E46 Fanatics Forum banner
1 - 17 of 17 Posts

·
Bradolf Pittler
Joined
·
2,805 Posts
Discussion Starter · #1 ·
[email protected]
[email protected]

Mods:

ECIS Intake, Shark Injector, UUC Exhaust, flywheel that doesn't help HP readings.

1. when we installed the flywheel, we had to disconnect the battery from my car for more than a couple hours... say 8 hours to do the install... does that reset my ECU?

2. Whats the stock HP reading on a 328ci? to the wheels anyone?

3. Mustang Dyno

4. When i dynoed at Altered Atmosphere with their Dynojet, with JUST my intake...
[email protected]
[email protected] what happend?

5. Are my expectations too high? i expected to do a little better....
 

·
Registered
Joined
·
207 Posts
yup. which dyno u take it to? Springfield Motorsports? the mustang place. if so their dyno is slightly off. i know because we took our race cars to Extreme in Jessup MD for that simple reason. :ben:

There are many variables to determining accurate dyno readings.

It takes a few minutes to get the engine and drivetrain warmed up on the chassis dyno, so you will need to take several runs before the data becomes consistent. I like to just run the car on the dyno for about 5 minutes before taking any data.

Make certain that you have a strong fan blowing air into the radiator or you will overheat the engine.

In first and second gears, the inertia of the engine and gearbox will reduce your horsepower readings. Third gear is a good choice for getting accurate data. All of my data is always taken in third gear. By the time you get up into fourth and fifth gears, the drivetrain losses are significant and reduce the horsepower.

When you start making data runs, go full throttle at a little over 1500 rpm and run it up to 4500 rpm. Do that over and over until the results stabilize and give power curves that are the same within 1 hp.
The problems arise from the fact that "power correction" fails to address anything except the change in density of air. For example, on a cold and a hot day the engine may have the same cylinder block temperature. This means that air entering through the head will be heated more on a cold day than it will on a hot day. The correction factor does not take this into consideration. It also ignores coolant temperature and oil temperature, which have been shown time and again to have a substantial effect on the measured power. Humidity also has a variable effect on power because it affects the point at which detonation occurs.
Hope this helps :thumbup:
 

·
Bradolf Pittler
Joined
·
2,805 Posts
Discussion Starter · #7 ·
We took the readings from my 4th gear, there was a huge fan in front of my car... and the weather was sorta cold...

when i dynoed my car last time with just the intake, it was very hot at altered atmosphere. this dyno was done at Curry's.

We did 3 pulls and the 3rd pull was the highest... now about my ECU... did it get reset when we disconnected my battery?
 
Joined
·
4,165 Posts
huyner328 said:
1. when we installed the flywheel, we had to disconnect the battery from my car for more than a couple hours... say 8 hours to do the install... does that reset my ECU?
Yes, disconnecting your battery resets some parameters in the DME (all in older cars, only some in newer cars).

Every BMW DME since Motronic 1.1 (1986) are adaptive. That means it takes into account your driving style and history for modifying the ignition/fuel curves.

It is not unusual for a car that has been driven calmly, cruise set at 55mph for long periods, to dyno lower than a car that is used more aggressively. It is also not uncommon for each successive dyno run to show an increase in power as the DME adapts during the runs. Very weird experience which I have personally witnessed.

- Rob
 

·
Registered
Joined
·
207 Posts
yup! different brands of dynos are set up differently and usually have a "power correction" percentage of around 7%.
 

·
Registered
Joined
·
2,294 Posts
did u dyno at Curry's? if so....the last time i was there...their Dyno was giving low numbers(although somewhat normal for the weather conditions and brand of dyno)...think it was a Mustang Dyno?


and a Flywheel does help HP readings on a dyno by allowing less power loss to the wheels...crank numbers are NOT effected by a light weight flywheel


Dyno's as a whole aggrevate me cause there is so many variables to consider when trying get an accurate reading..ex. brand of dyno, weather, etc....
 

·
Registered
Joined
·
138 Posts
I have a question for you guys...

How come when looking at dyno numbers from Bavauto and Turner motorsports for the 328's with intakes and the programmer upgrades their numbers are around 212 HP?

Are those crank HP numbers?

Also, when Killer Junior had his 325 dynoed with just the Benfer CAI, it showed like 175 HP, therefore does the 325 have more HP then a 328?:dunno: :dunno:
 
1 - 17 of 17 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top