1986 328 on the DynoHelp

<center><table border=1><tr><td>328 Dyno Chart
Dyno1.bmp (730.1 k)</td></tr></table></center>

In November, I had my 328 on the dyno. As you can see from the chart, it was diaappointing. I believe I should be seeing somewhere between 220-230 HP at the rear wheel. I am putting out 194.7 at the wheel. What I did notice is my A/F ratio is a high especially at WOT. I believe the car should enrichen to somewhere in the high 12 low 13 area for maximum power. After my dissappointing run, I started "troubleshooting". The car has nor has never run poorly. It doesn't miss, it doesn't seem to starin, it has good throttle response. I would have never guessed there was an issue until I put it on the dyno. I did find the microswitches were adjusted incorrectly. The idle switch never activated and therefore my car was in closed loop at idle and would "hunt" for the correct RPM. The WOT microswitch was closing but it did not seem to make much difference. I controlled it manually while driving (hooked up a switch) and it didn't seem to make any differnce. I knew it was activated because at idle when I closed the switch, there was a difference....Kind of bumped up the idle. I changed the fuel filter and replaced the vacuum hose the the Control Pressure regulator. I plan on changing the spark plugs and having someone fine tune the A/F mixture while on an exhaust gas analyzer. Any other suggestions? I am open to anything!!! Please help!!

Hi Mark and welcome to Ferrari Talk.

no time at the moment, will try to digest your input tonigt and give a few thoughts.

Regards, JRV

Mark
Welcome to the dyno club - I really appreciate you posting your graph.
Would look at a couple of easy things. You are right that *in theory* more power is made around 13.2, so may want to richen your mixture, measuring with a wide band as you adjust. It is amazing to me to watch how well your Kjet mech injection holds the mixture right near stoich. for best emissions performance, so should hold right near 13.2. It's been my experience that from about 12 - 14 the difference is only a very few hp, so you just need to get close in the neighborhood.
I've read other 328s dynojetting around 206, so you are not so much an outlier.

The other thing, and I know some people think it is voodoo, but I believe a K&amp;N has less resistance to flow than a paper element, and power is all about flow. Would be intersting to see a run with the filter element removed. My bet is 7 hp. Won't go into detail, but opening the exhaust up would help.

The other standard dyno things apply - ensure high normal tire pressure for optimal rolling resistance, ensure the parking brake is not dragging, clogged cat, lined up straight on the drum, etc, etc,.......

My 3.2, albeit converted to weber carbs and less good mixture control (I'm jealous!) dyno jet graph is at:
http://www.ferrari-talk.com/discus/m...tml?1073613477

good luck - this board is great for technical advice. Will be following with great interest.
best
rt

Mark,
Don't be to upset,dyno readings can and do vary many percent between different dyno's. Also air temp and density must be allowed for.If you are measuring the power at the wheel, remember there can be tire slip, clutch slip,power loss through worn trans or wheel bearings, brake drag,etc. Just tune your engine for max numbers on one dyno, and don't get caught up with other people quoting bigger numbers on another dyno. Apples and oranges.I agree with Rturner, Kand N air cleaner will produce more power. 7 hp seems reasonable.

Mark,
As others had said, there are statistical variations, so don't get too wrapped up in all this, esp. if the car is otherwise running well.

That said, here in the NW I have seen at least three 328s on a Dynojet and they were all very close to the same in hp. Mine was 214.5hp and 184.1 torque. The other two cars were within 4 or 5 hp of my number. BTW, I had a K&amp;N air filter and Tubi on my car WITH the cat still on.

I don't know if it would make much performance difference, but I do know that the 328's had the early steel Bosch fuel injectors, and as they age, the patterns get bad, and they can become leaky, causing hot start problems. I wonder if yours were acting up and had a faulty spray pattern, if that would effect engine performance? I am having mine changed to the upgraded brass ones (I have been having hot start issues and everything else checked out okay), and thinking of dynoing it again, to see if it makes any difference.

Hi Mark,

there is only an idle mixture (AF) adjustment for the system not any type off idle adjustment. Off idle mixture is controlled via Aux. Control Pressure Reg. and the Frequency Valve using Open Loop controlled by the Throttle Position Sensor (and coolant temp sensor when cold, in open loop) thru the Lamda Computer..

The dirty/worn injector theory put forth is a definate possibility and the other check you could do is Fuel System Pressure.

It wouldn't hurt to know exactly what system pressure your particular ACPR is keeping that system at. If the ACPR is getting tired or is out of spec this would be hard to detect with an ass dyno, but readily picked up with a chassis dyno.

Then there is always the art of fine tuning which takes the basic specs good enough for Gov. work and dials them in to a more real world book spec perfect.

Regards, JRV

Thanks everyone...My plan is to check/replace spark plugs, clean/replace injectors, check fuel pressure/volume, fine tune it on an engine exhaust analyzer and then recheck it on the dyno. I will keep you posted.

Regards,

Mark Manzonelli

Mark,
I would have the injectors checked on a machine, but wouldn't bother having them cleaned. New ones only cost $21.15 each, check threads here for details on part numbers and price, and where to buy.