A 3.2 which will run 8,000 rpm?

[911hillclimber]

Feasible?
My stock 3.2 peaks at 6100, and it would be a big advantage in a hill climb to run to 7,800 (say).
Keep the 3.2 barrels, keep cost down, no machining.
New hi compression pistons (what make?)
New rods? If so, what make?
ARP hardware for the rods
Cams....but which ones, 'S' spec?
Carbs and a distributor with points.

Is the crank balanced well enough? Have Fenn Lane flywheel and alum cover clutch.

Anyone like to venture a cost for these items?
DIY build.
I've been here before, but didn't get clear costs.

[Lightweight_911]

.
Is your reasoning to save a gearchange ?

If so, it would probably be cheaper to change gear ratios ...

[mean_in_green]

Perhaps ask over on impactbumpers.com?

[911hillclimber]

The idea is with more revs I can reach the next corner without having to change, say, from 2nd to 3rd and back after a few seconds.
This is the engine in my Lola.

I asked this question on imp Bumpers a few years ago, and the thread got messy.

[Gary71]

Won’t you just end up with a narrower power band higher up the range and still have the same problem?

If at the moment you are pulling from 3 to 6 in second I can’t see you ending up with a flexible enough engine to pull well from 3 to 8.

Maybe a compromise would making it durable enough to pull another 500rpm would help between two second gear corners?

You could always turbo charge it and fit a longer 2nd gear

[redrobin911]

Going through the same thing with my 65 race car as had some incompatibility issues with the curent engine spec and some unknowns so start from scratch.

From the crank to valves my 2p worth.

Crank - get it polished and balanced and while at it stick some new mains - get the flywheel balanced to the crank at the same time.

Rods - while Carrillo and other rods seem tempting (but pricey) I'm going for the chinese max-speed ones including ARP 2000 botls for £100 each inc VAT. should be be good for 8k rpm - maxspeed quote 9k rpm - not sure of their data, but if oldskool S rods will spin at 8K+ I cant see how the maxspeed ones wouldn't be equally as good if not better - I'm planning 7.5k rpm max power with the odd 8k if needed. Also the Maxpeed are matched and fairly light. L19 bolts are £150-200 extra but will allow the engine to spin even higher....

Cylinders mine are the used ones bored out +1mm and Wossner (81mm) S pistons (10.5:1 compression ratio) honed to match the cylinders - again pistons c. £100 a pot - not sure on the cost of boring and relining what you have??? but much cheaper than new cylinders IMO. But you might as well go for bigger displacement if regs allow you - don't ask me about bore and stroke option but someone will know how far you can go.

Dougherty Cams with their own race valve springs and titainium retainers. I'm using a DC60 cam - which is a peaky cam in a low displacement engine but would be better than an "S" cam by miles and quite torquey in a 3.2. Modern cams have modern profiles that work better with modern valve springs and retainers. Less than £1.5 - £2k for cams and springs.

New stainless steel valves £30 each x 12.

I've had many converstaions on the same subject with Andrew Mallagh - might be worth touching base?

[911hillclimber]

Great details, just the facts and figures I'm after.
Gary, you have seen the Lola and Loton Park, I think you know what I'm trying the fix.

[corner shop]

I’ve got some work going on via Neil Bainbridge so can help with some of the prices

JE pistons (2018) - 1200 + VAT (11.5:1 & twin plug, but I think all CRs priced the same) - my cams are timed at 5mm, so unsure if further machining will be required.
Pauter rods (2017) - 1695+vat
Cams - Elgin cams @ 1300 USD - mine are supposedly ‘Singer’ spec by Rothsport, but your needs sound semi-race/RSR spec to me. Neils team advised they have a number of specs they can grind on new billets.
GT3 Crank (2017) - 1800+vat

Starting with a 3.4 (3.2 + 98mm Mahle), the longer stroke crank gives 3540cc

On its current 10.2 CR and ill fitting valve stem seals(!), it hit 285bhp@6300/255 torque@5000 at Surrey Rolling Road. With a CR of circa 11.0:1 and twinplug, it should 8-10% more on both counts. Note, its running motec (£6k) and 45mm ITBs (£3k).

That’s the theory....then you weigh up against a rebuilt 3.6 as a starting point.

[smallspeed]

I think if you’re stretching rpm considerably and wanting driveability across the existing and new increased range then EFI (fuel and spark) is going to bag you the gains (if you can use it within your regs). Without this you’re going to move the powerband you already have..

Another option - have you thought about stretching out the final drive to keep in (a now longer) 2nd, and bump your compression ratio / retune for more torque than top end?
I’m assuming (possibly incorrectly) torque > power to a certain extent when hill climbing?

[911hillclimber]

Thank you again for these details. sobering numbers.

The car is Sports Libre, 'Liberated Sports' so anything goes, as in anything, over 2 litre.

I already have a demon Mike Bainbridge box, the tallest CW and an extended 2nd.
The 915 despite Mikes magic, is a clumsy old thing and no Hewland gearbox.

A Hewland is £8K minimum.
There are several hills where I come into the corner bouncing on the 6.2K limiter. To take 3rd is the option and poke the throttle, but then I have to cross the gate again back to 2nd while braking for my life. It is not easy, takes time and I do not have any to spare.
The box can easily go from 3rd to 4th instead of 3rd in the heat of the moment....

The current 3.2 has 247 bhp/ 225 lbft and is very very drivable; it will pull hard on WOT from 2K and get on with it like a steam train.
The car weighs 530 Kg.

A Boxster gearbox is the most obvious solution, and would be by far the cheapest mod.
The AUDI A4/Boxster 5 speed box is slick but not without it's installation issues.

[nj1052]

I think you already know that the only real solution to your gearing problems is to install a Hewland FGC with all the ratio options that offers plus the opportunity to make clutchless up shifts. The issue in not the motor, it is the gearing.

[fetuhoe]

I am not sure you will ever find a consensus opinion about how to specify an engine to achieve a particular set of objectives.

I think that you should start by looking at the gear ratio chart and trying to see how this integrates with your power curve and your theoretical top speed and where you to shift.

What do you mean by the 'tallest CW' and an extended 2nd ?

Do you use First Gear?

Using a Boxster gearbox to try to improve the gearshift will not necessarily deal with the mismatch in the ratio's and the power curve you are trying to resolve.

The Hewland will produce the flexibility you need in terms of available gear ratios whilst the Boxster will still limit you to the choices Porsche made to suit a mass market vehicle, it will also provide a much faster gearchange.

If you then modify the engine it will be easy to switch gear ratios to take full advantage of the improvements.

[911hillclimber]

If I could change gear like I imagine an fgc does, my probs would be over.
The Hewland cost is huge for the gain.
You do not see many (any?) flat 6 engines mated to a Hewland, so everything is custom, bell housing, starter motor and clutch.
I think the fgc also has a 'top, mounted shift input shaft so the gear linkage become a real issue.

The 915 box has the tallest cwp made for this box that Mike fitted along with a taller 2nd gear.
I use first to start only on the hills I use.

Top speed needs to be 110 mph in 4th.
My fastest speed is 100 mph at Shelsley Walsh.

If I could change gear quicker and reliably, all would be well.
The 915 has little gate definition internally and the car has none at all, so I have to change gear with precise hand movements.
I have driven a strong 911 with a 915 box fitted with VEVO internal shift gate and VEVO gear lever, short throw.
I think the box was built by Mike some time ago.

It shifted gears well, but I think a lot is down to the shift gate and short shift.

An option is to return the box to Mike to fit a VEVO gate and a taller still second ,it that will stunt the acceleration in second!
2nd and third are the most important gears most used.
Remember a run up Shelsley involves just 6 gear changes from start to finish, and I can do it in 31.58 seconds. This is a slow time but only involves one 3rd to 2nd, but other hills have more such changes so any improvement would give a better time.

Not altogether sure if there is a single action I can make to make the car work more efficiently.

[andytat]

Give Ian Heward a call at the Porsche Shop. A number of years ago I
sold him a Quaife 6 speed sequential box which was one of the first
boxes they produced with a Porsche bellhousing. It was a forerunner
to the 997 Cup transmissions that they make. He fitted it to his 996
turbo RSR race car but I think he changed to a stronger box as it used
to eat the crown wheel and pinions. I believe he sent it back to Quaife
for refurbishment and since then it's been under the bench. If he has
still got it you might be able to do a deal with him.
As others have mentioned 7,800 rpm will prove very expensive to achieve.

Andy

[Sam]

Fit taller tyres.