F-O,
you might want to look at Holley, they make
a manifold with the fuel injector mount holes,
already drilled.

 

thanks guys..
i will buy that book..
contact- i already have the intake and it already has injector bosses but thanks for the idea.. if the super dont work i will know where to look..

 

I had to laugh when I did the math for a 355.

50% is a tad over an 8-pack and 70% a tad under a 12 pack.

 

well i talked to doug mangrum (pro 5.0 contender) and hes hooking me up with a wilson elbow and a 90mm tb.. so problem solved..lol. for now.. now i gotta get some hood clearance.. also i bought a book..Graham Hansen's "how to build big cubic inch small block chevys" worth the money.. i learned alot.. and it also had all the info i needed..

 

I didn't say it, just read it .
To make power they have to be big but for the street I don't know if they have to be that big. Were not building indy cup cars or all out pro stock (most of us arn't).

 

An unmodified 90 mm to 4150 Wilson elbow is over 6 inches high (above the manifold carb flange), and has a volume of about 74 cubic inches.

Good luck with your project.

 

you're right...but we all know that motor isnt worth a hoot!

 

well i know i will have hood clearance.. as im buying a new hood..lol.. but i believe the manifold im using has a fairly large plenum.. its a 90mm wilson tb.. im still doing some research right now but so far this is the best bang for the buck..

 

well i measured a stock intake.. the total volume runners and plenum.. well it holds 4.8L of water.. kinda short changing the stock ci dont you think?

so do you guys agree that making the total volume of the intake the same as the ci would be benefical or just the plenum the total ci of the motor would be better...

 

Well Maximum Boost says 50%-70% for the plenum, I take that as not to include the intake ports of the heads, and most of the intake runners.
Got to find where plenum ends and where intake runners start.
Now I think How to build and modify chevy small-block V-8 cylinder heads said that the intake should be at least = the engine displacement in a high out put engine (or said some thing to that effect) but I can't find where I read it, because the index is only based on cylinder head only subjects (nothing on carbs or headers).

 

Super Victor at 5.5" to carb flange...hope its a 4" cowl and Im still picturing it in my head to be tight.

 

FWIW, LT1/LT4 manifold inlet ports are just about 1.0L total volume...give or take a bit.

So how do Cup engines make all that power with a manifold that obviously has a lot less than 5.8 L of plenum?

Pro Stock manifolds, when you can see them uncovered, seem to have large plenums, but they are making a more hp/cube than a Cup engine. (2.5 hp/cube vs. 2.3 or so)

Going back to this thread's subject, runner length is probably more important than plenum volume, especially for the 1.5-1.75 hp/cube a good street engine gets.

 

I was thinking about that, and wondering the same thing . I started to believe that runner length was the more important, because I started also comparing Pro stock and cup cars in my mind (2 of the baddest NA type motors) and I picture the cup cars as having little plenum volume.... I imagine they could benefit from a large plenum if allowed. But From the ones i have seen they basically are carb manifolds with no significant plenum, but they make all that power like you said. The Prostocks like you say have large plenums, at least the ones you can see seem to... But they also seem to have some good runner length.

I know each cars combo can be different among Pro stock or Cup cars but has anyone ever heard the length of the runners from any car of either type ? (TOP SECRET)


Also , I see you list the lt1 manifold inlet ports as being about 1.0L, but how many cans and/or cubic inches is the lt1 PLENUM,... a 6 pack? 3 cans ?.....

 

well it was gonna be a 4" cowl but there simply isnt enough room.. so im back to the super victor with a fabbed plenum.. as far as plenum design.. does any one know how bad it "hurts" the power to have the plenum go past the carb flange like this
? . . . . . . . .l (TB)
l . . . . . . . . l
V. . . . . . . . V
._________
[_________][}
_/ / /_\ \ \_ <--- intake

 

IF the 4.8L total is correct, then the plenum is about 3.8L which is about a gallon, rignt? Let's see, 1 gal. = 128 oz. and a 6 pack is 72 oz, so I make it about an 11 pack minus a few sips. Close enough?

Look at a GMPP P/N 12370854 or 12480048 SB2.2 Intake manifolds. You can pretty much estimate the runner lengths from the pictures. Half a foot , maybe, plus or minus a few finger widths?

http://www.gmgoodwrench.com/perfpart...405&section=ep