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08-24-2007 01:56 PM #1
Originally Posted by Paul Kane
I have a customer that brought me a 4.5 forged crank and rods from TMD.
He started running 6.50's with ported dove heads and a mech. roller cam.
That was last tear with 70 pass's on it shifting at 6,000 rpm's.
He basicly ran out of head.
This year he has a set of Blue Thunder heads he bought used on the same engine. and went to a larger mech. roller cam along with a 200 shot of N20.
He has had chaissis problems and has only run a best of 5.21.
He has over 80 pass's on the engine so far with no problems.
Not bad for a $450 imported crank.
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08-27-2007 09:21 AM #2
Originally Posted by erik erikson
I didn't say not to run one; I said that I am not a fan and that I prefer the smaller stroker cranks.
There is little journal overlap with the 4.5 stroker, also they pull the pistons way out of the hole at BDC, then there's the rod ratio, increased cost of building relative to the smaller stroker cranks, etc. But yes, the 4.5 strokers are indeed run with success and will continue to be offered as they, too, are a "drop in" rotating assembly without any crankcase clearancing required, etc.
And they also can make an engine more costly to bulild, as they need more air to breathe, ie more cam (a roller if you really want the BIG HP, but this is not necessary for the engine to run), aslmost always cost more $ to balance, more $ for better heads (ideally), etc. And then with all that power you have this cast crankshaft with minimal journal overlap and thereby minimized structual integrity. A lot or racers seem to be breaking the 4.5 stroke cast cranks at about 1000+ HP or above. That might be a lot of HP for others...but again, for me, I'm just not a fan and would rather go with a smaller stroke deal. Good thing the forged cranks have arrived.
The 4.3 stroker (521/533) makes for a practically "square" engine, which I personally like. More importantly, the 6.8 rodded 521/533 stroker puts the piston pins just .030" lower in the bore at BDC than the OEM 460...which I re-e-e-e-eally like. Great rod ratio. We recently completed a 528 (4.42B x 4.3S) combo that runs on regular ol' pump gas and a single carburetor, and produced 737HP on the dyno, and a diesel flat torque curve that hovered around 655-678 pounds from 4000-6500 rpm (didn't check lower rpms due to the jetr boat application of the engine).
I simply much prefer the 4.3 stroke over the 4.5 stroke deal.
Paul
429/460 Engine Fanatic
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08-27-2007 06:02 PM #3
Originally Posted by Paul Kane
In a marine application where the engine has to the rpm's for longer time frame I would prefer a shorter stroke.
A 1,000 + hp on a cast crank??
Why would you even try this???
At 600 hp I am looking for a forged crank.
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08-27-2007 07:44 PM #4
Thats why I like the fords........I am lookin at 550 -600 on the stock crankOf course ,I am only gunna turn it to 6000 rpm or so.
Last edited by shawnlee28; 08-27-2007 at 07:47 PM.
Its gunna take longer than u thought and its gunna cost more too(plan ahead!)
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08-28-2007 03:18 AM #5
Originally Posted by shawnlee28
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08-28-2007 08:31 AM #6
Correct,...........that one goes to almost 1000 hp.Last edited by shawnlee28; 08-28-2007 at 08:35 AM.
Its gunna take longer than u thought and its gunna cost more too(plan ahead!)
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08-28-2007 09:08 AM #7
Originally Posted by shawnlee28
Don't try this at home! 800-1000HP from a carefully selected, well prepped OEM crankshaft ought to hold up in an engine privided it is kept in good tune. But if you are building engine's of that HP level, you can certainly afford a better crankshaft. We use the cast cranks in our own engines but would not put one into a customer's engine.
Paul
429/460 Engine Fanatic
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08-28-2007 09:18 AM #8
MRC, here's a good budget, maintenance-free, pump gas stroker combo for the street:- Stock block with oiling mods
- 500 cube stroker kit with 4.14 stroke crank, 6.800 H-beam rods, .030" overbore 32cc dished pistons
- HV oil pump
- Lunati 61605 hydraulic cam
- Ported C9VE heads with 2.19" intake/1.76 exhaust valves, requisite port work, springs retainers, locks etc.
- Quality roller rockers, such as Crane Gold Series or equivalent.
- Weiand Stealth part number 8012 aluminum intake manifold
- Holley 950HP
- Recurved Duraspark distributor or MSD breakerless
- Headers
- (this makes a 9.8:1 c/r)
A well planned version of the above build ought to manage at least 550 HP and have the potential for much, much more with induction changes and a camshaft upgrade...but at the cost of fuel economy and preventive maintenance.
Paul
429/460 Engine Fanatic
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08-28-2007 10:38 AM #9
Just going to add my .02 to the mix; I have a 460+.060,line bored,decked,iron heads (76 lincoln) ported by myself on the exhaust side and gasket matched on intake side, 3 angle valve job, .020 milled from heads,flat top hyper-utetic pistons, arp rod bolts, all balanced,Comp Cams 270H kit, edelbrok performer intake with 750cfm carb,hedders with 2 in primarys,stock ignition with mallory box, stock oil pump,RV torque converter and C6 trans, very streetable on pump gas. This is in my 1963 Mercury Monterey 2 dr sedan and it suprises many a chebby that laughs at big heavy cars with the blue oval, my biggest problem is traction, I can fry the tires way past 80 mph if I launch too hard.Blue Oval Die Hard//N.S.M.C. Charter/Life Member//
Scratch building Cobra replica,302/T5 WC/3.0/9in.
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08-28-2007 09:00 AM #10
Originally Posted by erik erikson
I never said that I would "try this" with an offshore cast crankshaft, I said that a lot of racers are having such said experience. Why do you keep misinterpreting my posts? I already stated that it's a good thing that the overseas forgings have arrived realtive to such application(s).
And if you are saying that you are building bracket cars with 600HP motors that use the cast 4.5 stroke cranks, then that's great. I don't see a problem with that either. But if you are saying that you are having problems with the cast cranks above just 600HP and must then turn to a forged crankshaft, then I'd begin to question the integrity of the build(s) and the tune...although I have heard of a defective cast offshore crank snapping during a leisurely trip aboud the block during a 2000 rpm break-in...
Believe it or not, marine application race engines, including jet boats and v-drives, are going to larger stroker rotating assemblies and turning the engines slower...and finding greater ET's and traps speeds than with the shorter stroke peaky stuff of yesteryear.
Paul
429/460 Engine Fanatic
I saw last night on fb about John. The world sure lost a great one. I'm going to miss his humor, advice, and perspective from another portion of the world. Rest in Peace Johnboy.
John Norton aka johnboy