Intake Runner volumes
04-02-2016, 09:28 AM
#31
Registered
Here's something ya'll might find interesting reading....some stuff I have witnessed myself----I know of 3 different BBC engines with the exact same Cubic Inches (500+cid) dyno tested on the same dyno over the past year all destined for offshore applications.....a Roots 14-71, an M4 Pro-Charger and a Whipple 8.3L/510. All 3 engines were built with solid roller cams and inter coolers.
I do not have the liberty to give detailed specifics because these engines belong to customers of my builder.
The Roots 14-71 engine was destined for an offshore racing application and had the largest cam of the 3 engines, but the heads are some older aluminum designs with porting and the same size as the M4 Pro-Charger heads. The M4 Pro-Charger engine's cam was about 3* duration larger on a 112* LSA compared to the Whipple engine's 114* LSA "tight lash" cam.----therefore, the Whipple engine has the smaller/milder cam design.
All 3 engines made peak HP and TQ within about 10hp. The Intake runners of the heads of the M4 Pro-Charger engine were about 20cc larger than the Whipple's engine's heads. Both heads were a late design cnc ported head design of the same manufacturer---with the same exhaust port size/design and same size valves. The Roots engine heads were the same size as the M4 Pro-Charger's heads, but different manufacturer/design.
The M4 Pro-Charger engine was very impressive...it had the lowest Intake Air Temps between the 3 engines. However, it took 9 lbs of boost to make the same peak HP as the Whipple engine.....The Whipple engine only took 7.5 lbs of boost to make the same HP....and the Whipple did it at a 300rpm lower rpm rate compared to the M4 Pro-Charger engine. Both engines were timed at 32*. The Roots 14-71 engine made peak power with about 11.5-12 lbs of boost with the same peak RPM as the M4 Pro-Charger. I don't remember what the timing was for the Roots engine, but being that it was built as a racing engine destined for offshore racing with the heads that the customer had at the time, then I am sure the timing was set a little higher.
This is just my own observation/opinion...but I thought it is/was a very interesting comparison and from some of what I have heard in the past about the Pro-Chargers, I thought the M4 Pro-Charger would have kicked a little more arss in the HP per RPM per pound of boost, etc, department....and I am sure it would have kept going, but at the sacrifice of higher RPM.
Even though the Intake Air Temps of the M4 Pro-Charger were cooler than the Whipple, and the Whipple cooler than the Roots---the Whipple after a long pull on the dyno with a hard pull at the end, you could lay your bare hands on the surface of the blower case of the Whipple and it would be COLD to the touch....unlike a Roots. I thought that was very impressive.
I understand every engine is different and you can argue the finer details if you want, but the smaller intake runner CC sized heads of the Whipple engine beat the larger 20cc sized heads of the M4 Pro-Charger plus with the slightly larger 3* cam and tighter LSA...at least in this reference.
I do not have the liberty to give detailed specifics because these engines belong to customers of my builder.
The Roots 14-71 engine was destined for an offshore racing application and had the largest cam of the 3 engines, but the heads are some older aluminum designs with porting and the same size as the M4 Pro-Charger heads. The M4 Pro-Charger engine's cam was about 3* duration larger on a 112* LSA compared to the Whipple engine's 114* LSA "tight lash" cam.----therefore, the Whipple engine has the smaller/milder cam design.
All 3 engines made peak HP and TQ within about 10hp. The Intake runners of the heads of the M4 Pro-Charger engine were about 20cc larger than the Whipple's engine's heads. Both heads were a late design cnc ported head design of the same manufacturer---with the same exhaust port size/design and same size valves. The Roots engine heads were the same size as the M4 Pro-Charger's heads, but different manufacturer/design.
The M4 Pro-Charger engine was very impressive...it had the lowest Intake Air Temps between the 3 engines. However, it took 9 lbs of boost to make the same peak HP as the Whipple engine.....The Whipple engine only took 7.5 lbs of boost to make the same HP....and the Whipple did it at a 300rpm lower rpm rate compared to the M4 Pro-Charger engine. Both engines were timed at 32*. The Roots 14-71 engine made peak power with about 11.5-12 lbs of boost with the same peak RPM as the M4 Pro-Charger. I don't remember what the timing was for the Roots engine, but being that it was built as a racing engine destined for offshore racing with the heads that the customer had at the time, then I am sure the timing was set a little higher.
This is just my own observation/opinion...but I thought it is/was a very interesting comparison and from some of what I have heard in the past about the Pro-Chargers, I thought the M4 Pro-Charger would have kicked a little more arss in the HP per RPM per pound of boost, etc, department....and I am sure it would have kept going, but at the sacrifice of higher RPM.
Even though the Intake Air Temps of the M4 Pro-Charger were cooler than the Whipple, and the Whipple cooler than the Roots---the Whipple after a long pull on the dyno with a hard pull at the end, you could lay your bare hands on the surface of the blower case of the Whipple and it would be COLD to the touch....unlike a Roots. I thought that was very impressive.
I understand every engine is different and you can argue the finer details if you want, but the smaller intake runner CC sized heads of the Whipple engine beat the larger 20cc sized heads of the M4 Pro-Charger plus with the slightly larger 3* cam and tighter LSA...at least in this reference.
04-02-2016, 09:34 AM
#32
Registered
iTrader: (1)
Merc has (had) to use what GM supplied. Blue motors a little different scenario.
If GM continued with the 049's, they would still have the small valves.
Also, as a Manufacturer, you never wanna come out with power that will be hard for them to beat every 5yrs or so.
Say, when they introduced the 502, if they did the HP500 first and as a black motor, they would have kind of boned themselves.
If GM continued with the 049's, they would still have the small valves.
Also, as a Manufacturer, you never wanna come out with power that will be hard for them to beat every 5yrs or so.
Say, when they introduced the 502, if they did the HP500 first and as a black motor, they would have kind of boned themselves.
04-02-2016, 09:34 AM
#33
Heres another interesting topic. it came up on facebook a while back. Somehow, the talk of advancing, vs retarding cams came up. Typically, advancing a cam, makes more low end, retarding makes more upper power.
in this guys case, retarding his custom specd cam, 4 degrees from its intended install centerline, resulted in more power, from 2500RPM, all the way to peak HP rpm. He lost nothing, anywhere in the power band, by retarding the cam 4 degrees. My assumption, the cam was too small to start with. Was it a huge gain, not really. But hey, 16hp gain at peak, as well as a gain of 5lbs of peak torque, with no losses anywhere, seemed like a good move when dyno tuning. Of course, we don't know what happened between idle and 2500rpm, if any torque was lost, but are we going from idle, to sticks to the dash full throttle starts with offshore boats? Usually, everything is a trade off, but sometimes, you have nothing to lose, and only to gain.
in this guys case, retarding his custom specd cam, 4 degrees from its intended install centerline, resulted in more power, from 2500RPM, all the way to peak HP rpm. He lost nothing, anywhere in the power band, by retarding the cam 4 degrees. My assumption, the cam was too small to start with. Was it a huge gain, not really. But hey, 16hp gain at peak, as well as a gain of 5lbs of peak torque, with no losses anywhere, seemed like a good move when dyno tuning. Of course, we don't know what happened between idle and 2500rpm, if any torque was lost, but are we going from idle, to sticks to the dash full throttle starts with offshore boats? Usually, everything is a trade off, but sometimes, you have nothing to lose, and only to gain.
04-02-2016, 09:48 AM
#34
Registered
iTrader: (3)
Heres another interesting topic. it came up on facebook a while back. Somehow, the talk of advancing, vs retarding cams came up. Typically, advancing a cam, makes more low end, retarding makes more upper power.
in this guys case, retarding his custom specd cam, 4 degrees from its intended install centerline, resulted in more power, from 2500RPM, all the way to peak HP rpm. He lost nothing, anywhere in the power band, by retarding the cam 4 degrees. My assumption, the cam was too small to start with. Was it a huge gain, not really. But hey, 16hp gain at peak, as well as a gain of 5lbs of peak torque, with no losses anywhere, seemed like a good move when dyno tuning. Of course, we don't know what happened between idle and 2500rpm, if any torque was lost, but are we going from idle, to sticks to the dash full throttle starts with offshore boats? Usually, everything is a trade off, but sometimes, you have nothing to lose, and only to gain.
in this guys case, retarding his custom specd cam, 4 degrees from its intended install centerline, resulted in more power, from 2500RPM, all the way to peak HP rpm. He lost nothing, anywhere in the power band, by retarding the cam 4 degrees. My assumption, the cam was too small to start with. Was it a huge gain, not really. But hey, 16hp gain at peak, as well as a gain of 5lbs of peak torque, with no losses anywhere, seemed like a good move when dyno tuning. Of course, we don't know what happened between idle and 2500rpm, if any torque was lost, but are we going from idle, to sticks to the dash full throttle starts with offshore boats? Usually, everything is a trade off, but sometimes, you have nothing to lose, and only to gain.
04-02-2016, 09:56 AM
#35
Registered
iTrader: (1)
Tuning - fuel / ignition
Exhaust - we here this all the time
Cam / Head / Intake etc
Oil Level
Well, who would want a 560-hp engine if it could make 600 ?
That's for the owner to decide.
And yes, some boats will respond to smaller hp additions than others....so that is a factor.
Last edited by SB; 04-02-2016 at 10:03 AM.
04-02-2016, 09:58 AM
#36
Registered
so did all the heads listed in this test have 26° valve angles?because what we learned way back in the motorcycle days of the late 80's/90's was valve angle was the biggest gainer in flow.then make the ports bigger and straighter to get even more air in.
all about making the short side radius better.
all I know is aftermarket heads are better than stock,except in the case of merlin heads,they just plain suck.they need alot of work to make them right.
all about making the short side radius better.
all I know is aftermarket heads are better than stock,except in the case of merlin heads,they just plain suck.they need alot of work to make them right.
04-02-2016, 10:05 AM
#37
Always a fair point, however it seems someone always says this no matter what performance part thread.
Tuning - fuel / ignition
Exhaust - we here this all the time
Cam / Head / Intake etc
Well, who would want a 560-hp engine if it could make 600 ?
That's for the owner to decide.
And yes, some boats will respond to smaller hp additions than others....so that is a factor.
Tuning - fuel / ignition
Exhaust - we here this all the time
Cam / Head / Intake etc
Well, who would want a 560-hp engine if it could make 600 ?
That's for the owner to decide.
And yes, some boats will respond to smaller hp additions than others....so that is a factor.
What is interesting in that article, is 730ish hp from a 496ci engine at 6500rpm, with around 10:1 static compression and a 650 lift cam.
04-02-2016, 10:22 AM
#39
Registered
04-02-2016, 10:27 AM
#40
Registered
iTrader: (3)
i guess to see the 16 hp gain you would actuially need to do back to back dyno pulls with the cam straight up and then retarted.i know that sounds simple enough but even with a cloyes 2 peice timing chain cover and a cloyes hex a just timing set it still requires some work.all the rocker arms need to be backed off before making the cam adjustment and even if you think you moved the cam 4 deg without checking with a deg wheel you really don,t know exactly where the cam timing is at.imo the hex a just is great for helping the builder degree the cam but i would not trust the marks on it without redegreeing the cam after the move.
