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jimk04
Trainee


Joined: 10 Dec 2013
Posts: 73



PostPosted: Sat Aug 05, 2017 7:05 am    Post subject: Underdrive pulleys for 9x6 and 9x7 Reply with quote

I am having another batch of 4" pulleys made. This will be the 3rd run.
Hopefully back from the cnc shop next week and then to the anodisers.
Maybe 3 weeks until available.

****only suitable for pre .2 cars.....not for later cars with harmonic damper crank pulley******.

Will be 90gbp.

Please log any interest

Thankyou
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Last edited by jimk04 on Sat Aug 05, 2017 11:24 am; edited 1 time in total
 
  
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Phil 997
Fuji


Joined: 05 Dec 2015
Posts: 9879
Location: Bournemouth,Dorset

2009 Porsche 997 Carrera 4S

PostPosted: Sat Aug 05, 2017 10:50 am    Post subject: Reply with quote

Jim, will these work on a manual 997.2 if so very interested ,also do you have access to the shorter belts. Thumb Thumb
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jimk04
Trainee


Joined: 10 Dec 2013
Posts: 73



PostPosted: Sat Aug 05, 2017 11:19 am    Post subject: Reply with quote

Hi Phil

I should have added more detail to the initial post. Sorry.

I don't think these are suitable for any 9x7.2 as they changed to a harmonic damper style pulley.

Regards

James
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wot996
Silverstone


Joined: 21 Nov 2011
Posts: 102



PostPosted: Sat Aug 05, 2017 2:29 pm    Post subject: 4"underpully Reply with quote

Hi Jim

I take it that it would be suitable for my 996.1 tip?

As per Phil too, do you have access to shorter belts?

Regards

John
 
  
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jimk04
Trainee


Joined: 10 Dec 2013
Posts: 73



PostPosted: Sat Aug 05, 2017 2:36 pm    Post subject: Reply with quote

Hi John.

Fine for 996.

I can provide a belt or can give you the details for you to get one from wherever. Readily available.
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jimk04
Trainee


Joined: 10 Dec 2013
Posts: 73



PostPosted: Sat Aug 05, 2017 2:48 pm    Post subject: Reply with quote

Poor picture I'm afraid.....I am another disgruntled ex photobucketeer.




New ones may not be laser engraved.
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crash7
Monza


Joined: 28 May 2011
Posts: 229



PostPosted: Sat Aug 05, 2017 10:28 pm    Post subject: Reply with quote

Interested - Could you comment on if these differ from the RSS items?

Is the diameter the same?

Cheers

Last edited by crash7 on Sun Aug 06, 2017 9:58 am; edited 1 time in total
 
  
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Phil 997
Fuji


Joined: 05 Dec 2015
Posts: 9879
Location: Bournemouth,Dorset

2009 Porsche 997 Carrera 4S

PostPosted: Sat Aug 05, 2017 10:39 pm    Post subject: Reply with quote

jimk04 wrote:
Hi Phil

I should have added more detail to the initial post. Sorry.

I don't think these are suitable for any 9x7.2 as they changed to a harmonic damper style pulley.

Regards

James


Dam, thought that might be the case Jim thanks for the reply though . Thumb
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NLW73
Österreich


Joined: 27 May 2014
Posts: 890
Location: Yateley


PostPosted: Sun Aug 06, 2017 8:25 am    Post subject: Reply with quote

Jim

Would these work on a 996.2 gt3 mezger engine?

Also what do they help with? Reducing resistance and helping to spin engine faster?

Thanks nick
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jimk04
Trainee


Joined: 10 Dec 2013
Posts: 73



PostPosted: Sun Aug 06, 2017 8:36 am    Post subject: Reply with quote

Mick.

Sorry no the gt3 is a different fitment.
I'm not sure if the Mezger has a dampener on the pulley as well. ..meaning your'e best leaving it alone.

The principal is you are slowing down the auxiliary consumers such as pas/ac/alternator. ..therefore reducing parasitic losses on the engine.
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kas750
Paul Ricard


Joined: 31 Mar 2013
Posts: 3379
Location: Chorley lancashire

2006 Porsche 911

PostPosted: Sun Aug 06, 2017 2:23 pm    Post subject: Reply with quote

jimk04 wrote:


The principal is you are slowing down the auxiliary consumers such as pas/ac/alternator. ..therefore reducing parasitic losses on the engine.


I have thought about this mod many times.
Are there are any published figures to show any increase in power?

Adrian
 
  
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jimk04
Trainee


Joined: 10 Dec 2013
Posts: 73



PostPosted: Sun Aug 06, 2017 3:06 pm    Post subject: Reply with quote

I have read reports from some that proclaim a revelation after fitting one of these.
I however don't buy into that. If you are doing a few cheap bolt on upgrades. .....throttle body....sports cats.....light flywheel......I think it all adds up to a sum greater than the parts.....which is what I have done.
But please don't think your car will feel a different animal for fitting an under drive pulley.

Another benefit is you are slowing down the pas pump which is known to overheat on hot track days....admittedly not a problem for most people.

I guess if you are the type of person that can't leave cars alone you will do this regardless. But I understand it isn't for everyone.
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ragpicker
Paul Ricard


Joined: 14 Apr 2013
Posts: 3123
Location: North East England


PostPosted: Sun Aug 06, 2017 4:17 pm    Post subject: Reply with quote

Yeah, I think i'd give one of these a go... Would need the shorter belt though as others have said. Please put my name down.

One of the few mods I've never tried, might as well have a go on the old boxster and see if it makes any odds... Thumb
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James.hunter1985
Newbie


Joined: 28 Feb 2017
Posts: 37



PostPosted: Mon Aug 07, 2017 7:56 am    Post subject: Reply with quote

Yes please - I would definitely have one please Thumb
Also where to get the belt Rolling Eyes
 
  
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kas750
Paul Ricard


Joined: 31 Mar 2013
Posts: 3379
Location: Chorley lancashire

2006 Porsche 911

PostPosted: Mon Aug 07, 2017 8:22 am    Post subject: Reply with quote

jimk04 wrote:
I have read reports from some that proclaim a revelation after fitting one of these.
I however don't buy into that. If you are doing a few cheap bolt on upgrades. .....throttle body....sports cats.....light flywheel......I think it all adds up to a sum greater than the parts.....which is what I have done.
But please don't think your car will feel a different animal for fitting an under drive pulley.

Another benefit is you are slowing down the pas pump which is known to overheat on hot track days....admittedly not a problem for most people.

I guess if you are the type of person that can't leave cars alone you will do this regardless. But I understand it isn't for everyone.

Ok thanks for that.
 
  
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drabux
Spa-Francorchamps


Joined: 01 Oct 2014
Posts: 369
Location: Bath


PostPosted: Mon Aug 07, 2017 10:28 pm    Post subject: Reply with quote

I saw dyno figures a while ago of about a 7 whp gain.
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Marky911
Suzuka


Joined: 04 Jun 2009
Posts: 1045



PostPosted: Tue Aug 08, 2017 2:51 pm    Post subject: Reply with quote

I like the idea of these but your water pump will suddenly be running slower, which isn't ideal especially the M96/7 engine. Any info anyone?
 
  
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jimk04
Trainee


Joined: 10 Dec 2013
Posts: 73



PostPosted: Tue Aug 08, 2017 2:55 pm    Post subject: Reply with quote

Valid comment.
All I can add is that my water temp doesn't seem to be any different. I have sat in a French traffic jam in 30 odd degree heat and it didn't deviate from just above the 80 mark.

It has been noted that slowing down the water pump may actually help at prolonged elevated rpms due to the oe pump starting to cavitate at higher engine speeds.

I have no proof of the above. ..just a comment I read on one of the American boards.
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996lee
Hockenheim


Joined: 26 Aug 2014
Posts: 649
Location: South Wales/Nottingham


PostPosted: Tue Aug 08, 2017 4:42 pm    Post subject: Reply with quote

Had my rss under drive pulley in for a couple of years now and think they are a great cheap mod and these are half price or less of what I paid Thumb
It's not affected temps
It has made the steering a little heavier which is a bonus imo
And the butt dyno felt the benefit again imo Thumb
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Marky911
Suzuka


Joined: 04 Jun 2009
Posts: 1045



PostPosted: Wed Aug 09, 2017 8:28 am    Post subject: Reply with quote

Thanks for reply Jim and thank for your feedback Lee. Going to have a word with my Indy and see if he's fitted any and if so, what's his opinion.

[Columbo voice] Just one more thing [/Columbo voice]
Jim does your pulley require the TDC (top dead centre) boss to be ground down before it'll go on?
Not sure I'd want to do that.

Thanks.
 
  
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