Classic Retrofit CDI+: Dyno Results

[Jonny H]

Hi,

As we start to get uptake for our CDI+ box, I thought I'd start a thread for dyno / rolling road plots.

First up, an Australian customer who runs a 1969 2.0L Race Car.

This is one of our units straight out of the box with no timing curve adjustments (at the moment)

I'll let him explain:

Jonny

I am still waiting for the correct exhaust system for the car to help with the mid range "hole", but thought I would get a quick dyno run in for starters.
I have gained from approx 4900 rpm up and what is really surprising is the bump in power up at the top. Did a few runs and this was always repeatable.
Blue run is Bosch CDI and red line is CDI+
Hopefully the exhaust will smooth things out and then I can start fine tuning and playing with ignition advance.

Rob

[universeman]

This is exactly the proof you/we need for this product! Excellent, can we get more? How about offering your early customers a small discount in return for sending in their dyno results, definitely will help you sell more!

[mysocal911]

Originally Posted by universeman

This is exactly the proof you/we need for this product! Excellent, can we get more? How about offering your early customers a small discount in return for sending in their dyno results, definitely will help you sell more!

Before making conclusions, i.e. increases of almost 20 ft-lbs of torque at some RPM,
additional independent tests with an observer, needs to be done in the U.S and not by a car
hobbyist. The HP gains at less than 6,000 RPM, is less than 10 HP and in some cases
less HP than the Bosch unit. Besides, we really don't know the condition of the original CDI.
Given that, would a random sample of 10 cars show no significant difference in either
torque or HP between the two CDIs?

So, Porsche and designers at Bosch have been "asleep-at-the wheel" for the last 25
years for not continuing to use a CDI type of design, right? Please!

[universeman]

Yes, I agree - that's why I said can we get more!

People do enjoy upgrading ignitions to MSD etc., and the programmability of the newer systems blows away what was possible in 1982 (to use my car's age). So no, we're not saying Porsche has been asleep at the wheel, just that it's possible (perhaps) to upgrade the systems that were originally designed in the dawn of the computer age to something more modern.

Porsche or Bosch could do the same, if they cared to (notice that Porsche Classic is now offering a head unit/nav system for classic 911s, maybe they're admitting that the Blaupunkt tape decks they were putting in back then are no longer state-of-the-art?? How can that be??

[Jonny H]

Originally Posted by mysocal911

Before making conclusions, i.e. increases of almost 20 HP at some RPM, additional
independent tests with an observer, needs to be done in the U.S and not by a car
hobbyist. Besides, we really don't know the condition of the original CDI.

We are trying to do this exercise right now but am struggling to find someone with a working dyno! This plot came in last night from Australia. We are in the UK and have nothing to do with it so it is fairly independent.

Could you help us test this is the U.S. or recommend somebody?

In actual fact since posting I noticed that the Torque plot doesn't look like Torque at all - it should cross the HP at 5252 RPM for a start. I have asked the guy to explain what the top pair of graphs actually is.

Originally Posted by mysocal911

So, Porsche and designers at Bosch have been "asleep-at-the wheel" for the last 25
years for not continuing to use a CDI type of design, right? Please!

We are offering a plug and play solution for the CDI box that is 100% new and has been designed against the Porsche components. Quality and reliability were our design goals. Performance, through electronic timing adjustment was secondary.

Although we knew the PSU was more efficient and that we had dual sparking, we did not expect to see any performance improvements prior to adjusting the advance. It has come as a surprise that almost all of our customers and the specialists we work with have reported improvements in engine pickup. The dyno plot here is the first time we have some data to back that up but we do need more!

[mysocal911]

Originally Posted by universeman

People do enjoy upgrading ignitions to MSD etc., and the programmability of the newer systems blows away what was possible in 1982 (to use my car's age). So no, we're not saying Porsche has been asleep at the wheel, just that it's possible (perhaps) to upgrade the systems that were originally designed in the dawn of the computer age to something more modern.

An ignition system design functionality only requires five key factors from the spark;
energy, voltage, voltage rise time, dwell time, and max RPM. Once those factors are
achieved from a system, no real gains from another ignition system results. The Bosch
system achieves all with exception of dwell time and max RPM provided by an inductive
ignition system presently used by all automotive OEMs.

[mysocal911]

Originally Posted by Jonny H

In actual fact since posting I noticed that the Torque plot doesn't look like Torque at all - it should cross the HP at 5252 RPM for a start.

Great point!

[wwest]

Originally Posted by mysocal911

Before making conclusions, i.e. increases of almost 20 ft-lbs of torque at some RPM,
additional independent tests with an observer, needs to be done in the U.S and not by a car
hobbyist. The HP gains at less than 6,000 RPM, is less than 10 HP and in some cases
less HP than the Bosch unit. Besides, we really don't know the condition of the original CDI.
Given that, would a random sample of 10 cars show no significant difference in either
torque or HP between the two CDIs?

So, Porsche and designers at Bosch have been "asleep-at-the wheel" for the last 25
years for not continuing to use a CDI type of design, right? Please!

No. Once the dwell could be controlled dynamically the ignition coil inductance could be selected for both high and low RPMs. Especially true of COP.

[mysocal911]

Originally Posted by wwest

no. Once the dwell could be controlled dynamically the ignition coil inductance could be selected for both high and low rpms. Especially true of cop.

Do what?

[wwest]

Originally Posted by mysocal911

Do what?

At idle the dwell time can be the same as at maximum RPM, off-time varies with RPM.

[Jonny H]

Back on topic and in case anyone was wondering, I received a reply about the top trace.

It is 'delivered torque' so it is subject to a multiplier. I believe it is used when you're trying to see the effect of tuning changes.

[wwest]

Improve Bosch OEM CDI spark power by a 1.6 multiplier for less than $75.

http://www.ebay.com/itm/ACCEL-140008-ELECTRONIC-SUPER-COIL-FORD-GM-FOR-ELECTRONIC-COMPUTER-IGNITION-/281809980404?hash=item419d2f0bf4:g:AlgAAOSwWnFWBZf 7&vxp=mtr

[VFR750]

JonnyH

The torque curve does look more like a scaled hp. Perhaps they are trying to relate it back to wheel hp.?

Either way, i would be interested to hear how the programmed advance works out. Maybe a stock looking alternative to the msd with programmable timing.

[Jonny H]

Hi VFR,

I had confirmation, the top is 'delivered torque', it is multiplied up so the tuner can more readily see improvements made by ignition timing and other changes. Not 100% sure but I think one of multipliers may be the advance value itself which would explain why it doesn't drop down at higher RPM.

There is a detailed technical manual which explains the operation of the advance for download on our website: Home

[Jonny H]

Not really a dyno result but a nice bit of feedback from one of our customers.

Car is a 74T on Weber carbs:

Classic Retrofit CDI+ Feedback

Thanks Mike!

Update: CDI+ units are curently being assessed by Dave at TRE and also dyno'ed at 911Design in Montclair.

[chris_seven]

The Torque and Horspower that you have provided on this plot are relatively meaningless in absolute terms.

There are several issues which need to be looked at in some detail.

I wonder why the engine torque curve continues to increase to virtually 7000rpm - this would be very unusual and I think needs an explanation.

As you have said Torque and Horsepower have to cross at 5252 rpm due to the basic dimensions of the equation which takes the measured value 'Torque' and calculates the value of Horsepower.

To ensure that results if this type are meaningful and comparable to other Dynos it it useful to know the type of dyno being used and how speed and toque are measured.

Interia Chassis Dynos are relatively repeatable but very poor in terms of correlation between two different installations.

The capacity of the dyno in terms of the absolute torque it can measure is also part of the muddle.

These figures are particularly difficult.

If the torque figure is correct then the engine should be producing 317BHP and if the BHP is correct the torque should be 127lbsft.

The reason dyno plots are generally shown on comparable scales is to show that they do, in fact, cross at 5252 and that any torque measuring system has been zero'd correctly.

I really have no idea what 'delivered' torque can mean. If you don't measure delivered torque how can you calculate Horsepower?

If the measured torque figure has been scaled up I am not sure of the value of this procedure. The resolution of the measurement won't improve.

Most dynos always measure delivered torque apart from inertia dynos which calculate torque from angular acceleration.

Having designed and manufactured Torque measuring systems and the associated dynos used in both the Aero engine and F1 industries for more than 20 years I find this data is very poor and I wouldn't have paid the bill

The only way to resolve the issue is to try to access the raw data and re-draw the curve.

If we are to make a clear and objective evaluation of a new product then presenting clear and accurate data must be an important criteria.

I really think you need to access an good quality Engine Brake as manufactured by Kahn, Schenk or AVL to make real conclusions. There are a couple of good engine dynos of this type that are set up for 911 engines in the UK, one is at Jondel Racing and the other at BS Motorsport.

I would also say that if the horsepower reported is a corrected value than at 165BHP it isn't a great engine.

I would also like to understand how changing an ignition module improves HP by 6.5% at around 7000rpm unless original Bosch CDI systems are particularly poor.

A comparison with a Permatune and an MSD would be interesting.

My criticism isn't aimed at this product but the generally poor data produced by supposedly expert shops.

[Jonny H]

Hi Chris,

Don't shoot the messenger as I had the same issues understanding it! This is the first run of a 2.0 litre engine which had poorly setup carbs and a bad exhaust.

You mention BS Motorsport, we are working with Neil to validate the performance at the moment.

>>>If the measured torque figure has been scaled up I am not sure of the value of this procedure

Apparently, the 'value' is that it you are magnifying the result so it is easier to see if your tuning experiment made a difference. This is a race car, they dont care what the value is, just that it was better than the last run. That kind of makes sense to me.

>>I would also like to understand how changing an ignition module improves HP by 6.5% at around 7000rpm unless original Bosch CDI systems are particularly poor.

Three reasons:

1) The Bosch unit suffers reduced primary voltage to the coil as the revs rise. At 7000 RPM the primary voltage can be as low as 230V. Our unit produces 300V at all RPM.

2) Our system is dual discharge - it produces two sparks right across the rev range. If you have a poor combustion chamber design like a 911, you are increasing the chances of burning the fuel. Despite the name, the MSD can only serve up a single spark beyond 3000 RPM.

3) The Bosch units are old. Many people run them without knowing their condition.

[Tippy]

When the AFR's are leaner, the hp is higher. Makes sense as that thing is pig rich.

[wwest]

As RPMs rise to that level, cylinder compression declines, no need for ~300 volts.

Not a good explanation for 7000 RPM rise in HP.

At 7000 RPM there really isn't enough time for a second spark to be effective.

Bosch units being old does necessarily mean reduced performance.

[Jonny H]

^ Do you have other theories as to why we are seeing improved performance then?