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Beaky

32. vs. 3.2 with ITB vs. 3.4

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Yup, bite the bullet on that........................

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Nice - what else?

Cams?

BBTB?

using Jaz?

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Full spec not dialed in yet, but yes to cams, lightened rods, ARP's. wider throttle body (67mm) and I also need new heat exchangers.

Steve at Jaz will be doing my rebuild

  

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5 minutes ago, SP72 said:

Zingy!

With the lightened sport clutch which was done last year, I hope so.

If I can get a healthy say 260bhp and good low down torque then I'll be happy. 

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5 hours ago, Beaky said:

Yup, bite the bullet on that........................

Good luck - I've been pleased with my 3.4 conversion, adding the 964 cams definitely helped make it a bit more zingy - still very tractable in traffic etc.

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2 hours ago, Beaky said:

Full spec not dialed in yet, but yes to cams, lightened rods, ARP's. wider throttle body (67mm) and I also need new heat exchangers.

Steve at Jaz will be doing my rebuild

  

I'm sure your engine builder will check...  but I was surprised just how close the piston/valve clearance is on my 3.4 (Mahle P&C) with 964 cams. If you go for anything higher lift or longer duration than 964 spec then you'll likely need bigger cut-outs machining on the pistons as per Shirish's latest build.

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9 minutes ago, MaxDiesel said:

I'm sure your engine builder will check...  but I was surprised just how close the piston/valve clearance is on my 3.4 (Mahle P&C) with 964 cams. If you go for anything higher lift or longer duration than 964 spec then you'll likely need bigger cut-outs machining on the pistons as per Shirish's latest build.

Thanks for the head up. It will probably be 964 cams but will also investigate 993ss cams

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Think you’ll comfortably reach your target, especially with a higher rev limit the rods, cams etc will allow you

Are you staying with standard h/ex?

Get it dyno’d before - the one at EvolveMS in Luton was very accurate when we had a get together there a few years ago

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Which h/ex is nearly on par with oil or tyres as to which is best, so going standard h/ex at the moment as I do like my heat as I use her all year round, salt permitting.

 

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Beaky, as you are getting your pistons and cylinders from the exact same source as mine, I believe them to be JE pistons with valve relief pockets, meaning you could use way more cam than a 964. I chose 993ss as highly recommended by many but you could go a little more with a 3.4

chris 

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4 hours ago, Chris T said:

Beaky, as you are getting your pistons and cylinders from the exact same source as mine, I believe them to be JE pistons with valve relief pockets, meaning you could use way more cam than a 964. I chose 993ss as highly recommended by many but you could go a little more with a 3.4

chris 

Hi Chris, Sounds like a plan,

What are you doing for valves and springs, spring retainers?

Edited by Beaky

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12 hours ago, Beaky said:

 going standard h/ex at the moment as I do like my heat as I use her all year round, salt permitting.

So you are going 3.4 and yet standard heat exchangers and exhaust?

Not going for these? 

 

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Valves are standard, springs will be race versions, Nick recommended not using Ti retainers as they can wear but I may throw in a set for extra Rev-ability

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15 hours ago, Beaky said:

Full spec not dialed in yet, but yes to ... lightened rods, ARP's. 

So standard rods but made lighter, yes? Not going for new lighter rods to start with? 

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31 minutes ago, Dr Rock said:

So you are going 3.4 and yet standard heat exchangers and exhaust?

Not going for these? 

 

All still in the melting pot for finalisation on spec..................

22 minutes ago, Dr Rock said:

So standard rods but made lighter, yes? Not going for new lighter rods to start with? 

Sorry I meant Lighter rods - Carillo's I think they are called

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33 minutes ago, Chris T said:

Valves are standard, springs will be race versions, Nick recommended not using Ti retainers as they can wear but I may throw in a set for extra Rev-ability

This Is beyond my knowledge, so will rely on Steve to recommend based on the other bits. 

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She's booked in for the 9th May 

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Exciting times!

You decided on cams yet?  Chris makes a good point above -be interesting to know what FennLane recommend.  Neil was planning on Mod-S cams on mine until I approached William Knight re his spec.

Does keeping Motronic limit cam choice, or if its purely piston shape. 

Do the JE pistons mandate twin plug?

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Probably go with 993ss’s, these seem to be in vogue at the moment, believe Fraser has them in his car and is happy with the result and probably about right for what/how I want to use the car.

 

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7 hours ago, Beaky said:

Probably go with 993ss’s, these seem to be in vogue at the moment, believe Fraser has them in his car and is happy with the result and probably about right for what/how I want to use the car.

 

Believe!? Fact! Love them. Not that I am vastly or in any way experienced with camshafts, but I can really feel the double kick as the revs rise :001-17-revto9k:

They idle like stock as well.

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Sorry Beaky if this is akin to a mini hi-jack but in the interest of some learning....

Based on knowing almost nothing but planning great things in future (:rolleyes:), I have to ask - surely Ti retainers save only a couple/three grams each? wouldn't money better spent doing something with better valves - lighter version or machined or something?

Then thinking further about this how much weight could be saved with expensive, lighter rods (Carillo, Pauter etc)  versus standard? Surely the best impact would be lighter pistons that are accelerating more and travelling further each rotation - these could also have compression bumped up nicely and be cut out for more aggressive camshafts such as the 993SS?

So could the (almost always finite amount of) money be spent better (suppose this is predated on fact one prefers a more responsive motor over simply a torquier version....) on keeping it 3.2 but with better pistons or con rods (or both) and camshaft rather than simply going bigger which involves new pistons in any case and new barrels at very least?

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Ti retainers are half the weight, so 11g vs 22g.

Carillo rods are about 70g each lighter than stock and all weigh the same, and you would balance the pistons as well, while you are there.

408EFD63-C535-4023-A76C-085E5F928FDD.jpeg

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Hi all, JE pistons don't mandate twin plugs, they will work single plug, but you can retard (?) the timing somewhat meaning more power as the flame front ignites more quickly, you can then time it to happen nearer TDC so less negative work (flame starting to burn while piston is still rising) is done = more power, plus a more complete burn = more power.

Chris

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Thank you Dr Rock - useful info.

I wonder how much lighter (or similar such as Wossner which seem highly rated) would be than the Mahle versions?

I presume that already the almost 500grams saving from Ti retainers and Carrillo rods makes an enormous difference at engine speeds - both in terms of responsiveness and risk of high rpm failure/engine life (thus increasing allowable rev limit/power).

 

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