409 blower intake

[yellow wagon]

Just remember with a roots blower, you just a pulley change away from more or less boost. My 333s have a 2.195 intake turned down to a 2.150. Tony Shaffer still installs hardened seats in all his heads. They work really well.

I guess thinking out loud, even if you end up at 8.5:1 final compression you could run a bit more boost etc. I like the snappy throttle response more compression provides but a half point isn't a big deal. This is a really cool project so looking forward to reading along the way. Lemme know if you need any other info on the 333s or anything else.

 

[Don Jacks]

Why are you stuck on such large valves????????? You dont need any bigger than 2.19-1.72's to meet or exceed your goals.If it's because you already have the big bl.ock valves,they're longer making valve train geometry a real pita,and 1.88 exhaust are a problem on the larger 409 bore.On a 348 they'd be a nightmare!

 

[MRHP]

Jack Gibbs told me to! Seriously, Jack had said to use them, but he may have assumed a 409 build, not a 348. Most likely my mistake. 2.19 and 1.72 it is then. Thanks for pulling me back to reality Don. I too like the snappy response of a higher compression motor Jason. Just worried about the tuning.

 

[Don Jacks]

Use an MSD Boost timming unit an set it to pull 1/2 to 1 degree per pound of boost.That way you can set your timming for really good low end,and keep the timing in line for boost.

 

[MRHP]

Will add that to the list.

 

[303Radar]

Just remember with a roots blower, you just a pulley change away from more or less boost. My 333s have a 2.195 intake turned down to a 2.150. Tony Shaffer still installs hardened seats in all his heads. They work really well.

I guess thinking out loud, even if you end up at 8.5:1 final compression you could run a bit more boost etc. I like the snappy throttle response more compression provides but a half point isn't a big deal. This is a really cool project so looking forward to reading along the way. Lemme know if you need any other info on the 333s or anything else.

I know when talking to ProCharger about my setup (348 punched out to 431), they said I could safely run 8 - 10 psi (I need to double check) of boost with a 10:1 compression. This would improve my power by 60%. If this is correct and my cam is roughly setup for 450 hp naturally aspirated, theoretically, I have a 720 hp engine.

I know I had thought about a lower CR to run more boost, but it sounded like the setup might more exotic than my builder was comfortable with.

However, any time more boost is just a pulley change away, keep the smaller pulley's handy!

Good luck and I can't wait to see this.

 

[MRHP]

Just waiting for the machine shop to call with the results. I have been researching camshafts for this 380 and I am even more confused than in the beginning.Damn.

 

[1961BelAir427]

What RPM range Brian? What type of cam - - flat tappet or roller......solid or hydraulic ?
Also what transmission (and convertor if automatic) ?

 

[MRHP]

5500-6000 rpm, hydraulic flat tappet, T 10 2.88 first gear in my car with a 4.30 gear 28 inch tire. I want a dependable street motor, that may see a little track time. I am still looking for a gasser, but the motor would likely land in my car for a while.For tuning and such.

 

[1961BelAir427]

I am FAR from claiming to be any kind of expert, but these are my thoughts:
I'd guess something around 224 / 236 @ .050" and around .560" on about a 112* Lobe separation angle - maybe as much as a 114* LSA. You don't want to go too big on duration because you aren't planning on high rpm. Blowers tend to favor higher lobe separation angles and more exhaust duration to help get all that forced air out. Gross lift will fall where it will depending on the lobe that gives the duration you want and the rocker you use.

What has your research come up with?

 

[models916]

This is in my 40 over/409 crank. 11:1, 333 head, 4:56 30 inch tires. 700r4 3,500 stall, idles at 1,000 pulls good to 5,500. I run Rhodes lifters so it seems pretty tame under 2,500.

 

[MRHP]

Comp 11-404-4 grind is what I was looking at but?..........

 

[1961BelAir427]

That looks like a really good one. I'd have thought there would be more than 7* additional exhaust duration, but they know what they are doing a lot better than me. Perhaps it is a percentage thing - 7* split on a smaller cam may be more (percentage wise) than 10* split on a larger cam. Does that make sense?

 

[Don Jacks]

Due to the small displacement of this engine,11-404-4 is too big.It'll peak about 500 rpm higher than he wants.It'd be good on a 434.A better grind for his intended use and rpm range would be a small block grind[12-404-4] in this 380 incher.

 

[Skip FIx]

Just remember too with boost you can get by with less airflow as you are making your own atmosphere. Sometimes you need a little more intake valve spring pressure.

 

[models916]

Comp spec'd that cam with 1.7 rockers and said I could punch it up with 1.75 later. It's an Extreme Energy cam.

 

[303Radar]

I don't know how to compare cams proportionally side by side. But thought I'd put them side by side for grins.
The left is for my 434 build with forced induction and the right one is copied from Model's post above.

 

[Don Jacks]

While these are good cams for thier intended use,blowers work better with a wide seperation angle.303'S CAM would be too big for a little 380,given the maximum rpm that Brian wants to adhear to,but should be great in his 4 in.stroke engine.

 

[Skip FIx]

I'll disagree it's too big for a 380. Even the hottest street 400 Pontiac used a 231/239@ 0.050. I ran a 228/228@ 0.050 in my '78 original smgger 8:1 400

http://www.chevrolet.com/performance/crate-engines/small-block-zz4-350.html just a step smaller but only a 350
And about the same a the GM 383 crate motor's cam
http://www.chevrolet.com/performance/crate-engines/small-block-zz-383.html

 

[MRHP]

Got intake today, pictures to follow. Block checked out good, waiting on bore size.