HP Manifold Performance

[BSB67]

It was another clear illustration to me that when it comes to making power with restrictive exhaust, you might have to forget a lot of what works for "normal" applications.

Although I agree with this, I would say that this is also generally true for motors with headers too, just maybe not as often.  Half of the stuff that we learned from real life track testing that resulted in something noteworthy or significant, were discovered by either a complete mistake, or trying for an opposite outcome. And these are counter (today"s) conventional wisdom. I think if I followed the performance advice given on these forums, all of my cars would or would have slowed down .5 sec.  

And honestly, I think the gap between what works in a bracket race car verses a street car (even if they are at similar performance levels) is even a bigger difference than between a manifold verses header motor.  

[PRH]

And honestly, I think the gap between what works in a bracket race car verses a street car (even if they are at similar performance levels) is even a bigger difference than between a manifold verses header motor.  

I don't know that I agree with that exactly, but I do feel that "what's important" for the two different philosophies(track only vs street/strip with the emphasis on good street manners) are often completely different.
(Actually, after re-reading what you posted, I guess we're saying the same thing)

The street/strip type builds, built with the intention of having decent street manners, wouldn't differ all that much as far as the "car" part goes, whether it was built using headers or not.

[c00nhunterjoe]

Everyones idea of "street friendly" varies a great deal. I will say 90% of people that post on this forum do not own chargers that i consider to have good street manners. The posts are constantly plagued with overheating in traffic, boiling fuel, hard to start cold, loads up when idling,soft brakes, soft steering. Etc etc, and these are mostly 13 to 14 second 1/4 mile cars. I enjoy cruising the 10 second max wedge on the street. Its 13:1, open header and on slicks, but it fires up cold or hot and idles all day without overheating or loading up. I like to cruise, not have my eyes glued to the gauges all the time cause im worried about temps or fighting to keep it running.

[cdr]

Everyones idea of "street friendly" varies a great deal. I will say 90% of people that post on this forum do not own chargers that i consider to have good street manners. The posts are constantly plagued with overheating in traffic, boiling fuel, hard to start cold, loads up when idling,soft brakes, soft steering. Etc etc, and these are mostly 13 to 14 second 1/4 mile cars. I enjoy cruising the 10 second max wedge on the street. Its 13:1, open header and on slicks, but it fires up cold or hot and idles all day without overheating or loading up. I like to cruise, not have my eyes glued to the gauges all the time cause im worried about temps or fighting to keep it running.

I too love driving mine , it aint a 10 sec car but its VERY fun on the street & is very easy to drive, the new disc brakes should help slow down my 120 mph blast on the street.

[PRH]

I enjoy cruising the 10 second max wedge on the street. Its 13:1, open header and on slicks

I'm at the point now where that would def not qualify as "street friendly" for me anymore.

[BSB67]

And honestly, I think the gap between what works in a bracket race car verses a street car (even if they are at similar performance levels) is even a bigger difference than between a manifold verses header motor.  

I don't know that I agree with that exactly, but I do feel that "what's important" for the two different philosophies(track only vs street/strip with the emphasis on good street manners) are often completely different.
(Actually, after re-reading what you posted, I guess we're saying the same thing)

The street/strip type builds, built with the intention of having decent street manners, wouldn't differ all that much as far as the "car" part goes, whether it was built using headers or not.

The large lsa, stock or stockish converter,  taller street gear, and true street tire actually become a very compatible combination.  Vaccuum seconday tuning is completely different.  Shift points are different, as some examples

[BSB67]

Everyones idea of "street friendly" varies a great deal. I will say 90% of people that post on this forum do not own chargers that i consider to have good street manners. The posts are constantly plagued with overheating in traffic, boiling fuel, hard to start cold, loads up when idling,soft brakes, soft steering. Etc etc, and these are mostly 13 to 14 second 1/4 mile cars. I enjoy cruising the 10 second max wedge on the street. Its 13:1, open header and on slicks, but it fires up cold or hot and idles all day without overheating or loading up. I like to cruise, not have my eyes glued to the gauges all the time cause im worried about temps or fighting to keep it running.

My premise is that the car is running right. 

[c00nhunterjoe]

I enjoy cruising the 10 second max wedge on the street. Its 13:1, open header and on slicks

I'm at the point now where that would def not qualify as "street friendly" for me anymore.

My point, while a bit extreme, is pretty much as russ just stated above as well. The car is spot on. You dont have to do anything to it. Just fire it up and go. It is surprisingly bearable inside for what it is. (It has a full interior) the chassis and steering is dialed perfect. I can one hand the manual box in parking lots, the manual brakes stop it with little effort at 130mph. Its just a fun car. Now, do i take it on the interstate? Hell no, but for cruising around town and on our back roads, 50mph is no problem.
  If i had 1/3 the headaches that the majority seem to have on these and other boards, i wouldnt want to bring my car to the grocery store, let alone run it down the track.

[PRH]

This will probably be mostly off topic...... but using my car with the 383 in it is a pretty good example of the "race car" philosophy in play, as opposed to the car being set up with  having decent street manners as part of the equation.

Nothing in the motor would have precluded it from being capable of driving cross county.
The only part in it even close to being a "race car" piece was the solid flat tappet cam.

Unported 906 heads, trw pistons, stock crank(external balanced 400 cast), stock rods, stock oil system, mechanical fuel pump, crank driven water pump, etc.
Just under 11:1cr.

As for the "car" part of the equation........ open headers, 4.56 gears, 5400 stall 8" converter., cal tracs, slicks/skinnies..


No other race car parts though. Stock gas tank, oe 5/16" line, full interior, heater, wipers, flat steel hood(no fresh air), battery up front, etc....... 3670lbs race weight.
It went 11.26@119 just like that, and ran 11.40's often in typical summer air.

Now, take that same car and make it what I would consider a more street friendly combo(3800 stall, 3.91's, drag radials, closed exhaust, 12-15 deg less cam........it's going to slow down a full second(add some exhaust manifolds to the mix and it will probably lose another .3-.4).

To retain the same street manners as the as the slower combo, but have the 11.26 performance........it's going to basically need to make another 100hp over the original "no consideration for street use" package.

If all you care about is ET.......it's the cam/converter/carb/hook.......assuming the fuel system is adequate and the long block is decent.

[c00nhunterjoe]

Thats very similar to the setup i had in my charger for years. Nearly identical 383 except i had 516s on it amd full exhaust. 4.30s with a 4 speed. It saw 108-110 mph through the mufflers and bone stock suspension. I took it on the highway when needed and drove it on 100 mile road trips frequently.  I considered it perfectly streetable.  Alot of people say my setup wasnt street friendly and your proposed 3800 stall, 3.91s and drag radials would make heads spin as well. I love your combination by the way, out of curiosity,  what trws are in it?

[PRH]

and your proposed 3800 stall, 3.91s and drag radials would make heads spin as well. I love your combination by the way, out of curiosity,  what trws are in it?

Okay......a little less cam even, 3.55's or 3.23's, and a hemi converter.......slow it down another .5 or so.......now it's a mid 13 second car.
Which is my point........"decent" ET's aren't that hard.
Take a low-13 second "street" car, swap in a few real race parts......it's way quicker in the 1/4.

Decent ET's with the kind of road worthiness most people are looking for these days.......much harder.......and/or expensive.

The motor has 2315's in it with valve pockets cut in them, and the block was decked so they stuck out .020 with that cast crank that was "stroked" .013".
I swapped in a stock steel crank and they only stick out about .012 now.

The current "plan", which has changed several times, is put the 4 speed back in with 4.10's, and the motor has been detuned with a 20deg smaller cam and less compression. The heads flow more now though, and I'm hoping it makes within 40hp or so of what it did before.
I'll dyno it before it goes in the car.

In that configuration I'm hoping for solid 12's at 108-110, not really killing it on the line with the stick or trying to rip the shifter out of the floor during shifts.
The 60' times will be way way off from how it was before though(mid/low-1.50's), so the car will go from running what it "should"(on paper), to likely a more typical "underachiever".

[BSB67]

My 383 4 speed GTS weighs the same as your car, MP 280° cam 3.91, MP template ported 906 heads, 10.something:1 compression (cannot run on pump gas alone), Eddy Performer (not an RPM) and 4779 carb, 13.1s @108 with a badly slipping clutch.  I think it might go 110 with a new clutch.  It has 1 5/8 headers, full exhaust on G-70-14 tires.

[PRH]

Well Russ, that's encouraging.

My heap will likely/possibly gain a few pounds from how it was though.
No more light weight wheels and tires, took out the Cavalier buckets and the stock bench will be going in, and adding a complete exhaust system, and the 4 speed stuff is heavier than an auto with an 8" converter.

However, the roll bar is out and it has a fiberglass hood on it now........ Might be close to a wash.

Maybe it'll run better than I hope. If it goes 110 in fair air I'll be okay with it(for a while).

The first attemp at the engine detune ended up with less tq/hp than I had hoped for.
I dropped the cr to about 9.7, put some bowl ported heads on it with a 13 deg shorter cam, but slightly faster ramps and a real wide lsa ......and ex manifolds.
It lost about 45tq/65hp compared to the bracket race set-up.
The cranking compression was 200 with the bracket set up, but down to 155 in that detuned configuration.

I've since put an even shorter cam in it, and tightened the lsa up some.
Initially I think I'll just start out with the headers, but I think the cam would be okay with manifolds if I decide to try them out.

I'll see how the dyno numbers are before I decide if another tweak is "necessary".

[tan top]

interesting reading  guys .. thanks for sharing   

[BSB67]

Well Russ, that's encouraging.

My heap will likely/possibly gain a few pounds from how it was though.
No more light weight wheels and tires, took out the Cavalier buckets and the stock bench will be going in, and adding a complete exhaust system, and the 4 speed stuff is heavier than an auto with an 8" converter.

However, the roll bar is out and it has a fiberglass hood on it now........ Might be close to a wash.

Maybe it'll run better than I hope. If it goes 110 in fair air I'll be okay with it(for a while).

The first attemp at the engine detune ended up with less tq/hp than I had hoped for.
I dropped the cr to about 9.7, put some bowl ported heads on it with a 13 deg shorter cam, but slightly faster ramps and a real wide lsa ......and ex manifolds.
It lost about 45tq/65hp compared to the bracket race set-up.
The cranking compression was 200 with the bracket set up, but down to 155 in that detuned configuration.

I've since put an even shorter cam in it, and tightened the lsa up some.
Initially I think I'll just start out with the headers, but I think the cam would be okay with manifolds if I decide to try them out.

I'll see how the dyno numbers are before I decide if another tweak is "necessary".

Crazy how much that manual tranny weighs.  And now that you mentioned trannys, I did have Joe Liberty put together an all aluminum A Body tranny for me.  He did it with Mopar stuff he had on the shelf.  Those were the days.

My 383 blows about 195 psi, but it has Rhodes lifters.  Not really sure I would take the numbers to the bank.  But the motor is pretty crisp, and it won't run rattle free on pump gas with 38°.  Because it is a manual/light car w/ 3.91, I can almost drive around the rattle.

I think you know that I try to creep up to all the CR I can get away with, and the cam LSA/ICL are always factored into my thinking.  You go from ABC lobe installed at 102°, then switch up the LSA and install the same lobe at 114° and your cylinder pressure takes a noticeable hit.  I think the intake valve on my 508 does not actually touch down until like 78° ABDC.

[PRH]

As an example of how bad it can be if you're not paying attention.....
(I had nothing to do with this build)

Fresh rebuild of an original 71 440-4hp.
Recon original 346 heads, hardened ex seats, comp 911 springs.
Icon makes a couple of std replacement type pistons, low cr and hi cr...... Of course this was done using the low cr version with the resulting cr being 8.2:1.
Comp xe268h cam, stock intake, magnum ex manifolds, edelbrock 750 carb.
2.5 exhaust pipes, no mufflers, stock air filter installed.......

427tq/304hp........ At the crank!!!

Motor runs fine, no issues, no noises.......no power.
It probably made a peak tq number a little higher than that, but they started the pulls at 3000rpm, which is where the highest tq number was seen, and it dropped like a rock after that, so the actual peak was probably occurring at a lower rpm. Peak hp was at 4700rpm.

Customer obviously isn't happy with it since its weaker than when it was stock.

The decision was made to take a big swing at it.
505, 10:1, prepped/blended stealth heads, custom mild hyd cam, 800 Ede AVS carb.
Will still run the OE intake and exhaust manifolds....... Should be back on the dyno fairly soon.

This will be the mildest of these types of motors I've been involved with, but I'm not expecting big numbers at all.
I figure........ A gain of 125-150ft/lbs, upwards of 150hp........ So...... Still pretty far away from 500hp.
This motor will not only have the ex manifolds on it, but also the highly restrictive stock 4bbl intake manifold.
It may not be able to carry the tq curve high enough to get to 450hp.

We'll see.

I got word that this motor was on the dyno last week.

A pretty big improvement over the anemic 440 combo that it started out as.

With the ex manifolds, stock 4bbl intake, pump gas...... It made 625tq/475hp.
Roughly a 200ft/lb and 170hp gain..... Which should improve the seat of the pants experience

It's pretty likely it would have made over 500hp with a 6bbl on it.

[Yada]

As an example of how bad it can be if you're not paying attention.....
(I had nothing to do with this build)

Fresh rebuild of an original 71 440-4hp.
Recon original 346 heads, hardened ex seats, comp 911 springs.
Icon makes a couple of std replacement type pistons, low cr and hi cr...... Of course this was done using the low cr version with the resulting cr being 8.2:1.
Comp xe268h cam, stock intake, magnum ex manifolds, edelbrock 750 carb.
2.5 exhaust pipes, no mufflers, stock air filter installed.......

427tq/304hp........ At the crank!!!

Motor runs fine, no issues, no noises.......no power.
It probably made a peak tq number a little higher than that, but they started the pulls at 3000rpm, which is where the highest tq number was seen, and it dropped like a rock after that, so the actual peak was probably occurring at a lower rpm. Peak hp was at 4700rpm.

Customer obviously isn't happy with it since its weaker than when it was stock.

The decision was made to take a big swing at it.
505, 10:1, prepped/blended stealth heads, custom mild hyd cam, 800 Ede AVS carb.
Will still run the OE intake and exhaust manifolds....... Should be back on the dyno fairly soon.

This will be the mildest of these types of motors I've been involved with, but I'm not expecting big numbers at all.
I figure........ A gain of 125-150ft/lbs, upwards of 150hp........ So...... Still pretty far away from 500hp.
This motor will not only have the ex manifolds on it, but also the highly restrictive stock 4bbl intake manifold.
It may not be able to carry the tq curve high enough to get to 450hp.

We'll see.

I got word that this motor was on the dyno last week.

A pretty big improvement over the anemic 440 combo that it started out as.

With the ex manifolds, stock 4bbl intake, pump gas...... It made 625tq/475hp.
Roughly a 200ft/lb and 170hp gain..... Which should improve the seat of the pants experience

It's pretty likely it would have made over 500hp with a 6bbl on it.

Was the 505 10:1 setup used with stealth heads and is it possible to find out head cc and specs on cam?

[firefighter3931]

I got word that this motor was on the dyno last week.

A pretty big improvement over the anemic 440 combo that it started out as.

With the ex manifolds, stock 4bbl intake, pump gas...... It made 625tq/475hp.
Roughly a 200ft/lb and 170hp gain..... Which should improve the seat of the pants experience

It's pretty likely it would have made over 500hp with a 6bbl on it.

Very nice ! 

I wonder how it would have done with a CH4B vs the stock intake ? 

Those Tq numbers are pretty impressive. What were the peak RPM's for HP & Tq ?



Ron

[PRH]

The motor did use Stealth heads with the valve job redone and the bowls were blended.
I don't recall the head cc's, but the final cr was 10.4.

I'm not going to give out cam specs for a customers custom grind, but I will say it wasn't very big and it wasn't "fast rate".

I haven't seen a dyno sheet, but from what I recall the tq peak was 3200, hp peaked around 5000.

Ron, I'm sure the CH4B would be better....... Not sure if it would have been better enough to get to 500hp or not.
Maybe with some porting and a spacer it could get close.

I have no doubt an RPM and a set of 1-7/8" headers would have been worth 60hp+.

[Yada]

Thanks, trying to grasp all of this number magic for my own build.