Nicks Garage Dynos Headers, Alum intake, Holley vs Stock Manifolds, and AVS carb

[tallhair]

Very interesting comparison. I've looked for a test like this to no avail for a long time and stumbled across it today.

I know there's been other discussions but couldn't locate one. So here's what I found for those interested. It matches up to what Doug Thorley said in an article I read years ago in a magazine ... never been able to find that article on the web. He said stock Mopar HP manifolds and exhaust were great and headers on stock Mopar factory muscle car were worth 15 to 20 HP in stock trim with no other engine changes.

This engine does have a few refinements but he tests the stock stuff against aftermarket after the build.

I'd probably stay at step 2 but with a possibly bigger than stock carb.

Thought some would be interested.

 

[Turboomni]

Thanks for posting. That is some very interesting stuff there. Makes me even more hopeful for my 440 stroker build using HP exhaust manifolds.

 

[Turboomni]

I'd probably stay at step 2 but with a possibly bigger carb.

 

[jason99]

I can't identify manifolds just by looking, but if those are the "HP" manifolds I wonder what would be lost going down to the standard ones.

 

[mcmlvii]

Nick's youtube channel is one of my favorites. And as jason99 said, it would be interesting for him to throw on a set of log manifolds just to see the change in hp/tq.

 

[WorkerBee]

On Nick's tested motor I'd guess around 4 or 5HP & TQ loss with the log manifolds. If that was a stock 383 2bbl motor it would probably be even less.
Cam specs on Nick's test motor is .475 in and .480 ex. Duration @ .050" Lift is 224 in and 228 ex. LS 110

 

[70bigblockdodge]

IQ52 on FBBO tested a set of 1964 log manifolds(very tiny) against a set of hp manifolds. I don't even think it was a 5hp difference. Face it if you want to make power headers is the way to go. They are worth a easy 5% increase on a low 400hp engine, plus fuel mileage and weight savings over any manifold.
If your not racing in a class with rules on manifolds your just wasting money to have a look, that by the way looks just like a 383 2 bbl.

 

[tallhair]

IQ52 on FBBO tested a set of 1964 log manifolds(very tiny) against a set of hp manifolds. I don't even think it was a 5hp difference. Face it if you want to make power headers is the way to go. They are worth a easy 5% increase on a low 400hp engine, plus fuel mileage and weight savings over any manifold.
If your not racing in a class with rules on manifolds your just wasting money to have a look, that by the way looks just like a 383 2 bbl.

I recall that well and think there's even a post here on it. I can't recall the exact sequence of changes but once he actually put a performance intake and carb on it he didn't go back down to show the difference between headers and the logs though. So was not an apples to apples comparison like this one. It was also a low compression motor. The reason I said I always wanted to see a test like this is exactly the apples to apples comparison.

 

[mr. fix it]

I enjoy watching the series
Mopar through n’ through

 

[70bigblockdodge]

I recall that well and think there's even a post here on it. I can't recall the exact sequence of changes but once he actually put a performance intake and carb on it he didn't go back down to show the difference between headers and the logs though. So was not an apples to apples comparison like this one. It was also a low compression motor. The reason I said I always wanted to see a test like this is exactly the apples to apples comparison.

IQ52 or hey old guy on here test showed.
The logs make less than the hp manifolds ~5 hp and the HP manifolds make 15-20 less than crap headers. I think that's about a apples to apples to apples comparison. The compression ratio has little to do with exhaust flow other than maybe you could make the argument that a higher cr engine can squeeze more exhaust gases out.
Face facts the HP manifolds are marginally better than regular logs and that's mostly gained in the manifold to pipe area. The secret to headers is the length of tube allows the gases to cool slightly and the pulse blows straight into a chamber preventing the pulse to interfere with any of the other pulses trying to escape from their respective cylinders.
Headers work, exhaust manifold don't work as good. And no they are not just for racing the peak horsepower did not move down the rpm range on that engine with manifolds it was just less at the same rpm. Worse yet only 18 hp loss on Nick's engine, but 23 ftlbs. with manifolds and that's at 3000 or so rpm where all you guys with these big cars talk about living. Even a crappy harbor freight torque wrench will register that.
I think the test.on Nick's engine also shows that if more restricted manifolds did not help torque, a tiny diameter exhaust pipe is not going to help your torque either.

 

[tallhair]

IQ52 or hey old guy on here test showed.
The logs make less than the hp manifolds ~5 hp and the HP manifolds make 15-20 less than crap headers. I think that's about a apples to apples to apples comparison. The compression ratio has little to do with exhaust flow other than maybe you could make the argument that a higher cr engine can squeeze more exhaust gases out.
Face facts the HP manifolds are marginally better than regular logs and that's mostly gained in the manifold to pipe area. The secret to headers is the length of tube allows the gases to cool slightly and the pulse blows straight into a chamber preventing the pulse to interfere with any of the other pulses trying to escape from their respective cylinders.
Headers work, exhaust manifold don't work as good. And no they are not just for racing the peak horsepower did not move down the rpm range on that engine with manifolds it was just less at the same rpm. Worse yet only 18 hp loss on Nick's engine, but 23 ftlbs. with manifolds and that's at 3000 or so rpm where all you guys with these big cars talk about living. Even a crappy harbor freight torque wrench will register that.

15-20 less than headers is exactly what I said in the first post which was always my understanding of the diff in headers over stock based on reading back in the 80's to include Thorley's interview regarding Mopar performance cars specifically.

The point of posting this was to share a comparison of stock, similar to factory HP specs with the only change between tests being exhaust manifolds vs headers. The carb swap was a bonus. Nick did that, IQ didn't but I do appreciate the work IQ did and I participated in that thread back then so I'm familiar with it in here and the discussion on FBBO at the time.

Many have said, IIR in that article, and others that the power would drop off more the better the motor was and IQ tested a stock low compression motor/cam etc as he made mods and then didn't go back to the manifolds, not surprised but would have liked to have seen that.

I'm OK with 15 to 20 HP difference for a performance motor and not arguing that no one should ever use headers.

 

[jason99]

My interest in the performance of the manifolds vs headers is more around something where headers are not an option, like my 74 Monaco and Fury. At some point both are going to need a power plant refresh and any data is better than nothing.

My e-body that can have headers already has a set of TTIs and will stay that way.

 

[tallhair]

My interest in the performance of the manifolds vs headers is more around something where headers are not an option, like my 74 Monaco and Fury. At some point both are going to need a power plant refresh and any data is better than nothing.

Agreed. I wish Nick had tested the logs also.

 

[mr. fix it]

Very interesting comparison. I've looked for a test like this to no avail for a long time and stumbled across it today.

I know there's been other discussions but couldn't locate one. So here's what I found for those interested. It matches up to what Doug Thorley said in an article I read years ago in a magazine ... never been able to find that article on the web. He said stock Mopar HP manifolds and exhaust were great and headers on stock Mopar factory muscle car were worth 15 to 20 HP in stock trim with no other engine changes.

This engine does have a few refinements but he tests the stock stuff against aftermarket after the build.

I'd probably stay at step 2 but with a possibly bigger than stock carb.

Thought some would be interested.



View attachment 258362

These numbers are good if you plan on beating this engine down a 1/4 or 1/8th mile track but for most of us isn't this a moot topic?

 

[tallhair]

These numbers are good if you plan on beating this engine down a 1/4 or 1/8th mile track but for most of us isn't this a moot topic?

If it is too you can feel free to not pay it any attention.

I'd say this isn't the first thing discussed around that's a moot point or no point at all with no body minding. I'm not trying to change anyone's religion here. I just shared some info I came across that was interesting to me and thought I'd share.

 

[mr. fix it]

If it is too you can feel free to not pay it any attention.

I'd say this isn't the first thing discussed around that's a moot point or no point at all with no body minding. I'm not trying to change anyone's religion here. I just shared some info I came across that was interesting to me and thought I'd share.

True TH.
Not trying to start a bad vibe here. I know we all like to aspire to heights & have the best of the best if possible & we do discuss things that will likely not affect us one way or the other.

For those of us that can invest huge $$$'s into the engine bay so others can applaud us then that's great.

I will add that the numbers are very close for all the dyno pulls and most of us would not test our engines to this degree on a daily basis.

Apologies if I upset anyone on this thread with the previous comment.

 

[tallhair]

True TH.
Not trying to start a bad vibe here. I know we all like to aspire to heights & have the best of the best if possible & we do discuss things that will likely not affect us one way or the other.

For those of us that can invest huge $$$'s into the engine bay so others can applaud us then that's great.

I will add that the numbers are very close for all the dyno pulls and most of us would not test our engines to this degree on a daily basis.

Apologies if I upset anyone on this thread with the previous comment.

I'm not upset brother. I'm not for or against headers either so to each his own. I just don't happen to plan on putting them on a car that's in my current plans or a classic I may have in the future ... not saying I couldn't change my mind later, but don't plan on it. I'm also not putting anyone down that wants headers. There are good reasons for them and even if there's a guy who wants them and will never go to the track (or need them) that's their individual choice.

 

[70bigblockdodge]

Thanks for posting. That is some very interesting stuff there. Makes me even more hopeful for my 440 stroker build using HP exhaust manifolds.

This is one of the most confusing things. Using the McFarland formula (he was a engineer for Edelbrock) it uses the area of the port window that ideally will be able to support a certain CID. Turns out that a BB Mopar port window only supports ~ 470". So ported by someone who really knows what they are doing they can only support a engine over 20cubic inches smaller, meaning you purposely built and less efficient engine than a cleaned up and port matched iron heads on a 440. Honestly money would be better spent lightening the stock stroke rotating assembly and ditching the 5/64 piston rings especially if your going to cork up the exhaust.
It's your money do what you want, but your not making a efficient engine just bigger. You could get to the same place without the bigger stroke.
I'm not trying to get into a pissing contest just, looking at it from a different perspective.
A build like this is a double whammy of working against yourself. Will it work and will it pull down low, sure. You basically spent a lot of money to get back to square one.

 

[70bigblockdodge]

Cam specs on Nick's test motor is .475 in and .480 ex. Duration @ .050" Lift is 224 in and 228 ex. LS 110

This is the best info. Less duration at .050 than a Magnum cam with more valve lift. Win-win
The results show that that cam is up horsepower and torque over the Magnum cam/ engine rating even when the stock manifolds are back on. Over 500ftlbs. of torque.

 

[70bigblockdodge]

These numbers are good if you plan on beating this engine down a 1/4 or 1/8th mile track but for most of us isn't this a moot topic?

15-25 ftlbs. At 3000 rpm is seat of the pants noticable and may keep your quarter panel off the lug nuts of that tractor trailer your trying to merge with.