Turbo crank cases porting

[79 bronco]

Does anyone DO turbo crank port cases? Trinity racing did advertise this years ago.

Does it work?

Quoat from old Trinity advertisement

A tubo crank modificaion consists of cutting directional fins into the crank throws, porting the cases, and truing and welding the crank. this modification causes the intake charge to be pulled into the lower end, atomized more efficiently, and then blown through the transfer ports. This modification delivers power through the entire powerband.

 

[OConnor Racing]

Do you have a pic?

 

[Little-J]

I have seen this done.. Is basically looks like the side of your crankshaft has shallow spiral or curved grooves carved into its surface.. think vacum cleaner fan.. It has the blades that curve backwards so the mixture is recirculated inside the crank chamber..

So the mix will be pushed out from the gap in between the crank and the case towards the ports. They are very shallow to avoid removing too much material weakening the crank and decreasing the volume of the crank.

I dont think it works on all cranks, only the ones that arent hollow, but a blaster crank isnt so it should work. whether it works is another story..

http://www.snowmobileforum.com/atta...one-heard-mod-full-crank-closeup-pat-pend.jpg

 

[slickerthanyou]

If you weld a crank, I take it then you can't rebuild it? I heard of that also but no experience with it.

 

[Little-J]

yeah, Im not sure about that.. Id like to know though.. the weld they do is just a really small spot with TIG.. they dont actually add any new material, they just melt a bit of the crank and rod pin together..

BY THE WAY.. THAT LINK i posted before, is not part of my sig, its a pic of someones version of turbo-crank-porting-tuning thingy..

 

[OConnor Racing]

Here's a pic I found. Looks like a ton of work and would probably be very expensive. Not worth it in IMO.


http://i847.photobucket.com/albums/ab36/OConnorRacing/turbocrank.jpg

 

[YZ Otis]

Here's a pic I found. Looks like a ton of work and would probably be very expensive. Not worth it in IMO.


http://i847.photobucket.com/albums/ab36/OConnorRacing/turbocrank.jpg

Holy indexing,dude ..LOL ... bit of setup time in that one ..wonder how they lightened up the pin side for balance?

 

[phragle]

One needs to think about this.... the standard reed valve motorcycle motor has been around for how long?? They have been ported, piped, carbed etc. to increase power for how long?? There have been some major advancements, water cooling, power valves etc along the way. Today porting is a mathmatical formula of timing and durations that is continually being refined. A lot of things have been tried along the way, rifeling, turbo crank mods, silencers with spring loaded discs to act like wannabe power valves etc... If it actually worked and made a considerable difference, it would have been accepted and implemented industry wide by now. For many money isn't the object, making more hp is. How many shops do you see doing this turbo crank thing these days?

 

[mopar1rules]

If you weld a crank, I take it then you can't rebuild it? I heard of that also but no experience with it.

You can still get a crank rebuilt, once it has had its pins welded. It just takes a little more time for the crank rebuilder, as he has to grind away the weld bead. They pretty much just use the tig torch to melt part of the crank pin and counterweight together. They may add a little filler material, but not much.

 

[Kennedy_Power]

One needs to think about this.... the standard reed valve motorcycle motor has been around for how long?? They have been ported, piped, carbed etc. to increase power for how long?? There have been some major advancements, water cooling, power valves etc along the way. Today porting is a mathmatical formula of timing and durations that is continually being refined. A lot of things have been tried along the way, rifeling, turbo crank mods, silencers with spring loaded discs to act like wannabe power valves etc... If it actually worked and made a considerable difference, it would have been accepted and implemented industry wide by now. For many money isn't the object, making more hp is. How many shops do you see doing this turbo crank thing these days?

Right on man, and trinity made a lot of money doing nothing for power..

 

[Paulie B]

Yup pretty much a scam.
Now if we had half circle cranks like say a Raptor then it would be possible to do a turbo mod like I do to my Baja motors.

 

[slickerthanyou]

Yup pretty much a scam.
Now if we had half circle cranks like say a Raptor then it would be possible to do a turbo mod like I do to my Baja motors.

Am i missin something? What was done to that crank? Hey that's not what your suppose to be weighing on that scale!!

 

[Paulie B]

See how the ends come to a point?

This is a stock one.

 

[revin-it02]

Yup pretty much a scam.
Now if we had half circle cranks like say a Raptor then it would be possible to do a turbo mod like I do to my Baja motors.

this is not turboing a crank... this is knife edging the crank so it cuts through the oil better and reduce weight

however you should watch out how much you do, your throwing off the counter balance

 

[Paulie B]

this is not turboing a crank... this is knife edging the crank so it cuts through the oil better and reduce weight

however you should watch out how much you do, your throwing off the counter balance

Folks been callin it a turbo mod for years an years.
It forces the air up the tranfers and reduces windage.
This is a 1/5 scale 23cc motor lol
There is no counter balancer and vibration isn't an issue in R/C.
10,000 rpms is very high for your everyday 23cc weedeater motor.
Modded ones will hit 16-18k.
The ones I port and build like this one will hit 22,000 rpms.

 

[sicivicdude]

In the first picture from the snow mobile forum, I don't really see where the little grooves cut into the outside of the counterbalance would do much of anything. Any increases in power are probably a function of decreased inertial mass coupled with poor balancing characteristics. This results in the "feeling" of more power because you'd really like to believe that the hours that crank spent on the milling machine doing that to it actually made some power and the extra vibration that comes out of the bottom end supports the conclusion that it's putting out more "power" because it's vibrating more.

The second picture (and I have to say work of art, kudo's to the machinist for a pretty if possibly useless modification) looks like total and complete overkill. If the idea was to move the charge to the outside of the crankcase towards the trasnfer ports, it certainly looks the part. I'd be concerned also that the counterbalance is thrown dangerously off and would not want to be standing by the first time that engine was revved up.

Actually, what he's doing isn't really knife edging the crank either... Knife edging involves removing material radially along the outside edge of the crank counter balance so that there is a "knife's edge" on each side of the rod when that throw is at BDC:

I guess what he's doing to his cranks would be considered along the same category of "turbo'n" the crank because the slices on the leading edges of the crank would split the charge to each side of the case pushing higher pressure areas towards the transfer ports... I guess. I'm curious, how long does one of your cranks last once you've taken the grinder to them to shape?

 

[Paulie B]

The lil cranks I mod last until the bearing wear out and then I just buy another one.
It takes about a year +/- a few months.

 

[98blaster+4]

i dont see th point in knife edgeing a blaster crank. its not a 4 stroke engine with the crank dipping into a pool of engine oil. its only going through the air down there. and if it is going through liquid then somethings broken. might as well get one of those tornado inserts for the airduct

 

[mopar1rules]

It seems to me that "knife-edging" the crank on a banshee, would cause a reduction in the primary crankcase compression ratio?? More "material" that's not "there" to fill in that amount of "volume" down there. You know??

 

[sicivicdude]

"i dont see th point in knife edgeing a blaster crank. its not a 4 stroke engine with the crank dipping into a pool of engine oil. its only going through the air down there. and if it is going through liquid then somethings broken. might as well get one of those tornado inserts for the airduct"

I agree, a 2 stroke crank should not be dipped in anything and if it is, there's trouble! But the question is can tapering the crank "push" the charge up the transfer ports faster allowing high over-rev and a better scavenge.

The question is simply, do it and report back. I'd love a cheap crank mod that gave it more throttle response and maybe a HP or two.

"It seems to me that "knife-edging" the crank on a banshee, would cause a reduction in the primary crankcase compression ratio?? More "material" that's not "there" to fill in that amount of "volume" down there. You know?? "

There's the other side of the arguement and one you can purchase a piece to test out. Vito's sells their cranks now with the blue stuffer blocks for that reason. It stands to reason that the less volume you have to fill the faster you can do it. Short of not having enough charge in the crankcase at TDC to fill the top end during scavenge, the less fluid you have to slosh around in the bottom end only to NOT be sucked into the cylinder the more power you can put out and the crisper the throttle response.