JoeJErnst

The Belt Wrap Kit (BWK) makes a lot of sense logically, but there doesn't seem to be much concrete information out there about how much of an improvement it makes.

So... Here are some real-world numbers! I have been running my totally stock 2004 E55 (with Hoosier DOT Drag Radials) at the track a lot lately, and most of my 1/4 mile ETs were in the 12.20 range, with a couple 12.10's that seemed to come at random intervals.

I installed the BWK this weekend, and with no other changes, I ran a best of 12.045. What's even better is the consistency. I ran 4 times yesterday and only varied by 0.042s (12.087 worst, 12.045 best)

So the bottom line is I found it good for a half-a-tenth in the 1/4, with a bonus of more consistency.

Here's a link to my times:

http://myslips.com/profile.php?id=1879

EDIT: I guess these numbers aren't as "concrete" as I had originally thought. See post #10 & 16 below for more details...

jmb614

Did you install the BWK at the track, or were these separate track days?

shardul

iTrader: (1)

Some more info

https://mbworld.org/forums/cl55-amg-...lly-works.html

JoeJErnst

Separate days. I know weather can make a difference, but my worst time with the BWK is better than my previous best. I'm pretty confident that the BWK is good for about .05s on a stock car.

Hulk

On stock cars I don't think the wrap kit will make a difference but when it's a bigger crank pulley and/or smaller sc pulley that's where it might matter.

Was planning on buying new belts for with and without and then doing a test with different setups to see the difference

JoeNobody

Was your old belt worn out? I have BWK as well and it does make a little more power up high.

jmb614

Thanks

kponti

I believe that is exactly what he has shown to not be the case. Even on a stock car there is enough slip to gain a little et with the BWK.
Judging from the lack of gain on MPH, I can postulate that the shifts and launch is where you gained the most with the BWK. SO the shocks to the drivetrain did not cause the corresponding slip of belt like it would on a stock system

Hulk

That is why we will do a test with new belts with and without the belt wrap kit. On the same day.

Mike450

Your best 60' time resulted in your quickest ET. That's how its supposed to be and likely had nothing to do with the belt kit.

If you gained a mph or two on trap, id say you were making more power.

Concrete data would be runs compared from same day that were all logged. Way to many variables possible to attribute it to a belt mod. PCM pulling 1 or 2 degrees due to fuel octane inconsistency is a tenth alone.

kponti

Looking forward to seeing results on that

jmb614

Thanks Hulk, I know how much of a PITA this will be. Looking forward to the results!

Hulk

Will be done, when is another question lol..but we are working on it lol

carguyshu

its my understanding that you can just swap back on the original belt in the original configuration with the belt wrap pulley still on. It shouldn't be that hard to do back to back comparisons.

Hulk

Yes you can.
Not hard, it's just timing.

blackbenzz

Nice concrete numbers. Unfortunately your interpretation of the data is completely wrong. You gained ZERO from the belt wrap kit. Your trap remained the same = NO power gain. I guess if you paid in cash you could consider it a lightweight mod because your pockets are lighter. I can take a car and cut different 60's and say the ET gains are form anything I want (i.e. lucky rabbit's foot gained 0.1s). Any educated racer would take one look at those slips and say NO power gains from belt wrap kit.

Lots of sales on this forum are driven by BS and fanboyism. I can't remember the last product that actually showed real proven results on here. One guy buys it and posts ZOMGGGG my traction control light blinks 12 times now it's soooo fast!!! And everyone buys it

I'm glad someone knows what they are talking about
Don't you have to unbolt at least one side for the belt?

Hulk

Ya just the side With the extra pulley

Crissus

We should really measure boost aswell. In my case i have a constant 1PSI increase in boost compared to without BWK.
What does 1PSI more boost nets in Power on the engines? I think together with a Tune it will be more noticable.

What is stock boost on thees cars anyway? Anyone has solid proof by MB? I cant find any numbers by MB in the internet, even though i am german and these cars are german... grrr... I read here in one comment that the cars are supposed to have 0.8bar stock (thats 11.6PSI)
What did you guys measure as stock boost?
My CL55 made 0.68 bar (9.86 PSI) before the BWK and now 0.75bar (10.9 PSI) with BWK. If the 0.8 bar figure is correct, how comes my engine wise "stock" car makes less boost than it should? How comes the car is still a freaking beast and is still even a bit quicker than the factory claims?

Hulk

If you log then you can do the test, I'm sure it's colder where you are right now also and you have the autobahn to test without getting into trouble like here lol.

Buy a new belt to fit the stock setup tight and then test with the bwk. 3rd gear pulls.

Post up your logs.

Boost
Rpm
Tps
Iat

Yes more boost will mean more power

Crissus

Well its not logging, just momentarily seeing values that are refreshed every second. See the picture in the left corner. Its called Ultragauge.
The "old" belt before the BWK was just one year old and 8000KM (5000miles) with 95% grandpa style driving.

Hulk

Ya, that will not work for logging thats needed. I guess a trip to Mexico will have to be planned. We will see...

blackbenzz

You will only see gains if the belt was slipping before. It's not rocket science

m3j0n

ill be glad to join you, mexico isn't that far.... my BWK arrives on Friday

Hulk

Like I said timing. Friday is good Friday, then Sunday is Easter. This weekend is definately out

JoeJErnst

Thank you for educating me, although your diplomacy could use a little work.