carbon fibre pushrods

[pupjoint]

has this ever been tried before?  i remember reading somewhere about them but cant recall where and when.

a friend of mine back home, he has access to funny materials like these, he recently made some carbon fibre pushrods, stock length and currently being tested in a bone stock 1600 he drives to work.

he told me the CF ones he made weigh 19g each, stock is 39g and chromoly is 60g.

while i am not sure the details if he had any heat treatment done on the tips etc, but is CF a suitable material for pushrods? expansion rate? long term tensile strength?

[Udo]

I know some people in the us tried this 20 years ago , but did not work good. they expand zero . I saw one cracked in the pits . Looking not good

Udo

[henk]

i think for the heat it depends on wich epoxy he used.
you can have epoxy that is OK to use to temp. of 80,120,... degrees.
i love carbon,i have it all over my bikes but do not want to use it on my '67.

henk!!!

[magic]

yep, it could be SO cool! And they are fore real..... They're made in England, for the mini's... You know, the dog-house on wheels!? (cool cars! )
 But alas... Their engines are made of cast iron AND water-cooled, so they can cope with pushrods with zero expands!!!! And our engines can't...... sigh!

Magic

[magic]

Hmmm ....  suddenly had a thought....  The Minis, are they using hydraulic lifters?! Could we use the same combination? Carbon fiber pushrods for weight, and hydraulic lifters for expansion?!
 I know that you'r not using hyd. lif. in applications exceeding 5500rpm ..... However, is that because of the physical structure, or load-bearing capacity of the oil?!?..
If it's the last, would the weight of ti valves and carbon fiber pushrods not be the cure? I mean, can't you get hyd. lif. to work up around 7500rpm. If you only need a marshmallow to hold the valve up?!??
Can hyd lif. provide enough lift to compensate for the lack of expansion of the push rod.?!? Questions questions ....
 Now I lock myself inside the closet, and I will not come out until this is thought through and solved!!!.... I'd better take some food with me...... and a flashlight!

cheers magic

[dragvw2180]

 Like UDO said we tried them in the early 90's to lighten up the valve train. We used zero lash on our drag engine so expansion was not a big deal.  One came apart at a race and what a mess, that stuff spead everywhere inside the engine before we could get it shut down.  Mike

[Taylor]

The Pushrod weight is not important,  the rigidity is.  The springs force is multiplied, by the rocker arm, on the Pushrod. The higher the ratio the higher the force on the adjuster side. Lighten the valves and retainers, not the Pushrod. 

[Udo]

  One came apart at a race and what a mess, that stuff spead everywhere inside the engine before we could get it shut down.  Mike

This is what i saw at Phoenix in the pits. Looked very bad
Do not know what car it was
Udo

[Eric Ellis (57HotrodVW)]

The Pushrod weight is not important,  the rigidity is.  The springs force is multiplied, by the rocker arm, on the Pushrod. The higher the ratio the higher the force on the adjuster side. Lighten the valves and retainers, not the Pushrod. 

I had a related discussion with Terry Manton when ordering my pushrods. I ended up going with a much larger than expected OD and double taper, but thin walled set of Manton pushrods.

[Fiatdude]

I just ordered some custom length ACN Heavy Duty Aluminum Pushrods from Aircooled.net -- I was recommended them from someone who is running a 3 liter, big - growth engine

[magic]

 [Like UDO said we tried them in the early 90's to lighten up the valve train. We used zero lash on our drag engine so expansion was not a big deal.  One came apart at a race and what a mess, that stuff spead everywhere inside the engine before we could get it shut down.  Mike]


Hi Mike.

very interesting! Have always been fascinated by those who dare to explore new territiory! mostly it goes wrong, or there's just nothing gained..... And then, occasionally, someone discovers a new and better way of doing things..... thanks to all of you who have sacrificed blood, sweat and tears (and money!!) So today we look at the engines, that in the '70s was considered to be wild racing engines, to be fine street engines today....(maybe a little exaggerated) but you know..

Mike, do you remember at which rpm. it happened?

sincerely,  mads.

[dragvw2180]

 We shattered it on a pass , the max we ever turned them was around 7800. We did have titanium valves and retainers with the setup. The parts were from Pat Tafta , the owner of the "TASMANIAN DEVIL" and were something we tried. Our reasoning was less spring pressure at same rpm equals free hp.  Pat tried alot of differant things ( a 5 ltr type 1 w/blower )  and was not afraid to try something new. Mike McCarthy

http://www.thesamba.com/vw//forum/album_page.php?pic_id=639500

[Taylor]

We shattered it on a pass , the max we ever turned them was around 7800. We did have titanium valves and retainers with the setup. The parts were from Pat Tafta , the owner of the "TASMANIAN DEVIL" and were something we tried. Our reasoning was less spring pressure at same rpm equals free hp.  Pat tried alot of differant things ( a 5 ltr type 1 w/blower )  and was not afraid to try something new. Mike McCarthy

http://www.thesamba.com/vw//forum/album_page.php?pic_id=639500

Ironically enough,  that reasoning about less spring is most likely what caused the failure.

[pupjoint]

thanks for the feedback guys....

[magic]

hey pupjoint.

 Hope it's ok, that I use your post to ask a lot of questions to Mick!? But I just think that your original idea is quite interesting!!!
 So ... Micke!?   You write: "Our reasoning was less spring pressure that same rpm equals free hp"....
 Exactly! and that is on a race engine..... on a street engine, you will get the extra gain, that you reduce the heat in the cylinder heads ... Quite a bit!  And all this while you releive the load of the engine.... ie, less wear!    If you could get them to endure, it would be a win win win situation!!

and something else entirely ... You write: (a 5 liter Type 1 w / blower) HOW???!   the 5L. type 1 i mean! 

magic

[dragvw2180]

Sorry PUPJOINT ,
    I have to say I repeated something I was told but was corrected on the size of the engine by a freind, it was a 3.8 liter, sorry for the misinformation.  Pat Tafta bought a forge setup and made all the castings himself. I never saw it run but my friend John Toomey was there when Pat ran it . The one in the dragster blew up and the spare was sold to someone in Puerto Rico if I remember correctly. Mike McCarthy

Click on the link I posted and that is the car and engine, can't remember if it was featured in HVW or VW trends .

[delroyb]

To be fair, composite technology has moved on massively in the past few years. The ability of FEA sims etc to work out the exact layups etc for a set of specific loadings is astonishing. Unfortunately you need some serious computing power and knowledge to do this kind of thing. I am guessing that somehting alosng the lines of a filament wound tube would be the best bet, but the cost for a one off from a supplier would be big! One other intersting thing I ahve come across recently is the use of thin alloy tube cores, with CFRP spun around it, making use of both materials properties.

Shame the costs are prohibitive because it would be very intersting. On a totally differnt note, it is interesting to see that a lot of NASCAR bods are moving back to steel rockers over ally for better valve train stifness and valve control. New FEA techniqies are allowig them to make steel items as light as alloy, but stiffer. Just something to mull over.

[Frallan]

http://solutions.3m.com/3MContentRetrievalAPI/BlobServlet?lmd=1149596328000&assetType=MMM_Image&locale=en_US&blobAttribute=ImageFile&fallback=true&univid=1114293769330&placeId=62603&version=current

3M have had these for quite some years.
Harley Davidsson have used them successfully and probbaly others too.
Price? Crazy....I lost interest but it is high.

I myself bought a set of PRD Carbon pushrods way back in mid 80´s. We tried them on a 210 hp 2332 street engine for some time.
I recall that they ran fine and sound wise quite when we set them at zero cold.
Now the second the engine heated up, it had a valvetrain "rattle". and few times we measured lash hot, I do not recall exact what it was but far above what we wanted.
Anyway, he ran the engine very hard and at least 8000 rpm sprints. No problem.
Camshaft I remember was FK89.
I suggested that we try to set the lash a "mini-click" tight at cold but as the engine was not mine and the friend did not agree, we never tried that dirty trick.
After few days, out they came and I sold them.....

[andy198712]

Why is Ti not commonly used then?

[Frallan]

Honestly, not totally uncommon.
But in many racing classes titanium is prohibited.

3M composite seems really nice except the price.

[Bruce]

Ti doesn't expand enough.
It's expansion is even less than steel, so if you set them at zero lash, you will end up with less lift when the engine is hot.  Less lift=less hp.

[Frallan]

Ti doesn't expand enough.
It's expansion is even less than steel, so if you set them at zero lash, you will end up with less lift when the engine is hot.  Less lift=less hp.

Interesting. Did not think about it but of course these pages are ACVW.
When I refer to "some racing classes" It comes from literature that is not considering our preference.
In NASCAR they even say non magnetic metalls not allowed in order to exclude Ti and stainless.