67Barracuda273
New Member
What is bowl blending and how much horsepower could i possible gain from a bowl blend with my late 360.
Bowl Blending?
- Thread starter 67Barracuda273
- Start date
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Bowl porting gains;
It can gain a nice amount of power, but is combo dependent.
In a "In General" amount, it could gain 20 - 50 HP.
Part of the combo that needs to be looked at is cam, valve size and type, induction, etc....
Bowl porting is;
The area just under the valve. Picture it removed from the head. All that can be seen in the imediate is considered the bowl. This area is opened up to meet the valve sized and smoothed out to resemble a bowl. The valve comes out of the "Guide" which is ground down to increase the area to be smoothed.
It's best effect is the low lift to mid lift area, approx. to .500 lift.
It can gain a nice amount of power, but is combo dependent.
In a "In General" amount, it could gain 20 - 50 HP.
Part of the combo that needs to be looked at is cam, valve size and type, induction, etc....
Bowl porting is;
The area just under the valve. Picture it removed from the head. All that can be seen in the imediate is considered the bowl. This area is opened up to meet the valve sized and smoothed out to resemble a bowl. The valve comes out of the "Guide" which is ground down to increase the area to be smoothed.
It's best effect is the low lift to mid lift area, approx. to .500 lift.
7demon2
Registered User #1824
so rumble to take this question alittle further. in your opinion what can be gained with a set of stock valve (1.88) j heads, with a comp cam..... say a xe274h?
Thats a very good question. And I can not answer it.
I could plug numbers into a simple program like Desk Top Dyno or better sims and come up with 2 different answers. Theres alot to look at. Your question still needs clarification. Carb size, intake, headers or not. Detail detail details.
One detail most forgotten about or not searched for is the flow numbers of the intake and exhaust at various lifts until the flow stalls. From there you can choose a cam to comploment the head flow.
On the sims, they'll provided gerneric numbers. Yours could be better. Thus equaling more power.
Also, remember that one mans port work is/can/could be very different from someone elses work even though they only touched the same area and may even look the same.
From here, I hand the mike over to someone who has this exper. and can handle this question a whole lot better than myself.
I now shout out to BJRracing.
I could plug numbers into a simple program like Desk Top Dyno or better sims and come up with 2 different answers. Theres alot to look at. Your question still needs clarification. Carb size, intake, headers or not. Detail detail details.
One detail most forgotten about or not searched for is the flow numbers of the intake and exhaust at various lifts until the flow stalls. From there you can choose a cam to comploment the head flow.
On the sims, they'll provided gerneric numbers. Yours could be better. Thus equaling more power.
Also, remember that one mans port work is/can/could be very different from someone elses work even though they only touched the same area and may even look the same.
From here, I hand the mike over to someone who has this exper. and can handle this question a whole lot better than myself.
I now shout out to BJRracing.
7demon2
Registered User #1824
rumblefish360 said:
ok let's look at from a stock perspective. stock 340 intake, stock 340 72 thermoquad or equivalant. headers no. stock 340 manifolds not hp's
rumblefish360 said:
where do you get the flow numbers for intakes? never seen them. how would you use them in a sim like desktop dyno? i know that you can plug in head flow numbers but i have never seen any place to plug in intake flow numbers.....i could also be missing this!
rumblefish360 said:
boy truer words have never been said here!
rumblefish360 said:
lol
this is why i love your answers! it is a blend of truth and humor all rolled into one statement! :thumbup:D-mailman
Well-Known Member
I state over and over that there is really no down side to bowl work (porting). I know some will not agree...but a good 'bowl job' will not destroy port velocity, very important to street engines. As Rumblefish correctly stated, it picks up low lift flow, mostly under .500 lift. The seats and their angles are very important in very low lift flow, as is the criticle short side (port floor) as it 'turns' down over seats. Also back cutting of the valves has a big effect on low lift flow. A good 'bowl job', With good seats and back cutting of the valves and you will have a GOOD piece indeed. I would not hesitate to perform this work even on 'torque only' motors such as RV's, trucks ect. As for numbers...About 40 horsepower can be expected, 20 cfm or so depending on how 'deep' you go into the port. + = more, - = less. Even with factory manifolds, intake and exhaust...you will benifit. As always gentlemen(?) LOL, LOL. JMHO. Good luck. Terry.
BJR Racing
Well-Known Member
Bowl blending can increase HP and torque by a good bit when other parts are there to compliment the work done. The amount of power that you get will vary due to the limiting factors of the intake and exhaust systems and cams. It can be as much as 80 HP and as little as 10, but then not all can be directly claimed by bowl blending as there are the cam and the intake and carb that has a affect on this also and is worth something to the mix. As for the 1.88 valves and a stock or .030 over bore block and for the street and mild racing you can't go wrong, and with a 274 comp cams cam you definitly won't go wrong. Large valves are for high rpms and large cams and with a cam that is this small the smaller valve will flow more at low lifts with the 1.88 as velocity will be stronger also and move more air. Bowl blending will help the small valve more than the larger valve, as velocity decreases with the larger valve, thus loosing low rpm torque and HP.
But as Rumble has said that the work will vary from porter to porter even though they can look the same, also the valve job has alot to how the port will flow and where it will peak flow. But when the stock carb and manifolds are going to be used then the small valve is the key on both sides of the equation even through a good exhaust.
We have a 365 with bowl blending and gasket matching done and run stock size valves in the heads, it has a comp cams extreme energy cam .507/.510 with the heads above and a stock bottom end that has been refreshened and balanced for longivity. It runs on 87 octane pump gas the truck hit the scales at 3000lbs. and run 7.65 1/8 mi., through the stock manifolds on the intake and the exhaust with 2 1/2" and no mufflers, but a H pipe. Then we changed the manifolds and put a DP on and the truck now runs 7.40 1/8 mi. @ 96 mph still on 87 gas, so as you can see the intake and carb helped the bowl blending out some 25-30 HP more.
This engine put 354 HP to the ground and put out a good bit more than 400 HP out of the engine. The only way that the engine could do this is the fact that the heads are so efficent with the smaller valves. Larger valves loose efficiency in the heads this is why you have to run a larger cam with larger valves to create more efficiency in the heads, and turn more rpms. The efficiency with larger valves and cams comes from the turbulence created in the combustion chambers during the period of overlap at high rpms, this is why the HP is greater with large cams and heads at a higher rpm thust the engine hits it efficiency peak. But with a smaller valve and port the efficiency is lower and the need for larger componets isn't needed. Thus smaller cams and carbs. A engine is a air pump, the more efficent the pump the more air it will move and more HP it will make.
Heads need to be built for the cam and intake and exhaust used to get the most out of the engine that your useing. Some need more modifying and some less or different places. If your only useing a .480 lift cam then anything over .400 shouldn't be of concern as your only at peak lift once and have to go by the lower lifts twice. The need to make these the low lifts the strongest is very important. So when bowl blending the heads leave the short turn as tall and as sharp as possiable as this will speed the air up greatly and make it peak flow by .400 to .500 lift, thus makeing your low lifts as strong as possiable. Gasket matching will increase this by another 10-15 cfm's.
Sorry for being so winded, hope this makes it clearer.
But as Rumble has said that the work will vary from porter to porter even though they can look the same, also the valve job has alot to how the port will flow and where it will peak flow. But when the stock carb and manifolds are going to be used then the small valve is the key on both sides of the equation even through a good exhaust.
We have a 365 with bowl blending and gasket matching done and run stock size valves in the heads, it has a comp cams extreme energy cam .507/.510 with the heads above and a stock bottom end that has been refreshened and balanced for longivity. It runs on 87 octane pump gas the truck hit the scales at 3000lbs. and run 7.65 1/8 mi., through the stock manifolds on the intake and the exhaust with 2 1/2" and no mufflers, but a H pipe. Then we changed the manifolds and put a DP on and the truck now runs 7.40 1/8 mi. @ 96 mph still on 87 gas, so as you can see the intake and carb helped the bowl blending out some 25-30 HP more.
This engine put 354 HP to the ground and put out a good bit more than 400 HP out of the engine. The only way that the engine could do this is the fact that the heads are so efficent with the smaller valves. Larger valves loose efficiency in the heads this is why you have to run a larger cam with larger valves to create more efficiency in the heads, and turn more rpms. The efficiency with larger valves and cams comes from the turbulence created in the combustion chambers during the period of overlap at high rpms, this is why the HP is greater with large cams and heads at a higher rpm thust the engine hits it efficiency peak. But with a smaller valve and port the efficiency is lower and the need for larger componets isn't needed. Thus smaller cams and carbs. A engine is a air pump, the more efficent the pump the more air it will move and more HP it will make.
Heads need to be built for the cam and intake and exhaust used to get the most out of the engine that your useing. Some need more modifying and some less or different places. If your only useing a .480 lift cam then anything over .400 shouldn't be of concern as your only at peak lift once and have to go by the lower lifts twice. The need to make these the low lifts the strongest is very important. So when bowl blending the heads leave the short turn as tall and as sharp as possiable as this will speed the air up greatly and make it peak flow by .400 to .500 lift, thus makeing your low lifts as strong as possiable. Gasket matching will increase this by another 10-15 cfm's.
Sorry for being so winded, hope this makes it clearer.
BJR Racing
Well-Known Member
Sorry Terry,
For posting the same answer,
But you beat me to the punch and said the same thing.
For posting the same answer,
But you beat me to the punch and said the same thing.
7demon2
Registered User #1824
hey there is a excellent answer if i have ever read one. you guys rule! i only hope that alot of people are paying attention to these great answers and asorbing this great information that 9 times out of 10 cannot be found surfing the web. experience speaks loudly and in volumes......
Thanks Bobby and Terry.
I was trying to form an answer in my head as to what the out come could be. But theres so many variables to the equation.
I have noticed, in general, if you build an engine that is going to have some power, the amount of HP can be increased well with ported heads to the tune of 2 HP per 1 cfm of air flow. You can exceed this easy. Or fall way short. But for typical street builds, thats about what the engine is capable of doing without over caming and large carbs where a smaller one will do etc....You know, pushing the limit(s). (*Headers should be used with such guessing thoughts on probabl projections on power and torque as well as a basic package that is, in general, optimized for performance engines, not sci/overscienced out.)
You can have a head flow tested at a shop that has such devices for this. In the Mags, they have a machine by the name "Super flow"
I stopped into BJRs for a chat (While on vaction) and he showed me a tons of stuff. (Actuallly, a tad more than I could consume in the head for the day)
He has such a machine for his use on head work.
The machine measures the amount of air flow when the valve is lifted of the head. You take note at certain lift points. Like .300, .400, .500 etc or more often.
The Desk Top Dyno has a section where you can input these numbers for a more acurate prediction of how the actual engine will perform.
This takes alot of guess work out. One head porter will do more/better work or not and these numbers can be used to determine if the head cam carb intake combo are a good playing band or just a bunch of noise makers.
One port job could just do well to .450 lift while the other one, thats said to have the same work done will flow well to and over .500 or even .530 lift. Does that mean ones crap and the others magic. No. Just level/amount of work done.
And thats just taking the skill side of it out of the picture.
Comp Cams took the time to design cams for use with exhaust manifolds. These should out perform the extreme series cams in such a case due to the longer exhaust durations.
I was trying to form an answer in my head as to what the out come could be. But theres so many variables to the equation.
I have noticed, in general, if you build an engine that is going to have some power, the amount of HP can be increased well with ported heads to the tune of 2 HP per 1 cfm of air flow. You can exceed this easy. Or fall way short. But for typical street builds, thats about what the engine is capable of doing without over caming and large carbs where a smaller one will do etc....You know, pushing the limit(s). (*Headers should be used with such guessing thoughts on probabl projections on power and torque as well as a basic package that is, in general, optimized for performance engines, not sci/overscienced out.)
You can have a head flow tested at a shop that has such devices for this. In the Mags, they have a machine by the name "Super flow"
I stopped into BJRs for a chat (While on vaction) and he showed me a tons of stuff. (Actuallly, a tad more than I could consume in the head for the day)
He has such a machine for his use on head work.
The machine measures the amount of air flow when the valve is lifted of the head. You take note at certain lift points. Like .300, .400, .500 etc or more often.
The Desk Top Dyno has a section where you can input these numbers for a more acurate prediction of how the actual engine will perform.
This takes alot of guess work out. One head porter will do more/better work or not and these numbers can be used to determine if the head cam carb intake combo are a good playing band or just a bunch of noise makers.
One port job could just do well to .450 lift while the other one, thats said to have the same work done will flow well to and over .500 or even .530 lift. Does that mean ones crap and the others magic. No. Just level/amount of work done.
And thats just taking the skill side of it out of the picture.
Comp Cams took the time to design cams for use with exhaust manifolds. These should out perform the extreme series cams in such a case due to the longer exhaust durations.
Thanks. I am a big kid at heart and a clown when around kids. Family gatherings have all of them on my back wrestling and playing. I figure, if your not haveing a good time, your sleeping. So why not laff it up!?!?!?
BJR Racing
Well-Known Member
Rumble,
Centerlines also have alot to do with the power and where it comes on at, you could have a cam with alot of duration @ .050 but with the centerline being low the overlap will be high and with the centerline being high the overlap will be low. The centerlines are the main thing that effects compression, or should I say cylinder pressure. This has a direct effect on HP and torque.
Centerlines also have alot to do with the power and where it comes on at, you could have a cam with alot of duration @ .050 but with the centerline being low the overlap will be high and with the centerline being high the overlap will be low. The centerlines are the main thing that effects compression, or should I say cylinder pressure. This has a direct effect on HP and torque.
Yep. I'm on that. I think you say that in ref to my ref of the extreme cam to the other comp cam.
The Comp Cams cam for manifold exhaust is set up quit differently. There mostly for stock set ups looking for more power, not pocket ported heads and headered cars. Something I should have pointed out.
But thats cams.
I'll stick to the head subject. Once you start mixing the 2, the whole thread changes to engine build instead of whats involved with certain head work.
The whole picture can go on and on and on.
7Demon2 asks good questions. I still couldn't put a number on a stock J head with 1.88's and a pocket porting could produce in HP. But I think it would be noticed when you drive.
The Comp Cams cam for manifold exhaust is set up quit differently. There mostly for stock set ups looking for more power, not pocket ported heads and headered cars. Something I should have pointed out.
But thats cams.
I'll stick to the head subject. Once you start mixing the 2, the whole thread changes to engine build instead of whats involved with certain head work.
The whole picture can go on and on and on.
7Demon2 asks good questions. I still couldn't put a number on a stock J head with 1.88's and a pocket porting could produce in HP. But I think it would be noticed when you drive.
7demon2
Registered User #1824
rumblefish360 said:
hey rumble what cams are you refering to here? i thought the extreme energy series were the better cams, do in part to their duel patterns? i would think the longer duration would be better for poor flowing exhaust systems.
D-mailman
Well-Known Member
7Demon2, Yes I do agree, with the knowledge of some of the people on this site like Rumble, BJR and Moper and there are many others.. well it is MY favorite Mopar site and the BEST in my opinion. I learn something about everytime I log on. Two thumbs up.. Lead on gentlemen Terry.
7demon2
Registered User #1824
:thumbup: :thumbup: the board is nice but, i hope to meet some of these guys one day. i would love to send my heads to bjr this winter. shipping would probably kill me though :sad:headsbikesmopars said:
7demon2 said:
:thumbup:
think the same but i would actualy like to meet alot of you guys who have all these nice cars and that realy try to help out!
this board realy helps out and there is always someone who knows what you need to know!
The Comp Cams I refur to are the DEH line. Duel Energy. There Hyd. cams with some very wide duration seperations. Designed for stock exhaust systems as per Comp Cams. There are 3 listed in the paged catolog. I'll list them.
advertised/ @ .050 duration/lift/centerlines/RPM range
255DEH-255/275-203/219-.442-.462-110-1200-5500 RPM
265DEH-265/276-211/227-.442-.462-110-1600-5750 RPM
275DEH-275/284-219/235-.462-.482-110-2000-6000 RPM
Now if we step up to the plate for some power making with the likes of headers, aftermarket intakes with or without head porting, I would not bother with these cams.
Next to the extreme cams, there lazy and slow.
Extreme.............XE274 - 274/286-230/236-.488/.491-110- 1800-6000 RPM
Ex-hi-lift .. .......XE275HL 275/287-231/237-.525/.525-110- 2000-6000 RPM
Mech.Extr...........XS274S 274/280-236/242-.502/.511-110- 2200-6200 RPM
Mech roller Extr....XR274R-274/280-236/242-.564/.570-110-2200-6300 RPM
Notice how in order, the duration at .050 against the advertised duration goes up as well as against the DEH cams.
If you took notice....the roller isn't any more aggressive than the mech cam. Except in lift. Which is quit nice for a street engine. Fits Edel heads max lift easy.
If you did want one more agressive, Comp could whip one up easy or you could take a peak at there cam cores/special ramps listed in there catolog. But I would caution against doing a pick a grind number out of the catolog. Talk to the experts. That roller is very capable and IF you have a roller 360 engine allready, I'd do that one over the mech one.
To me, this is where the extra expense would be OK with me.
PS, anytime anybodys on Long Island............
I also travel afr to pick parts up. Sometimes it's cheaper than mailing them. UPS/FED-EX etc....But it's more about seeing the country and meeting people.
advertised/ @ .050 duration/lift/centerlines/RPM range
255DEH-255/275-203/219-.442-.462-110-1200-5500 RPM
265DEH-265/276-211/227-.442-.462-110-1600-5750 RPM
275DEH-275/284-219/235-.462-.482-110-2000-6000 RPM
Now if we step up to the plate for some power making with the likes of headers, aftermarket intakes with or without head porting, I would not bother with these cams.
Next to the extreme cams, there lazy and slow.
Extreme.............XE274 - 274/286-230/236-.488/.491-110- 1800-6000 RPM
Ex-hi-lift .. .......XE275HL 275/287-231/237-.525/.525-110- 2000-6000 RPM
Mech.Extr...........XS274S 274/280-236/242-.502/.511-110- 2200-6200 RPM
Mech roller Extr....XR274R-274/280-236/242-.564/.570-110-2200-6300 RPM
Notice how in order, the duration at .050 against the advertised duration goes up as well as against the DEH cams.
If you took notice....the roller isn't any more aggressive than the mech cam. Except in lift. Which is quit nice for a street engine. Fits Edel heads max lift easy.
If you did want one more agressive, Comp could whip one up easy or you could take a peak at there cam cores/special ramps listed in there catolog. But I would caution against doing a pick a grind number out of the catolog. Talk to the experts. That roller is very capable and IF you have a roller 360 engine allready, I'd do that one over the mech one.
To me, this is where the extra expense would be OK with me.
PS, anytime anybodys on Long Island............
I also travel afr to pick parts up. Sometimes it's cheaper than mailing them. UPS/FED-EX etc....But it's more about seeing the country and meeting people.
Have any of you tried the Lunati VooDo series. They have more lift and duration on the exhaust side to help with those stock exhaust manifolds.
Mike
Mike
Nope, but there specs look good. Agressive.
I've got a mid 80's 318 and some Magnum heads I want to put together just for fun. I'll put it in my 66 Dart while I'm overhauling the orig. HP 273. I've been looking at the Lunati cams pretty serious. Hopefully someone has tried one an will respond to this thread. Mike
The Magnum heads will work better.
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