sbc 421 dyno results

[LB9GTA]

Finally got my sbc 421 together and put it on the dyno

Here are the specs:
4.155 bore x 3.875 stroke, 421sbc nitrous motor
12-1 compression, 5.6 dome
Jones cam (lift.699 int, .659 ext) (dur @seat 316int 320ext) (LS112)
AFR245 unported heads with LGM shaft mounts (1.7 int, 1.65 ext rockers)
Edelbrock 2970 ported
Mark Whitner 1050 dominator
Used 1 3/4 dyno headers

With 110 octane fuel made 586 TQ @ 5200 and 686 HP @ 7200 with 34 degrees timing
https://ibb.co/nBMmpc
https://ibb.co/m2Kgpc

With 94 octane pump gas made 567 TQ @ 5400 and 657 HP @ 6500 with 30 degree timing
https://ibb.co/e3A1Nx

Overall really happy!
https://ibb.co/csTP9c
https://ibb.co/eQPLhx

Can't wait to spray a 300hp shot to the engine
I have to install my powerglide 1st before I spray, no way my th350 I have now will hold the power

[user-30257]

Looks like a legitimate number. Should be fun. Those heads are fast and respond well to increased cross section. And short turn work.

Mark builds some great carbs

[67RS502]

why 112lsa?
also why such a small header?
My 420 picked up 1.5mph by changing from a 1 3/4" to a 1 7/8" (per pipemax)

[GARY C]

why 112lsa?
also why such a small header?
My 420 picked up 1.5mph by changing from a 1 3/4" to a 1 7/8" (per pipemax)

Probably this.

Can't wait to spray a 300hp shot to the engine

[Warp Speed]

why 112lsa?
also why such a small header?
My 420 picked up 1.5mph by changing from a 1 3/4" to a 1 7/8" (per pipemax)

Probably this.

Can't wait to spray a 300hp shot to the engine

Needs a smaller header with a 300 shot?!? Lol

[racinnut15xm]

why 112lsa?
also why such a small header?
My 420 picked up 1.5mph by changing from a 1 3/4" to a 1 7/8" (per pipemax)

Probably this.

Can't wait to spray a 300hp shot to the engine

Needs a smaller header with a 300 shot?!? Lol

They were dyno headers, likely his car headers wouldn't fit on the dyno hopefully he will enlighten us.

[CamKing]

Needs a smaller header with a 300 shot?!? Lol

Not the headers. The LSA.

[CamKing]

BTW, that 112 LSA is misleading. The distance from max lift on the exhaust lobe, to max lift on the intake lobe is 108 degrees.

[LB9GTA]

Yes, the dyno headers were 1 3/4. That's the biggest he had.
I have 1 7/8 on my car. Probably need to go to a step header when I spray a bigger shot

Yes, this engine is made for nitrous.

[GARY C]

why 112lsa?
also why such a small header?
My 420 picked up 1.5mph by changing from a 1 3/4" to a 1 7/8" (per pipemax)

Probably this.

Can't wait to spray a 300hp shot to the engine

Needs a smaller header with a 300 shot?!? Lol

Good question, the consensus was always bigger but others question that due to the increase in cylinder pressure. I had a long conversation with Calvin about that, maybe he will chime in and share his thoughts.

There is a lot of thought out there on nitrous engines, cams, pressure differential across the valves but I don't know many that have done back to back testing with the different theory's.

The one nitrous engine I dynoed was an 11.1 357 SBC that made 530 on motor, 710 on a 150 shot and 820 on a 300 shot with an 1 3/4 dyno header because that's what he had.

[Casper393W]

I built a 304CI 2V Ford Mod Motor that runs 8.80's @ 155 on a 300 shot @ 3150 lbs and we had a set of off the shelf Edelbrock Victor series headers 1 5/8 to 1 3/4 stepped with a Merge Collector and I thought once we put a set of 1 7/8's headers on it we would gain alot but it only picked up marginal amount.

Funny stuff happens sometimes, you never know until you test

[GARY C]

BTW, that 112 LSA is misleading. The distance from max lift on the exhaust lobe, to max lift on the intake lobe is 108 degrees.

Just curious, what makes a 108 cam a 112 on paper?

The little bit of track testing I did back in the day with a wide lsa "nitrous cam" advertised of course never seemed to make a noticeable difference, if anything it hurt 60' and et on straight motor.

One of the fastest guys back then, mid 2000 ran a 421 SBC, Chevy II on drag radials with a moderate sized herbert cam on a 106 lsa, the car would run 5.50's on a 78 pill and a 5.30 on a 102 pill... really made me question the "nitrous cam" theory.

His engine dynoed 675 horse.

[MadBill]

...Just curious, what makes a 108 cam a 112 on paper? ...

I hope when Mike explains this, he recalls what a CJ it turned into a few years back when the discussion of how LSA/LCA should be specified became heated...

[GARY C]

...Just curious, what makes a 108 cam a 112 on paper? ...

I hope when Mike explains this, he recalls what a CJ it turned into a few years back when the discussion of how LSA/LCA should be specified became heated...

Yeah, I don't want to see that, I am guessing it has to do with asymmetric verses symmetric lobes...I hope thats the correct term but probably over simplified.

Maybe best to avoid it all together.

[cjperformance]

The lift peak does not necessarily fall at the central point between valve open and close.
So it may be 108 between lift peaks and 112 between the open/close center points.
OR , this cam is made from an advanced rubberized billet that self alters its advertised and dynamic LSA's, possibly marketed as the "lift n' twist" billet! ah now I've done it!!