986 2.5 underdrive pulley dyno graph

[transtlye]

i have just installed the RSS underdrive pulley and had gotten it dyno tested today. The car is a 97 boxster 2.5L. I think some people will be interested in the results. it started at 199hp for the first run. they had pulled it 5 times and every time i had gotten about 1-2hp more. i called it after the fith pull because it was starting to get hot. the final result was 206.5. When it was stock i had dyno tested at 200.9-201.1hp.

[IMG]IMG]http://i899.photobucket.com/albums/ac197/transtlye/1271541660420.jpg[/IMG][/IMG]

[violametallic-S-]

nice results. I have my pulley sitting in a box for my 3.2, waiting for a nice day to install it.

[Cloudsurfer]

RSS also makes a harmonically dampened underdrive pulley, designed for the M97 3.8 motors, that fits just fine on any of the rest, provided you use the longer bolt.

Seems like a pretty good idea to me to get some damping onto the crank in these things.

[edevlin]

"RSS also makes a harmonically dampened underdrive pulley, designed for the M97 3.8 motors, that fits just fine on any of the rest, provided you use the longer bolt. Seems like a pretty good idea to me to get some damping onto the crank in these things."

would this help those of us with lightweight flywheels to dampen some of the harmonics normally handled by the DMF?

Ed

[Cloudsurfer]

Originally Posted by edevlin

"RSS also makes a harmonically dampened underdrive pulley, designed for the M97 3.8 motors, that fits just fine on any of the rest, provided you use the longer bolt. Seems like a pretty good idea to me to get some damping onto the crank in these things."

would this help those of us with lightweight flywheels to dampen some of the harmonics normally handled by the DMF?

Ed

Yes. Hence why it's on my motor

[chaudanova]

Cloudsurfer, what are your driving impressions with the harmonic RSS unit?

[Jake Raby]

I haven't stopped the development of the dampened UDP. We are still working on the project as an exclusive product for our updated engine program.

[Jake Raby]

Continually we see exactly 12-15% variations between either of my engine dynos with the same engine installed into the vehicle and evaluated on our dyno-jet chassis dyno. This is the same differentials with either air-cooled or water cooled Porsches.

I am less concerned with actual peak numbers than most any person you'll meet. Our dynos were bought to be developmental tools so repeatability trumps any peak number.. Last week I did 5 runs back to back on the dyno jet and attained less than .75 HP of differential across the entire average RPM range. That repeatability is whats necessary to do the level of developmental comparison that I am interested in.

[Gilles]

Jake,

I was very interested on installing the LWFW along with the Sachs spring clutch disc but got cold feet after reading one of your posts where you mentioned that the dual mass flywheel cancels the harmonic issues and that there were several engines that failed because the dual mass FW was replaced with a LWFW.

Do you think that would be safe to install a LWFW (AND) an underdrive crank pulley with a harmonic balancer?

I saw an ad from a company called ATI Racing and they told me that it was possible to manufacture an underdrive pulley with a harmonic balancer.

However, I was not aware of the RSS UDP until this post, but the ones from ATI seem beefier.

Somewhere I read that some of the older Porsche engines had a harmonic balancer build into the crank pulley as well, but I am not sure if these would fit or if they would do the job once done by the dual mass flywheel.

What do you think?

Regards,
Gilles

PS, this is the link to ATI:

http://www.atiracing.com/products/dampers/damper_tech.htm

.

[Cloudsurfer]

Originally Posted by Gilles

Jake,

I was very interested on installing the LWFW along with the Sachs spring clutch disc but got cold feet after reading one of your posts where you mentioned that the dual mass flywheel cancels the harmonic issues and that there were several engines that failed because the dual mass FW was replaced with a LWFW.

Do you think that would be safe to install a LWFW (AND) an underdrive crank pulley with a harmonic balancer?

I saw an ad from a company called ATI Racing and they told me that it was possible to manufacture an underdrive pulley with a harmonic balancer.

However, I was not aware of the RSS UDP until this post, but the ones from ATI seem beefier.

Somewhere I read that some of the older Porsche engines had a harmonic balancer build into the crank pulley as well, but I am not sure if these would fit or if they would do the job once done by the dual mass flywheel.

What do you think?

Regards,
Gilles

PS, this is the link to ATI:

http://www.atiracing.com/products/dampers/damper_tech.htm

.

ATI makes great stuff, unfortunately they do not have any applications that would benefit us, hence why I went with the RSS unit.

[Jake Raby]

I have been developing a harmonically dampened UDP for over two years now.. As soon as I saw the other companies making similar companies I halted the development because theirs is cheaper and few people buy "better" these days.

[extanker]

Originally Posted by Jake Raby

I have been developing a harmonically dampened UDP for over two years now.. As soon as I saw the other companies making similar companies I halted the development because theirs is cheaper and few people buy "better" these days.

aint that the sad truth

[Gilles]

Originally Posted by Jake Raby

I have been developing a harmonically dampened UDP for over two years now.. As soon as I saw the other companies making similar companies I halted the development because theirs is cheaper and few people buy "better" these days.

Jake,
Do you think that would be OK to install a LWFW (with a Sachs spring disc) as long as a harmonically dampened UDP is used as well?

[chaudanova]

Originally Posted by Jake Raby

I have been developing a harmonically dampened UDP for over two years now.. As soon as I saw the other companies making similar companies I halted the development because theirs is cheaper and few people buy "better" these days.

Jake,

Seeing as you stopped development of the dampened UDP, can you give an honest breakdown of what you think between the 4" undampened unit that you have been using lately, versus the aforementioned dampened unit that Cloudsurfer installed by RSS? (Even if you haven't had a chance to get your hands on the other unit in person yet, perhaps you could give me a theoretical comparison).

I don't know the dimensions of the RSS unit, but am curious if going with the smaller and lighter 4" UDP, has more benefits than the perhaps larger and heavier dampened unit...

Please feel free to PM me if you think this would start any unnecessary controversy. I'm very open-minded, and since I would like to install an UDP soon, I would just like to know the pros/cons before going with a particular unit.

Thanks in advance

[Bobiam]

Originally Posted by transtlye

i have just installed the RSS underdrive pulley and had gotten it dyno tested today. The car is a 97 boxster 2.5L. I think some people will be interested in the results. it started at 199hp for the first run. they had pulled it 5 times and every time i had gotten about 1-2hp more. i called it after the fith pull because it was starting to get hot. the final result was 206.5. When it was stock i had dyno tested at 200.9-201.1hp.

[IMG]IMG]http://i899.photobucket.com/albums/ac197/transtlye/1271541660420.jpg[/IMG][/IMG]

I'm not trying to be critical or anything, but a max 5.5 HP gain (less than 3%) does not seem worth the effort/cost. Do you feel there is a noticable difference in the seat of the pants? I was thinking about a Raby UDP but am hesitant based on these results. Any encouragment to offer??

[Steve Tinker]

Bobiam,
I can't comment on the OP's choice of pulley, but I fitted the Raby pulley 3 months ago and its not the HP increase (which according to the graph is minimal), but the torque increase from low revs that has impressed me. Yes, you can definately feel it in the seat of the pants, especially from 1,500 - 5,000 rpm, after that it academic....
As an additional bonus, the cabin is much quieter due to lower accessory rotational noise....

[Gilles]

Bobiam,

Two years ago I installed a (BBI) UDP, the main reason was to reduce the accessories because I was overheating the steering pump at the track.

The first failure was the high pressure fitting at the steering rack, the second failure was melting (somehow) the bottom of the reservoir with an o-ring failure and lastly the dealer ended replaced the PS pump along with some of the high pressure lines that were damaged when the hot fluid leaked.

However, I am planning to install a cooler on the low pressure return line (along with an Accusump) before heading back to the track
.

[Jake Raby]

Smart people understand the torque increase is where its at...

[dsisco]

Originally Posted by transtlye

i have just installed the RSS underdrive pulley and had gotten it dyno tested today. The car is a 97 boxster 2.5L. I think some people will be interested in the results. it started at 199hp for the first run. they had pulled it 5 times and every time i had gotten about 1-2hp more. i called it after the fith pull because it was starting to get hot. the final result was 206.5. When it was stock i had dyno tested at 200.9-201.1hp.

[IMG]IMG]http://i899.photobucket.com/albums/ac197/transtlye/1271541660420.jpg[/IMG][/IMG]

was wondering what mods you have already done to your car?

how did you get 200hp at the wheels stock when they only have that at the crank?

Just curious
i

[sparker]

I too am curious about the 200hp at the wheels - any hints???

Sam