Hi Everyone in Mopartsland,

Did you see the the Header versus cast manifold test on Nick's Garage!

Once Covid gets itself under control I hope to return to the drag-strip again.
This time with my street car a 1971 Plymouth GTX, 440 sixpack.
(Very rare in the UK and around the world, as you well know).

So whats my plan, to run in UK 'SUPERSTOCK'.


I couldn't believe my eyes when I saw Nick doing a stock Hipo manifold test against a header!!!

I always thought they would be a restriction BUT that RESULT is OUTRAGEOUS...

Look here LOOK HERE

Welcome to the party. #WOMANifolds #Justice4Nick

LOL !!!! good stuff

OMG I thought folks might NOT notice the other SIMILAR thread...

This thread is about the SHOCKING results of an UN-RIGGED Fanimold test...

The other thread is about something completely different... DYNOWARS...

Anything Nick says is TOTALLY TRUE as the GREEKS invented the MODERN WORLD...

Easy there, friend - it sounds like you’ve had too much to think!

Nick's video is one set of tests on one combination. That is all it is. It is not what everyone can expect on every combination. So, don't read too much into it. Nick's combo appreciated the headers more than most of the combos that I have swapped headers onto. But that doesn't mean he is wrong on that combo.

Frankly, I am a little surprised at the amount of debate on here that surrounds one test that almost all of us have done at one time or another. Most of us older guys have swapped manifolds for headers over the years. Some of us have done it many times.

This Engine Master's header dent test is even more interesting, IMHO: www.dailymotion.com/video/x3vupq0

Some of us get it. The factory HP manifolds can be good performers, up to a certain threshold. Cam, compression and other factors will determine how quick you get to a point where headers make a difference. If you hardly ever break 5,000 rpm on a stock-ish motor in a street car, it probably isn’t worth your time to make the swap and give up low rpm torque. If you are getting into single planes and solid lifters, you are leaving a lot on the table after 350-400 hp and a good pair of headers will give you some real gains.

Every car is different and every driver is different. Personally, I’d rather a torque monster that’s all-in by 5,500 because that’s all I’ll ever use it for. Your mileage may vary.

Mmmmmm,

It looked like a 440 with an iron sixpack too me?
Thought the valve covers were awful but the rest seemed OK.

That’s the exact same combo I want to run so it seemed ‘right up my street’.

SO the results affected me greatly and I was deeply shocked.

A good Moparmate a few years said to me “ those hp manifolds are very restrictive”.
NO I SAID this cannot be, now I know, HE WAS RIGHT.
His Hipo 440 had terrible feuling issues, that never got overcome till he ran headers.
Always fouling plugs in traffic and heavy deposits on the valves...

NICK has proved it, without a doubt...

All hail the snowflakes...

The only thing that Nick proved is that headers ultimately outperformed manifolds on THAT motor and on THAT dyno. You would need a lot more testing to give any numbers with confidence. If it was one-size-fits-all, header manufacturers would be screaming those numbers from the rooftops. You will pretty much always gain peak HP with headers over manifolds unless something is really wrong. WHERE you see that gain (is it even useful?), and how big it is with YOUR combo will dictate if the swap is worth it for you.

To make the motor perform its best it has to be tune from the air cleaner to the exhaust tips for the best results, my deal on the 2.5 inch system being removed at the races really shocked me
3.0 I.D. pipes verses the 2.5 inch and the differences in the two different types of muff was a real eye opener, it is the total system effect that makes the differences

Sounds like a long duration camshaft (.509) and it could explain why the manifolds did poorly. I think a better cam like the Mopar .528 would help the manifolds a lot.

Cab, do you have a link to that thread? Thanks

So funny, the guy could say his bread is white, but one will say I see some gray specks, another says it was made with gravy, then another said he cooked it to long, then another says wasn’t cut evenly. Just can’t take it for what it is can we?

44hp difference??

Ppfffffftttt.

https://board.moparts.org/ubbthread...-stroker-my-a12-upgrade.html#Post2553328

Exactly. The bigger the mismatch then the bigger the gain. I've seen over 100 hp difference before by changing the intake manifold so 100 hp on the exhaust side is within reason. Or you can flip the script and design an engine that would have basically zero difference between HP manifolds and headers. People who just look at the two numbers don't understand what is really going on.

I'm thinking this is another 'throw together' engine supposedly from a Roadrunner?
First thing that is very obvious is 'EARLY HEADS' pre 68 as there are NO core plugs in the ends.
The chances of them being 915's is very rare, so probably 'common and garden' 516's...

Closed chamber heads with low comp pistons and a BIG camshaft.

Should make 400hp all day long with that set-up...

Bet its still got the 1.60 exhaust valves which hurt the exhaust side with HP manifolds...

What real world engine would show zero difference between HP manifolds and headers?

I heard Nicks gonna do a water pump dyno test next, then someone will complain about what oil pan’s on it.

I wonder if he will be using distilled water, well water, city water, or RO water.

😳