I agree that you need to look at your A/F tables.

Do you have an A/F meter or can they stick a probe up the tailpipe while they do another dyno run?

Might show you what is happening above 4500 rpms.

I did not know you have megasquirt for EFI.
what are you using for ignition?
Seems bouncy to me.

Rich

Ok, answering my own question, for those interested...a topic that's been likely gone over dozens of times times here over the years and earning a big sigh from some veterans...

9.6 / 2 = 4.8 (formula for area of a circle...Pi x r squared: take half of diameter)

4.8 x 4.8 = 23.04 (...square that number)

23.04 x Pi = 72.35 (multiply by 3.142)

72.35 x 7.1 = 513.65 (multiply above result by stroke length...71 mm in my case)

513.65 x 4 = ~2055 ml (...multiply that volume by number of cylinders)

Had I learned what I know now sooner I would have had the 1.8 heads ported and changed the valve train and cam. Perhaps another day. Oh well. Will just have to accept life with just 95 HP on this one for a while.

Hi Rich, that blue line was, I believe in 4th gear and that made it inconsistent, or so I was told. It has Subaru injectors, MSD + electronic ignition with new plugs, wires and a powerful coil.

I'm inquiring about the AFR report. Learning as I go here...

For those curious about potential temperature issues with this combination, the car does have an extra oil cooler and a deep sump, so we are quite cool on that front. Pun intended.

M.i.M.

You need more data from these pulls than just HP.

Get the AF readings and timing statistics for each pull.

It just seems a bit early for you to be running out of power...

My theory is you are either running out of fuel, or your timing is wrong.
The heads will go further in stock form, so I do not think you are running out of air at 4500 rpms.

the jagged trace of 4th gear looks to indicate a problem too, ignition and fuel needs to be looked at further.

When you see this on a denote the engine needs spark plugs. It only occurs when in a higher gear at WOT.

Thanks for chiming in here Mr. Raby. The plugs are new, but we will do a check on them.

Here is the AFR chart from the first test, before we realized the throttle was not getting wide open. Hope to have the other one later today.

Mike

So the operator ran this car on the dyno multiple times and wonders why it was down on power when it's that lean?
Give up with these guys and have it tuned when it gets to you

Thanks for the input. Hope you're right!

More fuel.
I think you need a new tuner!

The red line was clearly too lean. Then it was adjusted to about 13.5. Is this with some degree of certainty too lean?

Does the octane that's in the car make a difference here? It was running 87 at the time of the test. Apparently the higher the octane the higher the optimum AFR., at least according to this article / thread.

http://www.914world.com/bbs2/lofiversion/i...hp?t193629.html

The timing is set at 5 degrees advanced. We are going to advance more, but could use some feedback here about what's best with this 1.8 cam.

M.i.M.

There is no "optimum" AFR. The 14.7:1 is best for complete burn while keeping catalytic converters happy, but it is not the single and only best ratio.

Our engines seem to like to be a bit richer, especially while accelerating. On the order of 12-13:1. Cruise can be 13-14.7 or so, and idle can be whatever it needs to be to get the 3% CO reading and an idle that doesn't hunt.

Different octane numbers don't really change the preferred mixture for any given set of circumstances.


I agree with the above comments about finding a different tuner. Someone doesn't appear to know WTF they're doing...

Your power levels appear to be at least in a reasonable ballpark over all, if a touch low for a 2056 with a stock cam and such. Though the power dropping off so quickly does not seem quite right.

That said, you can drive around at or under 4500 RPM all day. Most of us don't get over 5K on a daily basis, I don't think.

--DD

Thanks for your input here Dave. Apparently I was wrong in my post about the blue line being too lean. According to what you say here the lower numbers are more rich and higher is more lean. I was assuming it was the other way around.

What do you think about the timing advance? Should it, IYO, be more than 5° advanced?

M.i.M.

Too lean for WOT as it should be 11.5-12.5 to start at low rpms.
Timing should be set at 28 degrees @3500rpms so the Max advance in all in. Is the vacuum advance hooked up?

The vacuum advance is hooked up. The AFR is at 13.5. Timing is advanced 5 degrees. We will advance it to about 25, but believe the AFR can stay where it is.

Set the timing with a timing light to 28 degrees @ 3500rpms. Yep, it's a pain to do. Pelican Parts has a timing mark guide you can see to make sure its right.

http://www.pelicanparts.com/techarticles/9.../914_timing.htm


Yep, I've used this before!

Are the injectors firing sequential or batch? If sequential I'm thinking 2 might be called out in the wrong order? With the sudden drop in power and still running rich could the engine be sucking puddled fuel? I helped a guy tune the maga squirt on a subaru that dropped power right at 5k , but the a/f was 16.5.

Jcl

As may be pretty clear to most, I'm no a car-tech guy nor the one working on this vehicle. I'm learning a lot as I go, but this suggestion sounds pretty odd to me. Without learning more about the possibility suggested here, I'll be bold to just say that I would certainly presume the injectors fire sequentially. 16.5 is very lean. I guess that was your point?

It's a shame that while the car was going to the dyno shop I wasn't aware that the timing was only advanced 5 degrees when it should be around 27. This, based on what I've been reading, is the most likely cause for loss of power in the higher RPM range, (along with the limitations of the relatively small valves and cam). This, IMO, should have definitely been the first thought and suggestion of the guys at the dyno shop.

I've learned a lot since I began this thread and I hope it's not just been educational for myself but many others as well, and will remain so for many in the future.

Next thing to look into and learn more about for me is this notion of the FI firing non-sequentially.

M.i.M.

I stand educated. My source: http://www.sdsefi.com/techseq.htm

I am not sure yet, but I reckon it's likely batch. ? Apparently it doesn't make any noticeable difference, surprisingly.

You need to richened the mixture. A dyno run is wide open throttle

Wot needs to be 12.5 ish on a 914 at redline
Richer as it is building up to redline is ok.

But running a car lean at redline is very bad and will lead to a failed engine

Redline is at 5600. Apparently I won't ever be taking this thing over 5000 and if I use a higher octane the burn will be slower and cooler as well as partially compensate for the current AFR (with 87 octane) being a bit leaner than your recommendation. For use as a daily driver I think I should be OK with the AFR at 13.5. No? I will test the car with different octane ratings and perhaps buy a sensor to measure the AFR. If I do I will post the results. It seems to be debated as to whether octane ratings affect AFR significantly or not.

As far as heat, this car seems to run very cool, generally under 175 F iirc. Is this TOO cool? It has an extra oil cooler and a deep sump.

M.i.M.

No it needs to be richer. 12.5 through the range while under load/wot

Cruising at third throttle on the hwy is not full load.
12.5ish. (12.1 - 13.0) is where you need to be under load

You really need a new shop
They should know this and more
Your timing can't be that far off and they are using the wrong timing mark on the flywheel is my guess. You need someone that knows this motor if you are going to do it remotely.

Fire them. Get the car delivered. And do it yourself

D-jet fires the injectors in pairs, diagonally across the engine. One cylinder gets its fuel pretty much as the valve is opening, while the other gets sprayed against the back of the intake valve.

L-jet is batch-fire, with all four injectors being triggered twice per cycle (with half the required fuel quantity being injected each time). I believe that means that every cylinder gets fuel against the back of the closed intake valve, and also gets fuel when the intake valve is open, but I could be wrong on that.

--DD

Your a wealth of info Mr. Darling,

The car has an OEM 1.8 cam. Care, Dave, to chime in again regarding timing advance and the stoichiometric AFR?

Nope.

The whole question of "optimum" timing and mixture are complex enough, and I don't know enough, to be able to tell you what they are remotely like this.

Setting things up with the stock settings is usually a good start, and is generally quite good enough for driving around on a stock motor. But if you are trying to get the "best", then you need to experiment. Small things in the exact setup of the engine, or the environment, or whatever, can add up and mean that the "best" is different for different examples of the same motor.

--DD

You should set it up so at partload (which could be driving on the freeway at 70mph) up a slight incline so its not coasting, the AFR range is 13.0-13.9 to one. Forget 14.7 to one AFR as that is too lean for a aircooled engine.
Wide Open Throttle should start out at 11.5-12.0 to one and at 5000rpms be 13.5max.

The engine has to be timed correctly at 28degrees @3500rpms BDTC hoses off and plugged on the dizzy. This is because the mechanical advance has to be at max advance to set it correctly and mostly dizzys are all in by 3200rpms. We do not set it at idle nor do we care what it is at idle.