Ok guys whats your suggestions on a 390 engine build with a wiend 871 blower on top of it? I figured compression ratio should be about 8:1-8.5:1. What parts should I use and approximately how much power will the blower add to the engine. I originally figured I would build an engine that produced about 300 Hp. at the rear wheels naturally aspirated. What would this engine produce by adding a blower? I will be putting this engine in a 74 F-250 with a T-18 and it will be used on the street and offroad and maybe the strip just for fun.

 

In most applications I've seen, forced induction is good for about 50% increase in power.

You need to get Larry (aka FreightTrain) in here. He's running a blown FE in the power range you're talking about. let's say 450 RWHP is about 530+ FWHP. you're going to need a good solid bottom end, but it's certainly manageable for an FE.

 

Interesting, lets see here. I'm sure I can dream something up.

Lets try:

1. Edelbrock heads (Edit: duh, blower intake... )
2. Crane 343941 cam
3. Mr. Gasket embossed shim head gasket, .020" thick
4. Keith Black part number KB150 pistons, gives .010" deck clearance, and .030" quench space for optimum detonation and pinging resistance. Has 20cc dish.
5. Stock block, crank, rods...
6. Headers, 750cfm carburetor.

Comes up to 9.236:1 static compression, and 8.122:1 dynamic compression. According to the Desktop Dyno, naturally aspirated this motor would make 410hp @ 5500rpm, and 436ft-lbs @ 4000rpm.

With an 871 blower at a 1:1 belt ratio, no intercooler, and limited to 8psi, Desktop Dyno shows it to be 591hp @ 6000rpm, and 581ft-lbs @ 4500rpm.

If we up the belt ratio to 1.5:1, add a 70% efficient intercooler, and up the boost limit to 15psi, we get 699hp @ 5500rpm, and 711ft-lbs @ 4500rpm. For this combination, be sure to use an FT block or a mirror 105 block.

Oh, and the above numbers are at the flywheel, and one should include the standard Desktop Dyno margin of error.

 

390 bored .030 over.
2 600cfm carbs
blue thunder blower intake
Edel RPM heads
Crane 541 Roller cam
H beam rods
forged steel crank
8:1 CR
30% overdrive pulleys
Max boost 15 psi.
2" primaries into 3.5" collectors out 3" exhaust

800hp @ 7000rpm
610tq @ 6000 rpm

 

Please disregard my above numbers, they were run with the wrong blower.

Using a Weiand 8-71 blower and my above build combination:
1:1 ratio, 8psi boost limit: 525hp @ 5500rpm, 537ft-lbs @ 4500rpm
1.3:1 ratio, 15psi boost limit, 70% efficient intercooler: 661hp @ 5500rpm, 675ft-lbs @ 4500rpm.

I think you'd be better served by the Paxton Novi 2000 centrifugal blower that I originally ran it with.

Oh and Randy, 7000rpm on the street? That would be one heck of a motor, but I think it would lead a very short life, even with the bottom end you spec'd. It'd probably be beneficial to keep the RPM's down for a street driven truck.

 

I've been thinking about supercharging for awhile now and I figure I can do it for around $2,700.00. Thats $1200.00 for the blue thunder intake and about $1,500.00 for the 871 blower. I figure I can turn the boost up or down depending on what I am doing with the truck. How much CFM do I need to run for the carb? I see two different cams were suggested the 941 and the 541 should I go with the roller or stick with the 941? I would like to keep it somewhat reliable (if thats even possible). I not looking for 600HP but would like the power to be significant throughout the RPM range (if it happens to give me upwards of 600HP well great, if not, so be it. Can I still run it on 87 octane fuel?

 

Oh I love it !! A Blown FE in a Truck!!! Yeah !!

Russ

 

I have 9:1 in my stock 390 at 15% underdriven get 6 lbs of boost! The cam is mild solid lifter Crower .531 lift(like 240/250 @ .050). The motor is all 1968 stock parts, so I keep it tame to keep from having it show it's parts on the street.

I would call any cam manufacturer and ask them for blower cam recommendations for your motor build. Roller or solid, but the roller will be a bit more rough on valve springs(all depending on how radical a profile you get).

I turn mine 6K rpm only, with stock rods(rebushed/new bolts). I would recommend putting cross bolt caps on the block if you plan on anything higher rpm. These caps walk around pretty bad(I've seen one of mine before I crossbolted). It will polish the cap mating surfaces to a mirror finish....not good!

The one thing I would watch with putting this in a truck is cowl clearance. I did some quick measuring on my '69 and it looks like the blower itself will come right into the extension of cowl. This is with 6-71, an 8-71 might be even worse? Not sure how it would bolt to manifold(do they make a 8-71 manifold?, or is it one of those welded tunnelram versions?) With my Blue thunder verison the blower sits just a few inches from rear of manifold, so look at your truck, use a stick to make a line up from manifold a few inches from rear and see what it runs into. Just a heads up that there might be space issues....not that you shouldn't try it!

PS: when figuring costs.........don't forget the DRIVE!!!!! Manifold, blower...and you need the drive assy to make it all work. I had near $1500 in all the related accy's. Heck the gilmer belt is $100!
If you buy the complete kit from like BDS, it's like $3500. This is no carbs, linkage, etc!! Ching, ching, ching......

 

I have too say, I would go with a HP Performance Turbo..I just read a test done on a 5.0....

They tested the same engine with the Novi 1200 and the HP Performance Turbo and the Holley 171
and the results were..

Holley 174 Blower= average street hp- @2500 to 6000rpm- 394hp

Paxton Novi 1200 " "@ 2500 to 6000prm- 412hp

HP Performance Turbo A 2500 to 6000rpm- 460hp

All tests were conducted on a 310hp 302 (5.0)

Minimum boost 4.5 psi
Maximum boost 9.5psi

Holley 174 Blower Peak @ 535hp @ 6000rpm- Peak TQ 513 @ 4600rpm
HP Performance Turbo Peak @ 600hp @ 6000rpm - peak TQ 617 @ 4200rpm
Paxton Novi 1200 Peaked @ 617hp @ 6000rpm - Peak TQ 561 @ 5200rpm

Hope this Help some??

Russ

 

[QUOTE=Freightrain]
The one thing I would watch with putting this in a truck is cowl clearance./QUOTE]

Good point. That darn cowl has derailed a few of my plans already. I had a tri-power intake I wanted to use but it just didn't measure out. And Dennis at DSC keeps tempting me on Ebay with those Blue Thunder dual-quad set-ups but I'm pretty sure it won't fit; too much coin to risk buying one to try.

 

I ran a tunnelwedge 2x4 intake and still run a med riser 2x4 intake on my '69. No problems! I run the oval air cleaner with 1" element and it just clears everything. Not sure if the 3x intake sets up different? I know the "factory" quads work. Not sure how the BT intakes measure up?

I would bet that fact the turbo is more effecient, plus the fact it does not take HP to make HP! I would bet the blowers take 10 hp to run? Give or take? Depending on the boost?

 

The 1" element gives you enough surface area for the two carbs? Now you've got me thinking. Freightrain, you are a very bad man!

 

Well, hmm, maybe it's 1 1/2" tall filter? What ever the std replacement is? Got me wondering?? Might have to measure it now. I know it's not very tall. Maybe I'll try and get a nice underhood shot showing how it all fits(barely).

I've run this set up for near 15 yrs now!

 

So if you were to run a 6-71 bds system at 6 psi.....you could cam it to red line at 6k and run a stock reconditioned and arp assembled bottom end? I would think you would need to run a 8-8.5:1 static CR. to maintain a very happy pump status but i dont really know im just guessing.

 

My hot rod is a cruiser....and I don't abuse it very hard at all. Not worth blowing it up!!
It has survived 4 yrs now and want to keep it that way. I blast on it, but not very often, and usually don't use all the boost possible. If I were to drag race it constantly or at all I think it would be short lived. The rods may take it, but the 35 yr old cast pistons may not!

I want to gather pieces to upgrade it, but that's for another day.