4lb lower safe?

So I’m currently debating on a pulley setup for a new ported Eaton I’m looking to buy. Currently my car has a 2lb Metco lower pulley that the previous owner installed. I’ve got a 2.93 upper pulley to work with. I’m trying to break the 500whp mark (and possibly WTQ).
Would it be safe to put a 4lb lower pulley ring on, or do I have to worry about snapping the snout off the crank?
I know that other people run this setup, but I cannot locate a caged 4lb lower.

The crank will be fine. Alternator lifespan and beltslip with the small upper pulley may become issues though.

olympic said:

The crank will be fine. Alternator lifespan and beltslip with the small upper pulley may become issues though.

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Yeah I figured the alternator pulley will have to be swapped to a 3.2” (the current alternator is on its way out I think).
I do also have a BilletFlow 4 piece Idler set with a 100mm aux idler for some belt wrap.
But the crank should be ok? Would hate to break that all for maybe 20-30 more hp

Plenty of guys running 4lb Metco lowers without issue, myself included. Modifications always carry a risk but this one is low. The guys who rip the crank snouts off are usually running big 3.4-4L blowers.

I ran a 4lb lower on my ported Eaton setup as well as the 2.3 tvs setup. Plenty of guys running them with no issues on the smaller blowers.

Yes.

Just like everyone else said, yes, you should be fine. It is true that there are a lot of Terminator owners using a 4 lb. lower with a 2.93 upper with a ported Eaton. Since you have that 4-piece billet idler set, definitely install it.

Send it!!!! I ran a 2.94 upper and a 6lb lower! Made 525whp/570wtq around 18psi on a staggy stage 4 port, it did burn up my alt, but I switched to a bigger alt pulley and I was fine! I did have bad belt squeak that I could not get rid off!

chada1208 said:

Send it!!!! I ran a 2.94 upper and a 6lb lower! Made 525whp/570wtq around 18psi on a staggy stage 4 port, it did burn up my alt, but I switched to a bigger alt pulley and I was fine! I did have bad belt squeak that I could not get rid off!

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Seems like some good numbers, which I am assuming were on pump gas?
And I would love to not have to deal with weird noises, did it go away after the car warmed up? Do you think it was related to the alternator maybe not being lined up in relation to the other pulleys?

I've had a 6lb lower with a 3.5 Upper Whipple for about 50k miles. No problems.

Midnight_Cobra said:

I've had a 6lb lower with a 3.5 Upper Whipple for about 50k miles. No problems.

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Ok, well I guess upgrading my lower seems ok. Just trying to decide if I should stick to a 2.76/2lb combo or 2.93/4lb.

I would prefer (with ported Eaton) a 2.93/4 lb. combo over the 2.76/2 lb. One advantage is less chance of belt slip.

CobraBob said:

I would prefer (with ported Eaton) a 2.93/4 lb. combo over the 2.76/2 lb. One advantage is less chance of belt slip.

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I will keep that in mind. Can one use a 3.0" Metco alternator pulley with the 4lb lower, or is the 3.2" pulley needed for the 4lb lower if I go that route?

--Joe

carguy96 said:

I will keep that in mind. Can one use a 3.0" Metco alternator pulley with the 4lb lower, or is the 3.2" pulley needed for the 4lb lower if I go that route?

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I will say, just because you put on a different alternator pulley size, that will not bulletproof the alternator. I would always be weary of these "stock" alternators. Anytime it dips below 12.8v while driving, start saving money.

CobraBob said:

I would prefer (with ported Eaton) a 2.93/4 lb. combo over the 2.76/2 lb. One advantage is less chance of belt slip.

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People say this a lot. If you have the idlers then is there any advantage to the 2.93/4 lb.?

Doesn't the 2lb. Lower put less pressure on the crank? Isn't that an advantage?

I don't know any of this just looking to understand and get a detailed answer as to all the advantages and disadvantages of each set up.
Thx
KP

Sent from my SM-N950U using the svtperformance.com mobile app

KevinsVertTerminator said:

Doesn't the 2lb. Lower put less pressure on the crank? Isn't that an advantage?

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No

--Joe

2.93/4# on E85 is alot of fun on the street, even though a TVS would be even better

BLOWN9646 said:

2.93/4# on E85 is alot of fun on the street, even though a TVS would be even better

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Key E85. Not so sure 91 pump would be the best option

KevinsVertTerminator said:

People say this a lot. If you have the idlers then is there any advantage to the 2.93/4 lb.?

Doesn't the 2lb. Lower put less pressure on the crank? Isn't that an advantage?

I don't know any of this just looking to understand and get a detailed answer as to all the advantages and disadvantages of each set up.
Thx
KP

Sent from my SM-N950U using the svtperformance.com mobile app

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The pulley doesn't put pressure on the crank. The pressure comes from the belt and tensioner. If anything a larger pulley can reduce pressure because you don't have to run a tight belt to fight slip. The larger pulley has more contact surface. For that reason I prefer to run larger pullies to hit the boost level I want. Tight belts kill main bearings.