Aluminum Heads with Cast Iron Exhaust Manifolds

Gary B,
I wasn't disagreeing with any of this, I cited an example without going into huge detail that I've used several times that works.
I was also suggesting that it could really help put further down the line....because I've used that too.
I'm familiar with the stuff Vizard writes about for a very long time (well supported engineering already used everywhere except mainstream bolt on musclecar parts, for the most part).

My humor jpg was there to sarcastically point out that the OP hasn't come back with much since the microscope was possibly focused sharper than the context of the original question.
Hopefully that wasn't taken with negativity.

 

Thanks again for choosing to engage in this discussion, Jim.

While we all know that something of this caliber would most definitely see larger gains with better exhaust, the engine is in fact, designed to work best with headers. No one expected the manifolds to do as well as they did, which I think is the conclusion we can all draw here.

It also shows that ~700 hp is possible with manifolds, which I think is awesome considering the restrictions on the airflow.

To say those 1 7/8" headers had no business on that engine would be even more true for the manifolds; hence, I think it was just to be used as a reference point, a sort of 'let's see what this does' kind of test.

When you view it from this angle, it's quite valid. It shows a difference between two items, not necessarily the 'best' item. The difference between 1 7/8" headers and iron manifolds should have been leagues on that engine, but were not...

Trying to get 2 1/8" headers to fit might be a little bit challenging, but hey if you want that kind of improvement you could also add forced induction or nitrous.

Personally, I'm not trying to advocate manifolds as being equal to headers on a 700 hp engine, nor a 500 hp engine. I believe they do have their place though, even on 'performance' engines, with the right valve timing, and can be made to perform quite well--along with all the benefits that manifolds afford over headers, with the one exception being maximizing power output.

I hope this doesn't come off as too "", as I tried to be as tactful and tasteful as I could.

 

Hasn't this already been proven with the 8ish hp difference between untouched manifolds vs ported manifolds?

This would suggest something else is at work here besides 'reducing backpressure'.

I suspect reviewing the previously communicated exhaust tweaks will give insight.

I think realizing what can be done with less is exciting, and could even be implemented on header designs for improved exhaust flow.

I don't see this as any sort of 'attack' on any particular product, since everything has its place in the market.

Isn't improving what already exists the name of the game in hot-rodding? :TU:

 

^I got ~12 hp from stock to 2.25 on a dyno". The data is on George N's website for anyone interested.

 

If Jim wants to chime in I am sure he will, but the motor in question was not designed for headers.. it was designed as a max effort stock appearing engine, with exhaust manifolds.

Careful with the assumptions.

It is without question a tremendous feat to create the power he did, with the tremendous handicap of exhaust manifolds.



JW

 

8ad-f85 I didn't take any offense at all.
One last experimental idea I will add here...
From the iron manifold, extend the small exhaust pipe about 30" to 36" then let it protrude a few inches inside a 3" X pipe assembly.
This has been an interesting read.
Always admired "stock appearing" performance and hope there is more efficency to be discovered.

 

Fair enough. The engine may not have been deliberately designed to work best with headers, but that doesn't change the fact that it did (as would any 700+ hp engine...), nor does it negate the fact that the manifolds did so well with it, which was my actual point, along with all the rest of the points I made that so far have not been challenged.

Thanks for the clarification! I gather you're much more familiar with this engine, its owner, and the other specifications/details that I have been not made privy? I'd be very curious of the cam specs of that manifold engine that made 700 hp.

Feel free to critique the rest of my writing and let me know if anything else is remotely inaccurate. I'll assume (should I?) that everything's ok if no further commentary attempts to contradict it.

Let's see, if my math is correct, the 1 7/8" headers showed a 4.9% increase in power over the ported manifolds on a 700 hp build. If we took that same percentage and applied it to a 400 hp engine, those same headers would give ~20 hp over ported manifolds, IF the percentage stayed the same (which it probably wouldn't, given the circumstances and dynamics surrounding individual builds and their uniqueness), but puts it into perspective.

We can also see that this ~20 hp number does not correspond to other findings on such mild engines (showing ~5 hp, or only 25% of that previous percentage, and would equate to a 1.2% difference between headers/manifolds on that particular combination), so I'm sure it's a reflection of airflow (and its corresponding attributes of velocity, flow, and backpressure), or more specifically, the quantity of air moving through the engine (manifolds), and would have less to do with pulse wave gathering at this level of performance. I assert that this could be further enhanced by the aforementioned exhaust tricks. And why not? Are headers themselves not another way of manipulating the exhaust in order to maximize its evacuation?

May even make more overlap usable on manifolds this way, improving power further. Why stop at 'good enough for now'?

While it's easy to say that 'adding x item would yield y results' over and beyond the engineering intent, where does one draw the line? If the goals were met using the chosen componentry, then the outcome has been satisfactorily achieved. If you added this or that to improve power even further, what's the difference between that and adding other items to increase power simply to show that it could be done?

Empirical data is always useful, of course.

We can all agree that impressive results can be achieved, even with manifolds, and was really the original message conveyed a page or so ago.

Impressive results can be achieved within the limitations to be overcome, whether it be less cubes, manifolds, lower compression, stock components, etc., making 'impressive' a subjective experience and is (as always) relative.

ALL information I share here is free to everyone everywhere to use at will. My purest interest is to see this community thrive and improve in every way it can.

You never know when someone or something will spark some creativity or inspire someone to do something great.

You've got a good thing going here, Jim, and I'm very happy to be a part of it--even if its in some small way.

 

This was not Jim Rodgers max effort motor results. This was my motor that was built and dyno'd at Wildcat Performance. It was a mildly built street motor.

I don't know if Jim ever tested dyno power with headers. Maybe he will see this and chime in.






As for my motor performance at the track and progression with further mods....

Originally, I ran consistent low 13.0's, 13.03, 13.05, 13.03 over and over. I did make a trip further north and in 15-20 degree cooler weather, ran a 12.97 ! ! ! (which proved my local group who laughed when I said I had a 13 second car correct. Their response was along the lines of, oh... you feel the torque of that big block and think you have a 13 second car. You may get your feelings hurt when you go to the track...) Well, they were correct, I had a 12 second car, lol. I got the last laugh.


I have made some changes to my car and have improved the ET's. I swapped out my stock 1970 heads for a set of ported 1972 heads, they were ported by Killian's in Macon, GA along with a ported and matched Edelbrock intake (prior was non-ported Performer). Also included in the changes was a set of T&D 1.6 roller rockers. No dyno testing has been done with these changes. I know I dropped my originally calculated 9.5:1 compression with the 72 heads, but don't know the precise amount. I have contemplated installing some steel head gaskets to kick it back up.

I have been able to run lower 12.40's in some good heat with my new combo. Head flow sure helped out, even with a compression loss. I attached my cam sheet to display the I am currently running for an example.



Many thanks for finding my post with my original dyno information !!!





Mike

 

Hi Mike,

We were commenting on a different engine.. not yours..

In your thread from a while ago that was referenced here, User "Speedy" posted several of your dyno sheets from the session. They have your name on them..

He commented on them, and then went on to say this:

Gary used that quote to say that headers were only 30ish HP better even on a 700 HP engine, I commented that those were not the correct headers for that type of combo..

Was this not Jim Rodgers SA motor?



JW

 

I was confused about the talk of header testing on engines and thought it was referring ito my tests.

Thanks for clarifying.





Mike

 

This is not what I said. I said the manifolds produced very impressive results on a 700 hp engine, and that if those were not the correct headers for that combo, the manifolds would be even more so. If the engine was built with manifolds in mind, then which set of headers would have been 'correct'?

I was trying to emphasize the impressiveness of the manifolds on that combination, not the headers. :TU:

I also want to reiterate for the sake of clarity, that headers will almost always make more power than manifolds, especially on high overlap cams. Headers are in no danger of becoming extinct due to the fact that the Buick OEM manifolds do so well on any combination depending on the cam's timing events.

I have written a lot of material on this website scattered all over the place concerning different aspects of engines and transmissions, and even though my perspective isn't exactly orthodox most of the time, I do my best to convey information as accurately as I can with a different point of view to consider.

Going back over the material just in this thread alone will shed some light on what was actually said and the messages to be gleaned from what was said.

No negativity or bashing of anyone or anything, and sarcasm was kept at a minimum despite being under heavy fire.

 

This looks like the same cam posted in that other thread. I notice it shares many similarities with the KB 118 cam (or perhaps closer to the KB 113), in that it has extra exhaust emphasis commonly seen on cams with 'street' usage in mind. The old designs seem to take cues from the OEM cams and attempt to expand the cam's ability to dip a bit deeper into the earth's atmosphere. Do these cam designers have the same information at their disposal that the engineers did when attempting to redesign the way the engine breathes? There is much more to consider when taking in the entire picture of how it will behave and react in today's world, which is why the old OEM cams have been redesigned to accommodate the changes in fuel.

Just wanted to comment on some of the characteristics I've noticed on these type of cams, in that instead of less difference between .006 and .050 duration on exhaust emphasis, these cams have more, and tend to gravitate toward the exhaust lobe being gentler than the intake, where the inverse is observed with 'header' cams.

Seems this would permit more time, especially between partial opening events between .050 and .006, for exhaust to fully evacuate without the aid of pulse gathering. These designs benefit most from aforementioned exhaust tricks behind the initial post-head evacuation facilitators (manifolds).

Many different people have many different cam grinds, so one may very well conclude that there are just as many differences in opinion on which works best for any particular application. The same holds true for me, in that I'm of the opinion that there is still room for improvement. This is not to say that the other designs are not good, nor should it be perceived as any sort of insult or attack on anyone else's personal choice or opinion on camshaft recommendation or usage, but rather another point of view, with full awareness that there is still more to be learned as long as no barriers are placed, errantly believing that one already has all the answers, which is the largest learning inhibitor of all, IMHO. We're all human; we've all displayed these characteristics at some time or another.

This is a subject which has held much interest for me.

 

Something else related that I wanted to point out is that pipe size increases exponentially with larger diameters, so the difference between a 3" pipe and 3.5" is quite substantial, for example.

To put it into perspective, a single 3.5" pipe will flow slightly more than dual 2.5" pipes.

Making this 3.5" pipe oval would improve ground clearance, obviously.

A merge pipe that can be bought from Summit for 50 bucks would facilitate this nicely. It's a Flowmaster 2.5" into 3.5" "Y" pipe scavenger series.

Contrary to intuition, the single pipe outlet flows slightly more than the dual inlets. lol

You guys have fun with this in your own creations.

Here's an image showing what I say to be fact, and not simply 'theory'.

 

So, with the above statement, your 100% backwards. Those small headers were hurting that 730HP motor to the tune of maybe 45HP, vs the 2 1/8 Primary set that would be optimal on that build. So we saw a recorded 33 HP loss, then add another 45 for the proper size header for the combo, and we are at about 75HP loss, vs competition ported exhaust manifolds. so "and that if those were not the correct headers for that combo, the manifolds would be even more so (impressive)." is 100% upside down and backward..

Comparing the best ported manifold to the correct header, not too much of a leap to consider a 75HP loss in HP, and likely over 100 ft lbs loss in torque.

If you say so, but it sure looked like "See, you can use manifolds on high power Buicks" like you had stated previously... Sure, you could put your 500 cfm 2 barrel on it, and do some serious burnouts.. does not mean it's anywhere near the right part for the combo. I am not sure what color the sky is on the planet where bolting parts on, and losing 75HP is considered "impressive"... :laugh: Maybe a purple haze?

Then let's get it right... The correctly sized long tube headers WILL ALWAYS make more power than a cast iron manifold. No "almost" about it. Regardless of cam timing.

The difference might be small, and for reasons unrelated to performance, enthusiasts often choose to keep the iron exhaust manifolds.. that's a perfectly valid viewpoint. I have built plenty of Buick A bodies over the years with exhaust manifolds, ported or not.. but never was the reasoning "we are going to pick up performance vs headers"... it was sound, ground clearance, look, class rules ect ect.. There are plenty of combos I would not recommend headers, or ported manifolds on, because the cost vs benefit ratio is simply not there.

But to even imply that exhaust manifolds would somehow be enhancing performance IS JUST PLAIN WRONG.

----------------------

If you feel your "under heavy fire" then quit spouting ridiculous statements..

Not long ago, you stated that that your CS586 cam could make 500 HP on a near stock build. Yet with Beamers motor, we are seeing him running a cam that, while you point out correctly has the a similar intake advertised spec, is 30* larger at .050, and over .100" more lift. Completely different lobe center, so valve events are not close to where your cam is.

There is no comparison between those cams at all, and point of fact, this much larger cam, in a stock engine, makes 422HP.. right about where it should.

Let me stop you... no way your CS586 cam outruns this cam.. 30 years of experience building and dynoing this engine, tells me that. That CS586 is a copy of the factory 1970 Base 455 camshaft, which even the factory engineers knew they had to change out, to pick up power on the Stage 1.

500 HP is not anywhere near the realm of possibility with this type of build. I have built many 500+ HP BBB's and they take more cam timing, ported heads, and headers to get there with pump gas. With increased compression, fully ported all iron motors will just make 500 HP, and still sound nearly stock, with the correct part combo, but those specialty motors are outside the the parameters of the discussion here. And the camshaft timing is no where near stock.

Your user title, and the content of many of your posts, smacks of someone that just wants to argue that the sun is green instead of yellow.

And then you complain when someone calls you out. That disingenuous at best.. most folks see it as laughable.

I don't have any problem with theoretical discussions, until they cross over and fly in the face of reality. We need to keep both feet firmly on the ground here.

JW

 

Thanks Jim!

 

Thanks Jim!

x3 Let me jump in here and add that for emphasis. I do appreciate your response, and so now I shall give mine. If we go back and read the entirety of this thread, we will see that it is full of antagonistic, condescending, argumentative, and outright goading behavior...by me? Nope. By you.

I've been really nice about this whole thing, Jim, honest I have. Why you have chosen to target me as your whipping boy, well I'm not completely sure. I think I'll take a few moments to consider this.

No kidding? Except for the backwards part. I guess it's a matter of perspective? (it's 'you're', not 'your' btw) everyone knows the smaller primary headers were hurting performance and that larger ones make more power. Even I said this.

It seems you have it bass akwards here, Jim. Either that, or you are deliberately trying to twist it around to make me look ridiculous. I may look ridiculous, but not for those reasons.

I said 'the manifolds would be even more so', and then you insert your assumption of (impressive) when if you were to take it into context with the previous words in the sentence, you'll see that I'm talking about those particular sized headers being out of place. So then I'm talking about the manifolds being being out of place as well, but even more so. Need more evidence for this? Go back and reread what I previously wrote in another post that I was simply reiterating here in this latest quote by you.

It's not that I'm backwards, it's that you are either misunderstanding what I'm saying, or you're deliberately twisting it around. I would like to believe you are not so hateful, and so I'd wish to choose the former, though (sadly) past events seem to suggest the latter.

Your attempts to discredit what I have to say have now come to an all-time low, with a strong hint of desperation. But this begs the question: why?

Based on your words, it's evident to me that you have been paying very close attention to my posts in the past. Should I feel flattered? Or maybe there's more to it than this...

I don't consider not bolting on parts to improve power as a loss--simply not a gain. If the intent were to create something within specific parameters, then it's perfectly acceptable, as we can see here all across these boards with users employing all kinds of different parts for their combinations, so why the sarcasm?

When did I ever say using exhaust manifolds would enhance power? This is a deliberate attempt to misguide readers into believing this is what I actually said/claimed, for those who haven't spent the time going back to read what was actually said.

For one who pays so close attention to what I say, you sure do get your signals mixed up. This is more evidence that this is deliberate in a character assassination hit. What you are doing is obvious now, Jim. The question remains: why? (we're getting warmer, more on this further down)

Heavy fire is right, but not for reasons you claim, as those were debunked. I came under fire long before any of this, and I'm not the only one.

You prattle on and on about '500 hp' and I never said this. Again, you go off on a tirade about something I never even said. If you want to tell someone to be 'careful with the assumptions' while assuming things yourself, while outright misconstruing what was said, we all have to ask: why is Jim doing this? (even more, why are others jumping on the bandwagon and cheering him on? Same reasons, different scenario--more below)

You are highly respected here Jim, and so by default people are going to stick up for you. Add in the fact that no one (besides me, that I've noticed) has had the stones to stand up to your bullying. If they do, they risk getting deleted by the 'great iron gauntlet in the sky'.

This started here in this thread when I made such a bold statement as to say that a cam needs more than 10* of exhaust emphasis on manifolds with the BBB, and then your responses just got more progressively aggressive, going so far (as we can plainly see here now) as to end it all with deliberate misrepresentation of events.

I've done nothing wrong here, and I've done my best to be as civil as possible. I've not said anything here that cannot be verified.

And before you go deleting my posts and filling them in with your own words (you've done this before in the past), at least have the common decency to let everyone read what I actually said beforehand, please.

As a gentleman, you at least owe me that. I don't expect an apology, but I do expect honesty and integrity.

 

sometimes, less is more.

 

This is why I dont get involved in these discussions here anymore.

 

Answer.

NO.

Would you walk around wearing a lead vest and breath through a straw?