KS's hillclimbing odyssey

[Cortina]

Keith isn't a compression ratio of 9.3 still quite modest on a race engine?

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I would consider 9.3 LOW...ish ... even for a road engine. Higher CR = Higher power ... simple as that. Could go 10.25 - 10.5 with little consequence , apart from more power.

[Bruce M]

Not particularly easy on a type4 head.

They have very limited capacity for fly cutting the cylinder register on the head. Instead you need to weld up the combustion chamber & rework it… or buy billet heads (££££)

[jwhillracer]

A 2.7RS goes quite nicely on only 8.5:1 ……….

JW

[Cortina]

A 2.7RS goes quite nicely on only 8.5:1 ……….

JW

They certainly do .............. and even better with an increased CR !

[jwhillracer]

Yes, I have to agree!
JW

[KS]

Agreed that high CR can equal higher HP, but it also leads to higher combustion temperatures, which in a VW motor is a problem. I've built 'a few' VW motors over the years, for road, rallycross, rallying and drag racing and for a road engine, around 9-9.5:1 is a sweet spot. If the car was trailered to every meeting, and wasn't expected to do the occasional 500+ mile round trip, I'd be bumping it up, but this one has to live.

[Cortina]

Agreed that high CR can equal higher HP, but it also leads to higher combustion temperatures, which in a VW motor is a problem. I've built 'a few' VW motors over the years, for road, rallycross, rallying and drag racing and for a road engine, around 9-9.5:1 is a sweet spot. If the car was trailered to every meeting, and wasn't expected to do the occasional 500+ mile round trip, I'd be bumping it up, but this one has to live.

Sorry Keith - I'll have to complain about the "can" word ..... it DOES. Wether you want to or not .... is a totally different question.
(If necessary , I'll have to go and dig out the practical test (complete with my hand drawn graph) on a variable compression ratio engine from circa 1976 or 1977. University was a long time ago !!)

[KS]

Ooh, pardon me. I'll reuse the word 'can' - higher CR will lead to higher HP, but can lead to engine destruction. Which can (or is it 'will') hurt the wallet. Back in the early 1970s, running 14:1 in a VW race motor (typically anything from 1700 to 2180cc at the time) was commonplace. Not without reason were they often referred to as grenade motors!

A problem with the VW Type 4/Porsche 914 engine is that the heads flex, a situation made worse when running high compression ratios – even stock engines can show signs of this. Adding two extra studs to each cylinder ('six studding') helps a lot but requires welding and machining of the crankcase, plus, of course, mods to the cylinders and heads themselves. Not cheap and not something I can consider on a budget.

[KS]

Not particularly easy on a type4 head.

They have very limited capacity for fly cutting the cylinder register on the head. Instead you need to weld up the combustion chamber & rework it… or buy billet heads (££££)

Yup! Remmele's billet parts started at around £2000 for a pair of bare heads, plus finishing porting/polishing, valves, springs etc. Looking at around £3500 for a pair of heads ready to go (plus Brexit tax...). Outta my league.

[Bruce M]

There’s a few others I’ve seen on socials. klaus for example with his extra cooling channel underneath. Walter (NL) has a 3 valve OHC prototype too. None very cheap!

[rhd racer]

It wasn’t exactly cheap to have my heads machined for bigger pistons, big valves, bronze guides, reworked, flowed and polished either!

And that was 20 years ago. I should imagine the adjusted price of that is knocking on the door of £2k now

The car looks great in its new paint Keith


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[KS]

And today's good news is getting my entry accepted for the St Goueno hillclimb in Brittany. It seems all places were filled immediately, with the rest placed on a reserve list

[jwhillracer]

And today's good news is getting my entry accepted for the St Goueno hillclimb in Brittany. It seems all places were filled immediately, with the rest placed on a reserve list

Nothing beats getting a few entries in to focus the mind on getting the preparation finished. Or, often in my case, getting it started!

JW

[911hillclimber]

What date is the French hill climb please?

[KS]

First weekend of June.