Bradan F355 baseline dyno

Today, we baseline tested our F355 before starting the modification process. This is a stock 1995 F355 berlinetta. Both exhaust manifolds are leaking and will need to be replaced. Next week, the exhaust manifolds will be removed and all cracks will be spot welded. This is a temporary fix that will only be used to show any loss from damaged manifolds.
Image Unavailable, Please Login
Image Unavailable, Please Login

 

Mustang dynos aka the heartbreaker dyno eh? As a general rule, the Mustang dynos read about 6-7% less compared to Dynojets. Example is my 308 ran 185bhp on a Mustang then ran 200bhp on a Dynojet. Nothing changed other than the dyno. I think healthy 355s run about 320bhp at the wheels on dynojets. Glad you found out about your manifolds now before the engine fried

 

The mustang units tend to have the most accurate numbers. The difference being Mustangs are loading dynos that apply resistance similar to the road on the vehicle. Most Dynojet units use a simple free spinning roller with no resistance. The actual peak numbers are not that important to us. We are more focused on the power gain that each modification brings.

 

Accelerating a 3200lb steel drum = no resistance? I wouldn't say that.

When used properly both intertia and load dynos are very accurate tools.

 

+1 ....... dyno-jets have a 'massive' drum of which its weight is used for calibration. If roller bearings add any 'additional' friction on the drums one can get skewed results. Also depending on the lubricants used, different extreme temps can affect rolling resistance of the drum bearings. That said, any dyno can be subject to discrepancies if it is not regularly maintained/calibrated.

 

I have also heard the Mustang dyno is better for 'real world' bhp. Have also heard the Mustang gives more accurate torque figures while a dynojet yields more accurate bhp figures. Been tearing my hair out trying to remember what magazine wrote published the article on a fresh engine being tested at the flywheel, then on a mustang, then on a dynojet. It was a few years back. Anyone remember this one?

 

Also fwiw, welding the cracked manifolds isn't going to show how much of a power loss there is with bad manifolds as the tubes will still be badly deformed.

Only way to know would be to cut out the deformed tubes and replace with new.

Nice work on the car so far, it looks excellent

 

Not to be too off-topic, but if anyone wants to get surgically accurate with this stuff, go use one of the 3 maha dynos in the US or the 1 in Canada. The maha dynos measure rear wheel bhp and calculate drivetrain loss at peak bhp and any other bhp at a specific rpm one would like to know (loss changes at varying rpm). The flywheel bhp calculated from the wheels is very accurate, and I have yet to find anyone who is not surprised by how much power is lost through the drivetrain. Drivetrain loss shows is shown as bhp figure compared to flywheel. So the readout will say the engine makes 402bhp at the flywheel, but is losing 110bhp through the drivetrain at 8k rpm etc. Most drivetrains are showing 22%+ drivetrain loss on this thing at peak power. Very very interesting machine those clever Germans developed.

 

A local tuner put this together to help explain the differences between a loading dyno (mustang) verse a inertia based (dynojet).

"B) More precise measurement - Because inertia dyno's use a heavy mass to simulate the inertia of the car being tested it is hard to monitor minor changes in power. The large mass of the roller results in very minor changes in roller speed that inertia dyno sensors have a hard time picking up. If the sensor and computer don't see the change in roller speed the dyno graph will not show a dip in power. However, a loading dyno uses rollers with very little mass and directly measures power rather than calculating it. Quick drops in power will be picked up by the load sensor and will show on the dyno graph. This is very useful for finding problems and ensuring that your engine is running correctly.

C) Load can be controlled - With an inertia dyno the load exerted on the engine as it accelerates is based on the inertia of the dyno rollers. This inertia is set by the mass of the rollers and is not able to be changed. The inertia of the dyno rollers directly determines how fast the cars engine will accelerate through each gear. Ideally this inertia would be equal to the inertia of the car being tested but this is rarely the case. The inertia is almost always going to be higher or lower than the inertia of the car and as a result the engine accelerates faster or slower than it would on the street. This can have a bearing on how the engine is tuned and how accurate the dyno replicates real life conditions. Because a loading dyno is able to actively alter the load on the rollers it is able to change the rate of acceleration as the operator pleases. Realistic loads for the particular vehicle can be used or loads simulating driving up a hill can be used. This is easily controlled by the dyno operator." -Vette Doctors

When shopping for a machine we looked into both options. For our needs the mustang was the better fit.

 

Any deformed tubing will be replaced. The process will be similar to the Qv rebuild without rebuilding every runner. Photos of the rebuild will be posted next week.

 

Found the blow out.
Image Unavailable, Please Login
Image Unavailable, Please Login
Image Unavailable, Please Login
Image Unavailable, Please Login
Image Unavailable, Please Login

 

Wow!!!

Every time I see how deformed the headers get when they leak it makes me sorta sick...

John

 

Those headers sure are tired looking.

Will you be fitting any other header to them other than the refurb?


Great looking paint BTW!

 

Yes. We are currently manufacturing our first batch of manifolds.

Thanks!!

 

That is one of the worse ones I have seen...I certainly hope there is no engine damage already.

 

You ran the car with leaking headers, I would do a compression and leakdown now.

 

wow, Having a 348 I never searched threads on bad headers. That the first pics I have seen. Really.. Ferrari should have done a better job

 

I know I would have shut the thing off with those in there.... Geez.

 

just as a warning for others (like me) with stock headers? Thanks!

 

At least 89k per an old post of his earlier this year.

 

NASTY!!!!

It's a wonder the thing even ran right.

 

I'm anxious to see what the cylinder liners look like. With that kind of mileage and those headers I would expect to see some serious wear. Not wishing bad luck on anyone since I assume the engine is going to be rebuilt anyway.

 

John:

You literally took the words right out of my mouth. I was going to post the exact same thing until I saw yours'. This kind of thing keeps me awake at night.

 

EXACTLY

 

As stated earlier, we plan on rebuilding our engine shortly. We will post a full series of photos of this process.