Not another Inertia vs Load based dyno comparison please..Recently had a UTEC installed along with a RFS and larger Vortech jackshaft pulley (34T) and dyno tuned on a Dyno Jet..I was hoping for more power under the curve but as it turned out , little to no improvement in Tq over my previous Dyno (also a Dyno Jet w/o the larger pulley but with the Split Second Box..)

My question therefore is would tuning on a Dyno Dynamics be helpful in raising the mid RPM 's (2500 - 6000) power levels due to the inherent advantage of a load based vs inertia dyno and the tuning capability of the UTEC...Thanks

 

I don't think it'll help.

On a vortech, you are making much boost in the midrange due to the linear boost response. Your tuner probably has you tuned really rich at that point. Below 6 psi, you should have your A:F in the low 12s and run as much timing as you can.

 

 

The A/F is 11.5, timing not sure of...Nothing inherent with a load dyno that would allow finer adjustments at various engine load points to optimize both A/F and timing that an inertia dyno is incapable of doing?

 

Yes.
The DD will allow your tuner to steady state the vehicle allowing them to more closely match the available parameters to what they consider an optimum condition. The gains @ WOT might be slight but the gain in partial throttle and throttle response will be noticeable.

 

Dyno tuning for peak power to impress, is too agressive for the real world since most dynos don't LOAD to real world conditions...........the engine acceleration is too fast and knock can occur in quarter/half mile street runs as the engine heats up internally higher than on dyno [even with cooling outside air].
A fan larger than the car is required to partially compensate.

 

Are you agreeing that a load dyno will help pick up some partial throttle power not attainable with an inertia dyno..I am not impressed with peak power since I don't live there and part throttle power is what I am looking for..

 

If you are referring to a dyno that could simulate a more real-life testing environment, the DynoJet equipped with the Eddy Current Load Absorption Unit would do the trick. The Eddy Current braking system is phenomenally smooth, as magnets do the job, rather that braking pads making contact for friction stops/load.

I suppose with the real-life load setup, tuning would be more precise for performance. But adding load, could result in lower power curves.

Is that what you meant?

Happy 2008!

G

 

What I am trying to understand is whether I could pick up some additional power under the curve with an load based dyno (Dyno Dynamics) over what I had the car tuned on which was an inertia (Dyno Jet). I recently had a UTEC replace the Split Second unit along with a pulley change ( approx 6% increase in blower RPM) and I was hoping for some additional power but as it turned out , no increase..

 

FWIW dynos are used to track changes. if you go in between dynos, the absolute numbers are meaningless.

unless you were to run a baseline on a DD without the 34t cog, you wouldnt be able to compare the curves anyhow.

 

I see what you're saying, you were hoping to get back the lost of turns=rpm=whp due to approx 6% increase in blower RPM when you upgraded.

I would say the most accurate measurement would be to do the after-new-mod on the exact same dyno, as the previous dyno figures for the comparison.

The 6% of extra turns does increase the heat factor, as well. Heat equates to the law of diminishing returns, in this case compression ratio. A 6% return of whp, which is a 1:1 ratio, through the entire power curve might be overly ambitious.

Switching to a totally different dyno setup, and risk changing another entirely different set of varibales would skew your readings rather than help.

Not sure if I am making sense here....but sounds very close to what I am trying to say

G

 

I wouldn't expect a 6% increase in power but would think 3% was attainable. Since the blower rpm increase is linear with the engine rpm I would expect to see some gain with this pulley and dyno tune (same dyno as the last one which I am comparing it against). When I compare these two dyno tunes no increase in power (under the curve) is made with this pulley and a UTEC swap for the Split Second Box.

The UTEC allows for finer tuning (250rpm vs 500 rpm for the S.S. Box).

The fundamental question I keep asking is "can tuning with a Dyno Dynamics Dyno unleash some power that was not/is not possible with a Dyno Jet..Recognizing the only two variables that can be optimized are A/F and timing..Will a DD do a better job of finding some power than a DJ?





What I am asking is

 

I think that I am beginning to understand your question, what you are trying to get at.

My unprofessional opinion, neither inertia nor load bearing dynos permits optimal tuning conditions; a good tuning, whatever that may be, is totally dependent on the tuner, an understanding of the car being dynoed, how sampling is done by a particular dyno and the work around.

Most dynos, add a correction factor to compensate for possible power loss, which tells you that the resulting numbers generated are meaningless.

The only reason I see why a load bearing dyno would be a more superior tuning tool. It is how the A/F being sampled, whether it is based on a Sweep Test or Steady State.

Most load bearing dynos, I believe, give you both options, and, Steady State is the sampling of choice for tuning.

Steady State sampling of A/F tends to produce more real world A/F results. The sweeping method tends to capture the acceleration A/F, which is usually rich and may cause the tuner to over compansate for real-world application and tune the car too lean.

G

 

Guys, I think you're all going about this the wrong way. Dyno is just an imprecise measuring device. What it really comes down to is how well can you "test" your map on a particular dyno. Let's think about it for a sec. Your car puts power down to the wheels as the result of your tune on the engine. The dyno tries to measure that output shows you some number that hopefully means something to you. Dyno A may show 5 apples. Dyno B will show 3 oranges. Apples or oranges, you're still making the same power. Sure, you can say, I make 5 apples of power to make yourself feel better or for bragging rights but to me, that makes no sense.

Basically, when you're on the dyno, you want to induce certain loads and RPMs and record your findings at those load and RPM combinations which 'tests' your map. And by testing, on pump gas, that usually means listening for knock. You will always be limited by octane on pump gas so when it comes to timing, knock will always be your optimum point indicator.
As far as fueling, you want to get as close to optimal torque AFR as possible. A lot of the times, you won't be able to get near that AFR because of other limiting factors. In those situations, you usually have to make a compromise of some sort. How do you know how far you can push fueling? I usually look at EGTs to give me an idea when things are getting too toasty. To the OP, do you have an EGT gauge? How do you know 11.5 is a good mark for you?

So, all of this is just a long way of saying that a load based dyno may be a better tool for the job but it will not help you make more true power. If you covered load X at RPM Y during your tuning and established that 20 degree advancement is optimal, reproducing this same condition on another dyno will yield same results....all other factors like temps, pressure, etc. being equal.

As a side note, a good road tune following a dyno session is usually a good idea. Road tuning helps to reproduce real life conditions and fine tune the maps.

 

Well….When you put it that way............................I will have to agree. Why is it just numbers that gets us all wild up; why not a work-of-art?

G

 

Road tuning is the best way to fine tune.....you don't get a pretty graph, but a dyno just can't simulate real world driving. even a load based dyno isn't very realistic........think about this.......when was the last time your car held a single rpm as load was increased? NEver. it just doesn't happen like that.

 

Indeed. When tuning, I found that you usually end up making a curve in a shape of a knocked over L: blast through the load points within a very small RPM delta , hit some max load point and slowly walk your way down the load axis as you climb through the RPMs. Some areas of the map can be very difficult to hit, like high load and low RPM. Road tuning FTW!!!!

EDIT: As a word of advice to DIY tuners, do not get hung up on WOT tuning. As much as people may brag about their driving skills, throttle is not a binary device. I have not had trouble in the past covering my load/RPM ranges without even using a dyno. You can tune with 20%, 50%, 75%, etc. of throttle and make your adjustments. That sequence alone will probably cover 80% of your map. I will even go as far as to say that you can even effectively tune without a dyno, IF (big if) you are tuning on pump gas and IF you understand your blower efficiency ranges.: set your blower for reasonable efficiency range, establish fueling to produce reasonably high EGTs and complete the tune with timing which will be limited by your octane. It's really that simple. If you're tuning on high octane race gas, it's possible to exceed MBT so you'll need a dyno to tell you where that point is.