83Z28HO

Hi all,

I've decided I want to get a centrifugal blower for my 400. I'm still in the research stage, so I'm looking for advice/tips on how to set this up for boost, get the power I want (500+ RWHP) and remain totally streetable on pump gas.

So pretend for a minute you have this current N/A setup in your garage:

-400 SBC +.040, stock block
-Scat 4340 3.75" crank, Eagle 5.7 SIR rods
-KB147 Hyper. pistons (-18cc dish)
-Compcams XR288HR Retro-roller hyd. cam (236/242 dur. .050, 110 LSA)
-Dart iron eagle heads, 72cc chambers, 200cc intake runners (ported)
-Shorty headers with 3" catback exhaust
-RPM air gap intake, 750 Holley HP DP
-MSD HEI pro billet distributor

Now let's say you don't want to go EFI, so it'll be a blow-thru carb setup, and you don't want to ditch the iron heads unless you absolutely have to.

So.......how would you go about setting up the engine for boost, and which parts would you change? I want the power down low, I'd rather not spin it past 6K, so if the peak HP ended up around 4500 or so I think that would be perfect.
-And which supercharger kit would you get to make this kind of power?
-How about the fuel system - what to upgrade?

Thanks in advance for any tips/advice!!

archemedes

for blow through the only real kit is vortech. Holley has a special carb just for the blow through type. Upgrade fuel pump, and filter. I would also do a high volume (not a high pressure) oil pump, cam will probably need to be changed (call comp they will give you exact specs for your setup and last time I called it was free) the heads will be your limiting factor (with iron heads you can't run as high a compression as with aluminum)

FORCE_FED_Z

That motor specs out decently for a blower application- 4500 is kinda low for a blower motor. Superchargers make more boost the faster you spin them since its direct drive, unlike turbos which you can make your max boost lower.

Swap out your shorty headers for a set of long tubes- that will help your power down low. Also I'm assuming that your bottom end is a 4 bolt- if its not get it converted- splayed aftermarket is stronger than stock 4 bolt anyway.

Your big companies- Vortech, Procharger will be able to tell you which of their systems are going to work best for you.

83Z28HO

Thx for the replies archemedes and Forced fed Z -

Well ATI, Paxton are blow-thru kits right? Vortech is the price leader though. I was under the impression that any Holley carb can be built for boost? That's what I was hoping to do with mine.

And yeah, at least the way I understand it, the iron heads will limit my boost levels. How much, I'm not sure. Hopefully I'll be able to reach at least 500 RWHP without detonation issues. Already have a high volume oil pump, but I was considering going to a stock pump instead. My oil pressure stays pegged over 60 until it warms up, then it'll idle with 45 pounds. Seems too high. You're right, Comp's tech line is free - that's how I got the cam I'm running now.

What I didn't mention above is that the engine has to come apart anyway because I have TSS gapless rings in it, which unfortunatley not rated for boost or nitrous. So I plan to install a set of forged pistons in it with moly rings. I said 4500 rpm's, but bottom line is that I don't want to spin it past 6K. I don't think my valvetrain is up to anything past that, and honestly if I had to spin it over 6K to make power - I should be able to make the power without the blower, right?

I was hoping a blower would allow me to run a smaller cam, idle smoother and be more streetable. If I had to make 5-600 HP N/A, I'd need a bigger cam, suffer with low vacuum and rough idle, and lose some low end power.....but it would make gobs of power in the upper rpm range - but not "streetable" - at least not what I define as streetable....is that a wrong assumption?

I know dynos are subjective but heck, power down low has never been a problem with this engine. It made 490 ftlbs tq at 3500 rpm's (max) and 387 HP at 4500 rpm's - that was with slightly smaller cam...so I thought making the power from 0-6000 rpm's with a blower would be child's play. So I'm assuming too much?

archemedes

any holley carb can be modified, but the effort, and parts end up being close in cost to the new one

83Z28HO

Oh man, I didn't want to hear that! But I am still researching. I found this article - it doesn't SEEM very expensive to set up for boost. http://www.hangar18fabrication.com/blowthru.html

-Even if I did buy a blow thru carb off the shelf, wouldn't I need to still do alot of tuning since there is really no standard setup?

FORCE_FED_Z

Most blower motors people rarely spin past 6500k, set-up properly they make awesome torque curves- my torque was basically flat from 3500 to 6k with the power on a nice even rise all the way up.

If you are going to spend the money, spend another couple hundred on a custom grind cam. Get your exact specs, what you want and call a cam company and have them make a cam for your exact specs of what you want. Many off the shelf blower cams aren't necessarily that great either, so make sure you get one that will make the most of your motor-

83Z28HO

Thanks again FORCE_FED_Z -
Sound advice no doubt. I already planned to call Comp's tech line to see what they're take is on a cam. Of course, I won't have all the "specs" or pieces to the puzzle until I get the blower (looking like Vortech V2), and forged pistons in it. I'm trying hard to not get longtube headers unless it's really needed since longtubes and thirdgens don't mix well. I haven't seen but one setup that gives anything remotely related to ground clearance, and it was BIG $$.

Nice article you have on forced induction - VERY informative!
-Hope you guys don't mind me "picking your brains", but I'm not real computer saavy, and although I've done so many searches, that I've gotten to a point where some things contradict others - so the truth might be somewhere in the middle...my main goal is to do this right the first time because it's expensive enough without experimenting!. More Q's to follow I'm sure

FORCE_FED_Z

Its very expensive- and just when you think you have everything you need, something else will come up. Trust me I've been down that road and still heading down that road now with my current build-

6k under the hood and still counting...sigh...

archemedes

your current carb will need alot of tuning, just switching intakes requires tuning

83Z28HO

So are you saying a Holley boost carb will:
-Not require tuning - a bolt-on?
-Will require less tuning than a standard carb that's been modified for boost?
-Will not require much tuning if any?
-Or are you just saying that carbs require tuning in general?

archemedes

all carbs must be tuned, anyone that says otherwise, either doesn't know, or is too lazy to do it. Even the edelbrock carbs need tuning (even though they say they don't) the boost carb should work a little better than a standard one modified since everything was designed for boost

83Z28HO

Hey all,

Been awhile since I've posted, just figured I'd update on where my "project" is going.

The 400 is torn down again, had the block checked out, heads gone over, new JE -21cc forged pistons installed to keep compression at 9.1:1. Also had the rotating assy neutral balanced again. Decided to run another set of Total Seal gapless rings in it.

So far as the power adder I decided on, it'll be the new Magna Charger MP-122H semi helix supercharger, which Edelbrock now sells as their "E-Force" line of blowers. I hope to run around 8 pounds of boost. As with any engine project, this one is costing more than anticipated....par for the course I guess.

Once I get it together and tune it as well as I can using a WBO2 meter, I'll throw it on a chassis dyno and see what it does. With any luck, I'll hopefully net close to 500 WHP - but I'll see....

FORCE_FED_Z

I think with your combo you should be close to 500hp. With the iron heads you might a little more limited on the amount of boost you can run, but 8lbs on a 9-1 engine is plenty safe enough. Just don't get crazy with your timing and you should have a motor that is safe and still a lot of fun.

83Z28HO

Thanks Force Fed....I almost forgot about this post, no one answered it for quite awhile!

Ordered the blower yesterday, called Comp cams and they recommended a NX276HR cam for it - has 224/236 duration, 113 LSA and .502/.520 lift. Ironically, it's the same cam I had in mind before I called them!

I'm also getting a MSD boost retard ignition control to back the timing down 1-3 degrees per pound of boost if needed. Magnuson recommended I just start with the pulley supplied in the kit and see what kind of boost I get, and work up from there if I want more boost....but with iron heads (Iron Eagles) - I think I might be able to run premium pump gas and not detonate, but I'll see...