5.3L Truck Motor Cam-only
03-20-2013, 04:50 PM
#41
The intake and heads are different for the LS1 vs the LS2. I assume you would have specified if any of that was aftermarket or changed. The LS1 actually looks to be peaking sooner. Most likely due to the more restrictive heads and intake. I think this would be more exaggerated by larger cams as in this case where the intake and head combos are the restricting factor in the upper RPM ranges.
03-20-2013, 05:15 PM
#42
The intake and heads are different for the LS1 vs the LS2. I assume you would have specified if any of that was aftermarket or changed. The LS1 actually looks to be peaking sooner. Most likely due to the more restrictive heads and intake. I think this would be more exaggerated by larger cams as in this case where the intake and head combos are the restricting factor in the upper RPM ranges.
The LS1/LS6/LS2/LS3/L76/L99 ALL have the same runner length meaning that if you swapped them all around on different engines with the same variables and the only difference being the intake and could make the different cathedral versus square ports fit, that they would all peak at the same RPM because the runner length hasn't changed. I've measured them all. The only different runner length plastic OEM intake is a LS7 intake. The intakes are the same, no difference between a LS6 intake and a LS2 intake other than a throttle body which will not change peak power. Bolt ons like throttle bodies, headers and exhaust will not change peak power rpm.
I also said in my post that the LS1 was peaking sooner, are you reading my posts backwards?
03-20-2013, 05:58 PM
#44
Besides if you missed what I said, the LS2 and LS6 intake are the same runner length, the same runner dimensions and same plenum volume. I have measured them all myself. Every single plastic intake available for a LS engine I have measured. I have also measured the various single plane intakes aside from the All Pro single plane. I've also got dimensions on the Pro-Flo from Edelbrock. Haven't measured a Hi-ram though.
The only difference between that blue line and red line is 3.898" bore vs. 4.0" bore, 10cc in average port volume and 2 degree later EVC event on the LS2 engine.
03-20-2013, 06:11 PM
#45
While each of those intakes may have the same volume, I think I have seen test before that show they flow differently. Same with the heads. Along with that 10cc difference is how much flow difference? 15-20 cfm? That has to have an effect on where peak power occurs.
I will says though, as I have several times, I think the LS long runner intakes homogenize the results. I think the variation on an LS engine with good flowing heads and an open plenum intake will show a much greater variation in power curves as the displacement changes. For most people on this site, this will surely validate your claims that the displacement is not that crucial in relation to the power curve, but us carb guys may see different characteristics.
I will says though, as I have several times, I think the LS long runner intakes homogenize the results. I think the variation on an LS engine with good flowing heads and an open plenum intake will show a much greater variation in power curves as the displacement changes. For most people on this site, this will surely validate your claims that the displacement is not that crucial in relation to the power curve, but us carb guys may see different characteristics.
03-21-2013, 07:35 AM
#46
While each of those intakes may have the same volume, I think I have seen test before that show they flow differently. Same with the heads. Along with that 10cc difference is how much flow difference? 15-20 cfm? That has to have an effect on where peak power occurs.
I will says though, as I have several times, I think the LS long runner intakes homogenize the results. I think the variation on an LS engine with good flowing heads and an open plenum intake will show a much greater variation in power curves as the displacement changes. For most people on this site, this will surely validate your claims that the displacement is not that crucial in relation to the power curve, but us carb guys may see different characteristics.
I will says though, as I have several times, I think the LS long runner intakes homogenize the results. I think the variation on an LS engine with good flowing heads and an open plenum intake will show a much greater variation in power curves as the displacement changes. For most people on this site, this will surely validate your claims that the displacement is not that crucial in relation to the power curve, but us carb guys may see different characteristics.
Now, increased or decreased head flow does coincide with cross sectional area and how small or large that port is and the size of the intake/exhaust valve. Cross sectional area of the cylinder heads intake and exhaust runners, intake valve size and runner/port length are the main factors that will determine where an engine peaks in regards to RPM , along with stroke and rod length of the particular engine.
I'm not saying that displacement isn't crucial in relation to the power curve. It is extremely crucial to where power will peak. What I'm saying is that what makes up that displacement and how you arrive at that displacement is what is crucial. For a given rod and stroke length, bore does not have the influence that you would think on where power peaks in regards to RPM. It will add or subtract power, it will add or subtract vacuum and it will add or subtract drivability, but the affect on peak power RPM is negligible. Maybe if you went from something ridiculous like a 2.0" bore with a 4.0" stroke and 6.0" rod to a 4.0" bore with a 4.0" stroke and a 6.0" rod would show a discernible difference.
The only reason I posted that Polluter V.2 112lsa VS. Polluter V.2 111LSA was to show you that even with the same cam and same valve events aside from exhaust events(2.0 degree difference) that a 3.898" bore 346 cubic inch engine actually peaked earlier than a larger 4.0" bore 364 cubic inch engine with the same cam.
I think I've passed along some great information in this thread so I'll leave it at that.
Last edited by Sales@Tick; 03-21-2013 at 08:15 AM.
03-22-2013, 10:46 AM
#50
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Those dyno numbers just about confirms what I figured my car was putting down for power. 80k mile 5.3L with an MS3 cam, LS6 intake, 1 7/8 dynatech headers and 3" exhaust with a TH350. On motor my best was an 11.40 @ 118 and most calculators put it around 400 flywheel HP or 340-360RWHP range after drive train loss. 3125lb car.
My car with the above engine and 200 shot.
My car with the above engine and 200 shot.
03-25-2013, 02:06 PM
#54
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I was going to do a second stage but I hurt it a couple weeks later after a nasty lean spike on launch. So now the car is down for a cage and putting a PT88 in there to feed it.
03-25-2013, 11:06 PM
#56
Sorry, been slammed at work and working on the new house.
02 ls6 cam
Curious what your finding are when it is the same inches, 346 to 347 but a rod change from 3.098 to 3.125. What happens with the longer rod (.027") yet same top end(intake/heads/cam..
