VW type 1 (beetle) high ratio rockers
Discussion
Do higher ratio rockers (than standard)work well on a slightly improved engine?
Is any increase in power / torque worth the in cash?
Which ratio increase would you recommend for a standard engine - 1.25:1; 1.4:1; 1.5:1?
Engine is a 1300cc twin port with standard crank and camshaft, and is currently being run in after a complete rebuild.
The heads have had flow work and porting done, the exhaust is a spaghetti type thing and the carb is a Weber 38DGMS.
Whilst having it set up, the car gave a mighty 40 hp at the wheels.
Would these high ratio rockers make much difference to this?
Is increased lift a good thing with standard duration or would a cam change for duration be better?
It did have an Engle W100 fitted upon the first rebuild, but not having the case line bored caused (one way or another) oil starvation which destroyed the new standard crank and Engle cam. These were then replaced with both standard items (plus a line bore)in an attempt to save cash and because I'd read that the standard cams gave more torque due to their milder duration - I would like this confirmed also!
Anyroad up, any info gratefully received.
Is any increase in power / torque worth the in cash?
Which ratio increase would you recommend for a standard engine - 1.25:1; 1.4:1; 1.5:1?
Engine is a 1300cc twin port with standard crank and camshaft, and is currently being run in after a complete rebuild.
The heads have had flow work and porting done, the exhaust is a spaghetti type thing and the carb is a Weber 38DGMS.
Whilst having it set up, the car gave a mighty 40 hp at the wheels.
Would these high ratio rockers make much difference to this?
Is increased lift a good thing with standard duration or would a cam change for duration be better?
It did have an Engle W100 fitted upon the first rebuild, but not having the case line bored caused (one way or another) oil starvation which destroyed the new standard crank and Engle cam. These were then replaced with both standard items (plus a line bore)in an attempt to save cash and because I'd read that the standard cams gave more torque due to their milder duration - I would like this confirmed also!
Anyroad up, any info gratefully received.
Personally after losing the motor due to oil starvation i wouldnt have re used the original case.
the high ratio rockers will give some improvement over standard, and you could get away with using them with the stock springs, but heavier pushrods, Bugpack ones would be fine. for your application 1.25:1 is sufficient. 1.4:1 and above will require new heavier valve springs and setting them up with the correct shims to set the poundage on the seats. The W100 cam will need to be checked for gaulling of the bearing surfaces and to see if they are out of round, also the lobes would need looking at too if you was to try and re use that cam. it may be quicker and cheaper to throw a 110 cam into the motor. Though why you are tuning a 1300 i dont know...
surely a bolt in 1641 or 1679 barrel conversion would be beneficial, and would take better advantage of the weber carb.
edit to add: if you did want to go to 1.4:1 i do have a new set of autocraft rockers that i am not using....
the high ratio rockers will give some improvement over standard, and you could get away with using them with the stock springs, but heavier pushrods, Bugpack ones would be fine. for your application 1.25:1 is sufficient. 1.4:1 and above will require new heavier valve springs and setting them up with the correct shims to set the poundage on the seats. The W100 cam will need to be checked for gaulling of the bearing surfaces and to see if they are out of round, also the lobes would need looking at too if you was to try and re use that cam. it may be quicker and cheaper to throw a 110 cam into the motor. Though why you are tuning a 1300 i dont know...
surely a bolt in 1641 or 1679 barrel conversion would be beneficial, and would take better advantage of the weber carb.
edit to add: if you did want to go to 1.4:1 i do have a new set of autocraft rockers that i am not using....
Edited by DrDeAtH on Monday 18th June 19:13
OK.
You reckon that high ratio rockers will give "some" improvement over standard - can you give me any idea (roughly) how much; can you put a figure on it?
As far as your other points:
I re-used and line bored the case purely to keep costs down (£60 as opposed to £260).
The W100 went in the bin after I replaced it with a standard component, because , as you suggest, the bearing and cam surfaces were knackered.
1641 piston & barrel kits don't just bolt on - or, at least the one I bought from VW Heritage didn't - the barrels had a larger diameter than where they sit in the combustion chambers (heads would have needed machining, etc).
Tuning a 1300 - having never done a VW engine before, I fancied a go. Throw in a bit of d.i.y head work and a home-made inlet manifold for the non-standard carb and a flywheel skim at work...
I am curious to see what kind of mods actually work for as little expense as possible (aren't we all). At the moment, these mods have added 12 bhp at the wheels (from the rolling road).
Now, without going to larger valves - 'cos that would need different heads etc, fancy cam profiles, dry sump lubrication, larger swept volumes because it would go on and on and I can't afford it and for now, I'm happy with it.
Cheers
You reckon that high ratio rockers will give "some" improvement over standard - can you give me any idea (roughly) how much; can you put a figure on it?
As far as your other points:
I re-used and line bored the case purely to keep costs down (£60 as opposed to £260).
The W100 went in the bin after I replaced it with a standard component, because , as you suggest, the bearing and cam surfaces were knackered.
1641 piston & barrel kits don't just bolt on - or, at least the one I bought from VW Heritage didn't - the barrels had a larger diameter than where they sit in the combustion chambers (heads would have needed machining, etc).
Tuning a 1300 - having never done a VW engine before, I fancied a go. Throw in a bit of d.i.y head work and a home-made inlet manifold for the non-standard carb and a flywheel skim at work...
I am curious to see what kind of mods actually work for as little expense as possible (aren't we all). At the moment, these mods have added 12 bhp at the wheels (from the rolling road).
Now, without going to larger valves - 'cos that would need different heads etc, fancy cam profiles, dry sump lubrication, larger swept volumes because it would go on and on and I can't afford it and for now, I'm happy with it.
Cheers
personally i would of found a good used 1600 bottom end and tuned that. the rockers will give a few horses, but dont expect loads, specially with a stock cam.
best ways... probably would be to find a turbo off a renault 5 or later fiesta rs and use that. it will give good useable increases via a draw through intake system over and above the aspirated route you have taken so far.... bit more fabbing of brackets and an oil line or two, but it would work well.....
best ways... probably would be to find a turbo off a renault 5 or later fiesta rs and use that. it will give good useable increases via a draw through intake system over and above the aspirated route you have taken so far.... bit more fabbing of brackets and an oil line or two, but it would work well.....
OK. Thanks. Unfortunately , whilst I'd love to fit a twin turbo 2.4 or a Porsche unit, there are various competition regulations in place which state that engine capacities in certain classes cannot be exceeded. We run this little motor up to (generally) 1400cc class - non-period modifications are not allowed whatsoever; forced induction systems are not allowed whatsoever.
Only "basic" tuning improvements are allowed, and even then, only up to a certain point.
This is the reason for bothering with a farting 1286 (although, technically, it could be made to 1299), and this helps to keep motorsport at the cheap, clubman end.
Smiles per mile!
Cheers anyway.
Only "basic" tuning improvements are allowed, and even then, only up to a certain point.
This is the reason for bothering with a farting 1286 (although, technically, it could be made to 1299), and this helps to keep motorsport at the cheap, clubman end.
Smiles per mile!
Cheers anyway.
Night and day events: bit of autotesting; bit of production car trialling; mainly endurance and timed treasure hunt type trials (on and off public highways) with classic / historic "sports" car clubs.
To go too far in tuning for any one particular event type would affect another, and as we choose to use the motor for a number of different types of events, of course we must adhere to as many regs as possible.
Of course, without specialising in any particular area means we don't do so well in any particular area! On the other hand it's usually a good giggle using an otherwise standard motor (sometimes against very exotic motors) for events all over the country.
Also, it's used for the daily commute.
Yeah - octane booster is on the list and will be experimented with soon.
Compression ratios - again, it's crossed my mind and I need to give the heads a good coat of looking at because they're not like skimming a "normal" head are they? Would material be removed from the cylinder barrels where they sit in the heads or from the heads themselves?
Just out of interest, here are the current engine mods:
Carb - Weber 38 DGMS (spare one for my Scimitar); re-jetted; choke barrels have been "cleaned" and the throttle spindles machined so they're thinner to improve air flow. Usual K&N filter.
Inlet - manifold; home made - incorporating VW preheat tubes and standard (but cleaned out) inlet elbows.
Heads - gas flowed, although too much has been removed from the "squish platforms" in each combustion chamber but this hasn't affected idling or running at any speed. Have not performed flow bench tests so can't provide figures. Also ported to match inlet elbows and exhaust.
Valves - standard inlet & exhaust but with three angle seats.
Valve springs, pushrods and rockers - standard.
Exhaust - spaghetti thing (Empi single quiet pack); unmodified.
Crankcase - standard, line bored over size; standard crankshaft; standard camshaft.
Flywheel - skimmed; now 6kg exactly.
Oil pump - Shadek heavy duty 30mm unit.
Oil filter - standard strainer gauze.
Ignition - Did fit a Lumenition "magnetronic" when the motor was first installed, but it ran like a pile of poo so replaced with standard points and coil; runs beautifully.
Whether any one or a combination of these was the correct or most appropriate thing to do I don't know. They have made a measurable difference to the tune of 12 bhp (don't know the torque and this wasn't under full load 'cos we're still running it in) and I reckon for an otherwise "standard" 1286cc this is pretty good. Of course there will be further stuff to try, but without drastically moving away from being a 1286 I think I'm running out of options. If I can make 50 bhp I'll stop! Howzat?!
To go too far in tuning for any one particular event type would affect another, and as we choose to use the motor for a number of different types of events, of course we must adhere to as many regs as possible.
Of course, without specialising in any particular area means we don't do so well in any particular area! On the other hand it's usually a good giggle using an otherwise standard motor (sometimes against very exotic motors) for events all over the country.
Also, it's used for the daily commute.
Yeah - octane booster is on the list and will be experimented with soon.
Compression ratios - again, it's crossed my mind and I need to give the heads a good coat of looking at because they're not like skimming a "normal" head are they? Would material be removed from the cylinder barrels where they sit in the heads or from the heads themselves?
Just out of interest, here are the current engine mods:
Carb - Weber 38 DGMS (spare one for my Scimitar); re-jetted; choke barrels have been "cleaned" and the throttle spindles machined so they're thinner to improve air flow. Usual K&N filter.
Inlet - manifold; home made - incorporating VW preheat tubes and standard (but cleaned out) inlet elbows.
Heads - gas flowed, although too much has been removed from the "squish platforms" in each combustion chamber but this hasn't affected idling or running at any speed. Have not performed flow bench tests so can't provide figures. Also ported to match inlet elbows and exhaust.
Valves - standard inlet & exhaust but with three angle seats.
Valve springs, pushrods and rockers - standard.
Exhaust - spaghetti thing (Empi single quiet pack); unmodified.
Crankcase - standard, line bored over size; standard crankshaft; standard camshaft.
Flywheel - skimmed; now 6kg exactly.
Oil pump - Shadek heavy duty 30mm unit.
Oil filter - standard strainer gauze.
Ignition - Did fit a Lumenition "magnetronic" when the motor was first installed, but it ran like a pile of poo so replaced with standard points and coil; runs beautifully.
Whether any one or a combination of these was the correct or most appropriate thing to do I don't know. They have made a measurable difference to the tune of 12 bhp (don't know the torque and this wasn't under full load 'cos we're still running it in) and I reckon for an otherwise "standard" 1286cc this is pretty good. Of course there will be further stuff to try, but without drastically moving away from being a 1286 I think I'm running out of options. If I can make 50 bhp I'll stop! Howzat?!
upping the compression can be done a few ways.... you can machine the deck face off the barrels with a lathe(1)
you can machine the case spigots so that they are flush and then use deck shims under the barrels (2)
you can flycut the heads (3)
option 1 would possibly be the easiest if you have access to a lathe.
option 2 is best as it also gives you a better seating face for the barrel to locate on at the case end, but would involve a full tear down of the motor.
option 3 fastest method i suppose as it only means pulling the heads.
just remember you will need to set up the geometry of the rockers after all of the machining.
it is also beneficial to lap the barrels into the heads to get a good sealing surface, unless you are using copper ring gaskets.
you could get away with going up to 9.0:1 on super unleaded past that and you will find the motor will overheat.
i too just ran a bosch 009 and blue coil for years with no probs. my friend however had trouble with his pertronix ignitor thingy....
what oil do you run in the motor?
you can machine the case spigots so that they are flush and then use deck shims under the barrels (2)
you can flycut the heads (3)
option 1 would possibly be the easiest if you have access to a lathe.
option 2 is best as it also gives you a better seating face for the barrel to locate on at the case end, but would involve a full tear down of the motor.
option 3 fastest method i suppose as it only means pulling the heads.
just remember you will need to set up the geometry of the rockers after all of the machining.
it is also beneficial to lap the barrels into the heads to get a good sealing surface, unless you are using copper ring gaskets.
you could get away with going up to 9.0:1 on super unleaded past that and you will find the motor will overheat.
i too just ran a bosch 009 and blue coil for years with no probs. my friend however had trouble with his pertronix ignitor thingy....
what oil do you run in the motor?
Duckhams Q classic engine oil 20 - 50W Mineral.
Option 1 would be easiest - now then: how much to skim off?!
I have Peter Noad's book "Tuning Volkswagens" which is centuries old, and he suggests that the increase in comp. ratio due to 1mm removed from the heads is 0.65.
If 1mm was to be taken from the heads - I'm assuming your option 3 method - then this would be the same as removing 1mm from the cylinder barrels?
Which end of the barrels - you mention crankcase end; why not head end?
Option 1 would be easiest - now then: how much to skim off?!
I have Peter Noad's book "Tuning Volkswagens" which is centuries old, and he suggests that the increase in comp. ratio due to 1mm removed from the heads is 0.65.
If 1mm was to be taken from the heads - I'm assuming your option 3 method - then this would be the same as removing 1mm from the cylinder barrels?
Which end of the barrels - you mention crankcase end; why not head end?
i used 15w-40 with no problems with pressure or overheating.
turning the barrels down would be done from the case end as the top of the barrel is face ground flat. sealing the barrel to the case will be less of a problem than sealing the machined barrel to the head.
you need to know the cc of the chamber to get the comp ratio right with regards to the deck height, also the deck height of the piston.
supply those 2 things and i should be able to work it out for you
flycutting 1mm out of the heads will not give the same effect as turning the barrels down 1mm, as you are removing chamber volume from the heads, not reducing the deck height clearance for the piston. worst case, you would punch the heads with the pistons... messy
turning the barrels down would be done from the case end as the top of the barrel is face ground flat. sealing the barrel to the case will be less of a problem than sealing the machined barrel to the head.
you need to know the cc of the chamber to get the comp ratio right with regards to the deck height, also the deck height of the piston.
supply those 2 things and i should be able to work it out for you
flycutting 1mm out of the heads will not give the same effect as turning the barrels down 1mm, as you are removing chamber volume from the heads, not reducing the deck height clearance for the piston. worst case, you would punch the heads with the pistons... messy
Edited by DrDeAtH on Thursday 21st June 22:36
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