I want to supercharge my engine, advice?

[othtim]

So I just finished my engine two months ago, but I already feel like it's too slow.

Right now I've got a 355 w/ cast flat-tops, cast crank and rods, 9.5:1 compression, Vortec heads with mild bowl blend, and a comp xe268h-10 and all comp valvetrain. Performer manifold and q-jet. I'm guessing it's making around 380 HP. I have a holley blue pump and regulator right now. Shifting at 5500 rpm.

I'm thinking about adding a Vortech supercharger, and running low boost, like 3 psi, just to get it into the 450 HP range. Does anyone on here have any advice about the vortech supercharger? Is 3 psi safe with 9.5:1 compression? I could throw in a thicker head gasket and get it down to 8.5 or 9.0. Do I need a boost-referenced FPR with this kind of low-boost setup? I'm running about 5.5 psi right now. If I add boost I'm going to lower my shift point - half the point of the supercharger is to just widen my current power band. Do I need a wastegate at these boost levels? The Vortech site says its not required, but it sounds sketchy to me. ANy tips for running a q-jet blow-through? I've seen some tutorials online, looks like very minor mods required to run blow through.

Anyone ever done something like this? Any advice? I'm planning on buying a forged short block later and then upping the boost, but I want to keep it conservative with cast parts.

 

[Brick442]

A while back Chevy High Performance installed a Vortech supercharger on a stock crate zz383 sbc (which has 9.7:1 CR). They tested it with 6 to 7.5 boost and it put out nice numbers. With a blower-specific cam installed, I believe it safely ran up to 11psi. Granted, the zz383 is a brand new block with new 383 crank and 4 bolt mains, but I'd say you can run at least 6psi safely with your setup. Anything lower would seem to be a waste considering the money involved with a supercharger.

I'm going to be duplicating this setup on my zz383 soon.

 

[DRIVEN]

I think a Roots style supercharger like a Weiand 144 or 177 makes more sense on a carbureted application. Far less complicated to execute and probably less expensive. If timing and air/fuel ratio is where it should be, you should be fine with your current engine.

 

[dogsht]

"to widen my current power band" I looked up that cam its a 224-230 @ 50 duration 1600 to 5800 rpms range. It should work with your compression and still provide a fairly wide power band especially in a relatively light gbody. Makes me wonder what gears you have in the rear, how the cam was installed, and has this thing been tuned on a dyno? Do you have any quarter mile times/mph? It should not be overly peaky. It would benefit from a little higher than stock torque converter also. Not that it is required just that it would feel better out of the gate and anytime you step into the throttle.

I'm not anti to the blower idea just that I'm wondering if a simple dyno tune & any parts optimization might bring about power & feel that makes it almost feel like another motor. The Q-jet should also be great but has a bigger learning curve to tuning the flip side being once you get it right you don't have to keep messing with it every time the weather changes like a typical fuel slobbering square bore. If the cam, carb, timing, gear, & converter are reasonably optimized you might really start to like this setup. If not its nothing money and a blower or another 100 or 150 cubes wouldn't fix.

 

[othtim]

"to widen my current power band" I looked up that cam its a 224-230 @ 50 duration 1600 to 5800 rpms range. It should work with your compression and still provide a fairly wide power band especially in a relatively light gbody. Makes me wonder what gears you have in the rear, how the cam was installed, and has this thing been tuned on a dyno? Do you have any quarter mile times/mph? It should not be overly peaky. It would benefit from a little higher than stock torque converter also. Not that it is required just that it would feel better out of the gate and anytime you step into the throttle.

I'm not anti to the blower idea just that I'm wondering if a simple dyno tune & any parts optimization might bring about power & feel that makes it almost feel like another motor. The Q-jet should also be great but has a bigger learning curve to tuning the flip side being once you get it right you don't have to keep messing with it every time the weather changes like a typical fuel slobbering square bore. If the cam, carb, timing, gear, & converter are reasonably optimized you might really start to like this setup. If not its nothing money and a blower or another 100 or 150 cubes wouldn't fix.

hi dogshit. it's not the cam that's too peaky, it's the heads. that cam w/ the vortec heads lends a torque peak up around 4000+ rpm....and I can definately feel it. It's not dyno tuned or dragstripped, just street tuned at this point. Tracks closed for the year already. I would guess it would run high 12s, since I can destroy a bunch of my friends that are running low 13's and high 12's. But who knows.

also, Driven, one reason I want the vortech/procharger style is that it fits under the stock hood. i love suprising people when i pop my hood. lol.

edit:

At this point, I'm pretty much sold on the v-3 trim kit from Vortech. Under $2000 CAD is great 🙂 . I plan to run it on my current (cast parts) SB after putting in a thicker headgasket. I'm also going to drill a boost-reference into my current fuel pump, and just run it like that for next season, on whatever PSI it will allow me. Then next year I'll start saving for a proper forged short block and fuel system to run higher boost.

 

[HurstOlds]

Hi othtim,

If you get a chance, can you post up the Quadrajet blow thru links you came across? Sounds like an interesting read, I'd like to check it out

Thank you

 

[othtim]

Here's the first few i saw on google.
From what I can see, the modifications are fairly simple. And from what I've read, the boost leakage on the throttle shafts isn't that much.


http://www.originalho.com/TFProjectUpdate1b.html

http://www.carcraft.com/techarticles/cc ... 400_build/