Brzezinski cuts them open and closes them again...

Actually...... on legal tires, Harry’s best was in the 11.50’s, at MIR on a pretty good day.

However, I seem to recall him telling me it went 7.10-7.15 in the 1/8 on small slicks.

With sticky tires you could run mid-11’s pretty easy with 500ft/lbs, 475hp..... Std corrected off the dyno...... in a 3700lb car at a track that’s less than 1000ft elevation, in “reasonable” air.

How much you lose with the bias plies will depend on how well you get that part sorted out.

“If it were me”, I’d pick up another intake if you don’t have one....... do a back to back test against the stock one on the chassis dyno.

You’re probably already aware of it, but there’s a guy running in Supercar with a 451 in a 68RR....... and I don’t think he’s dipped into the 11’s yet..... but he’s knocking on the door(with legal tires). I think he’ll probably get it this fall.

He does a lot of his own work too.

I think he had some pics of his manifold posted somewhere.

Nice work on the garage

I like that little lip you leave at the upper/lower plenum transition.

I don’t know if it helps or not, but I like the idea of it.

I believe I saw some pics and posts from that guy on FBBO. I'll have to look around to see if I can find any of his intake manifold pics.

Thanks for the kind words about the garage!

if you find a link to the guys 451 build can you post a link?

if you find a link to the guys 451 build can you post a link?

like you, i'm working on finishing up a garage...then planning to get to work on my slightly ratty 67 coronet. Not looking to do a FAST build but probably 70's street racer style (to an extent), might build a 451 for it so i'm always looking at those builds.

That guy is me.

Basically, the 4 runners that have the sharpest turn coming out of the plenum flow the least...... the “inner” runners.
3,5,4,6.
I’d have to dig out my notes since I did that testing quite a while ago, but that’s how I remember it.
Not really much difference between upper and lower.

That’s tested as bolted to a ported head, and comparing how much flow is lost with the manifold in place(and it loses a bunch).

The overall best one I’ve tested was extensively modified by Jim Sieler for his Dart.
His motor was a very high effort build with several pretty high dollar parts in it....... and it made quite good power on the dyno.
He never quite got the car sorted out well enough to use all the power he had.
I’m sure if he would have stuck with it, there would have been some very low 11-sec ET’s...... and maybe even a “10” at MIR on a killer day.

He’s also a fun guy to have around at the track....... wish he was still playing in those classes.


It’s roadrunner2’s motor, in his car.

Edit: this is why it’s best not to go by memory.......
On a mildly reworked 301, all the ports lost about 20-21% compared to the head by itself(about 50cfm).
It looks like the % of loss is within about 1% for all runners, on one that has what I would consider a “normal” amount of rework.
At that level of rework, on a head that flows solidly over 280cfm, its about an 18cfm improvement avg for all 8 runners over the untouched manifold.

Jim’s intake averaged 13cfm better than the one with the “normal” rework, although some of his ports flowed over 30cfm better than the same runner on the one with normal porting.
What brought the average down was there were two runners that showed minimal improvement at all over the stock intake.
Runners #1 and #7.

To put it in perspective, the 8cyl flow average for the head with a radius plate was 286.7cfm.

The intake was tested bolted to the head with all ports blocked off except the one being tested, and a Holley 1000cfm 4150 carb mounted to the carb pad.

The 8cyl flow average for the stock manifold was 212.8cfm.

The 8cyl flow average for the normally ported manifold was 230.7cfm.

The 8cyl flow average for an ootb Performer RPM was 250.6cfm.

If Jim could have picked up #1 and #7 about 15cfm..... the 8cyl flow average would have been right there with the RPM.

Some of the runners on a cleaned up Victor only lost a few cfm compared to the head with the radius plate.

Basically, the 4 runners that have the sharpest turn coming out of the plenum flow the least...... the “inner” runners.
3,5,4,6.
I’d have to dig out my notes since I did that testing quite a while ago, but that’s how I remember it.
Not really much difference between upper and lower.

That’s tested as bolted to a ported head, and comparing how much flow is lost with the manifold in place(and it loses a bunch).

The overall best one I’ve tested was extensively modified by Jim Sieler for his Dart.
His motor was a very high effort build with several pretty high dollar parts in it....... and it made quite good power on the dyno.
He never quite got the car sorted out well enough to use all the power he had.
I’m sure if he would have stuck with it, there would have been some very low 11-sec ET’s...... and maybe even a “10” at MIR on a killer day.

He’s also a fun guy to have around at the track....... wish he was still playing in those classes.


It’s roadrunner2’s motor, in his car.

Edit: this is why it’s best not to go by memory.......
On a mildly reworked 301, all the ports lost about 20-21% compared to the head by itself(about 50cfm).
It looks like the % of loss is within about 1% for all runners, on one that has what I would consider a “normal” amount of rework.
At that level of rework, on a head that flows solidly over 280cfm, its about an 18cfm improvement avg for all 8 runners over the untouched manifold.

Jim’s intake averaged 13cfm better than the one with the “normal” rework, although some of his ports flowed over 30cfm better than the same runner on the one with normal porting.
What brought the average down was there were two runners that showed minimal improvement at all over the stock intake.
Runners #1 and #7.

To put it in perspective, the 8cyl flow average for the head with a radius plate was 286.7cfm.

The intake was tested bolted to the head with all ports blocked off except the one being tested, and a Holley 1000cfm 4150 carb mounted to the carb pad.

The 8cyl flow average for the stock manifold was 212.8cfm.

The 8cyl flow average for the normally ported manifold was 230.7cfm.

The 8cyl flow average for an ootb Performer RPM was 250.6cfm.

If Jim could have picked up #1 and #7 about 15cfm..... the 8cyl flow average would have been right there with the RPM.

Some of the runners on a cleaned up Victor only lost a few cfm compared to the head with the radius plate.

I don’t really like porting intake manifolds, so I don’t do much of it.

One thing I found interesting when testing manifolds is that they “usually” result in some amount of loss in flow from the head, when attached....... even when they are capable of flowing way more than the head they’re attached to.

Years ago I was messing with some std port Indy SR heads. I got them to flow in the 340 range, and was testing some manifolds on them.
An M1 single plane with very minimal plenum deburring and a gasket match would flow a little over 300cfm when attached to the head.
Or rather, the head would flow a little over 300 with the manifold attached.

So, we know the intake is good for over 300....... and yet when you bolt it to an unported 906 head that only flows in the 230’s...... the head still loses flow.

On those 286cfm 906’s in my previous post, that same M1 intake that was passing 300+ cfm when on the SR’s, knocked the 8cyl avg down to 263cfm.

Basically, the 4 runners that have the sharpest turn coming out of the plenum flow the least...... the “inner” runners.
3,5,4,6.
I’d have to dig out my notes since I did that testing quite a while ago, but that’s how I remember it.
Not really much difference between upper and lower.

That’s tested as bolted to a ported head, and comparing how much flow is lost with the manifold in place(and it loses a bunch).

The overall best one I’ve tested was extensively modified by Jim Sieler for his Dart.
His motor was a very high effort build with several pretty high dollar parts in it....... and it made quite good power on the dyno.
He never quite got the car sorted out well enough to use all the power he had.
I’m sure if he would have stuck with it, there would have been some very low 11-sec ET’s...... and maybe even a “10” at MIR on a killer day.

He’s also a fun guy to have around at the track....... wish he was still playing in those classes.


It’s roadrunner2’s motor, in his car.

Edit: this is why it’s best not to go by memory.......
On a mildly reworked 301, all the ports lost about 20-21% compared to the head by itself(about 50cfm).
It looks like the % of loss is within about 1% for all runners, on one that has what I would consider a “normal” amount of rework.
At that level of rework, on a head that flows solidly over 280cfm, its about an 18cfm improvement avg for all 8 runners over the untouched manifold.

Jim’s intake averaged 13cfm better than the one with the “normal” rework, although some of his ports flowed over 30cfm better than the same runner on the one with normal porting.
What brought the average down was there were two runners that showed minimal improvement at all over the stock intake.
Runners #1 and #7.

To put it in perspective, the 8cyl flow average for the head with a radius plate was 286.7cfm.

The intake was tested bolted to the head with all ports blocked off except the one being tested, and a Holley 1000cfm 4150 carb mounted to the carb pad.

The 8cyl flow average for the stock manifold was 212.8cfm.

The 8cyl flow average for the normally ported manifold was 230.7cfm.

The 8cyl flow average for an ootb Performer RPM was 250.6cfm.

If Jim could have picked up #1 and #7 about 15cfm..... the 8cyl flow average would have been right there with the RPM.

Some of the runners on a cleaned up Victor only lost a few cfm compared to the head with the radius plate.

I don’t really like porting intake manifolds, so I don’t do much of it.

I like that little lip you leave at the upper/lower plenum transition.

I don’t know if it helps or not, but I like the idea of it.

I'm curious about something else: the actual cylinder pressure.
If the weakest cylinder has lower % VE, this means it will not be as "full" of mixture (same volume, lower mass) when the intake valve closes. The actual output of that cylinder will be lower.
The question: are any stock manifolds so bad that this may be a problem? It might show up as a colder plug in a weak cylinder.

Bottom line is 600+ hp is available through the factory iron if you do it right.

The new engine is a 499” with 14:1 compression

In other words, it's a fairly decent running 383

In other words, it's a fairly decent running 383

Well, a little slower than what I'd like but, I've been progressing too.

The intake I was working on, that I mentioned in this thread, is about done. I had everything finished other than the port match. I Dykam'd it up, bolted it on and wouldn't you know it, it cracked up one of the ports when I bolted it on. I finished the port match on that port and took it to a guy that has been cast iron welding since 1972 and he said no problem. The intake has been welded for a few weeks and I plan to go pick it up on Thursday.

Like roadrunner2, I too called Dwayne for a custom ground cam but, mine is a solid flat tappet.

I took the heads back to K&G to be set up for the new cam, they are ready and I'll pick those up on Thursday too.

Hope to have the engine back together in the next month or so.

If everything goes as planned, I plan on breaking the new cam in on an engine dyno and making some pulls.

With the info roadrunner2 provided, it will be interesting to see the differences between a pretty mild combo like mine and what he has. Mine's 470 inches, only around 9.35:1 and again, a solid flat tappet. Everything else should be comparable; well, probably not the intake, sounds like some major voodoo going on there.

The reason I asked about whether or not the 9.35:1 was the original CR target is........ it seems like the cam duration might be a tad long for only 9.35:1.

With the restricted intake and exhaust, combined with the modest CR, the running dynamic CR starts to taper off pretty quickly once the limited airflow really starts kicking in.

Sometimes running a little less duration will spike up the peak TQ numbers, and if the shape of the curve after peak(same drop in tq/rpm) is maintained, it can yield a higher peak hp number.

I refer to that as, “start high......end high”.
It’s usually only applicable to the types of builds that peak pretty early and make more tq than hp....... which are basically always airflow limited in someway or another.

Those are good numbers for a streetable combo. With a sorted chassis and practice that will get you into the 11s.

Bill

Thanks, Bill!

What are the plans for the new engine, have you been working on it at all after the issues?

If I'm understanding you correctly, if the cam had a little less duration, it would potentially pick up peak torque and HP and carry the gains for a little longer?

Not exactly......... and without testing you wouldn’t know for sure.
And since the intent is to run it with ex manifolds, it would need to be tested that way.

What I’m saying is........ a shorter duration cam “might” make a higher peak tq number.
“If” that happened, and the fall off after peak tq was the same drop in tq/rpm as the current cam, for enough rpm after peaking........ it could end up making more hp.
But.... We’re not talking big changes here.
And I’m not really advocating you change anything........ I’m more just “thinking out loud”.
Again, the test would only be valid if you used the ex manifolds.
Trying to do R&D for an ex manifold combo........ by testing with headers...... is pointless.

Thanks, Bill!

What are the plans for the new engine, have you been working on it at all after the issues?

Just took it out on its maiden voyage. Put down an 11.28 and 11.21 both at 121.5. I’m pretty happy with that being the starting point for this build. Air was good but there was a head wind.

Bill

Nice job!!

Did it go back on the dyno?

That's awesome, way to go!

I fired mine up in the car on Friday night. I proceeded to work on the carb most of Saturday and got it about right where I want it at WOT, maybe just a touch more fuel is needed. I'd like to get the idle AFR down a little and I have one spot of the throttle at cruise RPM where it's running lean. It's really close.

I noticed my brakes were a little weird a few times when I was out but, would then be fine the next time I stepped on them, I thought "I need to look at those soon". Fired it up after cool down to pull in the garage, put it in drive and I have no brakes. I'd opened my fence to pull back behind my house but, planned on stopping, closing the gate and opening the garage door. The garage door was not open yet. I acted quickly and swung the car right between my garage and a tree, through some gravel, over my man door walkway, into my back yard and was able to slow down enough to slam it in park. I didn't hit anything and was lucky; maybe I needed to change my shorts but, everything else is okay. Pumped the brakes again and they were back. I backed out of my back yard back onto the driveway, opened the garage and almost began to pull it in but, decided to shut it off and push it in.

Pulled all the drums off yesterday, inspected everything and could find nothing wrong or leaking. The fluid was bad and the front bowl on the MC was almost empty, so; I sucked the fluid out of the MC, filled it up and started to bleed the brakes. The pedal was really good and then, all of the sudden, here and there, the pedal would just go to the floor easy. My wife was pumping and was yelling at me, "you're not getting the bleeder tight enough". I would tighten it some more and we'd be good and then, poof, we're not good again. I came to the front of the car and everything was fine, pedal was great and then all of the sudden, bang, it goes to the floor again and you can hear a slight leaking air sound. It would happen every 10-15 pumps. I got in the car and pumped the crap out of them, and everything felt great and then, bang, it goes to the floor and you hear the air sound again. [censored]!. I inspect everything again and this time, I see fluid on the back of the firewall leaking inside the car; it wasn't wet there at the beginning of the day. So, the MC is bad; I ordered a new one last night. It did what it did infrequently when I was driving it; I assume a seal is compromised but, just not all the way gone yet.

Could have been real bad if this had happened during the testing of the day.

The car has been in my family since 99, I have not once used the emergency brake, can't remember if my Dad ever used it, and have no idea if it's operational. It's probably time to see if it works. Hindsight, I'm glad I didn't try it because if it's not operational, the time I spent trying it would have probably been enough that I would have crashed into the door, most likely gone through it or pushed it off the tracks and into my truck, which is about 2 feet from my Wife's Mustang right now, so; it may have taken damage too.

Thanks for clarifying!

I was bummed we didn't get to test it with the manifolds. We'll just have to see what it does at the track.

I ran the old motor again this year (451” 10:1). It did improve to an 11.51 @ 119.78 besting all the 383builds before it. New motor spun a bearing on its first outing. Culprit was loose lifter galleys and a too inattentive driver. Once it got warm the oil pressure went down the drain. Maybe I’ll get it out next year, maybe I’ll work on putting the little motor into the 11.20s.

Bill

Curious , why wasn't the testing done solely with the exh manifolds?

Bill do you have a picture of what was stamped on the ID pad of that block? Chrysler did some goofy stuff saving blocks and had oversize lifters to fit in oversize bores, the 400 block we used for enginemasters had some odd scuffing of the lifters before we had the block bushed if I'm remembering right ..

I will check. But that block was decked severely and was probably erased.

Bill