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Posted (edited)

Horror picture for me, the last time this engine went Pop a few years ago. Went from flat out in 2nd to 1st instead of 3rd...

 

This engine plan is coming together slowly.

Wossner pistons

Carrillo rods with their 'weakest' bolts

Cams, springs, rockers from John Dougherty in the USA

WEVO internal selector in the box by MB Engineering who rebuilt this box ages ago after it lasted 7 gear changes due to Pilot Error.

Too scared to think about ignition yet, but keeping the carbs.

Getting expensive, Wife OK, might have to sell some 2 wheel toys next year to ease my conscience.

 

35715464_lola36046.jpg.95e62081583ce0a05282eebd9c59d4e3.jpg

Edited by 911hillclimber
Posted
5 minutes ago, 911hillclimber said:

Horror picture for me, the last time this engine went Pop a few years ago. Went from flat out in 2nd to 1st instead of 3rd.

That's what killed Perkles' Ark at Bugatti Le Mans back in the day :(

Posted

I cannot get anyone to 'guess' at the rpm limit for stock rods with ARP bolts, but all big guesses are sub 7000 rpm, so resigned to a set of forged steel rods.

Opinions in the USA are Pauter are less discussed, so presumably less failures.

UK quote is £1576 inc vat/4 weeks.

Also has advice from Rennsport that the crank will need cross drilling for oil to Clevite bearings. and Carrillo rods.

The more you delve, the darker the journey!

Posted

For reference, my 3.0 SC engine with stock SC bolts (and race springs and TI retainers) will rev to 7k :revs: (my peak power on 964 cams is at 6950

Posted (edited)
2 hours ago, 911hillclimber said:

The con rod bolts in the 3 litre and smaller engines have 10mm diameter bolts, the 3.2 had 9mm which makes things marginal.

You were asking about the rev limit for 3.2 rods with ARP bolts though (not stock bolts) ? 🤔

"I cannot get anyone to 'guess' at the rpm limit for stock rods with ARP bolts"

I can't believe that ARP rod bolts are not better than stock 3.2 ones (even if they're the same diameter).

Even if there weren't as strong as the mighty race engine-derived SC bolts ( 😁)  can't 3.2 rods be drilled to take 10mm bolts ?

You also seemed to have asked the same question about 10 years ago ;)

 

Edited by GaryH
Posted

Not sure drilling out the rods will give the reliability tbh.

Also, yes, have asked the same questions ages ago, and also hoping to find 'today's' solutions  from people.

Over time things change, companies improve the products sold, and suppliers stop trading, so updates are good. That is what I am trying to find out.

 

There are also choices to make; for example, Carrillo or Pauter for rods. Which ones may be better, may be cost advantageous, even both.

In the case of Pauter seems many like them (ie not had or read of failures) and they are cheaper, but not by much by the time they arrive here from California for example. I do not want to go to this work and considerable cost and make a mistake on parts choices, so I am asking advice and opinions hopefully from people who have done this before me if they read this thread. Several have helped in recent weeks on this forum and another.

Could stock rods and ARP bolts hold repeated red line levels of 7000, or 7500 or higher?

Nobody has an answer except 'fit Carrillo rods' which is an answer in itself. from a company that I feel know what they are talking about. That was this morning by email from them, taken 3 weeks to get such info from a reliable source, thought I would share it on here.

This engine change could be an £8000 ticket in parts and some services, so I tread carefully.

  • Like 1
Posted

Summary without ignition mods:

 


Just done my 'Spread Sheet'
Thought some would find the following prices interesting, all £ and inc vat
Wossner pistons: 1200
Pauter rods: 1500
DC60 or maybe softer Cams/spring kit/rockers: 2100
Crank bearings: 214
Gasket kits: 252
Flywheel bolts: 30
Rocker cover gaskets: 39
7100 rpm rotor arm: 34
intermediate brgs: 26
Loctite 574: 26
Crank oil seal: 34

Twin plug head machining, my estimate, 350
WEVO gearbox mod: 1700

Misc bottles/potions/cleaning fluids: 300

Total: around £6k ($ v £ @ 1.38)

Ignition?
 
Posted

I thought you were going to build a screamer Graham, the DC60 will work well from 4500 up to 7500. These are the words of John Dougherty:-

With 10.5-1 compression you can definitely use the DC60 camshafts.  These will give you more power from 5000 rpm
and up vs. the DC40.  4500-7500 rpm powerband   rough idle but easy to manage on the street.    Typical 240-250 rwhp numbers (for 3 litre engine)
Posted
On 13/09/2021 at 22:34, 911hillclimber said:

Not sure drilling out the rods will give the reliability tbh.

Also, yes, have asked the same questions ages ago, and also hoping to find 'today's' solutions  from people.

Over time things change, companies improve the products sold, and suppliers stop trading, so updates are good. That is what I am trying to find out.

 

There are also choices to make; for example, Carrillo or Pauter for rods. Which ones may be better, may be cost advantageous, even both.

In the case of Pauter seems many like them (ie not had or read of failures) and they are cheaper, but not by much by the time they arrive here from California for example. I do not want to go to this work and considerable cost and make a mistake on parts choices, so I am asking advice and opinions hopefully from people who have done this before me if they read this thread. Several have helped in recent weeks on this forum and another.

Could stock rods and ARP bolts hold repeated red line levels of 7000, or 7500 or higher?

Nobody has an answer except 'fit Carrillo rods' which is an answer in itself. from a company that I feel know what they are talking about. That was this morning by email from them, taken 3 weeks to get such info from a reliable source, thought I would share it on here.

This engine change could be an £8000 ticket in parts and some services, so I tread carefully.

Sure everyone can read the Bruce A book as easily as I can.  Presumably based on lots of accumulated experience, his answer appears to be (page 185) that the standard 3.0L rods are good for applications up to about 7,800 rpm but infers to achieve the same on the 3.2 the rod bolts need to be replaced with ARP (or, presumably, some other equivalent) bolts.  Also states that Porsche recommends the use of special racing cranks for sustained use over 7000 rpm but then goes on to state that if you restrict your use to 7,500 to 7,800, the 70.4mm (2.4 to 3.0L) cranks are quite reliable.  By which I would also infer that the 3.2 crank may not be so strong.  For applications with sustained use over 7,800 rpm he recommends the Carrillo rods. For race applications with a larger displacement (3.2 to 3.5L) engine, he recommends the GE100 cam profile.

Given the specialist nature of your application, it's probably worth talking to one of the established race engine builders, I'm sure some would be prepared to at least give some thoughts or advice without the carrot of doing the full engine build, particularly if you gave them some of the work, like prepping the heads, etc.  They may also have some parts that would be useful.  

Posted

Perfectly reasonable view on this engine.

I do take the Anderson book with care, it is an old book now, things and experiences change.

I might have a contact to a builder who would review my intents, and he is a hillclimber too, so understands things better for the application.

Getting hard facts is hard!

Nobody will quantify how many rpm the stock 3.2 rod/arp will take, so I'm forced to but rods, that 'force' is £1500.

At this stage I could be very easily persuaded to leave well alone and simply put arp bolts in, 964 cams and clean the engine, about £2000, add the WEVO mod to the 'box for £1600 or so and we are ready with a bit more pep for 2022 race season starting in April.

However, I like to do this garage stuff and have never built a well modified Porsche engine, just built 3 911 aircooled engines.

 

I will bite the bullet this weekend I think.

Posted

£1500 rods are cheap insurance 😉 :twocents:

When a rod goes it will be at max RPM, to make yourself feel better about the extra £ you've just spent, cost up a new block, full engine, new crank and anything else internally that has been damaged, possible gearbox rebuild if the engine locks solid, maybe you'll have to remake a new cooling fan assembly, no more racing for a while etc, etc

Posted (edited)

So basically you need 3.0 rods, 3.0 rod bolts and a 3.0 crank for racing applications ?

 So, basically a 3.0 engine ;)

Edited by GaryH
Posted

With 98mm pistons, back to 3.2 - simples

Posted (edited)

Indeed Peter, a 3.2 short-stroke would seem to be the answer for these tuned racing applications.

All the torque (of 3.2 displacement), power, increased rev range and the strength/reliability 👍

Edited by GaryH
Posted

But I don't have those bits. Doubt decent SC engines are readily available either.

Hello Peter, didn't know you popped over here too!

Had a short reply from Kent cams this afternoon. They could not help unless they get the cam spec from the likes of Tuttils etc. Doubt that will be forthcoming.

I'll have one more try with them and if that fails will pay the price and go to California and Dougherty Cams..

Conversely, Pauter have been in touch of their own accord to help I get the right parts from one of the UK dealers. There are several rod specs for 3.2 engines. Customer service.

As an aside; 3L/3.2p&B page 151 Anderson's book, such engines give around 250 bhp.

My current 3.2 does 262 recently on the rollers.

Posted
15 hours ago, 911hillclimber said:

Perfectly reasonable view on this engine.

I do take the Anderson book with care, it is an old book now, things and experiences change.

I might have a contact to a builder who would review my intents, and he is a hillclimber too, so understands things better for the application.

Getting hard facts is hard!

Nobody will quantify how many rpm the stock 3.2 rod/arp will take, so I'm forced to but rods, that 'force' is £1500.

At this stage I could be very easily persuaded to leave well alone and simply put arp bolts in, 964 cams and clean the engine, about £2000, add the WEVO mod to the 'box for £1600 or so and we are ready with a bit more pep for 2022 race season starting in April.

However, I like to do this garage stuff and have never built a well modified Porsche engine, just built 3 911 aircooled engines.

 

I will bite the bullet this weekend I think.

I suspect the issue is that most of us are not really racing, sprinting or hill climbing our cars.  So even if they have been modified, they probably don't get pushed that hard for long enough to see where the real failure points are.  Also, with some exceptions, these cars aren't really widely used for mainstream motorsport anymore and they are essentially 60s and 70s tech. At some level of other, the Anderson book at least has the advantage of having been written when these cars were more in the thick of it.  What I did was use the BA book as a starting point, then sounded things out online largely through an email/forum dialogue with a guy called Steve Weiner in the States - https://rennsportsystems.com/technical-articles/.  In return, I sourced some of the parts I used via Steve (at competitive prices) and had him refurbish and machine for twin plugs some large port 3.0L Carrera heads I sourced in the US. Overall, I'm really happy with the results - but it is really more of a hot road engine than anything for serious race use.

Posted

I've emailed Steve recently about the rods asking if the 3.2 stock rods/arp bolts could tolerate 7500 and his response was no comment, just fit Carrillos!

From that response I assume the answer is no....

Thus, I've settled on Pauter rods, have to make some decisions on this lot, and have had a doubt put in my mind about the Wossner pistons having pockets deep enough for the DC60 cams, so another email to try to resolve. I can buy the pistons from Design911 so saving Brexit etc shipping hassles (Wossner are German).

Biggest sticking point are the cams.

Seems Kent cams are not enthusiastic, Dougherty certainly are, just in the USA, but they have been clear what is right in some detail.

Hope to send orders very soon so kicking this little project off. Many people do not understand a UK hillclimb and the way the cars are hammered, usually on wide open throttle and to the red line repeatedly but bouncing off the rev limiter for quite short periods, around 5 seconds.

 

I think your summary of the position of the aircooled engine is spot-on.

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