[b-man]

Originally Posted by Baron Von Zeppelin

Looking forward to the realistically stock Dyno runs .

I'm guessing around 375+ gross hp, maybe closer to 400

Agree with this assessment.

Look here at this mild 455 I used to drive daily. According to the quarter mile MPH using the SD Performance online calculator it looked to be making 335 flywheel horsepower:

https://forums.maxperformanceinc.com...22&postcount=4

It wouldn’t be much of a stretch for your 455 SD with far superior cylinder heads, bigger cam, more efficient manifold / 800 carb along with a tad more compression to be making at least another 40 horsepower than my poor man’s 455 HO thrown together mix of OEM pieces.

[sdbob]

I'd be curious of a statistical comparison between your results and results from testing original SD. If I remember I sent you those results. Bob.

[Baron Von Zeppelin]

These are heavy cars.
Automatic with AC and 3.08 gears running 13 second quarters in stock form takes some juice.

[jhein]

Very exciting regardless of the outcome. A legendary motor, built back to spec by a guy that is about as talented and meticulous as you can get? Very exciting. I won't pick any exact number but I'll say it's at least 10% more than factory.

[johnta1]

Need to try a few passes with headers!
The stock exhaust killed the HP on the SD.

[mgarblik]

Originally Posted by sdbob

I'd be curious of a statistical comparison between your results and results from testing original SD. If I remember I sent you those results. Bob.

Yes, you did send me that information. It was really interesting and cool to see how the SD-455 engine responded to the changes they made during development.

Agree, headers and a nice full length 2.5" exhaust with 2 mufflers would help that engine in a big way. I have read up to 60+ HP and I tend to believe it. The Ram Air/SD exhaust manifolds are cool looking but extremely restrictive. I would be surprised if they were 10 HP better than a regular log manifold which they didn't make for them. The entire exhaust system looks just awful and restrictive, front to rear. I don't have any round port headers to even play with.

But on my 62 Catalina with D ports, we exchanged the long branch iron manfolds on the dyno with a tiny set of headers I had for a 350 Pontiac used in a 74 GTO. It picked up 29 HP with no other changes at all. 1.625" primary tubes. So the exhaust manifolds, even the better ones are still pretty bad.

[PAUL K]

The dyno information from sdbob is fascinating!

I won't be surprised if mgarblik breaks 400 on the dyno.


If shipping wasn't crazy I'd send a pair of headers for you to try. It'd be great to see what they're worth compared to the manifolds.

[Bob Eiler]

Mike, I have a set of JR 2 IN. headers you can use for dyno testing if so desired. I won't need them for a while as I'm having a hip replacement Jan 10.

[mgarblik]

Originally Posted by Bob Eiler

Mike, I have a set of JR 2 IN. headers you can use for dyno testing if so desired. I won't need them for a while as I'm having a hip replacement Jan 10.

Thank you for that offer, and I am local of course. I will contact you if that seems to be a worthwhile thing to try. The engine will never be run in the car with headers, so it would be purely for general knowledge. This is a restoration engine and if real power was the goal, dozens of things would be changed to gain an easy extra 100 HP. But I do want to verify the engine is making "correct" power as delivered by the Pontiac engineers.

On a side note, running the engine has been delayed by a few minor carburetor and ignition snags. Storing, even in a controlled environment, has caused some rubber deterioration in the carb. (pump), and the rotor locating lugs have disintegrated so it doesn't sit properly. Simple stuff, but getting parts takes several days instead of hours during the holidays. Going to try and run beginning of the week.

[SD455DJ]

Originally Posted by PAUL K

The dyno information from sdbob is fascinating!

I won't be surprised if mgarblik breaks 400 on the dyno.


If shipping wasn't crazy I'd send a pair of headers for you to try. It'd be great to see what they're worth compared to the manifolds.

Is this the factory dyno sheet you are referring too?

Dennis

[PAUL K]

Originally Posted by SD455DJ

Is this the factory dyno sheet you are referring too?

Dennis

That is one of them. The others tested some ported RAIV heads, P4B manifold and General Kinetics SFT cam. They were cranking out over 600 HP. It motivated me to build a clone of that factory test engine.....and buy a car to put it on.

[Skip Fix]

Originally Posted by PAUL K

That is one of them. The others tested some ported RAIV heads, P4B manifold and General Kinetics SFT cam. They were cranking out over 600 HP. It motivated me to build a clone of that factory test engine.....and buy a car to put it on.

So did you?

I had seen the SD dyno before. So much for RA/HO/SD manifold as good as headers!

[77 TRASHCAN]

Originally Posted by Skip Fix

So did you?

I had seen the SD dyno before. So much for RA/HO/SD manifold as good as headers!

So...Is this comparison with stock "RA" manifolds, or the "opened up" version that RARE sells???

There's a good article on the SD Performance website, under tech tips. Dave built a slightly unusual stroked 400 (to 496 cubes). It was tested with RA manifolds and headers. On this particular engine, the power difference was only slight. It was a pretty cool build!!!

[PAUL K]

Originally Posted by Skip Fix

So did you?

I had seen the SD dyno before. So much for RA/HO/SD manifold as good as headers!

Blocks machined, heads need to be assembled and I'm waiting on the car to be delivered..... Just finished the carburetor

[Elarson]

Here's a teaser

Eric

[Elarson]

A well dressed crew chief

[PAUL K]

Nice ..... Hopefully the "clutch" guy shows up


Good luck!

[77 TRASHCAN]

So Mike,
Is the dyno session still going to happen, as planned?
Jeff

[Elarson]

As a matter of fact, Boss Bird clutch guy is here.
Dyno day is done. I'm sure Mike will publish results later.

Eric

[Mr Anonymous]

Twas a good day!