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There was a time I was curious what the truck I had would put down, on average (2004 5.3 truck). When I went looking around numbers were all over the map so it's just been a thing ever since.
The 5.3s respond better with a mild cam than a 5.7 I think it's because there stock cam is milder in the 5.3 so looks like a bigger difference and also a few less cubes makes them respond better.
The 5.3s respond better with a mild cam than a 5.7 I think it's because there stock cam is milder in the 5.3 so looks like a bigger difference and also a few less cubes makes them respond better.
Not really. If you compare the cam size to the engine size, you'd see it's the same deal.
The 5.3 uses a 190 degree intake duration cam, the 5.7 uses a 197 degree for the later LS1
One of the cam suppliers say on their website (is it Isky??) say for every 50 cid in cubic inches increase for 2 valve V8 you have to increase duration by 10 degrees to get the same effect in RPM range, how that translates to HP apples to apples I don't know but I'm sure it does have an effect. This cam in link would only make about 35 rwhp in a LS1 not 60 plus hp as in this 5.3. I've looked at countless dyno averages to confirm it and from own experience with a mild cam in my own LS1.
Isnt this same reason people put bigger cam in a 383 stroker? of course that is on the more extreme end of the scale.
One of the cam suppliers say on their website (is it Isky??) say for every 50 cid in cubic inches increase for 2 valve V8 you have to increase duration by 10 degrees to get the same effect in RPM range, how that translates to HP apples to apples I don't know but I'm sure it does have an effect. This cam in link would only make about 35 rwhp in a LS1 not 60 plus hp as in this 5.3. I've looked at countless dyno averages to confirm it and from own experience with a mild cam in my own LS1.
Isnt this same reason people put bigger cam in a 383 stroker? of course that is on the more extreme end of the scale.
Here is a graph that says similar
That 216 cam in a 5.3 is an increase of 26 degrees cam timing. That's the same as putting a 223-228 cam in an LS1, the LS1 would gain 60 also.
Of course if add 26 degrees cam timing to one motor and only 14 or so on another, the gains will be higher on the one you added 26 to..
You originally said the 5.3 responds better to a mild cam than a 5.7 does. Well a cam that's mild for a 5.3 IS NOT mild for a 5.7, it's smaller than a baby cam for a 5.7
If your point is that a 216 duration cam will make a larger increase in a 5.3 than it would in a 5.7, then duh, of course it would. You gave the 5.3 way more of an increase in cam than the 5.7. That's the polar opposite of apples to apples.
Back on topic. Sorry for getting off track.
Last edited by 00pooterSS; 03-25-2020 at 09:40 PM.
That's right, I meant 50 cid more total engine displacement, graph is per cylinder, so if I had a cam in a 5.3 I would go 10 degrees duration more if I wanted a cam to behave in the same way in a 6.0 litre (close to 50 cid difference), maybe just a tad less?? This was from a reputable source just can't find the link now. Even more if it was a 383.
Quote If your point is that a 216 duration cam will make a larger increase in a 5.3 than it would in a 5.7, then duh, of course it would. You gave the 5.3 way more of an increase in cam than the 5.7. That's the polar opposite of apples to apples.
That's my point you got it,
From what I've seen there's nearly twice as much increase in HP out of the same mild 216 cam in a 5.3. compaired to a LS1.
But is the difference here is greater partly because the baseline is lower because the 5.3 often has a milder stock cam?
Then I see yours with good info making 250 exhaust only and the loop of wtf just started all over again lol.
I apologize for clogging up your thread. I'm just going to take the info you provided as the right info and run with this..... 210-220 ish stock. 250 bolt ons, maybe 270 full bolt ons and tune for gen 3-4 5.3 trucks. And I'm assuming with full bolt ons a good tune 93 octane and light wheels they can do as high as 300
And then of course your cammed numbers. Thank you for the testing and info, I've been wondering for a while what these things do when solid information is provided.[/QUOTE]
The biggest thing to keep in mind is its a dyno. They are a useful tool. Nothing more or less. Ive owned 2 different dyno's in the past. I was unhappy with both of them. It was hard to reproduce numbers. Hard to get loads accurate. So After I sold my last one I swore not to use them for anything more than if a customer really wanted me to. If a car gets driven on the street. I prefer to street tune it. If its a race car I use the dyno to get it as close as we can and then track test it.
Anyways, this DIMSPORT that Diesel Freak bought. Although quirky in its own way as far as layout etc Is the best dyno I have ever used. It is the only dyno that will do the same thing all day long if you dont change anything. It seems to be fairly accurate and every vehicle Ive ever tuned on it. Ive guessed a nice ballpark number.
I just picked up the stuff from the machine shop yesterday for the engine Im putting in the truck. I didnt plan to dyno it but if you guys would like me to I can.
3.903 bore 4cc dome's, gen 4 rods, ls1 crankshaft, balanced.
Btr 235/242 111 "stage 4" ls1 car cam, oem ls7's, .660 springs/titanium ret.
Tea 243's with oem valve size.
Using the oem truck intake still and a 4,200 stall converter though.
03-25-2020, 05:00 PM
