[69428HOj]

Looking for feedback on this dyno result. New build specs :
The base motor was the 1969 XG block 428. It was bored and stroked to a 467, I am disappointed 420hp 502 tq.* I was wondering if I could get feed back on what may be the choke point on this.

*Here are the spec's.

Cam spec's:

Comp Cams Hydraulic flat tappet

Duration @ .050" 240 intake, 248 exhaust

Lift .508 intake, .510 exhaust

Lobe separation 110 installed at 106.5

Intake opens at .050" 36 degree's, closes 68 degree's

Exhaust opens @ .050" 82, closes 34 degree's

rod bearing clearance .0024" to .0027"

Main bearing clearance .00324" to .004"

Comp Cams break in oil 15W50 Only use for break in must be changed to Valvoline VR1 20W50 racing oil after initial break in before dyno pulls.

Cylinder head flow: 1969 #62 heads
Average flow from .100" to .600"* 198 cfm @ 28" intake Peak flow @ .600" 248 Intake Average flow from .100" to .600"* 153 cfm @ 28" exhaust Peak flow at .600" 212

Engine compression is 9.5-1 recommend minimum of 91 octane fuel preferably 93 octane

[JLMounce]

How was the compression pulled back to 9.5:1? With those heads on a 467 you’re at or over 11:1.

Opened up the chambers? Pistons in the hole, dished pistons?

What’s your total advance set at?

If the tune is being neutered to keep the engine from pinging, there’s where your power went.

[69428HOj]

To be clear, i dont know ****e, so ill do my best to help so you can help me. I may have to go back to builder to get you answers. I believe they are dished 10cc.

[69428HOj]

Dyno run attached

[PAUL K]

Chassis dyno?

[69428HOj]

Engine dyno. Dyno operator well known and repected also.

[Navy Horn 16]

Your compression is low and so is your head flow. Those are actually pretty good numbers considering.

If you want big numbers, get some aluminum heads that really flow and bump that compression up another point.

[69428HOj]

Well I could have but it is a matching number engine, wanted to keep it stock as possible. 475 hp is what i was told to expect and that was good enough. Stll has 750 cfm Qjet, iron heads, long branch manifolds. Only diff is performer intake.

[johnta1]

Average flow from .100" to .600"* 198 cfm @ 28" intake Peak flow @ .600" 248 Intake Average flow from .100" to .600"* 153 cfm @ 28" exhaust Peak flow at .600" 212

What's the flow at .500"?

[Scott Stoneburg]

It's really not off by much. The head flow is a little better than a stock 428. But my stock 428 had 10.75 compression. So head flow and compression will make a difference. IMO

[tooski]

Originally Posted by 69428HOj

Only diff is performer intake.

From other threads in this forum, a performer intake is worse than a stock iron intake. A performer RPM would be better.

[tom s]

Has to be a bigger dish,I get right at 11-1 CR.Was the builder at the dyno runs?At 9.5 with that cam you should have been about 475.Tom

[pastry_chef]

x2 - Performer intake is a problem.

The full head flow table would be nice to know.
Who ported the heads?

Any idea if the block was decked, how far down the pistons are?

Seems you have 1.5 rockers, 1.65 rockers will benefit if you have the clearances.

You dynoed with long branch manifolds, were there pipes connected? what diameter? Mufflers?

[Lee]

Looks about right. You could probably make more torque and the same HP, but at a lower rpm with a smaller cam.

You've got a torque engine, don't worry about the HP. I was running solid 11's and only putting about 360hp to the wheels, but a LOT more torque than you have, with an iron headed 455 (and a much smaller cam). I beat a lot of bigger cammed, but otherwise similar, Pontiacs with it. IMHO, you either need a smaller cam, to a LOT more head/CR.

[krisr]

What do you want to do with the engine/car? I'm running a 400 with e-heads, similar duration cam but in hydraulic roller and ~0.600" lift and solid roller bushed lifters (hybrid setup). With 3.9 gears and a 28" tyre and a turbo 400 it's consistently 11.7 @ 115mph @ 3700lbs. But I built the car for the street that I take to the track 10-12 times/year with friends to have a boys day out racing and **** talking. If you want a low revs street car to fly around in, what you have will put a smile on your face each and every time if you put a good converter and the right gears in it.

[tom s]

My 455 with less cam although a Hyd roller and bone stock 48 heads and true 9.5 made 449 with long branch.Imo it's got some more in it somewhere.Tom

[lust4speed]

Numbers are not really that bad. What has been done to the distributor and has the timing curve been checked? I don't see anything wrong with the 9.5:1 compression. My son's Firebird with 670 heads and 9.1:1 compression runs 11.30's at 119 on 91 octane.

[Cliff R]

Those numbers are considerably "low" for the combination of parts, even at 9.5 to 1 compression. With that much cam I'd expect 480-500hp and another 20-30 ft lbs peak torque.

I've built and dyno'd 455's with untouched heads, not even a port match and with a 231/240 @ .050" cam they will make around 440hp/530tq.

+2 on upgrading the intake manifold, the Performer is OK for a mild 400 build buy has no place on the larger engines as it starts to become a restrictor plate past about 425hp or so. My last engine would not even make a pass at the track with one in place and it was only 514hp. When I tried to test the Performer intake the engine "bogged", surged, and would not pull well into the higher rpm range. No amount of tuning helped, removed it, put the stock intake back on and all was fine.

I attached two dyno sheets of the same 455 engine build with only a cam swap. This engine used professionally ported #96 heads to 250cfm, 9.3 to 1 compression, RPM intake and a Q-jet. The first cam is obviously too small and LSA to tight, the second cam really woke that engine up, and the owner and dyno operator said that it actually idles better (smoother) and more responsive off idle and at lower rpms.....FWIW......Cliff

[pastry_chef]

Dyno and track results
Same cam you have also only 1.5 rockers, only 220 CFM head.

He would also gain with 1.65 rockers.
http://forums.maxperformanceinc.com/...d.php?t=802889

110 LSA is perfectly fine.

Some may not know who Len Caverly is.
A former Engine Master competitor with his own dyno and has the clear picture.

Originally Posted by LCaverly

I do Pontiacs and yes a 108 cam will out perform a 110 or 112 cam every time on a typical 455 street build. It may not idle better but will certainly perform better!!!! And if I am serious about a street strip build it will be tighter than that.
Len C

http://speedtalk.com/forum/viewtopic...596311#p596311

Originally Posted by John Wallace

I raced a 463 CID Pontiac with a 104º LSA roller cam and it ran great.

In Super Stock back in mid 70's it was the hot setup for the SD 455 and they were one of the fastest at that time.
(455 SD is what mine was)

[steve25]

As posted your cork as you put it is that standard Performer Manifold !

Running that Manifold with your cid motor with heads flowing anything over 220 cfm is a complete waste of time, this has been proven many times over in dyno test.

Once crutch is to run a 1 inch spacer and a 850 Carb , or a 950 with high gain boooster in all 4 corners.


With your set up you would see the same level of power with stock heads!

A new RPM Intake is cheaper then a new Carb and will get you the power you should have.