Stock 4v shortblock limits in 2023?

5.0 Hatch

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Now that 30 years have passed and loads of data from boosted 4v's has been collected along with advancements in tuning, is 450whp still considered the safe limit on a stock bottom end? Also, are 3v rods any different than 4v? it seems the 3v guys say the limit is 500whp.

I even see some mention 450tq, which would make hp way above 500 on a centrifugal.
 
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robvas

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I've seen this guy posting on bookface, seems to run well
 

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01yellercobra

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The parts haven't changed so limits aren't going to change. When I was in the 3V game 450 was the limit as well. As usual the rods are the weak spot. Some guys pushed the cast crank to 550-600. Though the ones I saw doing that were turbo guys.

There's always that odd one that lasts. Usually when the owner doesn't care if it blows it never blows. Then there are ones where the tune adds 1 degree of timing and it blows sky high.

That seems on the fast side given the weight and power. But I'm not a drag guy so take what I say with a grain of salt.
 

robvas

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Seems like back in the 2000's when people were boosting them, you had a mix of:

Pump gas (e85 either wasn't around or not popular yet)
Tuners that didn't know much yet
Non-intercooled kits (KB, Vortech)

That car is a bit of a freak though.
 

bird_dog0347

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I'm not sure, but I do know the engine combo (97 Cobra) I'm putting in my car made 450 to the wheels with a Vortech on it but to be safe it's getting new rods and pistons as well as tensioner fix and dowels. After that and a good tune to the Holley I plan to run it should be fine up to 7-800 which is WAY more than I plan to make.
 

RX1Cobra

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I've been making 440 rwhp for over a decade now with an Eaton and stock pulley. Afraid to go any higher.

In the next few years I'll build bottom end and put a tvs on it. Mines just a street car though that's rarely driven.
 

01yellercobra

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I was one of the guys with the bad luck. Had a D1 at 12psi I think and pretty much no timing. Heard a noise getting on the freeway one morning, but the car didn't act different. I found low compression on cylinder 8. Eventually when I pulled the heads I found three broken pistons.

The sad part is I wasn't even doing anything cool when it broke.
 

2003RedfireVert

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My stock bottom end 2V made 450w/400t on 12lbs. I kept the rpm under 6200rpm. Any non forged mod motor seems to be 400-450w as the agreed upon limit and I’m not sure why that would change over time. Rods are made of glass.

The guy above on fakebook is on borrowed time. It will blow up.
 

2003RedfireVert

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I was one of the guys with the bad luck. Had a D1 at 12psi I think and pretty much no timing. Heard a noise getting on the freeway one morning, but the car didn't act different. I found low compression on cylinder 8. Eventually when I pulled the heads I found three broken pistons.

The sad part is I wasn't even doing anything cool when it broke.
I loved my D1! It was an early version. Whistled like a mad man. Gear noises lol everything…I loved it.
 

bird_dog0347

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My engine is out of a 97 Cobra and has a Vortech V1 SC with the Aftercooler and I too love the sound on it! I get that an Eaton would likely make more average power and power down lower, I just love the sound of the Centri.
 

Blkkbgt

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My stock bottom end 2V made 450w/400t on 12lbs. I kept the rpm under 6200rpm. Any non forged mod motor seems to be 400-450w as the agreed upon limit and I’m not sure why that would change over time. Rods are made of glass.

The guy above on fakebook is on borrowed time. It will blow up.
After watching Steve Morris on YouTube explain how and when connecting rods break I think keeping the rpm down is more important than most realize particularly with stock rods.
 

Badaz01

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I blew mine in 240 miles when I put my D1 procharger on at 10 psi. I’ve since built the engine and have been running 16 psi for 5k miles with no issues until I recently broke a cam sprocket bolt. But on the bright side when we pulled the heads the bottom end is still solid. Cross hatching and all still visible.
 

5.0 Hatch

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I blew mine in 240 miles when I put my D1 procharger on at 10 psi. I’ve since built the engine and have been running 16 psi for 5k miles with no issues until I recently broke a cam sprocket bolt. But on the bright side when we pulled the heads the bottom end is still solid. Cross hatching and all still visible.
What failed and what caused it the first time?
 

FIREBALL

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So what is the weak link in a 2001 cobra?, the rods?, we have forged cranks right? If its rods can they be shot peened and polished like old school?
 

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