Aluminum Heads with Cast Iron Exhaust Manifolds

Do TA Stage 1 heads make any sense if you're going to use cast iron exhaust manifolds with a stock diameter exhaust system. 455

Getting heads done over here is very expensive...

What are realistic hp figures you can achieve with a stock "looking" engine? Quadrajet and stock exhaust...


Thanks...

 

Are you restricted (legally) to using exhaust manifolds and stock size exhaust in Switzerland, or is this a budget issue?

 

No it's more a "I want it to look almost like stock" personal issue

I don't care about matching numbers..but the look has to be factory style.

 

It can't get in if it can't get out.

There's improvements to exhaust manifolds (porting) as well as exhaust system tricks for better flow you may wish to consider if this is the path you choose to take.

 

You can probably achieve about anything you want with a good plan.
The limitation on power production is how your research, goals and budget lead you to the project's final execution.

Search the site...there are numerous builds and cars using manifolds as well as threads on exhaust.

 

Sure, you can use them, I did that years ago in a 72 Stage 1 convert I built for a guy down South.



That motor made 485 HP/520 ft lbs of torque as you see it here. It had a 288/94H TA cam.

We actually did a two day dyno thrash with this motor, as those are one of the very first sets of TA Stage 1 SE alum heads.. with a 413 cam, headers and SP-1/Holley this motor made 588 HP 560 TQ

But he wanted the stock look for this cruiser.

Us the Fel-pro exhaust manifold gaskets between the alum head and the manifolds.

Built this car 13 years ago, never heard of any problems from the manifolds. I know the guy still drives it often.

We went with an X exhaust system i built in the shop, and it sounded pretty good. Was an N-25 exhaust thru the bumper car..



JW

 

For the lose of almost 100 hp I would go with the headers. A free flowing exhaust also gives better throttle response, better gas mileage. Will have the motor run cooler as well... If you want to make it look stock, have the headers coated in Flat black.


Michael

 

there is a thread here somewhere about ported vs unported exhaust manifolds vs. headers. The manifolds weren't not a huge hindrance until big power was made. maybe someone has the link?

 

The test between headers vs. ported manifolds did not show more than around 10 HP difference. A big plus for manifolds is a more noise free exhaust and the stealth stock look.

 

No, keep in mind the 100 HP more was also with a different cam, intake and carb, along with the headers. Take a bit more time to carefully read the text.


Header gain or loss is a percentage.. so base output of the engine is the key factor.

ON this 500 HP build with headers, I tested full length headers, stock manifolds vs street strip and full competition ported Gessler exhaust manifolds.

I did this about 13 years ago.

The stock exhaust manifolds cost the motor right around 25 HP over headers. Actually cost more torque than HP.

Street/Strip ported ones were 3HP better than stockers

Competition ones, with enlarged outlets were 8 HP better than stockers..

Keep in mind, that is on this engine...

I never publicized the test, because that was for my own information, and was just one test.. maybe we did something wrong, maybe there is another factor.. and I am adamantly against negatively commenting on other folks work, it's not my place to say something they are doing is not working as expected.

I have always felt that if your going to sell a product like this, it's on you to do the testing, dyno and racetrack, to support any claims your making.

I have done a couple dyno tests, with similar results since.

I only mention Greg's name now, because he is no longer offering the service, and has moved on to other things. Both sets of his manfolds had a ton of work done to them, and the quality of the work was very good. My question was " should I be recommending that my customers spend money here" and to find that out I had to do some testing.

What we found lined up exactly with what my dyno guy had seen from dozens of other ported manifold tests, across the vast spectrum of manufacturers and engines. Headers vs manifolds is more about design difference, than it is about the actual parts.

I am planning on acquiring a set of ported manifolds for the upcoming test car program at the shop here, to do dyno comparison, and then real world testing at the race track. We will keep those around, and test them thru each phase of the buildup.. from stock. all the way up to 600 HP street bruiser, and evaluate at each level. I can assure you, what they cost for power will change dramatically, as the build increases the demand on them.

This will again not be an attempt to validate or disqualify anyone's work, I can attest that doing these exhaust manifolds is a ton of work, and several hundred dollars for the porting is not out of line..

We will be just looking to quantify actual power gains on the dyno, and ET reduction, MPH increase on the drag strip.

JW

PS.. I don't have my usual documentation to show you, because this 2 day test was done so long ago, I was not taking electronic copies of the dyno sheets.. I simply had the paper ones. Somewhere in my files, I have those 30+ dyno sheets in a folder, I have not taken the time to look for them.

I also remembered while writing this, when the motor was in the 580+ HP configuration, we bolted the exhaust manifolds on it to see what they would cost us.. I can't recall exactly which ones, I tend to think it was the stockers.. and I know the motor made 522 HP.. so it cost about 60 HP.. Ron, my dyno man, made the comment that this was the first time he had seen 500HP thru "log type" manifolds. He actually was impressed..

I have built a couple stock appearing motors since then, that made just about 500 HP, all iron..

 

Jim- as long as we are talking iron parts, have you ever tested a stock iron intake vs. an edelbrock back to back?

 

many times...

On a 500 HP build, out of the box performer and stock iron are virtually identical.. because the performer needs the port exits opened up to be as big as the iron.. with a portmatch, the alum manifold (B4B or Performer) is on average about 12HP better.

Higher power builds also can gain power up top, at the expense of mid range torque, by milling the center divider down a bit. My testing indicated that you could trade about 10 ftlbs at the torque peak, for about 10 HP at the HP peak.

Spacers also can help.. I once picked up 21HP with a 1" spacer under a 1000 TQ... that was exceptional, normal spacer gain is in the 8-12 HP range, with similar torque gains.

The best spacer design for overall gain, with a Holley, is the Dart Cloverleaf type spacer, with the HVH Super Sucker beating it on some builds, but not on others.. I would recommend either one.

JW

 

Thank you Jim Weise for all the excellent information.

I'll ask this question because I don't see it in the thread yet, and that is the difference the "X" pipe did, particularly on manifolds. This is a subject of much interest to me, and would be great if you could share what knowledge you have on the subject.

Putting manifolds on an engine and then testing it with divorced pipes on a dyno would logically and reasonably show a substantial loss vs headers and divorced pipes on the same dyno, since we know the headers are doing far more than the manifolds in terms of scavenging and much more efficient exhaust evacuation.

With an "X" pipe introduced, I wonder what the actual differences would be, since the exhaust system would be aiding the manifolds in a way they could not achieve on their own.

If you plan on doing more tests, it would be nice to see this tested as well, if there was a way you could manage it on the dyno. If you can't put it behind or underneath, maybe do a crossover from the driver's side to the passenger side under the oil pan, much like the single exhausts were designed, only run both pipes on the passenger side to a universal "X" pipe that has its inlets/outlets parallel to each other?

You could show everyone how effective or ineffective the "X" pipe would be, and whether or not it held a candle against headers.

If this isn't feasible or isn't something you'd be interested in, I understand.

Thanks in advance.

 

Something else to consider is the way the engine breathes using the valve timing events.

If an engine is set up to run optimally using headers (high overlap with scavenging playing a large role in power production) with a high power output (say over 500 hp), the manifolds are going to perform abysmally.

The more restricted the exhaust, the more exhaust emphasis that is going to be needed, so the engine would need another camshaft profile to perform optimally.

This would make the comparison more of an 'apples vs oranges' because you'd be testing two different engines.

Perhaps create an engine that would be engineered more toward using a restrictive exhaust that would perform as best it could using manifolds and an "X" pipe, then swap over some headers on that same engine and make a comparison with that.

I'm not trying to start a controversy here (honest), but to have an open discussion about this subject.

 

Asking about exhaust manifolds vs headers use on aluminum heads, it is completely understandable to do so. I had a post years ago from my motor build and dyno pulls with different carbs and headers vs ported manifolds. The difference between headers and manifolds was somewhere around 5-7 HP. Mind you, I was running iron heads though. That thread was lost in a rebuild of the board server and I could not locate it to link for reference.

That leads me to suggest porting the manifolds to help that power adder of the aluminum heads to breath out a little easier. Jim Rodgers does port them still, and I am not sure if Greg Gessler does any longer. I would suggest contacting either or both of them if you are not comfortable porting them. They both have great reputations.



JW...

I am looking to do exactly what you pictured for an exhaust on my car now. I do have an old TT X pipe system and butcheed tailpipes to the N25 tips right now. The head pipes are having problems sealing to my manifolds and are quite leaky also. Do you have any recommendations on which systems to go with today? I was thinking pypes for the downpipes and X, with TA tail pipes. TA dos not have an X system, and I want an X, not a H system. But I understand TA can make the tail pipes for N25 tip mating.


Any advice is helpful.

 

Great point also. I had a cam designed for me that had longer duration in the exhaust to allow more time to push the air through smaller manifolds.

 

Gary,

We did in fact cam the engine with manifolds in mind.. we ran both the 288-94H with it's extra 10* of exhaust and 114* LCS and we also ran a 288-92H, with just 4* split and a tight 110 lobe center.

Biggest difference was that the 114" lobe center spread the power out, I don't recall the exact numbers, but they were substantial, and all the figures I quote here are with the best Exhaust manifold cam.

Now, in recent years continual evaluation of cam profiles has lead us in the direction of wider lobe centers, on most builds, regardless of exhaust equipment.

X pipe testing will have to be done in the car, as the dyno setup would not allow it..

The way the cart/absorber are situated it would be impossible to place the X at the proper location.. here is a picture to illustrate.



I will be doing that testing in the TSP test car, over the next few years. I don't expect "huge gains", but we will see.

Mike,

I believe that system is a combination of parts..

TA downpipes
DR GAS crossover kit
Gardner exhaust hangers (muffler and N-25)
Long case dynomax mufflers
TA 2.5" talipipes
Aftermarket N-25 tips.. can't recall who I got them from.

The hardest part was by far the tailpipes.. had to put an extra bend in them for the bumper exit, so if TA has something now for that, it will save you some trouble.

JW

 

...and to follow this logic, anything you could add in the exhaust system that would aid in the evacuation (an "X" pipe), would outperform divorced pipes, but the question is: by how much?

I know it would depend on power output, so the more you had, the more restrictive the manifolds would become ("X" pipe or not), so an engine producing less than 500 hp (say 400-450), one could realistically expect the manifolds and "X" pipe to do pretty well with the right camshaft.

I'm very interested in seeing if anyone has anything else to add to all this (the information you gave is much appreciated).

 

While off on the tangent here, any tests comparing headers should include prudent data such as "the rpm range the header is intended to assist scavenging in".
It's misleading to use a header that 'maths out' to boost midrange torque but then talk about how it was 'only 8 hp better' than a ported factory manifold that closely resembles a shorty header, which helps closer to peak hp...for example.

Maybe another suggestion would be to use a dyno that can hold a stable run in the actual rpm range where said headers show a strong benefit.
Those long tube headers are meant more for ET reduction via shift recovery torque increases, and many types of engines show 50-100 numbers increases below peak torque, where streetable response is certainly important.
"Many types of engines" equates to the silliness that fairly simple relationships between how heads breathe and cam timing to work to the engineer's design intent, and supercedes the idea that those things only apply to Buicks, for example.

Buicks do have pretty good manifolds, enough to work with the overall package very well if you understand the big picture.