[Jay S]

That SD455 on the Facebook marketplace link was cool.

BS meter is running pretty high on the number 16 SD heads that flow 340CFM, especially when it mentions the “mildly worked over heads”. That’s pretty hilarious.

That 455SD engine, with the numbers it’s is making sounds more like about 310 -315 cfm on the head flow? Which would be a feat! The dude must have a very CFM friendly flow bench.

6X and 4X have good flow potential.

High compression Ping monsters, LOL. I like that…

[PAUL K]

Originally Posted by sdbob

Yes,headers. Then increasing cr to 12.5 big increase. I m the guy who had a friend at the Pontiac dyno room that got me the sheets form 1970.

Are those the sheets Pete McCarthy posted in his magazine and Rocky used in his book?

[johnta1]

Yes they are. Bob also gave me a copy of them. I used the info when I ran the SD 455 in my car.
The best improvements were headers (duh! for a race car) and when I put the 'domed' pistons in for 10.5 CR. That also helped a bunch. Ran a .700 lift roller and the engine was still very docile. But a beast when throttle mashed.

[PAUL K]

Originally Posted by Jay S

That SD455 on the Facebook marketplace link was cool.

BS meter is running pretty high on the number 16 SD heads that flow 340CFM, especially when it mentions the “mildly worked over heads”. That’s pretty hilarious.

That 455SD engine, with the numbers it’s is making sounds more like about 310 -315 cfm on the head flow? Which would be a feat! The dude must have a very CFM friendly flow bench.

6X and 4X have good flow potential.

High compression Ping monsters, LOL. I like that…

A professionally ported SD-455 head flows 285-290 with a basic race port job. 330 max effort with moving the pushrod..... Advertised 340 cfm is probably hurting the chance of a sale but helps the dreamers dream.

[PAUL K]

Originally Posted by johnta1

Yes they are. Bob also gave me a copy of them. I used the info when I ran the SD 455 in my car.
The best improvements were headers (duh! for a race car) and when I put the 'domed' pistons in for 10.5 CR. That also helped a bunch. Ran a .700 lift roller and the engine was still very docile. But a beast when throttle mashed.

Was there anymore info/details that came with the dyno test?

I ran ported SD heads on my Firebired in the mid 90's. The car went into the nines through the mufflers, weighing 3900 lbs. with a shot of spray. The SD engine are Bad Azz!

[Skip Fix]

I knew I had seen/read them somewhere!

[Stan Weiss]

Originally Posted by PAUL K

A professionally ported SD-455 head flows 285-290 with a basic race port job. 330 max effort with moving the pushrod..... Advertised 340 cfm is probably hurting the chance of a sale but helps the dreamers dream.

Paul,
I am not on Facebook so maybe there are parts of the post that I can not see. But I didn't see the seller say anything about the head flow cfm. I only saw that in GTO-relic's post.

Stan

PS Does anyone still have a copy of the dyno sheets that they can post?

[PAUL K]

Originally Posted by Stan Weiss

Paul,
I am not on Facebook so maybe there are parts of the post that I can not see. But I didn't see the seller say anything about the head flow cfm. I only saw that in GTO-relic's post.

Stan

PS Does anyone still have a copy of the dyno sheets that they can post?

Agree.... 730 is an optimist number. I doubt you'll see dyno sheets

[johnta1]

Was there anymore info/details that came with the dyno test?

If you're talking about the dyno sheets that Bob has.

http://pontiac-power.com/sd-dyno-menu.htm

[Stan Weiss]

Originally Posted by johnta1

If you're talking about the dyno sheets that Bob has.

http://pontiac-power.com/sd-dyno-menu.htm

John,
Thank you very much.

Stan

[PAUL K]

Originally Posted by johnta1

If you're talking about the dyno sheets that Bob has.

http://pontiac-power.com/sd-dyno-menu.htm

Thanks a bunch!

[sdbob]

Each test sheet basically listed what was done to the engine for that test. Then a one page report was sent telling the recommendations. Larger diameter exhaust system was one. I do not have sheets copied to computer just hard copies.

[GTO-relic]

flow numbers are only part of the story...
the discharge characteristics of the intake valve/chamber are just as important,
Pontiac intake ports 1968-up had the scallops in chambers,
to deflect flow in 4 different directions, as the valve opened/closed.
to see how it works, the intake port must be pressurized,
with the flow bench in exhaust mode,
and the chamber faced sideways, and intake valve opened.
then epiphany still strike.
if heads are only flowed with chamber down,
that's only half the picture or less,
it's just a number. better than nothing,
however, you need to see how chamber side is working too.
when the chamber scallops are ground away,
and the quench pad opened up like the spark plug side,
it completely changes the flow and burn characteristics of the head.

[GTO-relic]

https://www.motortrend.com/how-to/su...-flow-testing/

check out the Mondello wet flow testing rig

[Stan Weiss]

Originally Posted by GTO-relic

flow numbers are only part of the story...
the discharge characteristics of the intake valve/chamber are just as important,
Pontiac intake ports 1968-up had the scallops in chambers,
to deflect flow in 4 different directions, as the valve opened/closed.
to see how it works, the intake port must be pressurized,
with the flow bench in exhaust mode,
and the chamber faced sideways, and intake valve opened.
then epiphany still strike.
if heads are only flowed with chamber down,
that's only half the picture or less,
it's just a number. better than nothing,
however, you need to see how chamber side is working too.
when the chamber scallops are ground away,
and the quench pad opened up like the spark plug side,
it completely changes the flow and burn characteristics of the head.

I am not sure what you are seeing. But my understanding is at low lift you want the flow to be worse when flowed in this direction.

Stan

["QUICK-SILVER"]

Originally Posted by Stan Weiss

I am not sure what you are seeing.

Appears the tanker cars in relic's trainwreck are hauling nitro.

Clay

[GTO-relic]

factory stock round port head combustion chambers were opened up on quench side of the chamber, right from the factory

[GTO-relic]

quench pads, side spark plug Boss 429 head

[PAUL K]

We port a lot of factory iron heads and have made decent power in the past. We spend about as much time as it takes to read this thread on the combustion chambers and a lot of time on the ports and valve job.

We can post pictures stolen from the Internet forever and accomplish very little. Does anyone have before/after track tests or dyno numbers showing results of these chamber modifications? ...asking for a friend

[steve25]

The shallow side of the chambers being opened up was done more in response to the tuliped intake valve used in the IV heads then anything else.

Later I will dig out the 1989 article that I think I still have on SD455 motor built for SS with ported heads making 590 hp .

I recall that Kip Martin during the dyno session picked up 90 Hp by just tuning changes.