Ideas on increasing power without losing ANY torque
07-30-2010, 03:40 PM
#1
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Ideas on increasing power without losing ANY torque I am trying to think of some parts that would increase the power a wee bit and not lose any torque on the low end. I am pulling a hard vacuum @ WOT, something like 95 kPa so I know I can loosen up the restrictions without loosing low end, but what have we for ideas?
Right now I am 375 lb-ft. @ 2500 RPMs and the power peaks around 5500. I am thinking a FAST 90 with some 1 3/4 LTs with a merged Y pipe. I don't want to open it up too much so I don't decrease velocity to keep the stellar torque, just reduce the choke on the top end.
408, -8cc dish pistons, stock 799 heads, 0.045 Cometic gasket for 11.5:1, MS4 installed 2* retarded, LS2 chain, Melling high volume pump, Mac Mid Headers, LS6 intake, ported TB, stock MAF, MTI Lid.
What do you think?
Edit: I am not opposed to going inside the engine, open to all ideas/theories/suggestions
Right now I am 375 lb-ft. @ 2500 RPMs and the power peaks around 5500. I am thinking a FAST 90 with some 1 3/4 LTs with a merged Y pipe. I don't want to open it up too much so I don't decrease velocity to keep the stellar torque, just reduce the choke on the top end.
408, -8cc dish pistons, stock 799 heads, 0.045 Cometic gasket for 11.5:1, MS4 installed 2* retarded, LS2 chain, Melling high volume pump, Mac Mid Headers, LS6 intake, ported TB, stock MAF, MTI Lid.
What do you think?
Edit: I am not opposed to going inside the engine, open to all ideas/theories/suggestions
Last edited by 1SLwLS1; 07-30-2010 at 03:48 PM.
07-30-2010, 05:43 PM
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Well, when I plan on matching the top end to the SB, I plan on doing lightly ported L92/LS3 heads with LS3 valves, FAST 102, Kooks 1 7/8 stepped to 2" with a flow merge y-pipe. At that point, I will probably ditch the MAF as I will beyond the 500+ power limit of the stock piece. Not sure if I would want to upgrade to a larger unit @ that point. I will talk with my tuner when the time comes and make an educated decision.
If I do all of that, I would figure that my low end torque would probably suffer a bit, move the peak higher and further down the range. So I am wondering if just a FAST 90 for cathedral ports, some cheap 1 3/4 LT's and properly built y pipe would only increase power, and not change the low end but for better.
Edit: Also maybe a quality ATI damner would help some.
If I do all of that, I would figure that my low end torque would probably suffer a bit, move the peak higher and further down the range. So I am wondering if just a FAST 90 for cathedral ports, some cheap 1 3/4 LT's and properly built y pipe would only increase power, and not change the low end but for better.
Edit: Also maybe a quality ATI damner would help some.
07-30-2010, 06:01 PM
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LOL, well yes in a few years, I wouldn't mind putting some evil 78mm twins on the front, but that is a ways down the road and I would like to maximize this setup for N/A first, as with my goals, it will be a wee bit cheaper.
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07-30-2010, 09:46 PM
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Its not that abnormal for a setup like that to make a ton of torque and be low on hp. Torque is created much lower in the rpm band with that cam than peak hp, the heads, intake and exhaust are choking the breathing up top so its no surprise that the hp numbers are less than stellar while torque is decent.
Id be looking into an intake, then maybe a set of PRC 2.5 5.3 heads if youre on a budget and want to keep your CR up where its at. Id also run a set of 1 7/8ths headers, they will increase your tq but with the addition of a better breathing top end you wont even notice any loss in tq. If I were a betting man Id say with the better top end and a larger primary header you would be over 500rwtq and up 70+hp.
Id be looking into an intake, then maybe a set of PRC 2.5 5.3 heads if youre on a budget and want to keep your CR up where its at. Id also run a set of 1 7/8ths headers, they will increase your tq but with the addition of a better breathing top end you wont even notice any loss in tq. If I were a betting man Id say with the better top end and a larger primary header you would be over 500rwtq and up 70+hp.
07-30-2010, 10:02 PM
#12
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What size cam?
Looks like to me and this is just going by your dyno graph.....
looks like someone advanced the sh*t out of your cam.... you have all of the symptoms of a cam either degree'd wrong or advanced too much.... I hope you were not an experiment or they took the time to install and degree it properly... But cam companies have been known to make mistakes too....
Look at your torque , it peaked around 3900 and the power just died off...
At 5500-5700 your motor was done.........
I have seen something like this before when a guy tried to do a 113 + 6 or 8 and when a cam was advanced and not installed correctly....
Looks like to me and this is just going by your dyno graph.....
looks like someone advanced the sh*t out of your cam.... you have all of the symptoms of a cam either degree'd wrong or advanced too much.... I hope you were not an experiment or they took the time to install and degree it properly... But cam companies have been known to make mistakes too....
Look at your torque , it peaked around 3900 and the power just died off...
At 5500-5700 your motor was done.........
I have seen something like this before when a guy tried to do a 113 + 6 or 8 and when a cam was advanced and not installed correctly....
07-30-2010, 10:24 PM
#13
I am surprise your car has such a low hp peak considering the cam size. Just looking at the graph, I would say cam up and add some 4.10 gears to deliver more torque to the rear wheels.
Ah, just saw where you said you were pulling a vacuum at higher RPM. Sounds like you need the new FAST set up.
Ah, just saw where you said you were pulling a vacuum at higher RPM. Sounds like you need the new FAST set up.
07-30-2010, 10:26 PM
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Its not rocket science, 408 cubes trying to breathe through a straw(stock 799s, stock intake) and then having to exhale through a coffee stir stick(mid headers).
07-30-2010, 10:34 PM
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Its not that abnormal for a setup like that to make a ton of torque and be low on hp. Torque is created much lower in the rpm band with that cam than peak hp, the heads, intake and exhaust are choking the breathing up top so its no surprise that the hp numbers are less than stellar while torque is decent.
Id be looking into an intake, then maybe a set of PRC 2.5 5.3 heads if youre on a budget and want to keep your CR up where its at. Id also run a set of 1 7/8ths headers, they will increase your tq but with the addition of a better breathing top end you wont even notice any loss in tq. If I were a betting man Id say with the better top end and a larger primary header you would be over 500rwtq and up 70+hp.
Id be looking into an intake, then maybe a set of PRC 2.5 5.3 heads if youre on a budget and want to keep your CR up where its at. Id also run a set of 1 7/8ths headers, they will increase your tq but with the addition of a better breathing top end you wont even notice any loss in tq. If I were a betting man Id say with the better top end and a larger primary header you would be over 500rwtq and up 70+hp.
What size cam?
Looks like to me and this is just going by your dyno graph.....
looks like someone advanced the sh*t out of your cam.... you have all of the symptoms of a cam either degree'd wrong or advanced too much.... I hope you were not an experiment or they took the time to install and degree it properly... But cam companies have been known to make mistakes too....
Look at your torque , it peaked around 3900 and the power just died off...
At 5500-5700 your motor was done.........
I have seen something like this before when a guy tried to do a 113 + 6 or 8 and when a cam was advanced and not installed correctly....
Looks like to me and this is just going by your dyno graph.....
looks like someone advanced the sh*t out of your cam.... you have all of the symptoms of a cam either degree'd wrong or advanced too much.... I hope you were not an experiment or they took the time to install and degree it properly... But cam companies have been known to make mistakes too....
Look at your torque , it peaked around 3900 and the power just died off...
At 5500-5700 your motor was done.........
I have seen something like this before when a guy tried to do a 113 + 6 or 8 and when a cam was advanced and not installed correctly....
Yea, but it can only attain that peak if it can maximize the relationship between velocity and flow. 4.10s are out of the question. The highest rear gear I will ever go will be 3.73. I don't want to get stuck in the 120 MPH range in 4th screaming across the line banging off of the limiter. This is of course with future mods. If I to end up going twin 78s or something, the 3.42s will stay.
07-30-2010, 11:00 PM
#16
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Just think about whats actually going on when you reach the peak
The exhaust stroke is unable to get as much exhaust gas out of the cylinder and some exhaust gas is left in when the intake valve opens, in excess of the normal left there.The cylinder has some residual exhaust gas in it, and can not accept the normal amount of fresh air/gas mixture. When the motor reaches a point where it fails to fill the cylinder with fresh air and is combined with the left over exhaust gas.... And the motors ability to excuvate the exhaust gas has diminished.......
the 1 3/4 headers would not choke your motor to 5500rpms...
With the cam retarded 2*, your power curve does not exhibit a cam that is retarded..... 111 to a 113 and your motor is done by 5500? Something is not right
07-31-2010, 12:26 AM
#17
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WTF exactly......
Just think about whats actually going on when you reach the peak
The exhaust stroke is unable to get as much exhaust gas out of the cylinder and some exhaust gas is left in when the intake valve opens, in excess of the normal left there.The cylinder has some residual exhaust gas in it, and can not accept the normal amount of fresh air/gas mixture. When the motor reaches a point where it fails to fill the cylinder with fresh air and is combined with the left over exhaust gas.... And the motors ability to excuvate the exhaust gas has diminished.......
the 1 3/4 headers would not choke your motor to 5500rpms...
With the cam retarded 2*, your power curve does not exhibit a cam that is retarded..... 111 to a 113 and your motor is done by 5500? Something is not right
Just think about whats actually going on when you reach the peak
The exhaust stroke is unable to get as much exhaust gas out of the cylinder and some exhaust gas is left in when the intake valve opens, in excess of the normal left there.The cylinder has some residual exhaust gas in it, and can not accept the normal amount of fresh air/gas mixture. When the motor reaches a point where it fails to fill the cylinder with fresh air and is combined with the left over exhaust gas.... And the motors ability to excuvate the exhaust gas has diminished.......
the 1 3/4 headers would not choke your motor to 5500rpms...
With the cam retarded 2*, your power curve does not exhibit a cam that is retarded..... 111 to a 113 and your motor is done by 5500? Something is not right
You would be 100% correct with your notion if we had a comparison of my setup with straight up and 2* advanced. We don't though, and those items just cannot allow the 4.030 bore and 4.000 stroke to get the air it needs @ those RPMs. It makes perfect sense to me.
07-31-2010, 07:31 AM
#18
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I understand that you are secure with your builder, but I am going to side on physics and you can interpret what you want bro......
The LS6 intake, and those heads and TB are not the quote on quote optimal for a 408ci motor for building top end power, but there would not be enough of a restriction to make your motor tap out at 5500rpms...... Those are tune related and timing events related........
1 3/4 headers are sufficient and the LS6 intake has worked on motors that have been turned up to 6000+ EASY......
Its rare to see a engine peak torque so early, and peak power so early...... without it being a camshaft timing issue involved... I think even if you bought all of the other stufff you will still be dissapointed.....
The LS6 intake, and those heads and TB are not the quote on quote optimal for a 408ci motor for building top end power, but there would not be enough of a restriction to make your motor tap out at 5500rpms...... Those are tune related and timing events related........
1 3/4 headers are sufficient and the LS6 intake has worked on motors that have been turned up to 6000+ EASY......
Its rare to see a engine peak torque so early, and peak power so early...... without it being a camshaft timing issue involved... I think even if you bought all of the other stufff you will still be dissapointed.....
07-31-2010, 09:02 AM
#19
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Alright keyboard warrior, besides the fact that I have years of experience with these engines, youre questioning one of THE top lsx engine builders in the world. Anyone with any experience in engines can see exactly what is going on.
Are your valve reliefs cut for L92 valves? Youre going to have to mill a good chunk off to get the CR where youre currently at...
Are your valve reliefs cut for L92 valves? Youre going to have to mill a good chunk off to get the CR where youre currently at...
07-31-2010, 10:13 AM
#20
Alright keyboard warrior, besides the fact that I have years of experience with these engines, youre questioning one of THE top lsx engine builders in the world. Anyone with any experience in engines can see exactly what is going on.
Are your valve reliefs cut for L92 valves? Youre going to have to mill a good chunk off to get the CR where youre currently at...
Are your valve reliefs cut for L92 valves? Youre going to have to mill a good chunk off to get the CR where youre currently at...
Like everyone had stated, it needs to get more air in, 370 engines are making more horsepower and this one is revving like its a stock 6.0L truck engine.
Overall just a bad combination of parts.
Go find Kevins (WKMCD screen name) old thread about L92's on a 408 with 521 RWHP and great driveability.