new motor. need opions

Bracket Talk

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January 19, 2022, 07:00 PM

66belair

new motor. need opions

Hey guys.

I am building a new motor for this upcoming season. I have a shorty swing arm nelson car. I am building a 4.6 bore short deck big block with 345 3X heads. Question is, do i go with the 4.5 stroke 6.35 rods and build a 598, or 4.375 stroke and the 6.535 rods and build a 582. I have heard the 4.375 stroke will outrun and out last the bigger stroke with the short deck. I just need to know what combo you think is better for reliability and efficiency,

Thanks for the comments in advance

January 19, 2022, 07:19 PM

1320racer

I'd be more concern about who's building it when the question is reliability and if it must be a short deck build the 598, about the same price as a 582 but more power. That said, I wouldn't build either of those combos today. The most common engines in dragsters today are 615 and 632 and both go hundreds of passes before being freshened.

January 19, 2022, 07:55 PM

66belair

Hey ED. Glad you replied. I only have a short deck block so can't really go bigger than the 4.5 stroke.

January 19, 2022, 08:00 PM

Mike Rietow

quote:
Originally posted by 66belair:
Hey guys.

I am building a new motor for this upcoming season. I have a shorty swing arm nelson car. I am building a 4.6 bore short deck big block with 345 3X heads. Question is, do i go with the 4.5 stroke 6.35 rods and build a 598, or 4.375 stroke and the 6.535 rods and build a 582. I have heard the 4.375 stroke will outrun and out last the bigger stroke with the short deck. I just need to know what combo you think is better for reliability and efficiency,

Thanks for the comments in advance

Local has a 585 going 4.30's 4.40's n/a. 4 link dragster.

January 19, 2022, 09:28 PM

Goob

I'd go with the 582 with those cylinder heads.
I think that's the upper end of your flow capabilities. Great heads for a 555-565

January 19, 2022, 10:41 PM

Big Steve

With those heads I would consider a 565, 4.250 crank and 6.535 rods, It has a better rod ratio and a 565 will make close to the same HP as a 582. My 565 with cnc 345 Dart heads ran consistent 4.7x with a best of 4.68 at 2000 lbs.
JMO

January 20, 2022, 05:21 AM

1320racer

I missed the heads. If you are building a new engine around these heads, I agree with Big Steve

January 20, 2022, 07:32 AM

SCDIV1

My 584 with similar heads does not run as fast as it did previously as a 565 with the same heads, cam and intake.

4.610 x 4.375 + .400 rods 584
4.600 x 4.250 + .400 rods 565

I had a new custom grind cam cut for the 584 and did some head porting but that was never put back together and run

582’s and up generally like Head Hunter heads or 375X’s or something in that intake runner size in a conventional head.

The 565 shorter stroke combos run better and I have friends who have said the same thing with their experiences

January 20, 2022, 08:04 AM

TD3550

What intake are you thinking of?. SV Merlin,Sniper?

January 20, 2022, 10:24 AM

183N

quote:
Originally posted by SCDIV1:
The 565 shorter stroke combos run better and I have friends who have said the same thing with their experiences

I agree with this. Our stuff is 4.560 x 4.25 with +.400 6.535 rod and runs good, best ET of 7.32@182 / 4.64@148 with a 1.051 60. Runs faster than most of the 582 combos. I think the 4.25” stroke is a good combination.

January 20, 2022, 11:07 AM

SP 124X

quote:
Originally posted by 183N:
quote:
Originally posted by SCDIV1:
The 565 shorter stroke combos run better and I have friends who have said the same thing with their experiences

I agree with this. Our stuff is 4.560 x 4.25 with +.400 6.535 rod and runs good, best ET of 7.32@182 / 4.64@148 with a 1.051 60. Runs faster than most of the 582 combos. I think the 4.25” stroke is a good combination.

Gotta agree with this especially with the heads you have. My 555 runs rather well for what it is.

January 20, 2022, 12:02 PM

66belair

I was gonna run bm 2017r brodix intake. Is there intakes better than the brodix one? Thanks for the rplies guys. This was supposed to be a 565 untill i had to buy crank, so i thought it aint no more money so id go little bigger if i could.