TFS 245 vs. TFS 260
03-18-2019, 08:36 PM
#201
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Originally Posted by Floorman279
im doing ls7 heads with the ported msd.......just starting out with a stock ls7 since they are dirt and can save 1500 that i can swap out later......
I think you will be quite happy with your new motor.
03-19-2019, 09:25 AM
#203
Just breath as you would a human is my motto. Would you put a muzzel on Usain Bolt? From 3 great porters noticed heads flowing 420's that are a typical cnc program 1 was called a smaller port at 290cc. Heads don't controll anything but where a mixture is placed in the bore. If you blow thru a straw to push a ping pong ball you would want a straw that is what size to be most effective? Same thing goes for a engine. lungs = cam 2) throat = induction 3) straw = heads 4) ball = piston. The straw tell us how much lung & throat'' size is needed (or can be used) to be effective no matter the ball size. Your legs are the gears 4.56's for sprints, while 3.42's are used for longer runs. Why does everyone say it's alive?
Because It's Breathing!
Because It's Breathing!
Last edited by Smokey B; 03-19-2019 at 09:34 AM.
03-19-2019, 02:43 PM
#204
TECH Senior Member
What you smokin' lately Patron? I mean Smokey?
03-19-2019, 03:21 PM
#206
TECH Senior Member
03-19-2019, 05:07 PM
#207
see but my question is this, super advanced so stay with me lol, and this is a legit question.
if you built lets just say a 454, no wait one of those super air demanding 468. motor with the biggest donkey cam you could find, and built it to be reveed it to 8000, and it had stock LS7 heads with a stock ls7 intake. the ls7 intake clearly is nowhere near the amount of airflow for that, same with the heads, but we could still guess it would make lets just say 650 flywheel....sound fair? now i can guarantee you that if you put say a ported ls7 head on there, are you telling me that it wont gain hp and torque? of course it would, but wait, the ls7 intake is choking it...... shouldn't it not make anymore since the intake isn't allowing it any air? so if the ls7 intake truly is the limiting factor, then no matter what head you put on it, weather a stock ls7, a ported ls7, or some 305CC mast heads, that motor still wont make more than 650 hp......which we know isn't true.....but obviously it wont make amazing power like it should.
if you built lets just say a 454, no wait one of those super air demanding 468. motor with the biggest donkey cam you could find, and built it to be reveed it to 8000, and it had stock LS7 heads with a stock ls7 intake. the ls7 intake clearly is nowhere near the amount of airflow for that, same with the heads, but we could still guess it would make lets just say 650 flywheel....sound fair? now i can guarantee you that if you put say a ported ls7 head on there, are you telling me that it wont gain hp and torque? of course it would, but wait, the ls7 intake is choking it...... shouldn't it not make anymore since the intake isn't allowing it any air? so if the ls7 intake truly is the limiting factor, then no matter what head you put on it, weather a stock ls7, a ported ls7, or some 305CC mast heads, that motor still wont make more than 650 hp......which we know isn't true.....but obviously it wont make amazing power like it should.
03-19-2019, 05:45 PM
#208
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Interesting thought experiment... I think it results in a LS1Tech thread entitled - "468 Ported Heads Gained Torque Lost RPM But Same Horse Power WTF?", 43 posts (+/- 5) advising the OP to get a better intake, and 16 posts recommending aftermarket heads, and possibly (60% chance) a cathedral vs rectangle argument.
I think your hypothetical 468 gains peak torque by raising VE before the intake runs out of breath, but makes the same peak HP (within the percent error of measurement) just at a lower RPM. Peak HP fundamentally being the amount of air the entire assembly (intake, engine, exhaust) can flow.
For the intake to be choking the motor, how would you be able to tell? My vote would be to look at the MAP readings at WOT vs ambient. If you are pulling a vacuum at WOT, you are over-scavenging the intake, reducing the VE of the entire combination. I actually have a real world data point for this. I ran my current 428 with the stock LS7 intake temporarily to get it running. With the LLSR and ported heads. MAP at WOT was 90 KPa vs 101 ambient (KOEO). Now, let's say we swap the cam for a super-uber cam as suggested or we get the LSR 500 CFM heads from RFD on there (because why not?). Well the intake is already maxed out at high RPM, so what I suspect it will do is pull an even deeper vacuum at WOT, because the engine is now trying to move even more air than what is available. I predict it makes the same peak HP, but at a lower RPM due to the higher torque curve and falling faster past peak torque.
So, if your intake MAP is matching ambient and you add a bigger cam or bigger heads, then yes, you should make more power and I agree with the thought experiment. but if your intake is already over-scavenged I doubt it makes any more power -- just pulls a deeper vacuum. Especially with a 468 and a big cam even with stock LS7 heads, I think it is safe to assume you'd be pulling vacuum at WOT.
I think your hypothetical 468 gains peak torque by raising VE before the intake runs out of breath, but makes the same peak HP (within the percent error of measurement) just at a lower RPM. Peak HP fundamentally being the amount of air the entire assembly (intake, engine, exhaust) can flow.
For the intake to be choking the motor, how would you be able to tell? My vote would be to look at the MAP readings at WOT vs ambient. If you are pulling a vacuum at WOT, you are over-scavenging the intake, reducing the VE of the entire combination. I actually have a real world data point for this. I ran my current 428 with the stock LS7 intake temporarily to get it running. With the LLSR and ported heads. MAP at WOT was 90 KPa vs 101 ambient (KOEO). Now, let's say we swap the cam for a super-uber cam as suggested or we get the LSR 500 CFM heads from RFD on there (because why not?). Well the intake is already maxed out at high RPM, so what I suspect it will do is pull an even deeper vacuum at WOT, because the engine is now trying to move even more air than what is available. I predict it makes the same peak HP, but at a lower RPM due to the higher torque curve and falling faster past peak torque.
So, if your intake MAP is matching ambient and you add a bigger cam or bigger heads, then yes, you should make more power and I agree with the thought experiment. but if your intake is already over-scavenged I doubt it makes any more power -- just pulls a deeper vacuum. Especially with a 468 and a big cam even with stock LS7 heads, I think it is safe to assume you'd be pulling vacuum at WOT.
03-19-2019, 06:52 PM
#210
Interesting thought experiment... I think it results in a LS1Tech thread entitled - "468 Ported Heads Gained Torque Lost RPM But Same Horse Power WTF?", 43 posts (+/- 5) advising the OP to get a better intake, and 16 posts recommending aftermarket heads, and possibly (60% chance) a cathedral vs rectangle argument.
I think your hypothetical 468 gains peak torque by raising VE before the intake runs out of breath, but makes the same peak HP (within the percent error of measurement) just at a lower RPM. Peak HP fundamentally being the amount of air the entire assembly (intake, engine, exhaust) can flow.
For the intake to be choking the motor, how would you be able to tell? My vote would be to look at the MAP readings at WOT vs ambient. If you are pulling a vacuum at WOT, you are over-scavenging the intake, reducing the VE of the entire combination. I actually have a real world data point for this. I ran my current 428 with the stock LS7 intake temporarily to get it running. With the LLSR and ported heads. MAP at WOT was 90 KPa vs 101 ambient (KOEO). Now, let's say we swap the cam for a super-uber cam as suggested or we get the LSR 500 CFM heads from RFD on there (because why not?). Well the intake is already maxed out at high RPM, so what I suspect it will do is pull an even deeper vacuum at WOT, because the engine is now trying to move even more air than what is available. I predict it makes the same peak HP, but at a lower RPM due to the higher torque curve and falling faster past peak torque.
So, if your intake MAP is matching ambient and you add a bigger cam or bigger heads, then yes, you should make more power and I agree with the thought experiment. but if your intake is already over-scavenged I doubt it makes any more power -- just pulls a deeper vacuum. Especially with a 468 and a big cam even with stock LS7 heads, I think it is safe to assume you'd be pulling vacuum at WOT.
I think your hypothetical 468 gains peak torque by raising VE before the intake runs out of breath, but makes the same peak HP (within the percent error of measurement) just at a lower RPM. Peak HP fundamentally being the amount of air the entire assembly (intake, engine, exhaust) can flow.
For the intake to be choking the motor, how would you be able to tell? My vote would be to look at the MAP readings at WOT vs ambient. If you are pulling a vacuum at WOT, you are over-scavenging the intake, reducing the VE of the entire combination. I actually have a real world data point for this. I ran my current 428 with the stock LS7 intake temporarily to get it running. With the LLSR and ported heads. MAP at WOT was 90 KPa vs 101 ambient (KOEO). Now, let's say we swap the cam for a super-uber cam as suggested or we get the LSR 500 CFM heads from RFD on there (because why not?). Well the intake is already maxed out at high RPM, so what I suspect it will do is pull an even deeper vacuum at WOT, because the engine is now trying to move even more air than what is available. I predict it makes the same peak HP, but at a lower RPM due to the higher torque curve and falling faster past peak torque.
So, if your intake MAP is matching ambient and you add a bigger cam or bigger heads, then yes, you should make more power and I agree with the thought experiment. but if your intake is already over-scavenged I doubt it makes any more power -- just pulls a deeper vacuum. Especially with a 468 and a big cam even with stock LS7 heads, I think it is safe to assume you'd be pulling vacuum at WOT.
03-19-2019, 07:45 PM
#211
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Correct sniper not pulling vacuum at wot
03-20-2019, 09:10 AM
#214
10 Second Club
Well I myself thought a mid runner fast was capable of feeding my LS3. Dyno says it was the choke point. We swapped to the X1 LOD speedworks intake and nothing else (tune untouched) and gained 46 rwhp back to back.
03-20-2019, 09:54 AM
#216
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I guess another way to do it would be another map sensor in in the intake tract pre-throttle...?
03-20-2019, 10:07 AM
#217
10 Second Club
03-20-2019, 10:46 AM
#218
If we wanted to test it how would we? Put a TB Spacer and 90mm throttle on a 100mm sniper and check MAP readings vs 102mm throttle? If I had a 90mm mechanical throttle i'd be willing to do it. I can tell you the stock ls7 intake plus TB spacer with a 102 throttle had 90 KPa at WOT. But the throat of the stock intake is 90mm, so I know the 102 was really no better than a 90 for that purpose. it was a stop-gap measure to get the car running. I knew I'd be running a 102, so I didn't bother buying a 90mm throttle.
I guess another way to do it would be another map sensor in in the intake tract pre-throttle...?
I guess another way to do it would be another map sensor in in the intake tract pre-throttle...?
I think the important thing to look at in the manifolds though is whether or not the throttle area is the restriction or the runner size.
Last edited by KCS; 03-20-2019 at 11:08 AM.
03-20-2019, 10:48 AM
#219
10 Second Club
A true test would have to be swapping just throttle bodies and then back again, or if you use a spacer with the 90mm, you would need to use one with the 102mm. I’m pretty sure this has all heen done already so I don’t think anyone teally needs to test it again.
I think the important thing to look at in the manifokds though is whether or not the throttle area is the restriction or the runner size.
03-20-2019, 11:06 AM
#220
Big difference in the area just after the throttle body though. The LOD has the throttle body flange much further out front and has a nice gradual transition to the plenum. The FAST does not. It has a very abrupt transition into the plenum, which can effectively reduce the throttle body area by vena contracta.