Is that a stock Intake that you are talking about?

Do you have pics or is that the same one on pg #3?

 

Going with a longer runner to get a "ram tuning" effect in a 2K RPM or so window might work better depending on your RPM target. I wonder if the long winded Vic. Jr engineermike refers to is extending the topend because of an inertial effect that comes in late because of a large cross sectional area. The resonant tuning frequency of the Vic intake would also come in at a pretty high RPM level compared to the LS1 intake. The F1 stuff uses tuned runners to get max. VE in the intended operating range and technology is king there.

The Chrysler developed formula for intake runners came up a few pages ago. You can use it to calculate the runner length to optimize a particular RPM range. Simplified it is 84,000 divided by RPM target equals runner length ( including 6" for the intake port runner in the head to the valve head) . I have a link to a dyno test with several different length runners on a Hilborne injection system that bears out a sizable VE boost which corresponds with the runner length. Depending on your RPM target a Vic Jr might be great though, I don't know what the runner lengths are on those. I'll dig up the dyno page on the Hilborne setup and post it a little later.

Later, Michael

 

Is the intake port on the head exactly 6"?

What rpm target should we be aiming for? Mid rpm band or peak?

 

The 480+ RWHP was with a ported LT4 intake. The car lost 6-7 hp peak on the top end and 20 @ 7000 rpm with the sheet metal one, but remember it gained almost 50 lbs RWT @ 3000 rpm.

When I say stock, never mean "stock" except in that it was the part GM provided on the car. Hell, not sure if there is a stock part left in the engine that wasn't tweaked somehow or replaced.

The “stock” intake was extensively welded on the outside to add more meat for porting to straighten the path into the heads. It was then sanded and repainted to look like nothing had happened. Guess I could take pictures of the LT4 intake ports, but it was gasket matched to the off road LT4 gasket.

Hand ported another LT4 intake going about as thin as I dared and it dynoed less across the board as compared to the intake with extra welding that did 480 rwhp. So welding and raising the port of the stock ones does help. Wasn't always sure of that.

 

Speaking of which, has anybody heard from MR. Horsepower recently?

 

Great info again Denny. It would be simply awesome if you could dig up dyno sheets to back that up for future reference.

 

Thats what this board needs along with all of the automotive calculators, a catalog of dyno sheets from various members. Maybe with a search function that could search based on different modifications, displacement, heads, etc. It would eliminate the need for those "How much HP will my car make..." threads.

Just an idea, Admins take note.

Jeremy

 

Some I have and some I don't. With about a 1000 dyno pulls ya can't save everyone, but I do have quite a few of them saved for reference. When you see me write 5 or 6 it means I don't remember the exact number but it's ballpark close enough. If it's important to me, I'll try and find the information.

Was more **** early on testing things and saving the dyno sheets. Now if I need something, just go to the shop where the dyno is and look at the computer. Even then I have a hard time finding which ones I want as there is probably 300 in that computer alone and my partner in crime has a shaky filing system in which he can only find some things.

 

I know what yo mean Denny. I have a folder of old timeslips. There are LOTS in the 14 and 15 second range still... I was digging through my car recently and found a couple more under seats, in the glove box, center console, map pockets, etc.

 

So for the LE2 cam, it seems to pull like mad up top, if I wanted it to pull in the 3000-5000 range I would need a 15" intake tract on top of the 6" intake tract on the head?

What is the length of the intake runner on the stock LT1 intake?

 

The stock intake has 3" runners.
Once ya get over 12" total runner length(head and intake) ya start loosing HP across the board above 3500. That is with a performance intake and engine. Smaller dia runners have to be longer or so it seems.

 

So no one really has a mathematical formula for the correct length and diamater of the intake tract?

What would I want the intake tracts on the intake to be? 220cc and 6" long?

 

If you wanted to increase torque in the midrange then that would probably work fine. But I would suggest swapping cams too. If 3000-5000 is the range you want to be strong in then get a cam that is strong in that range.

Just my suggestion,

Jeremy

 

Try this one:

The runner measured from the valve seat to the plenum (the open area where they normally meet under the carburetor,) can be determined by dividing 84,000 by the length of the runner = the speed the runner will work the best. An example is:

84000 (constant) = 5250 rpm
16 (runner length)

 

16" minus the 6" tract in the head so a 10" runner in the intake? Correct? What diameter? Same as stock LT1 or can you go bigger to later accomodate 220 cc heads?