[61-63]

Hypothetical question here. Which would you prefer;

a 421 (4" stroke) based 433 cubic inch engine that has 9.47 cr and produces 388 lb. ft. torque @ 2000 rpm, a peak of 566 torque @ 5000 rpm, and a peak of
574 hp @ 6000 rpm - or -

a 455 (4.21 stroke) based 462 cubic inch engine that has 9.06 cr and produces
414 lb. ft. torque @ 2000 rpm, a peak of 555 torque @ 5000 rpm, and a peak of
555 hp @ 6000 rpm.

The above torque and hp figures were generated by Desktop Dyno5 and the engines are identical other than cubic inches and compression ratio. They both have the same hydraulic roller cam, induction (dual quads on an SD intake), and exhaust manifolds (SD long branch).

Just wondering what folks think.

[steve25]

Need more info here!

Street or drag?
What year , body type and weight car, also what Trans will be used ?
If manual type 4 or 5 speed?
What rear gears do you have and what will you be willing to go up to if need be?
What heads are you using, with either motor you will need some 270 to 280 cfm to hit those hp numbers.

[61-63]

'63 Catalina SD tribute car. 3.42 gear but with an M23Z trans which has very low 1-2-3 which results in 1st-3rd acting like the gear is a 4.10. The heads are the 127s fully ported by Jim Robertson which were covered in a thread in the race section about two months ago. All of the cfm, cam, exhaust, etc. etc. is in the Desktop Dyno5 input so it isn't really necessary to go into that stuff but to respond to the induction comment fuel is supplied by a 421SD 9770859 dual quad setup mounting two 600cfm AFBs..

Oh, just a street/cruise/mebby once a year one trip down the track type car. It isn't meant to be really street friendly and not an issue.

[PunchT37]

Tribute car needs a 421 based engine.

[61-63]

Originally Posted by PunchT37

Tribute car needs a 421 based engine.

Actually both blocks are 421s. The 455 would be a .090 over (sonic checked) 421 block with a 455 crank and pistons in it.

The thing here is me trying to decide which way to go with an engine for the car.
I have the stuff to do the engine either way and have been going back and forth forever and need to decide and get started. And wondered what people would say just for the heck of it.

[Steve C.]

Neither will make peak torque at 5000 rpm. And probably not make peak power at the same rpm.


.

[61-63]

Originally Posted by Steve C.

Neither will make peak torque at 5000 rpm. And probably not make peak power at the same rpm.


.

The #s are from Desktop Dyno5 who knows if they are correct? Forget the #s which engine would you go with as they are described otherwise?

[61-63]

I just checked both engines on Desktop Dyno5 again and both according to it make right at or over 500 torque from 3500 to over 5000 rpm. Again who knows how accurate that is?

[Steve C.]

Two examples tested on a engine dyno.

4-inch stroke combo with 310 cfm alum d-port heads, 248 degree solid roller cam with a single-plane intake.... peak torque at 4700 rpm. Peak power at 6100/6200 rpm.

4-inch stroke combo with 240 cfm '68 #16 iron heads, 250 degree solid flat tappet cam with a single-plane intake.... peak torque at 4400 rpm. Peak power at 6000 rpm.

Also the obvious, the peak RPMs with a dual-plane intake will be at a lower rpm.


.

[darbikrash]

Here is my 4" stroke 433 with Tri-Power in '64 Catalina, Iron heads ported by SD Performance flow around 260 CFM. Cam is an Ultradyne/Bullet lobe solid lifter, 239/243 .545 lift.

dyno_data_zpsnvm5frsm

[dmac]

Originally Posted by 61-63

Hypothetical question here. Which would you prefer;

a 421 (4" stroke) based 433 cubic inch engine that has 9.47 cr and produces 388 lb. ft. torque @ 2000 rpm, a peak of 566 torque @ 5000 rpm, and a peak of
574 hp @ 6000 rpm - or -

a 455 (4.21 stroke) based 462 cubic inch engine that has 9.06 cr and produces
414 lb. ft. torque @ 2000 rpm, a peak of 555 torque @ 5000 rpm, and a peak of
555 hp @ 6000 rpm.

Just wondering what folks think.

Personally I'd take the 455 with more torque in the rpm range I'd be driving in most of the time, and the lower CR is likely to be less sensitive to fuel. In fact, the lower CR is the bigger reason.

[ponchjoe]

I say go 440

[Jay S]

I say go for the 4.21. The simulators often don’t show what the hp gains are from extra stroke.

There are some decent Pistons options for 4.25 stroke as well, you can get 4.125” bore D.S.S. Pistons and not over bore the block so much.
Jay

[Squidward]

I like the 433. I don't see the sense in boring a block that far to get to the bigger displacement. For stated intentions, the ROI isn't there.

[Jay S]

For some reason I was thinking you where starting with a 389. Forgot it was a 421. I would do the 433 as well.

[Half-Inch Stud]

Do both and keep 1 for a spare

[rdtripn_rte66]

Originally Posted by Squidward

I like the 433. I don't see the sense in boring a block that far to get to the bigger displacement. For stated intentions, the ROI isn't there.

For a tribute - the ROI isn't there - put money elsewhere -

[Jay S]

A std 455 is a .058 oversize on a 421? Why .090? Does that block have major issues?

A used 4.21 crank and std 455 Forge Pistons would be economical. Pistons are more more expensive for a 4 inch crank. Especially if you go forged.

[61-63]

The 421 block I would use on the 462 build is already .060 over. I may be able to go less than .030 more we will see when it gets to the machine shop, but I am assuming it will need to be bored .030 more.

Thank you for the suggestion but I already have everything for either engine I've been buying/selling/horse trading this stuff for years.

[nmoreilly]

How about some pics of the project John ?