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.neilbardsley wrote: ↑Wed Jan 17, 2024 10:40 am Keith isn't a compression ratio of 9.3 still quite modest on a race engine?
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KS's hillclimbing odyssey
Moderators: hot66, Miggs, 58A - 71E, impmad2000, drummerboytom, Barry, Helen, Viv_Surby, Derek, KS, abm914, Mike Usiskin
Re: KS's hillclimbing odyssey
Royal Enfield .. still in India
GL 1800 Tour DCT, for pleasure / Fantic 240 Professional - play
Rally 911 (1966) build parked for a while
Rally 928 (work started again - inc serious weight loss programe !)
.... and now another VW Up GTI owner.
GL 1800 Tour DCT, for pleasure / Fantic 240 Professional - play
Rally 911 (1966) build parked for a while
Rally 928 (work started again - inc serious weight loss programe !)
.... and now another VW Up GTI owner.
Re: KS's hillclimbing odyssey
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 (££££)
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 (££££)
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- Me and DDK sitting in a tree! KISSING
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Re: KS's hillclimbing odyssey
A 2.7RS goes quite nicely on only 8.5:1 ……….
JW
JW
Life's a single timed run with no practice....
1970 914/6 2.4E/Webers
1970 VW Beetle project
1972 911 Hillclimber 3.2 MFI. Part of the family for 30+ years!
2006 Hymer Merc Starline 630
2000 T4 Van LPG
2000 Golf V5 Estate GT (Greyhound Transport!)
1970 914/6 2.4E/Webers
1970 VW Beetle project
1972 911 Hillclimber 3.2 MFI. Part of the family for 30+ years!
2006 Hymer Merc Starline 630
2000 T4 Van LPG
2000 Golf V5 Estate GT (Greyhound Transport!)
Re: KS's hillclimbing odyssey
They certainly do .............. and even better with an increased CR !
Royal Enfield .. still in India
GL 1800 Tour DCT, for pleasure / Fantic 240 Professional - play
Rally 911 (1966) build parked for a while
Rally 928 (work started again - inc serious weight loss programe !)
.... and now another VW Up GTI owner.
GL 1800 Tour DCT, for pleasure / Fantic 240 Professional - play
Rally 911 (1966) build parked for a while
Rally 928 (work started again - inc serious weight loss programe !)
.... and now another VW Up GTI owner.
-
- Me and DDK sitting in a tree! KISSING
- Posts: 2630
- Joined: Fri Apr 18, 2008 5:58 pm
- Location: Sunny Somerset, just above the water....
Re: KS's hillclimbing odyssey
Yes, I have to agree!
JW
JW
Life's a single timed run with no practice....
1970 914/6 2.4E/Webers
1970 VW Beetle project
1972 911 Hillclimber 3.2 MFI. Part of the family for 30+ years!
2006 Hymer Merc Starline 630
2000 T4 Van LPG
2000 Golf V5 Estate GT (Greyhound Transport!)
1970 914/6 2.4E/Webers
1970 VW Beetle project
1972 911 Hillclimber 3.2 MFI. Part of the family for 30+ years!
2006 Hymer Merc Starline 630
2000 T4 Van LPG
2000 Golf V5 Estate GT (Greyhound Transport!)
- KS
- Nurse, I think I need some assistance
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- Location: Cornwall
Re: KS's hillclimbing odyssey
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.
Re: KS's hillclimbing odyssey
Sorry Keith - I'll have to complain about the "can" word ..... it DOES. Wether you want to or not .... is a totally different question.KS wrote: ↑Wed Jan 17, 2024 6:00 pm 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.
(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 !!)
Royal Enfield .. still in India
GL 1800 Tour DCT, for pleasure / Fantic 240 Professional - play
Rally 911 (1966) build parked for a while
Rally 928 (work started again - inc serious weight loss programe !)
.... and now another VW Up GTI owner.
GL 1800 Tour DCT, for pleasure / Fantic 240 Professional - play
Rally 911 (1966) build parked for a while
Rally 928 (work started again - inc serious weight loss programe !)
.... and now another VW Up GTI owner.
- KS
- Nurse, I think I need some assistance
- Posts: 14953
- Joined: Fri May 07, 2004 3:12 pm
- Location: Cornwall
Re: KS's hillclimbing odyssey
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.
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
- Nurse, I think I need some assistance
- Posts: 14953
- Joined: Fri May 07, 2004 3:12 pm
- Location: Cornwall
Re: KS's hillclimbing odyssey
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.
Re: KS's hillclimbing odyssey
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!
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- DDK 1st, 2nd and 3rd for me!
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Re: KS's hillclimbing odyssey
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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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
Sent from my iPhone using Tapatalk
93 964 C2
99 Boxster 2.5 > 2.7 hill climber
71 914/6 3.0 - gone
'You see Paul, hill climbing is like making love to a beautiful woman. You get your motor running, check your fluids, hang on tight and WHOA..30 seconds later it's all over!' Swiss Tony
99 Boxster 2.5 > 2.7 hill climber
71 914/6 3.0 - gone
'You see Paul, hill climbing is like making love to a beautiful woman. You get your motor running, check your fluids, hang on tight and WHOA..30 seconds later it's all over!' Swiss Tony
- KS
- Nurse, I think I need some assistance
- Posts: 14953
- Joined: Fri May 07, 2004 3:12 pm
- Location: Cornwall
Re: KS's hillclimbing odyssey
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
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- Me and DDK sitting in a tree! KISSING
- Posts: 2630
- Joined: Fri Apr 18, 2008 5:58 pm
- Location: Sunny Somerset, just above the water....
Re: KS's hillclimbing odyssey
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
Life's a single timed run with no practice....
1970 914/6 2.4E/Webers
1970 VW Beetle project
1972 911 Hillclimber 3.2 MFI. Part of the family for 30+ years!
2006 Hymer Merc Starline 630
2000 T4 Van LPG
2000 Golf V5 Estate GT (Greyhound Transport!)
1970 914/6 2.4E/Webers
1970 VW Beetle project
1972 911 Hillclimber 3.2 MFI. Part of the family for 30+ years!
2006 Hymer Merc Starline 630
2000 T4 Van LPG
2000 Golf V5 Estate GT (Greyhound Transport!)
-
- Nurse, I think I need some assistance
- Posts: 18931
- Joined: Mon Mar 10, 2008 6:26 pm
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Re: KS's hillclimbing odyssey
What date is the French hill climb please?
73T 911 Coupe, road/hillclimber 3.2L
Lola t 492 / 3.2 hillclimb racer
Boxster 987 Gen II 2.9
Lola t 492 / 3.2 hillclimb racer
Boxster 987 Gen II 2.9
- KS
- Nurse, I think I need some assistance
- Posts: 14953
- Joined: Fri May 07, 2004 3:12 pm
- Location: Cornwall
Re: KS's hillclimbing odyssey
First weekend of June.