wannafbody

iTrader: (2)

One thing that needs to be considered is that an auto drag car is a different animal than a manual street car. An auto can have a converter change and is right in the power band. A dyno only reads from 2500 or 3000 up. For a manual street car, the clutch is released and the car might start at 1000 rpm. A big runner with an oversized valve will be a dog at lower rpm. That's where velocity plays a role and that isn't shown on a dyno graph.

I think the answer also lies in the fact that the smaller cam made more torque. So the right cam is more important than just slapping in a large cam and the largest valved head. It's about the combo. So many people think the larger cam will magically make more power than a smaller cam. "What size cam threads" on facebook and so many people are saying Stage 4 or MS4 cam with stock 241 heads, LOL.

G Atsma

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Boom. WORD....

stevieturbo

A Dyno reads wherever the dyno operator sets it up and runs the motor. They could easily set it up to run from 1000rpm.

Although it'd take a very bad combo on any LS to still be a dog even at 1000rpm.

Jtm2085

iTrader: (1)

I see the point that you're trying to make, but I'VW never understood it. Who cars what kind of power the car makes at 1-2000 rpms? If I'm racing or even leaving a red light aggressively, the car will never see 2k rpm .

G Atsma

If you're leaving a red light, aggressively or not, you still need to get from idle to above 2k RPM. If it bogs in that zone, it matters...

stevieturbo

You need to rev to 2k go get away from a stop ?

LilJayV10

iTrader: (39)

because racecar.

G Atsma

Not my point. You're idling, then starting out. All under 2k RPM, which didn't seem to matter above...

Darth_V8r

iTrader: (4)

This has no bearing on the thread but I love the sig pic of your skylark launching. Caryy on...

SLOW SEDAN

iTrader: (13)

True, I think a lot of people forgot how to drive a manual! If theres even a hint of a race it can easily be over 3k rpm. Some people on here talk like they lug their car around under 1500rpm all the time and try to save 1MPG, no idea why they are on a performance car forum.

If your car bogs at all with any setup you are doing it wrong. More likely to be a tune problem then a hard part.

G Atsma

You have to agree that there are some combos that are useless under 2k RPM.
Someone stated above that anything under 2k is not seen, as if the engine never operates there. Which is, of course, ridiculous.

G Atsma

This is what I am referring to in my reply to SLOWSEDAN.

SLOW SEDAN

iTrader: (13)

Which ones, have an example? I could see a 4.8L in a 2500 on 40" tires with a glide and stock diff being a dog, but most cars accelerate just fine if properly setup.

You said bog which is a specific term defining a problem. If an engine bogs you have a problem, but if the engine just doesn't have enough power to satisfy you then that's another thing.

Useless is a subjective term as the need for low end power can be directly related to how heavy a vehicle is, how its geared, what size tire your turning, etc.

G Atsma

I think we're losing track of my point. How can you leave from a stop (red light or stop sign) without the engine going below 2k RPM? That is all I was really getting at. Kinda got sideways.

ddnspider

iTrader: (26)

Slow is saying if you're going to race from a stop you're going to rev higher than 2k and launch, not leave the light at idle. You're saying the opposite, that you would be at idle blipping the throttle wanting something snappy off idle.

SLOW SEDAN

iTrader: (13)

With a manual you press gas to desired RPM before releasing clutch, with an auto you press brake and use gas to stall it up to however high it will let you go. I figured everyone knew that...

Yup, pretty much anyone racing doesn't leave off idle, unless they are very familiar with losing!

Jtm2085

iTrader: (1)

This is what I was getting at.

tech@WS6store

iTrader: (2)

The main issue with the "ls3 heads dont make tq" has been overlooked.
Most use these on much smaller cid engines and much smaller bores. Usually they put them on a 4.000 or 4.005 bore and poke em with a stick and expect them to make power. Even on ls3s same way. They are lazy down low because the airflow demand hasnt met the cylinder head sweet spot yet. Its the same as putting a 23xcc + cathedral head on an ls1. Its gonna be soggy down low.

Adding the stroke helped the torque in both situations. Real world comparison is 4.8 vs 5.3.
It always will when you target the same cr. But you cant with an SBE which is what most people do. Theyll put em on an lq4 because thats what the internet says and expect them to make all the horsepeppers and the tq. You can't mill an ls3 head to 58cc and make it work with any cam on an sbe 6.0 or 6.2. Thats 10cc off which is nearly .060 off. Thats a helluva lot and way more than i would ever do on something like that.
Obviously he wouldnt have to if he didnt use such a huge dished piston, but the cr were nearly the same based off what he said and calculated.

I also believe if that rect port cam had less lsa it would have made even more power down low and still peaked at the odd 5900-6100 mark he said. The main issue that was asked is, why 5900-6100 peak? Even with the ls3 intake and the fast 92 both ported to 95mm. Maybe it was the lid. Maybe it was the fuel pressure dropping or weak coils or just not enough of the keys touched on the keyboard.
He didnt post any of that info and we definitely wouldn't get to see the WOT scan to check timing and map pressure battery voltage etc anyway so that wont help.
The smaller cam beat the larger cam exactly how youd expect when the bigger cammed setup couldn't rpm like it should. It happens too often on the street like that and with such an early peak that original cam had no room to spread its legs.
Its a good before and after but nowhere near a direct comparison. The larger bore helped but as someone else said, put it on an sbe 6.0 and see what happens.

And as far as the dyno video, those are always too predictable to give them any merit.

psicko

They don't and 460tq out of a 416ci engine is certainly not proving otherwise.