points for the 2 systems. $65 for a new, optimum powerband. Even if it doesn't make as much total power, it will have a much better low&mid-range.

...kind of a "here's what I'm wanting to do" post... I guess I'm just hoping to bump it until someone with experiance (Ito), or someone with a good knowlage of rotary engines, and could give me some extra input.

88IntegraLS

Sounds like a good idea, doing dyno runs and superimposing the graphs of vdi open / closed on each other to see where the optimum actuation point would be for your new ports.

Sorry to hear about your past experiences with MS7. You might get more replies at the other place because there are more active members who have ported engines (Ito for one, who posts there a lot more than here).

j200pruf

iTrader: (4)

No a VDI manifold is a waste once you have a non stock ports. Mazda tuned them for the stock ports. I would suggest going with a aftermarket manifold and webber style TB's. I too am designing my own intake for bridged aux port motor, and though my design was "new", then looked and mazda pretty much did the same thing I am, with the RX8, only they used a plenum style.
Plus if you check out nopistons, you can find ito's posts about his bridged 6 port motors.

Liquid Anarchy

iTrader: (2)

I'll eventually go with an aftermarket UIM w/ individual TB's, I really want to keep the LIM w/ working 5/6th ports... the thought of torque appeals to me.

But currently, I'm not after the best setup. The total of everything done on this rebuild is coming out to under $500.

drago86

my best guess would be that the vdi closed will give you peak HP.

rotarygod

iTrader: (1)

The biggest problems with the VDI manifold are that the runners are way too long. The more extreme the porting the LOWER in the powerband the gain from the manifold (not the porting) becomes. It still gets narrower as well. Also the VDI itself isn't helping at the same rpm anymore. It will still have a benefit but at what rpm is anyones best guess. When you have an aux bridgeport, each port wants a different length intake runner. The aux ports will want a much shorter runner setup than the lower ones. Obviously this becomes a problem with the stock manifold. With a standalone ecu, you should be able to get it run just fine but obviously its potential won't be tapped until later. If you must use a stock manifold for the time being, my vote goes to the S4 manifold. Shorter runners and VDI isn't there to complicate things. I would go so far as to modify it by hollowing out the dynamic chamber into one plenum and using a different throttlebody but I also like doing tons of work. I did this on a stock ecu equipped car and it worked OK but when the standalone was installed it was nice. Good tuning retains much of the low end power that I lost from always having air flow through all the runners but the top end was great.

If you aren't going to raise the redline, then there shouldn't be any need to harden or clearance anything. Oil system mods shouldn't be necessary either. There is no such thing as overkill though so it is never a bad thing.

Liquid Anarchy

iTrader: (2)

I intend to redline it, but not on a daily bassis. More likely a few times a night on the weekends.

As per the " It will still have a benefit but at what rpm is anyones best guess." It's no guess when you hop on a dyno.


Like I said, I intend to do more later, right now, I'm just wanting it RUNNING. I've been looking at running individual TB's, and it could happen in the future... but I'm more concerned with it just plain RUNNING (That and the MegaSquirt Setup)

drago86

Rotarygod, because both ports taken as a whole will have much more port timming then stock, he would need a longer manifold because the port would open alot earlier. I also think the vdi will be all but usless. If you must use the s5 manifold, id bet almost anythign that a closed vdi will give you the best power. I also think the s4 manifold would be better, but i havent pluged anything into the equation,so its just a guess.

drago86

Also you dont need hardend statonary gears and a clearenced e-shaft for redline, My motor sees 500 over almot everyday and its no worse for the wear, just dont go over 8500ish with stock seals. I think an aux bridge with a mega squirt would run great, and im looking forward to dyno numbers.


Also when your done porting just take the ~port timmings and plug them into the equation, then measure the length of the s5 manifold, and see where it lies in regards to rpm tunning, i think it will be close, if its too long, consider an S4 manifold.

rotarygod

iTrader: (1)

Lets not get into a runner length argument again. Runner length needs to be shorter with increased port timing. The path needs to be longer for VDI to work in the same rpm range. Don't get those 2 mixed up. Besides, each port on the end housings has its own runner into the engine so when the rotor passes over the bottom one and completely closes it off, the timing for the upper one is different. Optimally each port needs its own runner like the Renesis has. Anything else is a compromise. Never the less I feel that it can be made to run very well when tuned properly.

Rotortuner

Rotorygod is completely right when he sais that increased port timing requires shorter intake leangths. Your going to need to fab something custom, with a good tig and some AL tubing, shouldent be too hard.

CJG

KiyoKix

I can't wait to see some dyno numbers on this subject already . I've had this idea for some time now, but wasn't really sure about it until I read some more (I want to read Judge Itos' posts...but I haven't really found anything except for just a couple lines on it ).