FI Discussion Thread for the Boost Atheists
01-08-2008, 04:36 PM
#251
Registered
I had always thought the max idle to pass inspection in Texas was 1000. It's actually 1200 rpm. There are many aftermarket tuners for various cars that idle the engine around 1000 rpm. I run 1000 rpm in my RX-7 as it's smoother and there are no downsides other than a small fuel penalty for idle fuel consumption. Fortunately this is negligible. With the larger e-shaft oil jets that I run, I need to hold 1000 to keep idle oil pressure where I want it anyways. Nothing wrong with 1000 rpm idle at all.
01-08-2008, 05:56 PM
#253
FI is not necessary either. But life is full of choices. I prefer the 1.1 idle.
30% more fuel consumption? Please say that in the right context. It is not a 30% overall more fuel consumption it is 30% more than a 900 rpm idle will get ya. So in the end---not very much at all.
I know of many cars that have a 1K idle. yall havent been around modified recip engines much have ya?
Track Ported rotaries idle much faster than 1.1 k.
oscd
30% more fuel consumption? Please say that in the right context. It is not a 30% overall more fuel consumption it is 30% more than a 900 rpm idle will get ya. So in the end---not very much at all.
I know of many cars that have a 1K idle. yall havent been around modified recip engines much have ya?
Track Ported rotaries idle much faster than 1.1 k.
oscd
01-08-2008, 06:12 PM
#254
I know of tons of cars that idle all over the place. I've been around motor sports for nearly 30 years one way or another, so I am well aware that there are a million different behavior profiles for engines in all different kinds of operating conditions and power expectations.
That isn't my point.
Why should one settle for these "compromises" if they aren't necessary?
My car is the same as yours. It rolled off the same factory line as yours did.
So why should you be content with things like and elevated idle just because your car is FI?
My car is FI and I make considerably more power than you do, but my idle and mid/low throttle behavior is exactly like stock.
Why settle for less?
That isn't my point.
Why should one settle for these "compromises" if they aren't necessary?
My car is the same as yours. It rolled off the same factory line as yours did.
So why should you be content with things like and elevated idle just because your car is FI?
My car is FI and I make considerably more power than you do, but my idle and mid/low throttle behavior is exactly like stock.
Why settle for less?
01-08-2008, 06:29 PM
#255
I know you have been around jeff---I was only making a point with the recip comment. I really like the R3's and you used to play around with those.
the 1.1K idle is not a compromise--it is what was wanted.
you have low speed and idle like stock because your oem pcm is running the engine during those times?
We are running a total oem maf system--the sensitivity of the maf at the lower flow rates is impressive as you well know.
Ok so you have more power--maybe you do---but at higher pressures. Turn yours back to a 6lb boost and you are putting out less than 300 to the wheel.
Ok i am done--no new info going on and this has been around and around
oscd
the 1.1K idle is not a compromise--it is what was wanted.
you have low speed and idle like stock because your oem pcm is running the engine during those times?
We are running a total oem maf system--the sensitivity of the maf at the lower flow rates is impressive as you well know.
Ok so you have more power--maybe you do---but at higher pressures. Turn yours back to a 6lb boost and you are putting out less than 300 to the wheel.
Ok i am done--no new info going on and this has been around and around
oscd
01-08-2008, 08:03 PM
#258
OK. Maybe I exaggerated the HP for a stock car a little. Let's say a stock car has 190 hp (totally within the realm of possibility).
So (190*5252)/2500 == ~400 lbft
It’s still an unbelievably awesome amount of torque. One that even leprechauns and fairies would be proud of.
01-08-2008, 09:30 PM
#261
Well, one of the benefits of the snail is that you can "tune" the system to what you want. In MM's case, the snail is able to pump more air at the same PSI as other systems because of the design. The choices made "tuned" the snail to the output of the car, so in a sense "tailor-made". All in the name of efficiency...which I whole heartedly approve of...
01-08-2008, 11:30 PM
#263
Registered
Why don't you just tune your car to run a lower idle then? With a standalone I've gotten stock ported rotaries to idle at 500 rpm? If 500 works, that must mean a higher stock idle is in fact unnecessary. Isn't that how this works? To say it's unecessary is subjective. It's an opinion that doesn't make it any less correct to do.
01-09-2008, 08:31 AM
#265
Jeff---no-- i havent dynoed my car. i am not a big dyno fan---unless --it is for evaluating parts to add to a car for a specific affect. I absolute hate comparing different car's dyno's sheets. It is a medium for a lot of non productive conversation. So many variables.
I admit i am still old school in a way and i do a lot of evaluation on the "feel" of the car. Not the most scientific i readily admit. Not the best for maximum results of modifications/engine tuning, i also readily admit. But for me it is the best evaluator of overall results. I try to personalize the engine response, suspension response, brake response to what i am trying to get etc. I have found that seat time is the best for me to do. It is a connection that ends up being more than just numbers. Objective? Mostly. Subjective? Some.
That personalization is one of the reasons I choose the FI kit that I did.
Just for comparison you personalized your own ride, made your own kit and ended up with a great set up---for you. You did it the best way ---for yourself. You shared your results and people can take that and use bits and pieces , if they like, to make their own. That is the way everyone should do it, but so many rely on what "others" say for a complete build.
Partial vicarious ism is OK
,
I am advocative also, of self install. Why FI a car(major mod) and end up not knowing how the end results were reached--or even what to look for if a little trouble starts. Who knows you may even spot something that could be improved on
I do plan on getting a baseline dyno , once my new coils, and midpipe gets here.
oldscdragger
I admit i am still old school in a way and i do a lot of evaluation on the "feel" of the car. Not the most scientific i readily admit. Not the best for maximum results of modifications/engine tuning, i also readily admit. But for me it is the best evaluator of overall results. I try to personalize the engine response, suspension response, brake response to what i am trying to get etc. I have found that seat time is the best for me to do. It is a connection that ends up being more than just numbers. Objective? Mostly. Subjective? Some.
That personalization is one of the reasons I choose the FI kit that I did.
Just for comparison you personalized your own ride, made your own kit and ended up with a great set up---for you. You did it the best way ---for yourself. You shared your results and people can take that and use bits and pieces , if they like, to make their own. That is the way everyone should do it, but so many rely on what "others" say for a complete build.
Partial vicarious ism is OK
, I am advocative also, of self install. Why FI a car(major mod) and end up not knowing how the end results were reached--or even what to look for if a little trouble starts. Who knows you may even spot something that could be improved on
I do plan on getting a baseline dyno , once my new coils, and midpipe gets here.
oldscdragger
01-09-2008, 08:39 AM
#266
Registered
I'd love to see the actual test data that verifies that's the resonant point of the engine based on those mounts! I suspect I'm not going to get it though.
01-09-2008, 12:30 PM
#267
i am not a big dyno fan---unless --it is for evaluating parts to add to a car for a specific affect. ...
I admit i am still old school in a way and i do a lot of evaluation on the "feel" of the car. ...I try to personalize the engine response, suspension response, brake response to what i am trying to get etc....
That personalization is one of the reasons I choose the FI kit that I did.
...
I am advocative also, of self install. Why FI a car(major mod) and end up not knowing how the end results were reached--or even what to look for if a little trouble starts. Who knows you may even spot something that could be improved on
I admit i am still old school in a way and i do a lot of evaluation on the "feel" of the car. ...I try to personalize the engine response, suspension response, brake response to what i am trying to get etc....
That personalization is one of the reasons I choose the FI kit that I did.
...
I am advocative also, of self install. Why FI a car(major mod) and end up not knowing how the end results were reached--or even what to look for if a little trouble starts. Who knows you may even spot something that could be improved on
Ultimately, its your own butt that you have to answer to. (That didn't sound right - but you get my meaning.)
A motor suspended in rubber is going to have an RPM at which the responsiveness of the mounts is equal to the torque roll of the engine.
Shall I make another video?
01-09-2008, 12:51 PM
#269
The NVH assessment for any car considers the idle speed.
The motor mounts have two operating "zones" - load and idle.
Under load, they need to keep the motor in one place. At idle, they need to cancel the motor's propensity to rock back and forth.
Their fundamental resonant frequency (or the first harmonic) ends up being somewhere just under nominal idle or they will be too hard.
The motor mounts have two operating "zones" - load and idle.
Under load, they need to keep the motor in one place. At idle, they need to cancel the motor's propensity to rock back and forth.
Their fundamental resonant frequency (or the first harmonic) ends up being somewhere just under nominal idle or they will be too hard.
Last edited by MazdaManiac; 01-09-2008 at 01:09 PM.
01-09-2008, 01:08 PM
#270
Except after total taco Tuesdays...which requires me to carefully recalibrate due to o-ring failure and fluid blowout...heh
01-09-2008, 01:18 PM
#271
I am actually disappointed in how poorly my butt is calibrated.
I find that even fairly significant increases in power only register slightly while minor decreases in power go off the scale on my ***-o-meter.
When I gained almost 70 HP between dyno runs on my MX-3, I thought nothing had changed.
But when I was convinced I had lost compression in one cylinder (I hadn't) and lost half of my power, I was actually only down about 15 due to a bad distributor cap and rotor.
I find that even fairly significant increases in power only register slightly while minor decreases in power go off the scale on my ***-o-meter.
When I gained almost 70 HP between dyno runs on my MX-3, I thought nothing had changed.
But when I was convinced I had lost compression in one cylinder (I hadn't) and lost half of my power, I was actually only down about 15 due to a bad distributor cap and rotor.
01-09-2008, 02:33 PM
#273
EvilTwinkie ***-o-meter Recalibration Procedure:
Take Jeep Grand Cherokee aka: "Marshmellow" to the kart races...
Drive the "marshmellow" to the kart track to drive around in torque less high speed "ball bearings" only to leave and feel like I'm driving on top of a flagpole with a marshmellow...
***-o-meter reset...