I understand the advantage of there being less stress on the crank when you internally balance an engine. I have heard that there can be gains of 20 horsepower between an internally and externally balanced engine. The explanation was that an internally balanced engine distributed the load more evenly across all the main bearing and therefore could see a gain of 20 horsepower from reduced internal friction. I could see a slight reduction in friction from an internally balanced engine. I think that a properly balanced, external balanced engine would only have a slight increase in internal friction over an internally balanced engine. My question is, how much horsepower gains has anyone you seen between an internal and external balanced 383 SBC?

 

considering most ford and Mopar engines are externally balanced, and I don't think they would throw away 20 (or even 10) hp, I don't think you will see any difference in most cases. The engine does not know if it was balanced with a harmonic balancer/flywheel or not and that is the fundamental difference between the two.

The only person I know that might have actual dyno experience is Mr Horsepower/ chuck riddick on the camaroz28.com board. He hangs out at the classic section most.

 

I agree with jcb999, In most cases to aquire acutal hp gains the whole roatating assembly must be balanced flywheel, crank. Harmonic balancer"yea balancers can be balanced" even the rods & pistons. Asuming you eliminate most of internal friction you would increse hp+ engine life. Im not going to even guess how much hp you would gain but when i swaped a fluid damper onto my 350 I gained 300 more rpm than with the stock balancer.
SSC

 

Here is a quote out of June 2001 Car Craft on page 55. They were talking about a Merlin 509 produced by World Products ..."Original Merlin 509s were externally balanced. Now the Scat 4130 forged-steel cranks are internally balanced with Mallory heavy metal. By reducing internal friction and equalizing bearing loads, this change alone adds 20 hp to the official 540hp rating. The bearings also last longer. Use a 396/427 neutral-balance flywheel." If this is true then to some degree it should apply the externally balanced 383's.

 

I think they are basically talking about going from a rough balanced motor to a combination that all parts have been individuallly weighed and weight removed accordingly. Mallory metal is very expensive. Your talking about 250 bucks minimum (internal not counting mallory) versus about 125 for a standard balance job. I don't think you can expect the gains to be similar accross the engine lines. The rotating parts on a 540 are much heavier than a SB.

 

If your 383 is making 540hp I wanna see it run. I dont see any advantage one way or the other. For the money you would spend to have heavy metal added to the crank you could buy something else to make the 3hp difference.

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87z 383,afr 190's, comp hyd roller(242/248-.540/.562,114 sep),Ported and polished mini ram, 30lb inj, 3.42 gears, tremec 5spd, , 1,3/4" slp headers, speed pro bank to bank-wb02.

 

The article said that the old Merlin 509, which they have produced for 8 years was externally balanced and was dynoed at 540 hp. The new combination 509 is making 580 hp, of which 20 of the new horsepower was due to internal balancing. World Products is a very reputable manufacture and has some of the best dyno facilities in the country.

I did not say my engine made 540 hp, it is closer to 510 hp.

 

The only benifit that I know about an internally ballanced sbc is that it is cheaper to get parts and you have a bigger selection.

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www.geocities.com/camaro1j/myz28.html


406
accel supper ram
6000 rpm Hyd roller cam
afr heads
spohn torque arm and crossmember
t-56 trans, [wier racing bellhousing and hydrolic throwout bearing]
9" ME rearend 3.91 Gears

 

you might be missing a subtle difference my friend. Externally balanced does not necessarly mean reballanced. They could have just put all the parts together and left it at that. The factory 502s are balanced externally, but they are not rebalanced.

[This message has been edited by jcb999 (edited May 28, 2001).]

 

I had my 383 internally balanced. Scat 1 piece rear main seal crank was used. It only cost me $50 in metal to balance. It was cheaper to balance it this way than to buy a 400 balancer and flexplate. I just used my existing 350's.

Sparks a flyin'

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1989 L98 IROCZ, Bored .030 over,Scat Crank,Dart PRO 1 Heads 200cc intake,ZZ3/ZZ4 Cam,Crane 1.6 RR,Edelbrock 3860 Hiflo TPI Manifold, AS&M LTRs, Edelbrock 58MM TB, Ported Plenum, TCI Reverse Pat Man Valve Body, SVO 24# injectors,TCI Streetfight Stall Converter, 3.23 Gears on Auburn Pro Posi, Some Suspension Mods

[This message has been edited by sparks383iroc (edited May 28, 2001).]

 

TTT