427 SBC Pump gas - Trying to get that 700Hp

[lefty o]

I'd sure want to know if those heads are backing up at higher lifts. Some AFRs seem to be pretty good at that.

Ha! The above post wasn't there when I started typing my two-sentence response, lol

If they are as cast they probably won't flow those numbers at those lift points.
427 cubes at 6500rpm needs 340cfm ,at 7000rpm needs 365cfm as reference. Not absolute but need something to shoot for.

the 235's are full cnc.

[nxtruck]

I agree with what’s already been said. If the duration numbers you listed for the current cam are .050 numbers, then I feel that they are about 20-25 too big. Also, I don’t think the 1 3/4- 1 7/8 step headers are helping. I’d want at least a 1 7/8 or possibly a 2” primary with a 3 1/2” collector.

[KnightEngines]

Too much cam duration, not enough lift.
Compression too low.
Afr heads are too small at the pinch & turbulent at high lift.

284/292 on 110 cam, .440-.450" intake lobe - .750-.780" at the valve, .420" or so ex lobe.

Port the heads properly, port the intake to match.

Comp up to 12-12.3:1

1050 4150 carb.

1 7/8" primary headers.

[garthpe]

I agree with what’s already been said. If the duration numbers you listed for the current cam are .050 numbers, then I feel that they are about 20-25 too big. Also, I don’t think the 1 3/4- 1 7/8 step headers are helping. I’d want at least a 1 7/8 or possibly a 2” primary with a 3 1/2” collector.

The car itself does have 1 7/8 headers , Its been a while but I want to say they are Hustler and at the time it was the only choice available for 3rd Gen camaros at 1 7/8 which my builder said was very important. They had to be special made and cost a small fortune, that part i do remember lol...Very tight as well and limits oil pan choices....We had to modify my oil pan by taking the bottom kicks out and even then the headers almost touch the pan so we wrapped them. I think now we have better choices which I plan on doing as my oil pressure has always been weird...Starts to drop over certain RPM and I always thought it was because of the oil filter relocation kit...( yes I need one of those also)....

So let me ask what effect would i see by dropping duration as suggested?

[PRH]

I’ve never built a 23* headed SBC on pump gas that made 700hp so I don’t really “know” what it takes to get there.

But, it strikes me as one of those things that falls into the catagory of, “If it was so easy........ everyone would be doing it”.

[golden_commando]

I'd like more compression too with that cam, also the way that the power curve flattens at 6200rpm shows that you may need more flow on the heads/intake

[ChopperScott]

For comparison sake, here's latest sbc build for my car. Not quite 700HP, but over 600 lb-ft of torque...

427 SBC: The Quest for 10.00 @ 135...on Pump Gas

[maxracesoftware]

Too much cam duration, not enough lift.
Compression too low.
Afr heads are too small at the pinch & turbulent at high lift.

284/292 on 110 cam, .440-.450" intake lobe - .750-.780" at the valve, .420" or so ex lobe.

Port the heads properly, port the intake to match.

Comp up to 12-12.3:1

1050 4150 carb.

1 7/8" primary headers.

Afr heads are too small at the pinch & turbulent at high lift.

Dart Pro 1 and Brodix Track 1 w/2.125/1.600 combo at 240-245 CC Intake Port volume
will have a much better Intake Port shape than any SBC AFR Head i've tested
in other words : a Dart Pro 1 and Brodix Track 1 w/2.125/1.600 even Flow testing as little as 312 CFM on my Bench
will easily make +20 to +30 more HP and at a much higher RPM point
proving that the Intake Port shape is superior to 245CNC'd AFR Head
and as far as all the other AFR's lower Port Volume Heads 227cc -235cc Heads ,
Dart Pro 1 and Brodix Track 1@245cc Shape will make +60 to +80 greater HP easily !
even though a 227 or 235 AFR flow test the same or greater Flow CFM
Flow CFM is great , but Shape is King !

the much better AFR Head to use would be the 245CNC version ( real Flow Numbers on my Bench )
IMO : the AFR 245 SBC is their best shaped Intake Port
if Dart Pro 1 and Brodix Track 1@245cc Shape were used in this Dyno test
it would have easily made +20 to +40 higher HP !
viewtopic.php?f=1&t=61930

a Dart Pro 1 215cc or 230cc is pretty horrible HP out-the-box ( one of the least HP Heads i've tested out-the-box shape )
Track 1's are a little more HP out-the-box shape
and many of the AFR's SBC will easily make a bunch more HP
but if you max-port a Track 1 or Dart Pro 1 .... its easily a bunch more HP than any maxed-out that AFR Heads offers !

this is on old Year 2008 420cid SBC pump gas published on YouTube Mar 18, 2011
https://www.youtube.com/watch?v=CWoYhrzBNGo

July 15, 2008 Chris and Eric Vardnou 4.155x3.875=420.4 CID
C & S Performance -and- Eric Vardnou's
420cid Pump Gas SBC 11:1 CR
154 Cranking Psi Exxon 93 Prem
Dart Pro-1 215cc Heads w/2.125/1.600
Peak TQ = 535.6 @ 6400 RPM
Peak HP = 711.3 @ 7600 RPM
ProSystems 1300 w/Power Valve
Dart Little-M Block std Cam location + size
Callies Magnum Crank
BME 5.850 alum rods
Diamond flat-top w/Gas ports 11:1 CR
Jesel Belt
Moroso 4-Vane enhanced
Chris Dyno Headers 2.000/2.125 4.000 Collector
36 BTDC Exxon 93 Prem
.025 hot lash
Royal Purple 5W/20 6 qts Hamburger no-kickout
Vacuum Pump = ManPrs: -15.2 inHg

COLUMN AVERAGES
Test: JULY1320
Corrected Torque and HorsePower
Range: 5500 RPM - 7900 RPM
EngSpd: 6700 RPM
STPTrq: 510.4 Clb-ft
STPPwr: 650.2 CHp
BSFC : 0.445 lb/hph
Fuel A: 134.7 lb/hr
Fuel B: 128.8 lb/hr
Oil P : 56.7 psig
WtrOut: 140 degF
ManPrs: -15.2 inHg
-------------------------------------

CamMotion solid roller R2872/3005-114 on 110CL
.480/.458 1.80/1.70 285.1/299.1
ProSystems 1300 w/Power Valve
Dart Little-M Block std Cam location + size
Callies Magnum Crank
BME 5.850 alum rods
Diamond flat-top w/Gas ports 11:1 CR
Jesel Belt
Moroso 4-Vane enhanced
Chris Dyno Headers 2.000/2.125 4.000 Collector
36 BTDC
.025 hot lash
Royal Purple 5W/20 6 qts Hamburger no-kickout
-----------------------------------------
154 cranking psi (10.5:1)
38 btdc from 36
83/93 from 86/96
40 btdc from 38
81/91 from 83/93

this particular SBC 420cid been running for 14 years now
its on its 3rd or 4th Owner
ran 9 second ETs originally in year 2008

Dart Pro 1's were just Soft-Chamber and new lite touchup Valve Job by Tony Bischoff BES in
Eric_Vernado_BES_Soft_Chamber_Jan_27_2021
2.125/1.600 4.125 Fixture
.....
ended up amost exactly same Flow Numbers as in 2007-2008

Eric Vardnou SBC 420cid.jpg

Eric Vardnou Dart Pro 1 2007.jpg

Eric Vardnou BES Soft Chamber Jan_27_2021.jpg

[maxracesoftware]

i just talked with Chris and Billy Carter
Billy Carter is now 3rd Owner of 1988 Mustang Car and SBC420cid Engine

2021-2022 Update:
new Steel Rods and 13:1 CompRatio Pistons + Q16 Race Gas
and new VJ + Soft-Chamber by BES
Chris ( from his memory ) said the SBC420cid made over 750 HP on Don's Stuska Dyno

Billy Carter's Daughter drove the 1988 Mustang w/SBC420 engine
its a 1988 Mustang "Trunk Model" or "Coupe" as Billy describes it
Cowl-Induction not sealed at all
2725 Lbs with Billy's Daughter in it
28x10.5 M/T "Stiff-Wall" Tires
2022 :
1st time out : Transmission Broke ... abort Run ...no ET Times
2nd time out : best was
ran 5.81 ET 1/8th mile @ 116.20 MPH with slow reacting Shift Relay making 8800 RPM shift point
9.30 ET @ 142.20 MPH
... no more new Runs yet to Date after discovering Relay problem
-------------------------

Before Engine Updates : as Dyno test @ 712 HP
11:1 CR on Exxon Pump Gas
2725 Lbs w/ Billy Carter's Daughter driving
6.030 1/8 Mile @ 113 MPH
5.850 Aluminum Rods

-------------------------

the 5.850 Aluminum Rods
lasted thru 13 years of Street/Strip driving , mostly Drag Strip Runs,
thru 3 Owners

[prairiehotrodder]

I'm helping a friend with a 423 SBC that has been disappointing as well. I've talked about it lots on speedtalk. It has some of the parts you are missing but still doesn't make the hp it should.

423 (4.185 x 3.875)
1050 QFT (4150 base)
13.3 CR
holley strip dominator
AFR 245NPP fully cnc heads
1.875 headers
custom grind solid roller (comp custom solid roller 274 / 282 @ .050 .660 lift 110 LSA installed 4 advanced.)

Never been on a dyno but i think its making around 575 hp. ( runs 10.30 at 130 in 3000 pound car)

[stealth]

2.470 CSA is too small for 427 ci and RPM.

I believe the heads are choke limited and that's all you're going to get ...

Calculations I get from assuming a 4.120 bore and 4.0 stroke (427 Cid)
Your RPM computed from your Cross Sectional Area of 2.470 and Bore of 4.120 and Stroke of 4.0 is 6,327.56 .

You show 6500 RPM where it maxes out.. .seems in line with calculation of 63247 RPM

[PRH]

Frankly, I’d be pretty surprised if the AFR 235’s flowed 330+ on my bench.

If you look at the dyno sheet from the original build........ you can see the VE taking a dive at the top.
There’s plenty of cam duration to support the testing range, so it’s likely running out of area.
The low-ish CR isn’t helping with that either(weaker “pull”).

[steve cowan]

I'd sure want to know if those heads are backing up at higher lifts. Some AFRs seem to be pretty good at that.

Ha! The above post wasn't there when I started typing my two-sentence response, lol

If they are as cast they probably won't flow those numbers at those lift points.
427 cubes at 6500rpm needs 340cfm ,at 7000rpm needs 365cfm as reference. Not absolute but need something to shoot for.

the 235's are full cnc.

I have seen full cnc heads before, but does not mean they size for that application, my opinion Tony (knight engines) summed it up for me.just because they are expensive, CNC and advertise as flowing good numbers at high lift is not always true,this is not a dig at anyone.i have never had a cylinder head that big for a small block on my bench but every 23 degree head I have had shows turbulence on the intake and exhaust.