Questions after a 3.0 dyno run

[AndyLuft]

Coming back from a dyno session yesterday I am a bit curious to know if there is more to be gained on my engine setup.
(Any feedback is welcome) ��

First off, car is completely restored so there is several small stuff that needs addressing before all is 100%.
For example the throttle cable was not able to go to 100% WOT. We estimated it is opening the around 93% so the dyno was done on this base.
Also my rotor cut in at 6000 rpm. I had the oem rotor replaced with a new «7000 rpm rotor». If I proceed to tight up the spring on the rotor, how do I confirm its releasing at 7k rpm?
Or is it worth to replace the ignition with something like classic retrofit / a aftermarket ignition system? What to choose in that case?

My aim is not horsepower, but rather achieve a engine that lasts and gives a great driving experience and that is true to look and performace to the era of the 70s Porsche racing. I like to think I have achieved some of it, but I lack the last bit of the puzzle ��

A rough overview on my setup:

• 3.0 09 base
• 3.0 Mahle motorsport 10,5:1
• ARP hardware
• Heads bored & ported, stiffer springs & titan retainers, reprofiled oem rockers
• S cams
• Weber 40 IDA3C
• 3.0 09 distributor (rebuildt)
• 3.0 09 cdi (original)
• 3.0 09 coil (original)
• SSI
• Dansk two in / two out
• 98 RON fuel only
• Custom engine harness

1. Throttle cable / pedal needs to be adjusted to confirm its opening 100%. That is done within the next days.
2. Is there much to be gained on another ignition system, and I assume that will potentially cure my rev limiter hitting at 6k?
3. Dyno run resulted in 232hp/311 nm. Limiter at 6k rpm.
Funny thing is that it got 1 hp more with the K&N airfilters than without them.

[Dpmulvan]

What about your carb jetting.

[AndyLuft]

Carbs are set up with;

Mains - 160
Tubes/mixxer - F3
Venturi - 36mm
Air Correction - 190
Idle jets - 60

We opened up the idle jets with a brooch(?) for the last pull.

[pocv0]

Curious regarding ignition timing. Did you have the distributor re-curved? With the same CR , Elgin E cams and 40 IDA 3C carbs, I'm running around 36 degrees total advance on my 2.7 liter.

[pocv0]

Also, I ditched the CDI and replaced it with an MSD 6AL Digital to set the rev limiter.

[Rosco_NZ]

Fuel is tuned for safety of the engine and makes little difference to HP, it’s all in the ignition timing. You want to be able to ‘tune’ the ignition curve .. much easier with a crank fire or locked distributor with pertronix and program the curve in software. Either use a programmable CDI box such as Daytona Sensors. Or use a rebuilt ‘dumb’ Bosch CDI box and install a programmable distributor .. the only one I know of is 123 Ignition. If I was doing my project again, this is what I would do. It can be programmed using Bluetooth on the fly so makes tuning so much simpler.

[icarp]

@ 275 flywheel hp you are running past to the limit of SSI header/heat exchangers !!!!!
and muffler .
I think you are doing pretty well. Is this a chassis dyno or engine brake ?

I like the 123 distributor very much, max advance for the 3.0 is about 29*

[AndyLuft]

Originally Posted by pocv0

Curious regarding ignition timing. Did you have the distributor re-curved? With the same CR , Elgin E cams and 40 IDA 3C carbs, I'm running around 36 degrees total advance on my 2.7 liter.

Yes the distributor is recurved and verified timing during the dyno. Ignition is optimal with the parts thats installed on this setup. Im at 27 degrees total on this run.

Originally Posted by pocv0

Also, I ditched the CDI and replaced it with an MSD 6AL Digital to set the rev limiter.

Is it worth the upgrade? Did you consider any other CDI`s before bying?
Im looking at the ashlocktechs CDI + upgrade, but little feedback written on the subject.

Originally Posted by Rosco_NZ

Fuel is tuned for safety of the engine and makes little difference to HP, it’s all in the ignition timing. You want to be able to ‘tune’ the ignition curve .. much easier with a crank fire or locked distributor with pertronix and program the curve in software. Either use a programmable CDI box such as Daytona Sensors. Or use a rebuilt ‘dumb’ Bosch CDI box and install a programmable distributor .. the only one I know of is 123 Ignition. If I was doing my project again, this is what I would do. It can be programmed using Bluetooth on the fly so makes tuning so much simpler.

Noted on the 123 igintion. It is tempting to go that route.

Originally Posted by icarp

@ 275 flywheel hp you are running past to the limit of SSI header/heat exchangers !!!!!
and muffler .
I think you are doing pretty well. Is this a chassis dyno or engine brake ?

I like the 123 distributor very much, max advance for the 3.0 is about 29*

Yes you are correct. The dyno used is a chassis DynaPack, hub based dyno (you can barly see the red dyno pack units in the background of the picture). I think the graph shows corrected flywheel hp.

Before the dyno run my engine builder told me to «use another muffler», so I guess you are right. What would be the other option here? 42mm spaghetti manifolds and rsr muffler?

[Rosco_NZ]

I don’t think many alternatives with rebuilt standard CDI, Ashlock would be the goto.
Did you measure actual CR? I think single plug with 10.5:1, you may also be knock limited .. I’d be wary about detonation doing damage, as would be your dyno guy..
Heat exchangers, and muffler and easier first stop.
The RS3.0 using MFI 8 S cams was 230hp .. so you’re probably doing well. I think you will need more cam to get more power at higher RPM’s. Comsider can upgrade at some stage .. I’d suggest Mod-S, DC43 or DC44

[Rosco_NZ]

You don’t say whether crank or wheel hP. Different dynos also give widely varying #’s. I’d be sorting your full throttle and upping the rev limit. For a tuned expensive engine, the clunky mechanical rotors are hard on the engine .. use the soft limiter in the upgraded CDI.

[icarp]

Dyna Pac is a hub dyno, 7% loss is standard for this dyno, so 247 hp at the crank.
This is more in line with a set of SSI's

Ian

[AndyLuft]

Originally Posted by Rosco_NZ

You don’t say whether crank or wheel hP. Different dynos also give widely varying #’s. I’d be sorting your full throttle and upping the rev limit. For a tuned expensive engine, the clunky mechanical rotors are hard on the engine .. use the soft limiter in the upgraded CDI.

Its measured on the hubs. Yes, im investigating for a new cdi/ignition system. But really somfar I have to say the oe stuff works great.

It did help a lot fixing the throttle linkage and having full WOT. Car feels a tad quicker/ more responsive.

Originally Posted by Rosco_NZ

I don’t think many alternatives with rebuilt standard CDI, Ashlock would be the goto.
Did you measure actual CR? I think single plug with 10.5:1, you may also be knock limited .. I’d be wary about detonation doing damage, as would be your dyno guy..
Heat exchangers, and muffler and easier first stop.
The RS3.0 using MFI 8 S cams was 230hp .. so you’re probably doing well. I think you will need more cam to get more power at higher RPM’s. Comsider can upgrade at some stage .. I’d suggest Mod-S, DC43 or DC44

Actual CR was measured to 10,3:1.
ok, that sounds good. Im not really seeking a new cam as this one makes the car very streetable. The high NM range makes it fun to drive at all speeds. What I am looking at is a new set of exhaust manifolds, more of a spaghetti type of manifold, and a matching muffler.

Originally Posted by icarp

Dyna Pac is a hub dyno, 7% loss is standard for this dyno, so 247 hp at the crank.
This is more in line with a set of SSI's

Ian

Correct, its a hub dyno.
Would you say the SSI`s limit is around 250hp. If aiming for more than that, one should have another set of maifolds or a larger dim SSI`s?

Heres my exhaust setup:

[PeteKz]

Andy, I'm coming into the thread a little late, but let me offer some additional thoughts.

If your objective is not a race motor, but a fun street motor, the dyno only gives you a small part of the picture. Race engines spend almost all their time either at WOT, or at low/no throttle, so with a race engine, you don't worry much about how the engine runs from 1/8 to 3/4 throttle (as long as it runs acceptably). Whereas, street engines spend most of their time in that range.

Therefore, a good street engine is harder to optimize than a race engine.

Major manufacturers devote the great majority of their engine development on both emissions and "drivability." The typical dyno runs we hobbyists and aftermarket builders use will only be done at WOT, so they will only tell you how much power and torque an engine develops under those conditions. The Car manufacturers use a variety of dynos, including chassis dynos, to develop the parameters that allow the car to run at maximum power, but also drive smoothly and within emissions constraints from idle to WOT. Building an engine that makes 600+ HP is easy, but building an engine that is smooth and docile and gets good fuel efficiency in the commute to work or to get the kids from school or to the grocery store, and then can launch up the on-ramp like a dragster by simply putting your right foot down, well, that's difficult. Manufacturers do that by bringing everything under computer controls and use variable valve timing, variable ignition timing, transmission shift maps, and other tricks.

Ignition timing makes a big difference in drivability. So does cam timing. In our engines, the cam is fixed, so you only can set the initial cam timing as a compromise. In a race engine, builders will try to set the cam slightly retarded to increase max horsepower at high RPM. But in a street engine, you should shoot for the middle of the timing specs or slightly advanced to get better low to mid-RPM torque. Again, for a street engine, pay less attention to the max HP figures and pay more attention to the the middle of the torque band. Then pay even more attention to how it drives at part throttle on the street.

The ignition timing is an area where you have much more flexibility. The 3.0 SC distributors are mechanical with vacuum. Although several shops can re-curve the distributor to give more mechanical advance, and bring it in earlier for better low to mid-range torque, it's still a "dumb" mechanical device, and if the new advance curve doesn't optimize for your engine, it's hard to change it. Enter programmable distributors and distributor-less coil-on-plug (COP) ignitions. Reiterating what Ian and Rosco said above, these allow you to easily customize the curves to suit your engine and driving conditions, and some offer knock-sensing to retard spark advance if you get detonation. The simplest and easiest to install of these is the 123 Distributor, of which you can read more about in other threads, but for your purposes, it looks period-correct, and allows you to change and experiment with RPM and vacuum advance curves. It also allows you to eliminate the Bosch CDI box and run straight to the coil, which will make it look even more "old school." COP systems eliminate the distributor and wires, which make the engine appear even cleaner and more "retro".

Bottom line: I think that on these engines, programmable ignition timing provides the most opportunity for optimizing both drivability and power/torque. You can set the RPM limit anywhere you want and change it easily.

SSI's and muffler: What size primaries do you have? There are other guys here who build exhaust systems professionally and for racing. They can tell you what combination will produce the most power. BUT, that's not what you want on a street engine. Stick to mid-RPM torque. The SSI's are probably as good a compromise as you can do. And they give you heat and defrost! Your muffler probably is a good compromise too. About the only way to find out if something is better is to swap mufflers. Better is subjective, and includes the sound it makes. I like quiet, so I use the stock 2-in 1-out and I know I'm leaving a few HP at WOT on the table. With a 2-into-2 muff, I'm guessing you want more aural presence. Run what you like.

Your 93% throttle opening is not as much of an impediment to power as you think. Of course, you should get it to open all the way, but the response of throttle opening to power output is not linear. Small changes in throttle at low openings have a lot more effect than small changes near WOT. You are not losing 7% of max power at 93% throttle opening. Maybe a couple percent.

The titanium valve retainers and stronger springs are unnecessary below about 7500RPM (depending on cam choice), and will wear faster and require more frequent inspections and adjustments. At this point, you probably won't pull your engine apart to replace them, but the stock parts would be better for your application.

Re the K&N air filter giving 1 HP more power: That's probably within the measurement and repeatability error of the dyno. You would have to do multiple back to back runs, with and without the filter, to see if that's a repeatable measurement.

[PeteKz]

One more thing you should consider: An AFR meter. I installed one on my car over a year ago, and now I wonder how I ever did tuning without it. I recommend that you get a dual unit, so you can put a sensor in each header and read how the carbs are working on the left and right banks.

[PeteKz]

Also check out the dyno graphs of SSI's towards the end of this related thread:
https://forums.pelicanparts.com/porsche-911-technical-forum/1165423-exhaust-header-size-my-rebuilt-2-7l-motor-3.html

[mikedsilva]

Originally Posted by AndyLuft

Coming back from a dyno session yesterday I am a bit curious to know if there is more to be gained on my engine setup.
(Any feedback is welcome) ��

First off, car is completely restored so there is several small stuff that needs addressing before all is 100%.
For example the throttle cable was not able to go to 100% WOT. We estimated it is opening the around 93% so the dyno was done on this base.
Also my rotor cut in at 6000 rpm. I had the oem rotor replaced with a new «7000 rpm rotor». If I proceed to tight up the spring on the rotor, how do I confirm its releasing at 7k rpm?
Or is it worth to replace the ignition with something like classic retrofit / a aftermarket ignition system? What to choose in that case?

My aim is not horsepower, but rather achieve a engine that lasts and gives a great driving experience and that is true to look and performace to the era of the 70s Porsche racing. I like to think I have achieved some of it, but I lack the last bit of the puzzle ��

A rough overview on my setup:

• 3.0 09 base
• 3.0 Mahle motorsport 10,5:1
• ARP hardware
• Heads bored & ported, stiffer springs & titan retainers, reprofiled oem rockers
• S cams
• Weber 40 IDA3C
• 3.0 09 distributor (rebuildt)
• 3.0 09 cdi (original)
• 3.0 09 coil (original)
• SSI
• Dansk two in / two out
• 98 RON fuel only
• Custom engine harness

1. Throttle cable / pedal needs to be adjusted to confirm its opening 100%. That is done within the next days.
2. Is there much to be gained on another ignition system, and I assume that will potentially cure my rev limiter hitting at 6k?
3. Dyno run resulted in 232hp/311 nm. Limiter at 6k rpm.
Funny thing is that it got 1 hp more with the K&N airfilters than without them.

I've done this a few times but am by no means an expert.

Your throttle opening may or may not make a difference. In my case it made a difference. Running 42mm throttle bodies on a single plug efi setup, my 3.0 engine was making approx X at the wheels but the TPS said I was open to 92%. My dyno guy got me to stand at the rear of the car (with ear protection) and then manually hold it open to 100% and we achieved an additional 11 hp. His conclusion was that if it made that much difference, then I could/should probably go up in ITB size. So unless you phsyically do the test, you wont know if you should chase that final 7% opening on your throttle.

Headers: I'm not sure what diameter your SSi are.. the smaller ones or the larger 1&5/8 ones. If you have the smaller diameter then you 'might' see an increase by going up in diam, however it will likely reduce torque at the bottom while you're chasing top end hp.

Muffler - if you want to know if your muffler is restrictive, do a run with and without the muffler changing nothing else.. I found that off-the-shelf mufflers can be restrictive.

These are my own findings based on personal experience, and your experience and results may differ.

[Rosco_NZ]

I’d caution against dropping the CDi box and running direct to the coil. CDi’s use a very low impedance coil designed for CDI systems. Yes if you replace the coil for one designed to run directly from the points. But Porsche ran CDI for a reason and simple kettering ignition will be inferior. Strong spark is the basis for any engine to run properly, especially old air-cooled technology with widely varying mixtures. Upgrade to an Ashlock CDI box & tune with a programmeable distributor.

[PeteKz]

Yes, you need to use a coil with between 1-3 ohms primary resistance, and about 8 KOhms of secondary resistance. They are about $75 or so at most retailers and can be got at any FLAPS if you have a problem on the road somewhere away from home base.

Let's not start the CDI vs. IDI debate again. A modern electronic ignition distributor is very different from olde points ignition systems. Note that Porsche went back to IDI with the Carraras and all subsequent cars, until they went to COP (also a form of IDI). AFAIK, all modern ignitions are COP or IDI.