Ok… Question on bbk shorty headers

[K4fxd]

The latter absolutely destroys the former everywhere in the RPM range.

Thats mostly a function of the gear. Put the 17 mani back on and you will see gains below 5500 according to all dyno graphs I've seen.

Anyway I'd love to test the 18 GT manifold against the 18 truck manifold.

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[WildHorse]

Ive heard 373s are so much fun. But I hear they are not as good on the highway?

I have no complaints. 6th gear is long you'll never notice.

 

[WildHorse]

Thats mostly a function of the gear.

Of course. But on a NA car I'd be a fool not to put in lower gears with a higher revving manifold. I'm sure you'd agree with that.

 

[K4fxd]

I always liked 3.91's but the short 6R80 first gear makes me shy.

 

[WildHorse]

I always liked 3.91's but the short 6R80 first gear makes me shy.

Yeah that damn first gear in those transmissions haha. But you'll get killer 60's if it hooks.

 

[K4fxd]

But on a NA car I'd be a fool not to put in lower gears with a higher revving manifold.

It all depends on how you want to use the car. If you want to spin it high you lose down low, so yea gears.

If mine was a second car I'd probably go with 4.09 and the CJ manifold along with some E85 and a stall converter.

If I wanted it for road racing I would buy another with a manual and go with 3.91's along with the GT350 mani and E.

For my daily I use the truck manifold, 3.15 gears and get 30 MPG on the freeway along with it being fun.

 

[Kingofhearts]

It all depends on how you want to use the car. If you want to spin it high you lose down low, so yea gears.

If mine was a second car I'd probably go with 4.09 and the CJ manifold along with some E85 and a stall converter.

If I wanted it for road racing I would buy another with a manual and go with 3.91's along with the GT350 mani and E.

For my daily I use the truck manifold, 3.15 gears and get 30 MPG on the freeway along with it being fun.

i may have to try the truck mani out definitely will be changing my gears. I’m thinking 355s tho. As it’s an auto and hear that 355s on an auto are equivalent to 373s manual

 

[WildHorse]

As it’s an auto and hear that 355s on an auto are equivalent to 373s manual

You have a very slight advantage in 1st gear only for acceleration.
blue 15-17 MT82 Red 6R80 both 3.73. 3.55 would be worse

 

[K4fxd]

I've got a set of 3.55's in the shop. I'll probably get around to installing them the first week of Aug.

I had 3.31's in my coyote truck with 30 inch tall tires and first gear was a joke, so that is why I'm not in any hurry.

 

[Kingofhearts]

You have a very slight advantage in 1st gear only for acceleration.
blue 15-17 MT82 Red 6R80 both 3.73. 3.55 would be worse

so much has changed since I’ve last looked into this. So 3.73s are better, 355 are great and have better gas mileage but that’s about it huh.

 

[K4fxd]

You have a very slight advantage in 1st gear only for acceleration.

Unless he goes with a 18 up manifold he will be shifting at 7000

 

[WildHorse]

Unless he goes with a 18 up manifold he will be shifting at 7000

1st gear yes, 2-5th nope. Auto horsepower vs manual horsepower along with the much closer ratios of the MT82.

 

[WildHorse]

355

is a great compromise gear.

 

[K4fxd]

so much has changed since I’ve last looked into this. So 3.73s are better, 355 are great and have better gas mileage but that’s about it huh.

Nothing has changed unless you want to rev the engine above 7000.

Changing gears will give you more seat of the pants power.

 

[K4fxd]

1st gear yes, 2-5th nope.

What RPM would he be shifting at then? Stock manifold.

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