Dyno Results

[PRHeads]

There was a thread over on moparts about 1-2 months ago where someone had dyno tested their 500”-ish stroker with headers and manifolds.
TF240 heads, similarly sized hyd roller(as the one in this thread), 6bbl.
90hp loss by installing the manifolds.

 

[rumblefish360]

Why you would do this is beyond me but if having the exhaust manifold look is what you want then so be it.

Truly the bottom line is, if the owner is happy with it, then that is all there is to it.

PRHeads, do you remember the output with headers on the engine?

 

[PRHeads]

Different dyno, and a different brand of dyno as well.
But they were showing about 100hp more with headers than the motor in this thread.
That motor did have a wider lsa on the cam too(113.5).

I agree with the sentiment that in the end, all that matters is the owner is happy with it.

 

[Challenger340]

No wars wanted,
just say'in for others intending to use Manifolds once installing the Engine in the Car ? after Dyno'ing with Headers ? that IMO....there may be a missed opportunity while on the Dyno ? not to make tuning adjustments for the Manifolds while still on the Dyno ? Some Engines more than others, don't like the now "polluted" Intake charge the reduced scavenging Manifolds entail versus Headers ?
What was once happy Timing/Jetting etc. with Headers, can be then NOT so "happy" anymore once the Manifolds are installed ?
And
Yes, we've see around 75-85hp loss on the Dyno going from Headers to Manifolds, using 110* LSA HR Cams/240'ish @ .050 at similar power levels(580's down to 500), and with the Factory Air Cleaner installed.
If I remember correctly without going digging for the sheets ?
the more concerning aspect for me from memory, was just how far the "peak" rpm events for HP/Trq dropped down to ? Some went from nice Street Engines to Truck motors very quickly.

 

[PRHeads]

I’ve done piles of tests through the years on various restricted oval track motors where we compared headers vs ex manifolds.
The differences were nowhere near 75-100hp, but as a percentage of total power output, it was probably about the same.

I regret never trying a set of headers on a FAST build, but it always seemed like we ran out of time testing the things that mattered to how the motor would be used in the car, so it just never happened.

That being said, I would have been quite surprised if those motors picked up 75-100hp by installing headers.
In my mind, I felt it would be more like 50hp or so.
Those motors ran as happy as could be with exhaust manifolds, with peak tq in the 4200 range, peak hp from 6000-6200 or so.

 

[Challenger340]

I’ve done piles of tests through the years on various restricted oval track motors where we compared headers vs ex manifolds.
The differences were nowhere near 75-100hp, but as a percentage of total power output, it was probably about the same.

I regret never trying a set of headers on a FAST build, but it always seemed like we ran out of time testing the things that mattered to how the motor would be used in the car, so it just never happened.

That being said, I would have been quite surprised if those motors picked up 75-100hp by installing headers.
In my mind, I felt it would be more like 50hp or so.
Those motors ran as happy as could be with exhaust manifolds, with peak tq in the 4200 range, peak hp from 6000-6200 or so.

Our 75-80hp loss with Manifolds included the factory Air Cleaner installed. I better close my cake-hole until I go dig up the sheet for actual Exh Manifold losses versus Air Cleaner losses.

 

[PRHeads]

We always ran the correct air filter assy for the application, since they have to run that way in the car.

Keep in mind, these were purpose built race engines........ not street/strip builds.
While they had the drivability of a grocery getter....... they were in fact race motors.

Also, just because I don’t “think” they would have picked up more than 50hp or so by putting headers on them doesn’t mean I’m right.
As I said, we never tested one that way.

But, if they would have picked up 75hp just by adding headers, they would have been making more power than “traditional” bracket type builds that had better heads, racier intake manifolds, bigger cams, etc.

On the other side of the equation, if you would have swapped the headers for manifolds on the bracket builds, I would have expected a loss of 100hp or so....... since those builds were done knowing headers would be used in the car.

 

[BSB67]

I think Dwayne summed it up pretty well. I don't dispute that meaningful power is lost with manifolds, but you cannot assume that it is necessarily a standard 90 hp loss.

Use my pump gas exhaust manifold car as an example and flip the question around. What power would it make with headers? Dyno power numbers themselves are a variable, as every dyno is different and some are stingy, others happy. So to avoid the "is your dyno happy argument", lets just say mine is between 550 and 600 hp. What is not of dispute are the track numbers. 120 mph @ 4150 lbs at 1750 DA. Corrected to std conditions it's 122 mph. Plug that into your Moroso hp calculator.

My motor has a custom solid roller cam. Pretty mild lobes for street. The guy that spec.ed it called it a lolly pop cam and runs fairly light valve springs (200/500). It has standard port Eddy heads ported by MCH. Other than that, its got pretty much Summit catalog parts, and machined by my local Ford machine shop. The cam has 54° overlap (seat timing), has a stock converter and 3.23 gears, drives through the neighborhood in 3rd gear at 1100 rpm and has 14" vacuum at idle. It does not have part throttle kickdown (PTK). So when I roll through a stop or a turn, it stays in 3rd gear and drives away smoothly. The car runs very similar to when my 440 had the MP 272°/.455" cam.

So, if headers added 90 hp to this car, the car should go 127 mph in standard conditions, Hellcat territory. That seems unbelievable to me.

 

[moper]

Duane I would have to ask him, but the 496 in Todd's Challenger I think gained 35-40rwhp going from the manifolds to headers - but that may have also bee with changing the pipes and mufflers, and that cam is the same solid flat tappet you spec'd years ago.

 

[PRHeads]

Dave, you’re closer to that build than I am, but here’s how I remember it........

The manifold exhaust was a complete crimp bent reproduction style with quiet mufflers.
The header system was a complete TTi 2-1/2” system with their 1-7/8x3 headers, with something like ultra-flow mufflers.......and I thought the difference between the two systems was about 50hp....... at the wheels.

 

[moper]

Manifold to bumper was complete reproduction: so compression bent, small, resonators, mufflers, stock tips etc. He swapped to the TTI setup and louder mufflers. I don't recall the "exhaust only" gain being 50 at the wheels but it might have been close. He also swapped on a larger carb and that got more power but I can't remember if he did them at the same time or went back for it.

 

[BSB67]

Manifold to bumper was complete reproduction: so compression bent, small, resonators, mufflers, stock tips etc. He swapped to the TTI setup and louder mufflers. I don't recall the "exhaust only" gain being 50 at the wheels but it might have been close. He also swapped on a larger carb and that got more power but I can't remember if he did them at the same time or went back for it.

Good information. Do you recall if the tailpipes were 2 1/2 or 2 1/4"?

 

[BSB67]

Thought I'd go back and pull out my time slips before posting this.

This was back when I was running a std stroke 440 in the Charger. Had the MP 272/ 0.455" cam. Exhaust manifolds, 2 1/2" compression bent head pipes, 2 1/4" DynoMax 17747 super turbo full length mufflers, and 2 1/4" compression bent tailpipes. I was running the car at the track regularly at the time, trying to get my first 12.99 time slip. This was back before FAST was started, but guys were already moving in that direction with guys like Bob K running high 12s in his stock A12 but before any rules. On this test-and-tune day my car was closer but still running low 13s. Right off the street it ran 105.77 mph. Bit of a cool down and got a 106.59 mph. Not great 60 fts and typical low 13s. Gave it a better cool down and changed plugs. It ran a 106.74 mph coupled with a good 60 ft (for me) and got a 13.008. I figured that I probably wouldn't 60 ft any better, and figured that 12s were not going to happen that day. Just for sh**s & giggles, I decided to remove just the tail pipes. Crappy 60 ft, but the car went 108.30 mph. Wow, on to something here. After challenging a big block Chevy guy to a heads up race (a good story for another time) I stage again, pull another crappy 60 ft (2.147 sec.) and ran a 12.982 @ 108.52 mph.

So if you believe the data and math, the compression bent 2 1/4" tail pipes cost about 15 - 20 hp on a 400 hp engine.

 

[moper]

Sorry no idea on the pipe sizes. I only built the engine and help the owner come to a decision on changes. It was a reproduction full system as at the time he wanted a 100% totally stock OEM look. He got it - it won it's class at Carlisle.

As far as exhaust improvements - the best way I found to check exhaust restriction quickly is temperatures of the pipes ahead of the mufflers with a temp gun. Any drop in those temps means you removed restriction. Gains will be realized when pipes are removed due to weight - especially when it's removing resonators and hangers and mufflers and pipes together. Temperature is only changed by adding or removing restriction.

 

[BSB67]

Sorry no idea on the pipe sizes. I only built the engine and help the owner come to a decision on changes. It was a reproduction full system as at the time he wanted a 100% totally stock OEM look. He got it - it won it's class at Carlisle.

As far as exhaust improvements - the best way I found to check exhaust restriction quickly is temperatures of the pipes ahead of the mufflers with a temp gun. Any drop in those temps means you removed restriction. Gains will be realized when pipes are removed due to weight - especially when it's removing resonators and hangers and mufflers and pipes together. Temperature is only changed by adding or removing restriction.

Thanks.

In my tail pipe post above, the tailpipes weren't actually removed, just disconnected.

 

[PRHeads]

On the car that Dave did the motor for, when it was on the dyno with the stock type exhaust, I think there was an incident where it blew the mufflers apart, and when it did, it picked up some power.
So they pulled the mufflers off, and it made a pretty noticeable difference.
And I believe that’s what prompted him to put the TTi system back on the car.

Dave probably knows the numbers, but I seem to recall with the TTi headers and exhaust it’s making around 470rwhp.

 

[friendofvirgil]

Yep, 3.54 or 3.55 in the Dana. (Can't remember which) Good all around ratio

In the world inside Dana, the 3.54 ratio is referred to as a 46-13 gear set across all Models. 46 teeth on the ring and 13 teeth on the pinion. If they are a Dana gear set, you’ll see this number stamped on both the ring and the pinion. This ratio was advertised by Mopar as a 3.55 maybe to not get confused with the Detroit axle 8.75 drop out carrier model ratio of 3.55. Who knows. Also, 4.10 ratio is referred to as 41-10.

 

[ksurfer2]

So after dealing with some ignition challenges, the car is up and running, a short test drive this afternoon revealed tons of power, lights up the tires with ease from a stop and a stab of the throttle at speeds approaching 30 mph will also result in tire smoke. Could I be making more power with headers? I am sure I could, but the car runs great, idles nicely at 900rpm and power delivery is smooth as silk. So, right now, I have exactly what I wanted. Someday if I want more, headers are easily added.

 

[PRHeads]

So, right now, I have exactly what I wanted.

Can’t argue with a satisfied customer!!

 

[BSB67]

So after dealing with some ignition challenges, the car is up and running, a short test drive this afternoon revealed tons of power, lights up the tires with ease from a stop and a stab of the throttle at speeds approaching 30 mph will also result in tire smoke. Could I be making more power with headers? I am sure I could, but the car runs great, idles nicely at 900rpm and power delivery is smooth as silk. So, right now, I have exactly what I wanted. Someday if I want more, headers are easily added.

That's great to hear. Congrats, and enjoy.