I'm trying to tune an LSx engine for maximum power at no more than 3000 RPM. To effectively capture the best intake resonance in an off the shelf part, I need to know what is available. I'm wondering if anyone has compliled a comparison of all available intakes from the 4.8 on up. Calculating the optimal intake length for a given RPM is pretty easy, but without having access to loads of stock intakes to measure like some of you have, it makes it tough to go to the junk yard and grab the right one.

Anyone have the raw data available somewhere?

Thanks,

Mike

 

You did mean max power, not max torque at 3000, right?

So what length (valve to plenum) did you come up with? What harmonic are you using?

Jon

 

I haven't done the math yet. Just "shopping" for data at this point.

 

Max power at 3000RPM? Why?

This might be what you're looking for.

http://www.smokemup.com/tech/ls1.php

 

Yea... power or torque?

Packaging should be interesting for this proposed intake, again depending on the harmonic

 

Something near 1 meter (valve to plenum) perhaps?

 

Well, on seat valve timing is important, and I don't have a cam selected. So what I'm looking for is the selection of stock intakes to see which one will be "closest" to ideal. Obviously a first order harmonic would require an intake runner that is like 12 feet long, so I'll be looking for a fraction of that.

The chart provided by ZMX has great info (thanks), but looks to be missing the truck intakes. I suspect they are longer, and if so, may fall right into phase.

And yes, the engine will be limited to 3000 RPM, so I need as much work (power) as I can get out of it down that low. If I could do better than 300 HP I'd be thrilled.

 

12 feet? What calcs do you use? I get just about 1 meter, as mentioned. With any LS manifold I've seen you will be working on the 3rd or 4th harmonic. The truck intakes aren't all that different in runner length, from what I've seen (but not measured). The 5.0L Daytona Prototype LS engines used the 90mm truck intake (before the FAST 102 R/T) and made power at 7000. It was slightly better than the LS6 intake in their 4500-7000 working range. My guess is that the straighter runners helped as much as anything over the LS6.

300 hp @3000 is 525 lb-ft. That's pretty stout for a 364 cube LS engine. You might do it with 400+ cubes. In this case bigger is better.

It would be interesting to see what heads the "gurus" recommend.


Jon

 

The 12 feet figure was just going from my memory – it related to a calculator I found concerning the old Dodge Max Wedge engine, but the main point was, I’m never going to be able to use the first order harmonic – 1 meter might as well be 100.
However, if the truck intakes are not all that much longer than the car versions, that’s good to know. They certainly look longer!
Also, I recognize that 300HP @ 3000RPM is asking a lot. I fully expect to use the 4 inch crank to help get me there (or at least close).

Thanks for the input!

 

what's the application?

 

What is the application? Is the 3000 rpm limit imposed by something like a propellor? Do you require an aluminum block for the "vehicle"?

Have you considerd a ~500 cube BBC? You only need to make 1.06 lb-ft per cube for a 496 or 160 psi BMEP. You should be able to do that fairly easily.

A 418 LS is going to need to make about 1.26 lb-ft/cube or about 190 psi BMEP. That's still doable.


Jon

 

At the risk of thread drift:



http://www.youtube.com/watch?v=7aVCo...layer_embedded

BBC is just too big and heavy for the application. Besides, this is a feasibility exercise. I'm looking to see just what the LSx can give - not hit a specific target. It will either be "good enough" or it won't.

 

http://www.worldcastings.com/product...um-block-.html

 

That 4.5 inch stroke would sure help the low end grunt! An aftermarket block is certainly a possibility down the road if the factory stuff looks promising.

 

I was wrong! It's more like 15 feet.... http://www.chrysler300club.com/uniq/.../ramtheory.htm