Dynoed the Maggie!
06-07-2015, 09:40 PM
#21
Exactly.......and this isnt the first time he's given bad advice.
I would bet any amount of money the guy with longtubes and 9psi would put a few cars on the OPs car even with the dyno numbers being what they are. Every dyno is different.
Sound like you're happy with the way it all turned out. End of the day, headers will in no way, shape or form hurt you.
I would bet any amount of money the guy with longtubes and 9psi would put a few cars on the OPs car even with the dyno numbers being what they are. Every dyno is different.
Sound like you're happy with the way it all turned out. End of the day, headers will in no way, shape or form hurt you.
06-08-2015, 01:05 AM
#22
You have to remember for a range of rpm your engine is suckin more air than the FI can put out, so after a selective rpm the FI catches up with the engine and boost is then applied to the equation. Your LS6 cam has 38.5 degrees degrees of overlap at 0.006, that overlap is to help the NA car suck in that little more air initially as well as charge the fuel with warm air to help the ignition spark up the mixture. On a SC at speed that overlap bleeds the charged air into the exhaust...
In high school you only get partial grade for simple answers...Explanation is required
Barrok69 has a similar setup but with 1 7/8 headers. And he claimed -10lbft but the variable was +2psi.
What i said is sound,
06-08-2015, 02:39 AM
#23
^^ I have no idea where you are getting this info.....but simply put it is wrong.
Call magnuson, whipple, kenne bell, procharger etc and tell them you want to run stock manifolds with stock cats because it'll make more power with the added backpressure. See how long before they either laugh or tell you that you are wrong.
Call magnuson, whipple, kenne bell, procharger etc and tell them you want to run stock manifolds with stock cats because it'll make more power with the added backpressure. See how long before they either laugh or tell you that you are wrong.
06-08-2015, 06:16 AM
#24
Laugh or not, it all depends on your setup. He is running a bone stock engine.
Lets think water hose. You turn the water on with the opening wide open, the water pours out nicely. You have full flow and no pressure, You put your thumb on it and it goes further, squeeze the hole smaller to the point you start to lose on your distance this is full pressure and no more flow.
Exhaust back pressure is the same concept. Yes you can flow more with bigger openings, but you want exhaust velocity. Velocity leads to proper scavenging, then better performance. You open your exhaust too far you lose velocity, you keep it too small and you risk engine damage.
Exhaust backpressure is <2psi...You can pressurize a bottle at 2.4psi and it will feel like your eyeballs are going to pop out of your head...You are organic, the engine isnt...
If you want to play the headers game, play it smart. Your stock headers are about 1 5/8 going into a 2.5" catback. Going 1 7/8 to 3" catback with a stock engine is a waste. Goin 1 3/4 headers into stock exhaust gives your cylinders the flow but the back pressure of the stock exhaust will help keep the gases at a higher velocity which you want...
I am running a heavily modified engine into 1 7/8 headers with a 3" intermediate muffler and 2.5" exit pipes. This way i may move my gases out of the engine, then as the gases cool the squeezin effect of the 3-2.5" pipes accelerates the air so there is no drop in power. I also added exhaust flaps where i will have them closed at lower rpm and open above set rpms for more gas flow. This way the exhaust gases are always at higher velocity and my engine isnt so choppy at low rpm...
You need to realize that some ppl only want your money, others just want to be heard. Once and a while you get someone who really doesnt care of either and offers free advice.
I have been down many paths, i have ported my share of tbs, played with different heads, cams, and intake manifolds. I made my share of mistakes, like porting the tb of my dirtbike to be 44mm straight though, i forgot the simple physics of velocity, when you squeeze any medium it will accelerate and when it accelerates it generates more power. You drop the velocity you drop the power. What we can do is assist the squeezin effect and smooth the path so there is less turbulence, and that is what a great porter will do. Smooth the path out so the air isnt turbulent but retain the velocity so you may gain more power...
Lets think water hose. You turn the water on with the opening wide open, the water pours out nicely. You have full flow and no pressure, You put your thumb on it and it goes further, squeeze the hole smaller to the point you start to lose on your distance this is full pressure and no more flow.
Exhaust back pressure is the same concept. Yes you can flow more with bigger openings, but you want exhaust velocity. Velocity leads to proper scavenging, then better performance. You open your exhaust too far you lose velocity, you keep it too small and you risk engine damage.
Exhaust backpressure is <2psi...You can pressurize a bottle at 2.4psi and it will feel like your eyeballs are going to pop out of your head...You are organic, the engine isnt...
If you want to play the headers game, play it smart. Your stock headers are about 1 5/8 going into a 2.5" catback. Going 1 7/8 to 3" catback with a stock engine is a waste. Goin 1 3/4 headers into stock exhaust gives your cylinders the flow but the back pressure of the stock exhaust will help keep the gases at a higher velocity which you want...
I am running a heavily modified engine into 1 7/8 headers with a 3" intermediate muffler and 2.5" exit pipes. This way i may move my gases out of the engine, then as the gases cool the squeezin effect of the 3-2.5" pipes accelerates the air so there is no drop in power. I also added exhaust flaps where i will have them closed at lower rpm and open above set rpms for more gas flow. This way the exhaust gases are always at higher velocity and my engine isnt so choppy at low rpm...
You need to realize that some ppl only want your money, others just want to be heard. Once and a while you get someone who really doesnt care of either and offers free advice.
I have been down many paths, i have ported my share of tbs, played with different heads, cams, and intake manifolds. I made my share of mistakes, like porting the tb of my dirtbike to be 44mm straight though, i forgot the simple physics of velocity, when you squeeze any medium it will accelerate and when it accelerates it generates more power. You drop the velocity you drop the power. What we can do is assist the squeezin effect and smooth the path so there is less turbulence, and that is what a great porter will do. Smooth the path out so the air isnt turbulent but retain the velocity so you may gain more power...
06-08-2015, 07:51 AM
#25
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There is absolutely no overlap with a stock cam. It is physically impossible to loss charge air out the exhaust.
You will see higher boost on an ls6 since the engine displacement is smaller. The same blower and speed will move the same volume of air. A larger volume (engine displacement) will have lower boost but it's moving the same amount of air. Within reason it's the same power. You pick up a little blower efficiency with lower boost pressure and for the same volume lower boost is lower air temp which could allow some more timing.
Our stock heads good. I don't know on the exhaust, but I don't really recall a noticeable change in boost when I installed headers. But the boost is so much a function of air temp the conditions could have been different. A cam definitely helps giving more duration to fill the engine displacement.
You will see higher boost on an ls6 since the engine displacement is smaller. The same blower and speed will move the same volume of air. A larger volume (engine displacement) will have lower boost but it's moving the same amount of air. Within reason it's the same power. You pick up a little blower efficiency with lower boost pressure and for the same volume lower boost is lower air temp which could allow some more timing.
Our stock heads good. I don't know on the exhaust, but I don't really recall a noticeable change in boost when I installed headers. But the boost is so much a function of air temp the conditions could have been different. A cam definitely helps giving more duration to fill the engine displacement.
Hey man,
Just got info from the tuner.
- 115 was the Manifold Air Temp
- 20 degrees of timing
- 11.5 airfuel
I'd be very pleased if I gained 25 rwhp with headers with a grand total of 500 rwhp. Plenty enough for this guy.....
06-08-2015, 08:04 AM
#26
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Laugh or not, it all depends on your setup. He is running a bone stock engine.
Lets think water hose. You turn the water on with the opening wide open, the water pours out nicely. You have full flow and no pressure, You put your thumb on it and it goes further, squeeze the hole smaller to the point you start to lose on your distance this is full pressure and no more flow.
Exhaust back pressure is the same concept. Yes you can flow more with bigger openings, but you want exhaust velocity. Velocity leads to proper scavenging, then better performance. You open your exhaust too far you lose velocity, you keep it too small and you risk engine damage.
Exhaust backpressure is <2psi...You can pressurize a bottle at 2.4psi and it will feel like your eyeballs are going to pop out of your head...You are organic, the engine isnt...
If you want to play the headers game, play it smart. Your stock headers are about 1 5/8 going into a 2.5" catback. Going 1 7/8 to 3" catback with a stock engine is a waste. Goin 1 3/4 headers into stock exhaust gives your cylinders the flow but the back pressure of the stock exhaust will help keep the gases at a higher velocity which you want...
I am running a heavily modified engine into 1 7/8 headers with a 3" intermediate muffler and 2.5" exit pipes. This way i may move my gases out of the engine, then as the gases cool the squeezin effect of the 3-2.5" pipes accelerates the air so there is no drop in power. I also added exhaust flaps where i will have them closed at lower rpm and open above set rpms for more gas flow. This way the exhaust gases are always at higher velocity and my engine isnt so choppy at low rpm...
You need to realize that some ppl only want your money, others just want to be heard. Once and a while you get someone who really doesnt care of either and offers free advice.
I have been down many paths, i have ported my share of tbs, played with different heads, cams, and intake manifolds. I made my share of mistakes, like porting the tb of my dirtbike to be 44mm straight though, i forgot the simple physics of velocity, when you squeeze any medium it will accelerate and when it accelerates it generates more power. You drop the velocity you drop the power. What we can do is assist the squeezin effect and smooth the path so there is less turbulence, and that is what a great porter will do. Smooth the path out so the air isnt turbulent but retain the velocity so you may gain more power...
Lets think water hose. You turn the water on with the opening wide open, the water pours out nicely. You have full flow and no pressure, You put your thumb on it and it goes further, squeeze the hole smaller to the point you start to lose on your distance this is full pressure and no more flow.
Exhaust back pressure is the same concept. Yes you can flow more with bigger openings, but you want exhaust velocity. Velocity leads to proper scavenging, then better performance. You open your exhaust too far you lose velocity, you keep it too small and you risk engine damage.
Exhaust backpressure is <2psi...You can pressurize a bottle at 2.4psi and it will feel like your eyeballs are going to pop out of your head...You are organic, the engine isnt...
If you want to play the headers game, play it smart. Your stock headers are about 1 5/8 going into a 2.5" catback. Going 1 7/8 to 3" catback with a stock engine is a waste. Goin 1 3/4 headers into stock exhaust gives your cylinders the flow but the back pressure of the stock exhaust will help keep the gases at a higher velocity which you want...
I am running a heavily modified engine into 1 7/8 headers with a 3" intermediate muffler and 2.5" exit pipes. This way i may move my gases out of the engine, then as the gases cool the squeezin effect of the 3-2.5" pipes accelerates the air so there is no drop in power. I also added exhaust flaps where i will have them closed at lower rpm and open above set rpms for more gas flow. This way the exhaust gases are always at higher velocity and my engine isnt so choppy at low rpm...
You need to realize that some ppl only want your money, others just want to be heard. Once and a while you get someone who really doesnt care of either and offers free advice.
I have been down many paths, i have ported my share of tbs, played with different heads, cams, and intake manifolds. I made my share of mistakes, like porting the tb of my dirtbike to be 44mm straight though, i forgot the simple physics of velocity, when you squeeze any medium it will accelerate and when it accelerates it generates more power. You drop the velocity you drop the power. What we can do is assist the squeezin effect and smooth the path so there is less turbulence, and that is what a great porter will do. Smooth the path out so the air isnt turbulent but retain the velocity so you may gain more power...
06-08-2015, 08:30 AM
#27
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Do headers only time that fi application need back pressure is when you are running some big *** turbos then certain amount of back pressure is needed to help spool the turbo faster other than that exception all fi applications will perform better with a headers. There is a reason why race cars have egt sensors. The faster you can get hot away from the motor the more power there is to be had. And the less chance you risk of melting a piston. With headers you should see 20whp and maybe 10tq
06-08-2015, 09:35 AM
#28
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Wrong, wrong, wrong.
You want flow, not necessarily backpressure. By allowing the cylinders to expel the burned gases more thoroughly, you allow more incoming charge to enter the cylinder in preparation to burn and create pressure and force the crank throw down thereby creating torque.
Naf, I don't really know where you get this stuff sometimes. You worry me.
06-08-2015, 11:44 AM
#29
FI love large LSA, Reason being it fills the cylinder better with less loss through the exhaust, thus in turn on a stock engine, FI like a little backpressure. The stock headers offer that backpressure.
Not AS true with a blower. The blower producing increased map pressure to a large degree overwhelms the effects of the low pressure wave from the exhaust. So the intake fill effects of exhaust scavenging is greatly reduced. But obviously we still need to get the exhaust out of the cylinder. Without scavenging it is more difficult. That is why you see blower cams with larger exhaust durations. Beyond that you need to optimize scavenging as much as possible (without adding cam overlap). This becomes a balance between velocity and pressure. The exhaust needs to be tuned for the desired application. But keep in mind with FI you are getting a lot more air and fuel into the engine and therefore more exhaust out. So short of going through all of the measurement and calculations that are beyond most hobbyists you can typically just go with larger less restrictive pipes and be better off.
Having said all of this, will there be cases where you go to larger exhaust diameters and lose power sure. But in those cases the cam is likely not well suited to FI.
06-08-2015, 11:49 AM
#30
Ls7/ls9 211/230
Gt9 215/245
Not much intake but plenty of exhaust. For that reason to expel all the exhaust gas and give the FI a chance to fill the chamber. Intake doesnt need to be large as you are boosted, but exhaust has to be long enough. Lsa here are 120-122.5 i need to investigate but here you are lookin at near zero overlap.
Gt9 215/245
Not much intake but plenty of exhaust. For that reason to expel all the exhaust gas and give the FI a chance to fill the chamber. Intake doesnt need to be large as you are boosted, but exhaust has to be long enough. Lsa here are 120-122.5 i need to investigate but here you are lookin at near zero overlap.
06-08-2015, 05:03 PM
#32
I'm really starting to like the V's lol. I don't know how many I counted at the last half mile shoot out. Funny part is one of the fastest ones there was white (cream) what ever color that is, wagon with a baby on board sticker.
06-08-2015, 05:37 PM
#33
Those are good numbers. Air temp was low and 20 degs is much more than I can run.
06-08-2015, 09:36 PM
#34
If I picked up 22rwhp on a stock engine, how would a car with a supercharger not gain at least that lol.
To see the gains from the headers you need to drop pulley size to compensate though. Otherwise you will likely not gain much because of the boost drop. The reason for that is you will make that same power more efficiently. So 475rwhp at 8psi and stock manifolds or 475rwhp at 6psi with long tubes(ballpark).
To see the gains from the headers you need to drop pulley size to compensate though. Otherwise you will likely not gain much because of the boost drop. The reason for that is you will make that same power more efficiently. So 475rwhp at 8psi and stock manifolds or 475rwhp at 6psi with long tubes(ballpark).
06-09-2015, 05:29 AM
#35
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If I picked up 22rwhp on a stock engine, how would a car with a supercharger not gain at least that lol.
To see the gains from the headers you need to drop pulley size to compensate though. Otherwise you will likely not gain much because of the boost drop. The reason for that is you will make that same power more efficiently. So 475rwhp at 8psi and stock manifolds or 475rwhp at 6psi with long tubes(ballpark).
To see the gains from the headers you need to drop pulley size to compensate though. Otherwise you will likely not gain much because of the boost drop. The reason for that is you will make that same power more efficiently. So 475rwhp at 8psi and stock manifolds or 475rwhp at 6psi with long tubes(ballpark).
barrok69 made 9 pounds of boost with headers and a 2.7 JS pulley. It appears that he gained boost with headers. I only made 7.66 pounds with a smaller pulley then him and stock manifolds. We are a country mile apart and I dont get it.
I like the idea of headers as every car I have had has gained power but this is my first supercharged car. We all know that headers arent cheap so I am doing my best to educate myself to see what gains will be had.
06-09-2015, 05:44 AM
#36
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I am confused. I thought I would gain hp/tq by simple bolting headers on with high flow cats. I allready have a 2.6 JS pulley on the car so I wont pulley down to a 2.5.
barrok69 made 9 pounds of boost with headers and a 2.7 JS pulley. It appears that he gained boost with headers. I only made 7.66 pounds with a smaller pulley then him and stock manifolds. We are a country mile apart and I dont get it.
I like the idea of headers as every car I have had has gained power but this is my first supercharged car. We all know that headers arent cheap so I am doing my best to educate myself to see what gains will be had.
barrok69 made 9 pounds of boost with headers and a 2.7 JS pulley. It appears that he gained boost with headers. I only made 7.66 pounds with a smaller pulley then him and stock manifolds. We are a country mile apart and I dont get it.
I like the idea of headers as every car I have had has gained power but this is my first supercharged car. We all know that headers arent cheap so I am doing my best to educate myself to see what gains will be had.
1. Your boost gauge is wrong
2. You have a cam and don't know it.
3. His dyno reads low.
06-09-2015, 06:35 AM
#37
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Absolutely agree.
Wrong, wrong, wrong.
You want flow, not necessarily backpressure. By allowing the cylinders to expel the burned gases more thoroughly, you allow more incoming charge to enter the cylinder in preparation to burn and create pressure and force the crank throw down thereby creating torque.
Naf, I don't really know where you get this stuff sometimes. You worry me.
Wrong, wrong, wrong.
You want flow, not necessarily backpressure. By allowing the cylinders to expel the burned gases more thoroughly, you allow more incoming charge to enter the cylinder in preparation to burn and create pressure and force the crank throw down thereby creating torque.
Naf, I don't really know where you get this stuff sometimes. You worry me.
Randy. How much boost are you making with headers and the 2.8? It would appear that you had good gains with headers? Lets hear it....
06-09-2015, 08:53 AM
#38
I am confused. I thought I would gain hp/tq by simple bolting headers on with high flow cats. I allready have a 2.6 JS pulley on the car so I wont pulley down to a 2.5.
barrok69 made 9 pounds of boost with headers and a 2.7 JS pulley. It appears that he gained boost with headers. I only made 7.66 pounds with a smaller pulley then him and stock manifolds. We are a country mile apart and I dont get it.
I like the idea of headers as every car I have had has gained power but this is my first supercharged car. We all know that headers arent cheap so I am doing my best to educate myself to see what gains will be had.
barrok69 made 9 pounds of boost with headers and a 2.7 JS pulley. It appears that he gained boost with headers. I only made 7.66 pounds with a smaller pulley then him and stock manifolds. We are a country mile apart and I dont get it.
I like the idea of headers as every car I have had has gained power but this is my first supercharged car. We all know that headers arent cheap so I am doing my best to educate myself to see what gains will be had.
Ported heads with GT9 cam go with 1 7/8 of the same quality headers
This way you keep the engine purring and you quench your thirst
06-10-2015, 05:45 AM
#40
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? Huh. You didn't respond back to the guys and you said no gains from headers. Let's stay out topic please...