This guy seems a straight shooter. He works at Westech performance who is the go to dyno place for the Hot Rod and Car mags of the past. He took his smog 360 and bolted on some decent parts and got over 460hp. Mild cam mind you and mild ported iron LA heads. Im questioning the
"Happiness" of his dyno because Nicks Garage just dynoed a 383 originally built to 335hp specs but with a big cam, M1 single plane and expensive Holly carb and did not make this power. In the 90s a legit mopar mag had a 375 hp 440 magnum where they added headers, 509 cam, single plane intake and Holley carb and they achieved 425 hp on their dyno. Just seems if it were so easy to build this power he got with simple parts and smogger pistons there would be no need to purchase zero deck pistons, aftermarket heads and such. BluePrint Engines offers a 408 stroker iron headed 360 that doesnt make this HP level. Im wondering if theres some of that 90s magazine embellishment going on in the modern video clip world here.

https://www.youtube.com/watch?v=Gf2CAPiFJgg

I believe none of what I hear & half of what I see

The most I saw in the video was 387 hp and 434 fpt.

I don't get into engine dyno numbers unless someone is comparing parts to parts and then the actual numbers probably shouldn't be taken literally. it's a numbers game for most but I do believe it's a misleading game. people don't like chassis dynos because you don't get the big cute number that the phony engine dyno gave and it's human nature to dislike what you don't understand. the power you feel is where the rubber meets the road.

. You are correct. I was wrong. I looked at wrong output. Torque. But is 387 hp possible with low comp ht pistons ?

Going to a closed chamber head from a stock smogger head will bump the compression up quite a bit, I could see those numbers being real.

I used to have a dish piston worn out 360 shortblock under a set of ported X heads that made 310HP to the tires on a chassis dyno and that was with a 3800 stall converter chewing up some dyno numbers. It ran 12.72 in my 3500lbs Barracuda.

There are "Stock" class low compression 340 and 360's that are into the high 10 second range in the 1/4. But the R&D that goes into them is way ahead of typical prep. Lots more to it than just pistons.

I'm glad you put the word stock in quotation marks. The word has little/no meaning in drag racing.

I've heard lots of rumors that Westech's dyno was 5-10% happy for a long time, not sure if they were verified or if it ever changed. Of course when people don't believe dyno results they always say the dyno is happy, maybe it is maybe it isn't. EDIT I watched the video, where did you get 460 HP? I saw 387

I honestly thought Nick's dyno was a little happy too, but that 383 makes me think maybe not. I wondered if he had a vacuum leak from the bottom of that M1 after he installed the paper gaskets, seemed like he still needed to jet the carb up a ton with annular boosters, 8 jets is like 12 with downlegs.

The numbers Nick got seem a little more believable, 450 HP seems impressive for that combo, but maybe we expect too little, and you know what they say about comparing dyno results. The one other thing about Nick's engine is he didn't say what size headers those were, but they sure look like Hooker 5209s (2 inch super comps), which I think are just too big. ALL of the details are important. I know this isn't about that Nick's episode though!

It does have a meaning, what it means is that these engines are built to meet the rules defining stock for that governing body. Nothing more, nothing less and with those rules these engines get turd polished to a high sheen.

It sure don't mean like how it rolled off the OEM assembly line, which is what most people think when the word stock is used.

and it doesn't mean it will last more than a handful of passes between freshen ups also.

The OP, 2boltmain, was interested in the power that could be made with "smogger" low compression pistons. OEM engines seem to always be assembled with pistons lower than published specs. Blueprinting & "Stock class" specs can still have them down in the hole .090" including head gaskets. Considering that they are still normally aspirated, and stock lift to boot, I thought it would be a good example showing the performance potential of lower compressions despite some of the other liberal rules. But there are still notable performances possible without taking the rules to the extreme.

15 years or so ago, I got a very worn, high mileage LA 360 give to me. It run, but smoked and needed gone through. I threw rings and bearings in the short block. Put very used, cracked Magnum heads on it that I ported with the MP porting templates and a mild cam in it. Smooth idle, very little lope. Iron intake with a slightly re-worked 3310. 3.55 gears behind a 999 tranny.

That thing would puff a bit of blue smoke under load, but ran an 8.10 in the 1/8th every time in hooked. A step up in cam and just a bit more converter and 7s would have not been a problem.

So yes, those low compression blocks work really well with the right combination of parts. Magnum heads are probably the key piece.

P.S. That was in a 72 scamp body.

Bob Mazzolini had a Sebring with a low compression 318 that would run low 10's. The 318 even had a QJet carb on it! Most people will tell you that a low compression 318 with a QJet carb can't run low 10's in a 3200 lb car but Bob would go round after round in that car. I think Bob sold that car but I seem to recall that it is still being raced.

I remember in the 1980s- guys taking smog motors that were sound motors and putting a cam headers and performer intake on them and they were STILL a turd. I specifically remember a 400 mopar, 350 Oldsmobile and a friend with a 454 from a late 70s truck. Low comp motors with sensible bolt on/bolt ins and they ran NOTHING like their musclecar era ancestors.

The 387 HP number seems believable or close, it really depends on the head flow. I would expect more like 350 but if the heads are flowing really well, sure, 387. I would believe 460 HP on a smogger bottom end too, I would just expect it to have heads and a cam that would support 500 HP on a built bottom end. I'm stating the obvious here but a given compression ratio doesn't mean that the engine can't make XXX power, it will just make less than if it had more compression.

If you take a smogger short block that is in good working order with good ring seal and put a great set of heads on it along with a good intake, headers, and the right cam for the application it is going to make impressive power. It won't make as much as a 0 deck, .040 quench, 11:1, freshly machined and torque plate honed engine with forged pistons and H beam rods and all of the other racey stuff, but how much power does that all add? The pistons and rods are worth nothing really, the 3 point CR increase, quench, and better hone job/ring seal I would guess 30-50 HP on a 500 HP engine. One point of compression is supposed to be worth up to a 3% HP gain, but that relationship really isn't totally linear. (I.E. going from 11:1 to 12:1 will not create the same gain as going from 7.5:1 to 8.5:1).

When you start with a smogger bottom end the combo will be more sensitive, and the low end torque loss will feel exacerbated by both the even lower dynamic compression and the fact that the engine started with less to begin with. The worse your starting point and the bigger you go with the cam the easier it will be to turn it into a turd. Those engines will want more timing and more aggressive ignition curves too. Also its worth noting that a smogger 454 truck engine also has peanut port heads which leave a bit to be desired vs passenger car oval port heads from an earlier big block chevy, so there's more to it than just CRs dropping for some of the smogger engines. What was in the 400? If it was a 509 cam with manifolds and a stock converter I wouldn't expect much from it, but you'd probably get away with the same parts in an earlier 440 and still run respectably.

Here is some reading from this board on smogger combos;

https://board.moparts.org/ubbthread...45/fastest-stock-smogger-360-combos.html
https://board.moparts.org/ubbthread...-stock-smogger-440-bottom-end-times.html

The numbers (387 hp) seem kinda happy to me.

As someone who used to buy used industrial electric motors
up to 1200 hp with rpm’s from 600 to 3600,
I know they can be bought on the salvage market pretty cheap,
especially if you do not need it immediately.

I wonder why dyno shops do not have a 3600 rpm electric motor
at a horsepower their 220/260 volt 3 phase service maxes out at
to use for periodic calibration?

Maybe they do not care?

Do happy dynos make happy customers?

the "happy dynos make happy customers" statement says it all.
especially when they have the readout papers to wave around in front of their pals.

I think you're right that this is the case more often than not.