Poly Stroker on the Chassis Dyno

[66 Sat]

I took my car to the tuning guy today and he put it on the chassis dyno to optimize it and see the difference between the 600 v/s Holley and the 700cfm Double Pumper I also have.

It's a 354 poly, 727 and made 341hp at the wheels with the 700 cfm and 334hp at the wheels with the 600. It was a filthy hot day, 90° by 11am and nearly 100° by lunchtime.

He was very impressed - said it was a really stout engine, the factory 4 barrel manifold is holding it back in his opinion. He didn't really make many changes as it was running great as it was. I was happy with the result but also a little bit disappointed as I was hoping he would find some magic horsepower gain.

For reference the stock 428 Cobra Jet Mustang he ran on there earlier this morning made 290hp. That was an auto too.

I was surprised the power started tailing off by 4,500rpm, I'll have to ask him about that, maybe needs a bigger cam?

 

[kiwigtx]

Nice.

 

[Rusty knuckles]

Very impressive! On a factory intake and I'm assuming stock heads? Really damn impressive!

 

[493 Mike]

I think your statement on the intake is spot on. Are the good aluminum intakes still available? Pricy but, I would think worth significant HP.
Mike

 

[toolmanmike]

Nice numbers. Congrats. What was your engine combo again?

 

[66 Sat]

It's a 318 poly with a 3.58" Scat forged crank, Scat rods, Ross pistons 0.065 over, 10.8:1 compression. Poly heads with a little bit of porting, 1.94"/1.60" valves, Schneider solid lifter cam 264F (220° at .050, 0.450 lift). Topped off with a factory cast iron intake and an 1850 Holley 600. It's got headers, stepped from 1 5/8 to 1 3/4, 2.5" dual system.
It's hardly exotic but all seems to work well. Not bad at all for a old boat anchor poly.

In saying that...if I'd started with a 440 and done all the above but with relevant parts for a big block, then I'd be probably at over 500 hp for no more cost.

The car drives nice as it is though, a nice blend of power and comfort.

 

[beanhead]

I'd be pleased as punch with that hp at the wheels from that engine...
And it's worth noting the bigger carb didn't hurt it, for all the guys that advocate putting 650s on big blocks.
I think you've got yourself a heck of a fun driver!

 

[toolmanmike]

It's a 318 poly with a 3.58" Scat forged crank, Scat rods, Ross pistons 0.065 over, 10.8:1 compression. Poly heads with a little bit of porting, 1.94"/1.60" valves, Schneider solid lifter cam 264F (220° at .050, 0.450 lift). Topped off with a factory cast iron intake and an 1850 Holley 600. It's got headers, stepped from 1 5/8 to 1 3/4, 2.5" dual system.
It's hardly exotic but all seems to work well. Not bad at all for a old boat anchor poly.

In saying that...if I'd started with a 440 and done all the above but with relevant parts for a big block, then I'd be probably at over 500 hp for no more cost.

The car drives nice as it is though, a nice blend of power and comfort.

And you did it with a Poly. Nicely done.

 

[Dako]

Poly owners, unite!

 

[Geoff 2]

Great result. The Poly. Most underrated engine......ever.

 

[hacksaw]

wonder what an airgap and a 4 hole tapered 1 in spacer would do for it.

 

[71Beeper]

I would think that the .450" lift cam is holding it back.
But, your combo works with the small valve setup.
Can a poly head be machined for a 2.02 / 1.80 valve set-up?

 

[toolmanmike]

wonder what an airgap and a 4 hole tapered 1 in spacer would do for it.

Chrysler Power Polysuperpac made Air Gap style manifolds a few years back. THey were pretty good manifolds from what I hear. THink about the runner lay out of a LA airgap and the difference in the Poly lay out.

 

[BSB67]

It's a 318 poly with a 3.58" Scat forged crank, Scat rods, Ross pistons 0.065 over, 10.8:1 compression. Poly heads with a little bit of porting, 1.94"/1.60" valves, Schneider solid lifter cam 264F (220° at .050, 0.450 lift). Topped off with a factory cast iron intake and an 1850 Holley 600. It's got headers, stepped from 1 5/8 to 1 3/4, 2.5" dual system.
It's hardly exotic but all seems to work well. Not bad at all for a old boat anchor poly.

In saying that...if I'd started with a 440 and done all the above but with relevant parts for a big block, then I'd be probably at over 500 hp for no more cost.

The car drives nice as it is though, a nice blend of power and comfort.

The cam is small, but likely a good match for the intake.

Can you share the rest of the cam specs (LSA, ICL, exhaust) and your lash settings.

 

[hacksaw]

Chrysler Power Polysuperpac made Air Gap style manifolds a few years back. THey were pretty good manifolds from what I hear. THink about the runner lay out of a LA airgap and the difference in the Poly lay out.

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thats the thing with them strait shot ... with them being a cross flow head i don't know why thay shouldn't be able to make a lot of power. looking at the pic ya have here makes me wonder if a single plane would work better. but from what i have been reading .. 4.50 is about the max lift without cutting the pistons to clear the intake valve.

 

[hacksaw]

I would think that the .450" lift cam is holding it back.
But, your combo works with the small valve setup.
Can a poly head be machined for a 2.02 / 1.80 valve set-up?

looks like ya can go 2.02 1.60 on the valves with what i been reading

 

[Dako]

looks like ya can go 2.02 1.60 on the valves with what i been reading

2.02 1.60 is what's in mine.

 

[toolmanmike]

thats the thing with them strait shot ... with them being a cross flow head i don't know why thay shouldn't be able to make a lot of power. looking at the pic ya have here makes me wonder if a single plane would work better. but from what i have been reading .. 4.50 is about the max lift without cutting the pistons to clear the intake valve.

It depends on how radical the cam is. I need to dig my Weiand out and take a look. Some say it's a single plane and looses low end torque.

 

[theman440]

Impressive -

 

[Geoff 2]

The Poly's were impressive with just a 2 bbl & 9:1 CR.

Below is a description [ blistering performance ] in an Australian car magazine of a stock 1961 Dodge Dart with Poly. These early Darts were very heavy & had the cast iron TF trans. The 1962 Dart had the new alum TF & was 400 lb lighter.