347 power expectations.

[mburger]

Hey folks.
I have a question that will likely only have subjective answers but even subjective answers will help.

What are the seat of the pants, tires break loose power/torque expectations from a 347 with Edelbrock Pro-Flo 4?

Info:
Mk1 ~ 2,150lbs
8.8 rear with 3:55 gears.
Cooper Cobra 295/50/15 rear tires.
Standard 4 link with coil overs.
Stock T5 from a '90 Mustang LX.
New clutch, flywheel etc.
Fresh BPE 347 with an Edelbrock Pro-Flo 4.
Cam Type: Roller
.543 Intake .554 Exhaust
218 Intake / 226 Exhaust duration
@ .050 - 112 degree lobe separation
About 1,000 miles on the engine.
Mike Forte Dyno'd at 439/439 (at the flywheel)
All of the parameters on the PF4 look good.

If I am driving about 30mph in 3rd gear about 2k rpm and I mash the accelerator to the floor, would you expect the tires to break loose?
I get a very slight hesitation and the engine ramps up the rpms and the car scoots in a hurry, but no spinning of tire.

I realize this is an odd question and subjective but I don't want to begin troubleshooting a performance issue when there is none.
All of the parameters on the PF4 look good. In 2nd gear it'll break them loose.
What prompted the question is that I'm feeling underwhelmed with the power. Maybe I was expecting too much with the BPE347?

If someone has a BPE 347 carbed or EFI it would be great to hear feedback on your experience.

[Gordon Levy]

The 439 is about right, depends on the days and the altitude and how dense the air is. I would guess around 425 to 430ish. The chassis is pretty good and at 2000 revs you are not making the torque to spin the tires. Do the same at 3500 revs and it will spin the tires.

[mburger]

The 439 is about right, depends on the days and the altitude and how dense the air is. I would guess around 425 to 430ish. The chassis is pretty good and at 2000 revs you are not making the torque to spin the tires. Do the same at 3500 revs and it will spin the tires.

Thanks Gordon!
One of the reasons I went with the 347 was because the example torque curve on the 347 was so flat. Time to experiment at 3500! :D

https://thefactoryfiveforum.com/attachment.php?attachmentid=148483&d=1621976688

[BradCraig]

Thanks Gordon!
One of the reasons I went with the 347 was because the example torque curve on the 347 was so flat. Time to experiment at 3500! :D

https://thefactoryfiveforum.com/attachment.php?attachmentid=148483&d=1621976688

Careful what you ask for! Be safe out there!

[TMartinLVNV]

I have a Sniper injected 347 and have to be careful with lack of traction. In second gear, the tires are pretty easy to break loose. In 3rd gear, it happens at times. I enjoy hearing the pipes at WOT when getting onto a highway. If I aggressively accelerate on the on-ramp, I will occasionally will break the tires loose in 3rd.

[Gordon Levy]

Even a 408 or 427 sb will have problems spinning the tires at 2000 revs. The engines are generally not cammed for bottom end torque. In these cars bottom end torque is not your friend.

[Papa]

Exactly what Gordon is saying. Mark -- look at where BPE cut off the data on your dyno. Mine was provided down to just 2900 rpm and the torque falls off a cliff below 3000 rpm. Maybe someone familiar with how dynos work can explain the issues of lower rpm data and corrections, etc..

https://thefactoryfiveforum.com/attachment.php?attachmentid=148484&d=1621980659

[mike223]

Not offered to be critical - more as guidance...

Flooring a manual shift car in third at 2000 rpm is pretty much "abuse".

Grab a different gear + go - don't lug it out of the hole - it's hard on the engine - sky high cylinder pressures begging to detonate and burn pistons.

Absolutely nothing good can come from it.


I wouldn't consider hitting full throttle below 3500 rpm - probably closer to 4k.

[mburger]

Not offered to be critical - more as guidance...

Flooring a manual shift car in third at 2000 rpm is pretty much "abuse".

Grab a different gear + go - don't lug it out of the hole - it's hard on the engine - sky high cylinder pressures begging to detonate and burn pistons.

Absolutely nothing good can come from it.


I wouldn't consider hitting full throttle below 3500 rpm - probably closer to 4k.

All good Mike. I normally never do this. I did it once, today just because I was feeling like the car should have more. Point taken though - thank you!

I also appreciate the cautions and I'm not looking to get myself killed, (or anyone else) or drive like an idiot on public roads.
If you all knew how I normally drive this car, things would make more sense. My rev limiter is set at 5200 - because maybe I'm being overly cautious.
When I'm driving, my shift point is usually around 3k and occasionally 3.5k.
Maybe I should be living a little higher on the tach, but I'm also conscious of the engine only having 1k miles on it.
TMartin - Definitely not my experience. 3rd gear onto an on-ramp is one of my favorite things. I just installed Boig's Quiet Pipes so the growl is gone.

[mburger]

Exactly what Gordon is saying. Mark -- look at where BPE cut off the data on your dyno. Mine was provided down to just 2900 rpm and the torque falls off a cliff below 3000 rpm. Maybe someone familiar with how dynos work can explain the issues of lower rpm data and corrections, etc..


Thanks Dave. Yeah, my torque at 2000 is more than likely near the bottom of the cliff.
Some days I feel "This close" to putting a Sniper or a carb on.

[rich grsc]

Not offered to be critical - more as guidance...

Flooring a manual shift car in third at 2000 rpm is pretty much "abuse".

Grab a different gear + go - don't lug it out of the hole - it's hard on the engine - sky high cylinder pressures begging to detonate and burn pistons.

Absolutely nothing good can come from it.


I wouldn't consider hitting full throttle below 3500 rpm - probably closer to 4k.
Sorry, you must have a pretty poorly tuned engine. At 2000, my 331 is ready for everything I can throw at it.
No torque at 2000,:confused: I can drive at 1500rpm in 5th and still accelerate smoothly without surging or bucking

[mburger]

Sorry, you must have a pretty poorly tuned engine. .... I can drive at 1500rpm in 5th and still accelerate smoothly without surging or bucking

The only thing I can think of that MIGHT be the issue is timing, but I've been over it again and again. Verifying #1 TDC etc...
"I can drive at 1500rpm in 5th and still accelerate smoothly without surging or bucking" - Ditto here. No bucking or surging. I can cold idle at 900 in 2nd all day, no bucking.
I will say this, and I've said it before, and don't want to get too far off here, but I'm just not impressed with the Pro-Flo4. The engine runs. Starts up fine when "cold". Cold is in quotes because I live in Florida.
I continue to get misses when cruising at 2krpm (no load) after changing the coil (bad windings), plugs - 3 times and went one step hotter, wires, 3 times as the first two sets tested bad. (way too high resistance) and cap and rotor.
Edelbrock support isn't the best - definitely not the forum. Other folks use the PF4 and love it, (as well as the forum) so it is what it is.
It just seems when I rev it, the best way to describe it is as if it has a huge heavy flywheel. It isn't a snappy rev if that makes sense.

Aside from my misses at around 2k no load cruise, the engine runs very well. I just feel like it should have more at the rear wheels. Again, I'm open to that I'm just expecting too much.

[Geoff H]

Does the pro-flo use a single or dual plane manifold? If single plane, could that be why the power does not come on the way you expect it in the lower rpm range?

Just a thought.

[rich grsc]

Mark that wasn't referring to your car having a poor tune

[bobl]

With that big throttle body when you floor it at 2000 rpm you are supplying well over 4 times the amount of air the engine needs at that rpm. I believe you have progressive throttle blades, so giving it half throttle or less will make all the power available at that rpm. More throttle will just make it sluggish and can actually reduce power. I had a 650+ HP engine on the dyno the other day. At part throttle it made 550 ft lbs of torque at 3000 rpm, but opening the throttle wide open lost 50 ft. lbs. at that rpm. It's just physics. If your engine was sitting on a dyno and you loaded it to 2000 rpm and opened the throttle you would instantly see just how unhappy it is under those conditions. Spin that sucker up and you won't be able to wipe the smile off your face!

[mburger]

Mark that wasn't referring to your car having a poor tune

Oops.


Never mind. :p

[mburger]

Does the pro-flo use a single or dual plane manifold? If single plane, could that be why the power does not come on the way you expect it in the lower rpm range?

Just a thought.

It is a single plane. The PF4 is a direct injection system so the throttle body and manifold are only supplying air. If I was running a TBI or carb, then yes, I completely agree.

[mike223]

Sorry, you must have a pretty poorly tuned engine. At 2000, my 331 is ready for everything I can throw at it.
No torque at 2000,:confused: I can drive at 1500rpm in 5th and still accelerate smoothly without surging or bucking


I explained why it was bad practice, nothing good could come from it, and why no one should want to do it.

I didn't say I couldn't do it.


Funny you should chime in since I had edited in "Not offered to be critical - more as guidance..." because I didn't want to sound like one of your typical posts.


Maybe bobl stumbled on the root of some of your your discontent... :cool:



If your engine was sitting on a dyno and you loaded it to 2000 rpm and opened the throttle you would instantly see just how unhappy it is under those conditions. Spin that sucker up and you won't be able to wipe the smile off your face!

[CraigS]

Back to your original question mburger. Your engine, and how you usually drive it sounds perfectly normal to me. My 351 gave near identical power level based, not on a dyno, but on your seat of the pants feel. I loved 2nd gear. I used to play w/ it when on an empty road; get to 2000 or so and mash the gas. It was fun to feel the tires spin up and the rear of the car to give a little wiggle depending on road crown etc. And at about 4000 the tires hooked and off I go to 55 or so.

[Avalanche325]

If you like spinning the tires.......you have the right tires.

I have a 500hp carbed 347. On mine I have to watch as the RPMs come up in 3rd. All hell lets go at 4500RPMs and I can break loose depending on the road surface and a million other variables. I have wider and much stickier tires than you. (Proper tire rant suppressed)

[NiceGuyEddie]

https://thefactoryfiveforum.com/attachment.php?attachmentid=148483&d=1621976688
https://thefactoryfiveforum.com/attachment.php?attachmentid=148484&d=1621980659

My 347's output is MUCH more like the 2nd photo, power kicks in tremendously at 3500rpm. It's similar to a Honda VETC at a certain high rpm.

I have almost the same setup: T5: 3.55 gears. Nitto NT-05 tires.

30mph / 2,000 rpm = most likely won't break loose
30mph / 3,500 rpm = will break loose with FULL throttle

For some strange reason, my 347 was built with a Holley 850 Double Pumper. It was too fast so I sold the carb after a few hundred miles and bolted back on my old Holley 570 Street Avenger. It's overall much more drive-able but you can feel (and hear) the fuel starvation near redline.

[bobl]

Exactly what Gordon is saying. Mark -- look at where BPE cut off the data on your dyno. Mine was provided down to just 2900 rpm and the torque falls off a cliff below 3000 rpm. Maybe someone familiar with how dynos work can explain the issues of lower rpm data and corrections, etc..

https://thefactoryfiveforum.com/attachment.php?attachmentid=148484&d=1621980659

The reason you usually don't get dyno data below 3000 is because it's too hard on the engine to go Wot at that RPM. You could run it at part throttle to get data, but doesn't really tell you much. So dyno operators will start the pull at whatever rpm the engine will take full throttle comfortably. When breaking in an engine on the dyno I will load it to down to 1000 - 3000 rpm and give it throttle until torque stabilizes at that rpm. That is usually a very low throttle setting.

Bob

[Olli]

The PF4 is a direct injection system

I think that you meant to say port injection. Direct would have the injector in the combustion chamber.

Olli

[Railroad]

I just installed Boig's Quiet Pipes so the growl is gone.
Did you tune the fuel injection after adding the Quiet Pipes?
,,,,,seems I saw a before and after dyno sheet showing about a 50 hp loss, plus not adjusting AF and timing after the installation may be hurting your performance.

[Avalanche325]

Remember that most of our engines are different from each others even if they are the same size. Some are very street friendly, and others are more snotty track focused. You can't drive them the same. But part of the fun is learning how to properly drive your individual setup. That is part of what gives a car a soul.

My big cammed carbed high strung snotty 500hp 347 is not happy at all with a 2000rpm 3rd gear full WOT stomp. It will bog (saying what the hell are you doing?) and then go. At 3000rpm, it will snap your head off, no waiting required. At 4000rpm, I had better be ready to catch the rear.

Check this out - https://www.youtube.com/watch?v=soJea7xEt-8&ab_channel=EngineeringExplained

[NAZ]

148538

Y'all are funny with all that lugging the engine with those stick shift cars.

And some engines just won't lug at all. Set the front brakes to 600 PSI & hold the line lock button, start in high gear, stab the gas from an idle until the two-step holds RPM at 6000 -- no lugging.

[mburger]

I think that you meant to say port injection. Direct would have the injector in the combustion chamber.

Olli

Yes! Thanks for the clarification.

[mburger]

Did you tune the fuel injection after adding the Quiet Pipes?
,,,,,seems I saw a before and after dyno sheet showing about a 50 hp loss, plus not adjusting AF and timing after the installation may be hurting your performance.

I have not made any changes to my settings, however I am able to save my non-default settings as well as the learned settings. I could then reset everything to their defaults with my current map and let it relearn. To be honest I hadn’t heard about a 50 HP loss as that seems excessive. I just hung up from Bob a few minutes ago and could have asked him.

[Railroad]

I have not made any changes to my settings, however I am able to save my non-default settings as well as the learned settings. I could then reset everything to their defaults with my current map and let it relearn. To be honest I hadn’t heard about a 50 HP loss as that seems excessive. I just hung up from Bob a few minutes ago and could have asked him.

While I am on my soap box, and this is not directed toward you or your car, some owners buy mega hp engines and then put the, it looks good air filter that would choke a lawn mower engine. Some never know what they have done and some say, something is not right. I do not think your are running out of air at 2K rpm, regardless of YOUR filter.

[NAZ]

For a quick check of air cleaner performance and potential power loss, click on this link: https://www.secondstrike.com/Technical/AirCleanerCalc.asp

[TriPower]

How well a car hooks up also depends on the rear end and suspension. I have 347 with 490 hp on dyno. Rear is 3.55 but also is Torsen with Gordy's 5 link or Watts link. NO fish tail if the wheels spins in any gear, even first.

A machinic friend works on mine and another Cobra with an IRS set up (Backdraft). He said it breaks loose very easily compared to mine.

I agree with others, at 3500 rpm it becomes ALIVE.

Lee R in Rockford ILL

Note I have had mine for 15 years and have 52000 miles on it. I estimate about 5000 miles on the track. Mostly on Road America.

[mburger]

For a quick check of air cleaner performance and potential power loss, click on this link: https://www.secondstrike.com/Technical/AirCleanerCalc.asp

Thanks NAZ. Interesting calculator. Playing around and punching in various filter sizes and types, at least according to this calculator you’re not losing much. I have seen comparison videos such as the infamous salad bowl video comparisons and they told a much different story. As has been discussed in other threads, with the displacement and RPMs that most of us are running, it seems the air cleaner really doesn’t make that much difference.

[bobl]

Thanks NAZ. Interesting calculator. Playing around and punching in various filter sizes and types, at least according to this calculator you’re not losing much. I have seen comparison videos such as the infamous salad bowl video comparisons and they told a much different story. As has been discussed in other threads, with the displacement and RPMs that most of us are running, it seems the air cleaner really doesn’t make that much difference.

I built a 347 very similar to yours this winter for a friend. It made almost identical power to what BPE advertises. I installed the thin oval Cobra air filter and lost 10 HP, which you probably would never notice. I've also tested a bunch of different mufflers and never seen any HP loss, up to the 500 HP level. I haven't had a chance to test the quiet pipes though.

[Lickity-Split]

148538

And some engines just won't lug at all. Set the front brakes to 600 PSI & hold the line lock button, start in high gear, stab the gas from an idle until the two-step holds RPM at 6000 -- no lugging.

Light the second bulb. Push the brake pedal. Press the trans brake button. Stab the gas to bring the RPM's up to 4,200 on the two step. Let go of the button --- no lugging :)

[TriPower]

I also have 315 NT05 on the rear and run them at 18 to 19 psi cold.

Lee R.

[AdamIsAdam]

Oh, are we playing show and tell with our dyno charts? I'm in! lol I had my car on a CHASSIS dyno last year and was VERY pleased with the results. Torque curve looks like the horizon and the HP curve looks like the rising prices of gas during the pipeline shutdown. My numbers look very similar to others, especially if you divide by .85 as a very loose estimate for crank power.

My car seems to pull strongly in any gear at any time. I don't floor it in 3rd at low RPM's, but as others have said, it will pull comfortably in all circumstances right up until the MSD box shuts things down at 6,200 RPM. My Tires are Nitto NT01 315 x 17 and when hot they grip pretty well. My NY roads suck, so they may break loose because of uneven surfaces (ie, pot holes!) more often than I would like, but I'm getting out of it under those circumstances in a hurry!

148565

[AdamIsAdam]

Oh, I almost forgot, I posted somewhere about air cleaners and it's worth mentioning again. I was very concerned that my 1.75" tall oval K&N filter was choking power. It's NOT. In fact, my car made the most power with the air cleaner on and hood closed with fan facing the car. It went up by about 5hp, but I assume that had more to do with the engine getting fully warmed up than the actual air cleaner. But the bottom line for me was that it's not hurting anything vs no air cleaner. So that's good because I like the looks of my oval air cleaner and I have very limited room for a taller element.

[mburger]

“ and the HP curve looks like the rising prices of gas during the pipeline shutdown.” hahahaha


Well I plan on driving the old girl to Ohio in June so whoever is interested can check it out. The old girl ain’t looking too shabby and perhaps a couple folks can take it for a drive and tell me what you think.

As usual you all didn’t disappoint and I appreciate everyone’s input. I am feeling better about things but more importantly I really enjoy learning from those that have the knowledge and experience that I don’t.

Thanks again!

[mike223]

Check this out - https://www.youtube.com/watch?v=soJea7xEt-8&ab_channel=EngineeringExplained


One important aspect I think he missed in his (otherwise excellent) explanation:

The fact that at lower rpms - the intake mixture has a significantly longer time frame to get in the cylinder during the intake stroke.


The engine is designed and built for maximum efficiency at higher rpms - plus

Opening the throttle increases the amount of air and fuel available - plus

Having more time for that mixture to get in the cylinder.


Equals - Potential Overcharge for Existing Conditions



It can set up exactly the same condition as running too much boost.

And comes with the same associated failure modes.

[Hoooper]

I have not made any changes to my settings, however I am able to save my non-default settings as well as the learned settings. I could then reset everything to their defaults with my current map and let it relearn. To be honest I hadn’t heard about a 50 HP loss as that seems excessive. I just hung up from Bob a few minutes ago and could have asked him.

Depends a lot on the pipes they are being compared to. For example, probably no loss or maybe a gain compared to stock FFR pipes which are pretty restrictive, but probably a loss compared to straight pipes. Here is a comparison that shows a wide open glasspack compared to a contemporary cobra very restricted exhaust.

http://www.classicchambered.com/classic/performance.html

FWIW, there is a lot more going on than just torque when it comes to losing traction. Tires, tire temperature, road temp, road surface, suspension setup, suspension type, etc.

[bobl]

Depends a lot on the pipes they are being compared to. For example, probably no loss or maybe a gain compared to stock FFR pipes which are pretty restrictive, but probably a loss compared to straight pipes. Here is a comparison that shows a wide open glasspack compared to a contemporary cobra very restricted exhaust.

http://www.classicchambered.com/classic/performance.html

FWIW, there is a lot more going on than just torque when it comes to losing traction. Tires, tire temperature, road temp, road surface, suspension setup, suspension type, etc.

The currect Factory Five side pipes are not restrictive up to at least 500 FWHP. I've tested them numerous times on my dyno. The older ones could have been and some of the other brands for sure.

[Avalanche325]

bobl,

You are making a good point. The best way to look at exhaust systems is "supports up to X HP". So virtually no loss up to that point. Then it can drop off dramatically. Same with air cleaners.

[Hoooper]

Not sure what the story is with the FFR pipes, maybe it was some old style that Ive seen talked about as restrictive on here. In any case, you arent losing low end torque because of the exhaust pipe size so burnouts at 2,000 RPM shouldnt be affected.

[Mike DiGiorgio]

If that risks detonation than you should get your fueling/ignition system sorted out. Yes the dwell time inside the cylinder is longer, but initial heat soak is non existent. TONs of boosted motors run there under full boost without issue and they have 3x the cyl pressure of an NA v8's Fix this issue via better setup and don't worry about putting your foot down

[mike223]

If that risks detonation than you should get your fueling/ignition system sorted out. Yes the dwell time inside the cylinder is longer, but initial heat soak is non existent. TONs of boosted motors run there under full boost without issue and they have 3x the cyl pressure of an NA v8's Fix this issue via better setup and don't worry about putting your foot down

Let's revisit this:


Remember that most of our engines are different from each others even if they are the same size. Some are very street friendly, and others are more snotty track focused. You can't drive them the same. But part of the fun is learning how to properly drive your individual setup. That is part of what gives a car a soul.

My big cammed carbed high strung snotty 500hp 347 is not happy at all with a 2000rpm 3rd gear full WOT stomp. It will bog (saying what the hell are you doing?) and then go. At 3000rpm, it will snap your head off, no waiting required. At 4000rpm, I had better be ready to catch the rear.


If conditions were the same at all rpms + throttle positions, centrifugal + vacuum advance would have no use whatsoever.

Personally, I do not care for vacuum advance in a race car.

I prefer to spin my advance in "fast + early" with centrifugal alone.

I've driven a number of pure "race cars" that were solid timed to 34-39 degrees BTDC (max performance). You can't start them with the ignition on, you have to start them by spinning them with the starter and then throw the ignition on + then idle at 2k+ rpms, and there are many things you'd better not ever do with the throttle (never, ever lug it).


So build your car + engine your way - but if you want to floor it in third gear @ 2000 rpms, I highly recommend you run a bunch of vacuum advance.


And if you don't understand that statement, you'd better be extremely cautious going to WOT with any high performance engine loaded hard at low rpms.

Because they're not all built to do things the same way.