[cogged cobra]

I'm just trying to get a better idea of when its necessary to upgrade from the stock Cobra crank?

I run a cog drive Procharger now, its x2 keyed, with an ATI dampner, and the everything was balanced precisely. But I'm starting to see more and more guys snapping off the snouts of the Cobra cranks, mostly guys running the big twin screw blowers - Whipple and KB.

Starting to think that the cog really beats up the motor and I am really putting the entire motor on the line everytime I'm at the track with the car. If the crank broke and the chains came off and I lost timing, the entire motor could end up junk.

I'm contemplating a move to a big, single turbo 88mm+, and I just want to figure out if a move to the new Boss 5.0 block is necessary (Teksid now), and if I need to upgrade to a stronger forged crank, or possibly a billet piece.

I would probably turn out the #'s I make now with 5 less psi thru an 88, and it will be much easier on parts.

I know Joey Bridge goes high 7's with a stock Cobra crank and a Teksid block, so it seems like there may be no need to re-invent the wheel here - just have it assembled by a pro, and go race.

 

[stickcar1990]

stock crank and block should be fine, less your shootin for HUGE nimbers. nice thing about the boss block though is going to be the bigger bore. easier to get an aluminum rod in there. we make good power on a stock dimension 4.6, [email protected] in nmra trim with a 47-88 turbo. that crank has been turned down to a honda rod journal to allow the aluminum rod. kellogg said not to do this, but its held up good for us.

 

[cogged cobra]

stock crank and block should be fine, less your shootin for HUGE nimbers. nice thing about the boss block though is going to be the bigger bore. easier to get an aluminum rod in there. we make good power on a stock dimension 4.6, [email protected] in nmra trim with a 47-88 turbo. that crank has been turned down to a honda rod journal to allow the aluminum rod. kellogg said not to do this, but its held up good for us.

Good info, thanks. The 47-88 definitely seems to be the big single of choice and would provide enough flow to get me where I'd like to be.

Shortblock is 9.2:1 right now and I'm hoping it'll be in good health at the end of this year, so I may just use the same motor. Although, I'm sure some flat-tops and 10.0:1 would really help spool the 47-88.

Can you share what compression you guys run?

Also, would my Oliver billets be ok in a turbo setup? Is an aluminum rod better suited to lower the rotational weight?

Any special crank prep at that power level?

 

[Collinsautomotive]

the compression won't hurt the spool up won't help much either. It'll be a benefit but you'll get more from cam timming.

The rods should be ok upto 8000 rpm or so. The piston is really,really light.

Stock crank. Good shot peening, turn the journals down 10-20 thousandths to put a better fillet in it get it stress relieved and then get it nitrided and micro polished.

Good info, thanks. The 47-88 definitely seems to be the big single of choice and would provide enough flow to get me where I'd like to be.

Shortblock is 9.2:1 right now and I'm hoping it'll be in good health at the end of this year, so I may just use the same motor. Although, I'm sure some flat-tops and 10.0:1 would really help spool the 47-88.

Can you share what compression you guys run?

Also, would my Oliver billets be ok in a turbo setup? Is an aluminum rod better suited to lower the rotational weight?

Any special crank prep at that power level?

 

[298 snake]

u would have to go with a bigger cid to spool that turbo i was goin to put a gt 47-88 on my 298 cid cobra manley i beam rods mahle extreme duty forged pistons 8:8 to 1 and i was told i wouldnt make shit at low rpm but once u get up to about 7000 to 8000 rpm the motor will finally come alive just my 2 cents

 

[Collinsautomotive]

whoever gave you this info was entirely full of shit. I would not build a high powered stroker 4.6. Not with a 3.750 arm. If your willing to offest grind the factory crank pins to a 3.630 or so stroke you can build a good piston but thats still really marginal. Stick with a stock stroke. as for getting the turbo up. Cam timming and intake manifolding as well as a proper turbine wheel,housing and wastegate arrangement can make that work.

u would have to go with a bigger cid to spool that turbo i was goin to put a gt 47-88 on my 298 cid cobra manley i beam rods mahle extreme duty forged pistons 8:8 to 1 and i was told i wouldnt make shit at low rpm but once u get up to about 7000 to 8000 rpm the motor will finally come alive just my 2 cents

 

[298 snake]

im saying y go through to that when u can run two 62mm turbo still spool the turbo faster than the 47-88 and still make wicked power down low with minimum lag and continue to build power at the top end

 

[George Klass]

We are making about 2500 HP at 9200 rpm with a stock Cobra crank. The only thing we did is to cut down the the circumference of the counterweights and add some heavy metal.

 

[Bandit28]

Stocker FTW, I have seen many spin upwards of 8500 and making quite a bit of power doing it.

 

[cogged cobra]

im saying y go through to that when u can run two 62mm turbo still spool the turbo faster than the 47-88 and still make wicked power down low with minimum lag and continue to build power at the top end

Its easier to package a large single over twins.

I think the 47-88 is the perfect single for drag 4.6. Getting the car to leave hard is all in the turbo setup, cam selection, tune, and converter. I dont really care if the car leaves a bit soft as that will help with traction when the track is marginal. if it can 60' in the 1.3's and trap close to 170, I'll be happy, lol.

Gonna stick with the stock stroke for sure to help keep piston speed/oiling under control when the RPM's get up there.

I currently run the billet Melling pump. Are you guys having success with the conventional pumps at this level, or switching to external belt driven pumps?

Any recommendations on places that can build a set of some nice stainless forward facing headers?

 

[298 snake]

top end fabrication can build some when i talked to them about some headers for mine they said they have been building alot of ford racing shorty headers and putting a v band on them and the headers look amazing for 3 times less that turbo headers

 

[Collinsautomotive]

stock pumps and stock style pumps get maringal at 8000+ rpm. I would be worried about thrust bearing issues trying to break the pump gears. when the thrust bearing fials to carry the load it galls up the pump gears and front cover plate.

So good converter pressure control is a must. I would say to keep the converter pressure down under 100psi and you should be ok.

Its easier to package a large single over twins.

I think the 47-88 is the perfect single for drag 4.6. Getting the car to leave hard is all in the turbo setup, cam selection, tune, and converter. I dont really care if the car leaves a bit soft as that will help with traction when the track is marginal. if it can 60' in the 1.3's and trap close to 170, I'll be happy, lol.

Gonna stick with the stock stroke for sure to help keep piston speed/oiling under control when the RPM's get up there.

I currently run the billet Melling pump. Are you guys having success with the conventional pumps at this level, or switching to external belt driven pumps?

Any recommendations on places that can build a set of some nice stainless forward facing headers?