M20 B3x Naturally Aspirated Stroker build past, present and future

[ForcedFirebird]

The g37 resonance tuning link I posted in your exhaust thread reminded me of the type of dyno being used, and I was wondering what you were testing on? Rollers, or bolted to the hubs themselves? I ask this because a friend of mine is a very good mechanic, and was the lead electrical tech for Toyoda in our area for sometime. In a conversation with a mutual friend (also very intelligent) the principles of dynamic tuning was bought up (explained to him by Roman, our mutual friend.) The typical roller dyno is not dynamic, and is really only used to lean out the tune, and the majority of the tuning is done while driving the car on the road. This is done like this because the car is not ever driven completely on, or off full throttle. The car is tuned under the circumstances in-which it is desired to be driven. On the other hand, a hub mounted dyno is in fact able to be tuned dynamically, and most, if not all of the tuning can be done on that dyno. I am just beginning to get into in-depth tuning and understating engine design to the fullest and was wondering if you could shed some light on the topic, and/or correct my understanding of what I have stated above.

There is truth here. I often tune the car to behave on the street and sacrifice power for drive ability, and to be safe for a longer life span.

[pantelones]

The g37 resonance tuning link I posted in your exhaust thread reminded me of the type of dyno being used, and I was wondering what you were testing on? Rollers, or bolted to the hubs themselves? I ask this because a friend of mine is a very good mechanic, and was the lead electrical tech for Toyoda in our area for sometime. In a conversation with a mutual friend (also very intelligent) the principles of dynamic tuning was bought up (explained to him by Roman, our mutual friend.) The typical roller dyno is not dynamic, and is really only used to lean out the tune, and the majority of the tuning is done while driving the car on the road. This is done like this because the car is not ever driven completely on, or off full throttle. The car is tuned under the circumstances in-which it is desired to be driven. On the other hand, a hub mounted dyno is in fact able to be tuned dynamically, and most, if not all of the tuning can be done on that dyno. I am just beginning to get into in-depth tuning and understating engine design to the fullest and was wondering if you could shed some light on the topic, and/or correct my understanding of what I have stated above.

[digger]

Little bit off topic, but where did you source your new throttle cable. I was trying to find one a while back, but settled for a 2nd hand one. Ended up being similar in stickiness so I just pumped some wd40 down the throttle tube which seemed to help :/

Also those are some great numbers :)

just went to the bmw dealer last year was about $100 ish

[bmwandhonda]

Little bit off topic, but where did you source your new throttle cable. I was trying to find one a while back, but settled for a 2nd hand one. Ended up being similar in stickiness so I just pumped some wd40 down the throttle tube which seemed to help :/

Also those are some great numbers :)

[digger]

Ahh I see. I pretty much figured that you were trying to eliminate the "plenum constraint" so to speak, but the way you changed the trajectory of the air rushing into some of the trumpets would be interesting to see on a dynamic model. All in all, your design looks great, but a booster-less (or electric booster) brake set up would be nice to eliminate the limiting space for a larger plenum yet. Also, why did you choose a cone filter apposed to the flat style used in the s54 CLS plenum?

I used a 4” inlet so that inlet velocity would be nearly halved assuming flow was the same. A small inlet would nozzle (aim) the flow to a certain point inside the box. hence I tried to minimize this by making it easier to convert velocity to pressure (pressure recovery) . I didn’t use a CSL style filter because of space. I think I could use panel filter if I did it again but it would not be as large as the CSL one.
It would be so easy without the booster there, if only they moved it on RHD cars…..

If I understand this correctly your basically stating that the small plenum is hurting low velocity despite the small runner size because it isn't feeding the runners enough air (at 2500RPM) to utilize the small runners to increase velocity, correct? And, the one that you have designed doesn't have that issue due to the fact that there will always be enough air in the plenum to keep the trumpets fed the air that they need to operate at an optimal efficiency?

One theory I had is that at low rpm the plenum (due to its size) was creating a slight amount of “negative boost” which caused a slight dip in the torque curve. Even the Dbilas with its big diameter manifold and plenum boosted torque in the 2600-3100rpm range (albeit by a lesser amount) and it has a larger plenum than the factory manifold.

Another theory I had was If I look at the open trumpet run this also shows signs of boosting torque at this rpm so perhaps the shorter runners 200-300mm work better in this range than very long runners 400mm+ like the OEM one. Maybe the fact that the length I am using works best at 5500-6500rpm means that at half of this engine speed it also works well?

You could probably model something in EAPro or similar and study pressure traces etc.

[pantelones]

I Played around with similar things before in solid works but you need port pressure as a function of time and pressure depends on the inlet so it is iterative. The solve time is a lot longer. I designed the airbox to be large so that it is effectively like open trumpet. If I had used a smaller volume airbox then there would be more Merit in a transient analysis.

Ahh I see. I pretty much figured that you were trying to eliminate the "plenum constraint" so to speak, but the way you changed the trajectory of the air rushing into some of the trumpets would be interesting to see on a dynamic model. All in all, your design looks great, but a booster-less (or electric booster) brake set up would be nice to eliminate the limiting space for a larger plenum yet. Also, why did you choose a cone filter apposed to the flat style used in the s54 CLS plenum?

The BMW manifold plenum has small volume and if you compare the torque curve the small plenum of the BMW appears to hurt torque at 2500rpm (even with long skinny runners) but helps at 3500rpm. Where as when I added the airbox there was no real tuning happening over the open trumpets just an overall small increase. plenum /airbox volume appears to work in a narrow rpm band where it resonates at the same frequency as the engine but you get a negative boost elsewhere

If I understand this correctly your basically stating that the small plenum is hurting low velocity despite the small runner size because it isn't feeding the runners enough air (at 2500RPM) to utilize the small runners to increase velocity, correct? And, the one that you have designed doesn't have that issue due to the fact that there will always be enough air in the plenum to keep the trumpets fed the air that they need to operate at an optimal efficiency?

[ForcedFirebird]

HP+ are nothing like these. Sending PM to keep your engine thread from getting cluttered.

[digger]

The pads I use are very aggressive. Carbotech XP20 front, Hawk DTC 70 rear. They are able to bring the car from over 100 to 30 just after the 200 foot marker on the track, but when slowing on the street, it sounds like a garbage truck. They will put your face in the dash at the end of my street, first thing in the morning.

hawk HP+ are also similar to this otherwise i would try them.

[digger]

I Played around with similar things before in solid works but you need port pressure as a function of time and pressure depends on the inlet so it is iterative. The solve time is a lot longer. I designed the airbox to be large so that it is effectively like open trumpet. If I had used a smaller volume airbox then there would be more Merit in a transient analysis. The BMW manifold plenum has small volume and if you compare the torque curve the small plenum of the BMW appears to hurt torque at 2500rpm (even with long skinny runners) but helps at 3500rpm. Where as when I added the airbox there was no real tuning happening over the open trumpets just an overall small increase. plenum /airbox volume appears to work in a narrow rpm band where it resonates at the same frequency as the engine but you get a negative boost elsewhere

[ForcedFirebird]

The pads I use are very aggressive. Carbotech XP20 front, Hawk DTC 70 rear. They are able to bring the car from over 100 to 30 just after the 200 foot marker on the track, but when slowing on the street, it sounds like a garbage truck. They will put your face in the dash at the end of my street, first thing in the morning.

[pantelones]

please sell it and use something better in that case.

I actually LOL'd

Ha yeah..... I just don't understand why people think that they can argue with physics.


Anyways, have you done a dynamic flow test like this?




I was brushing up in Solidworks for some projects in the near future, and will be designing manifolds for both intake and exhaust using the flow simulator. I also really like the way Newman made his turbo manifold in Sw and used the 2d drawings for templates. This video was pretty neat in showing how to maintain the overall length while changing the tubes themselves.






Good progress digger! :up:

[digger]

For street pads, maybe. I bear with the noise and just leave my race pads on all the time (use it in events about once a month). Can't keep the wheels clean for long with them, either though.

my wheels get dirty but the jurids and textar have the best initial bite when cold which makes the pedal feel a little more linear.

tried some race type pads ages ago (local brand) but they needed to get to temp before they started to bite, they did bite very very well though.

will need to do a big refresh, lines, calipers rebuild at rear and maybe BBK or just a rebuild of front calipers etc then a flush and bleed etc

linkage for RHD that goes across from the drivers side to the passenger side to the booster doesnt help and sometimes adjustment helps.

i guess the lower vacuum from the engine doesnt exaclty help either

[ForcedFirebird]

im running stock pads and rotors, the stock pads feel alot better than others ive tried.

For street pads, maybe. I bear with the noise and just leave my race pads on all the time (use it in events about once a month). Can't keep the wheels clean for long with them, either though.

[digger]

What kind of pads are you running ? A decent pad makes a huge difference if you are not already running them.


Also, we are going to need some videos up in here.

im running stock pads and rotors, the stock pads feel alot better than others ive tried.

[evandael]

damn. that's a nice powerband and excellent results for 80's engine architecture.

nearly 100 more bhp than a stock m20!