Wood's '408' low-buck Magnum build!

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Woods74

Woods74

Broke Senior
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Hi all, I am kicking around the idea of upgrading my 360 Magnum to a 408 while I finish up my body work since I'm taking my engine out.

Goal is somewhere in the 450HP/500TQ on 87-89 octane, max 10:1 compression. Street driving mostly. A few auto-x and drag runs a year.

I have currently from top down:

Holley Sniper EFI with electronic distributor
Edelbrock rpm air gap intake
OOTB RHS Indy-X 62cc 1.92/1.625 heads
500 mile Hughes 1110 springs w/ 2.2L retainers
Bullet ROLLER HR280 re-grind .226 int./ex. @ .50 112LSA .525 1.6 lift
Doug's headers 2 1/2" X-pipe
5 speed
3.73 Rear gear 26" tires



I've been researching parts and came up with:

Crank:
Scat Forged Standard Weight Crankshafts 4-360-4000-6123

Rods:
Scat Pro Comp I-Beam Connecting Rods 2-ICR6123-2124

9.8:1 Pistons:
ICON Premium Forged Pistons IC745-STD



Mission plan:

Stripping and taking the block down to a local machine shop to assess what I'm going to need to do. I don't immediately see a need to bore it, when I 'refreshed' this engine back in '11 they still had cross-hatch pattern in all bores. Maybe 2000 miles since. Runs great, even with a bastard piston.

What requests should I make of the shop to look over this block to get it ready?
What parts do I need to include when it comes time to check the balance of the new assembly?
What cam should I pick to best work with the heads and new stroke?
What other parts should I use for this? Piston rings, head gaskets, bearings, oil pan etc.


Thanks, hope y'all are having a chill Sunday.
 
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Woods74 said:
Thanks OFFICIAL, I suspect the cam should go as well.

Ran into this beautiful piece of information from MRL on the subject:

"We did a 408 stroker last year with the XE275HL cam, 1.6 rockers and the RHS heads w/1.92/1.625 valve and did no port work at all, not even a cleanup, and it made 465hp 520tq."

RHS pump gas 360

408 xe274
Click to expand...

On his dyno...
 
Apparently roller cams carry 8-10 * more duration than flat tappet cams? I'd like to verify this information.

Also looking at Oregon cams regrind #1331

232 int. 240 ex. @.050 112 LSA .560 int. .568 lift 1.6
 
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5 speed an od?
shaft rockers? run what you have or iron rockers
roller tip rockers require a B3 kit to work properly
do you like the rpm range on the cam you have?
run it or get a cam with just a touch more duration for the additional cubes
you'r not building a race car
easy to change the cam later and awfully hard to pick anything better without seat of the pants experience
 
Yes sir, 5 speed OD. Thanks for the vote of confidence, I like the range. Pulls hard from 1800-6200. I've mistakenly over-revved it several times because its hard to tell when it let up.
 
Woods74 said:
I've been researching parts and came up with:

Crank:
Scat Forged Standard Weight Crankshafts 4-360-4000-6123

Rods:
Scat Pro Comp I-Beam Connecting Rods 2-ICR6123-2124

9.8:1 Pistons:
ICON Premium Forged Pistons IC745-STD
Click to expand...

The only problem I see with you choices is the pistons. They are for a LA block which has a taller deck height. Those pistons MAY stick out of the top of the deck. Their compression height is 1.465. You may have to use a thicker head gasket to get the compression you want. ICON does make a Magnum specific piston with a 1.445 compression height. The flip side to those is you have to bore at least .030, since they do not have a standard bore available. The only other option that might work is to go with ICON's FHR series pistons. They have a 1.450 height and are available in standard bore sizes, and budget friendly. The FHR's are not their premium piston, but still a good piston from my research. I just went through this myself, so I know the choices you are facing. The only other thing I might suggest is contact Scat directly to buy a kit. They did a piston substitution for me at no extra cost, plus met Jeg's/Summits discounted pricing with free shipping. They may even be able to custom build you a kit. Also, their price for balancing is better then my local shop by a considerable margin. Just things to consider.

United Engine Machine IC9977.STD: Chrysler 408ci FHR Forged Pistons 23cc Dish | JEGS
 
yes he needs more cam for max but he likes the rev range
I'd still run what he has first
else the only way to get an improvement would be with one of Mike Jones inverse radius profiles
Street Performance | Jones Cams
he could keep similar seat duration but bump up the area under the curve big time
 
A lot of blanks to fill in on the Desktop Dyno. I came up with 417 HP @5000 and 512 tq@2500. Nothing wrong with a mild stroker. The 500 lb/ft of torque will be fun.
 
DrEamer said:
The only problem I see with you choices is the pistons. They are for a LA block which has a taller deck height. Those pistons MAY stick out of the top of the deck. Their compression height is 1.465. You may have to use a thicker head gasket to get the compression you want. ICON does make a Magnum specific piston with a 1.445 compression height.
Click to expand...
The 745's will stick out .003" from a nominal Magnum deck. Use a Felpro 1008 at .039" thick and you'll have a nominal .036" quecn/squish gap.... will be nice. Adjust as necessary....
 
back to a up top question
how does overlap affect a sniper?
is that why the 112?
if he goes longer does he have o use a wider lsa to hold overlap down"
/looking fwd to the results
 
I was recommended by IMM a 242@ .050, 113lca, .535 lift w/ 1.6 ratio.

I wiped a rod bearing, awaiting a pull. Currently playing on the 05' WRX that's going for 400whp hidden in the background on the current page of my build thread. 1-2 weeks I'll have it out and apart to assess what I need to build..
 
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Quote from 408 cam "behavior"

"As rnaz said but it was a secondary thought. I want excellent street manners, WIDE torque curve, good vacuum for brakes and non temperamental tuning. That's why I only went with 236@ .050. I didn't want a torque turd either. Rather have a wide torque curve for better performance everywhere....and that's what happened. Also, the more cyl head flow you have the less cam you need. Vice versa also. 526hp and 496 torque is enough for 11's and no cage needed. Made 470lbft from 3300 (lowest pull went to) to 496lbft at 5100. That's FLAT. It ought to pull like a freight train. Can you imagine with a 100 shot? (That's as far as I'd go with stock block and cast stroker crank). I figure a 3K to 3200 stall and send it down the road.

Thing is, there's a few more hp in it. Compression is only 10.2:1. I'll take another cc out of the chambers or so to get me to 10.5:1. Also, 93 pump gas will work better with a 114lsa. Less peak cyl pressure and more AVG.--
------------------------------------------------------------------------------------------
I'm running a 236/242 @ .050 with a .580 lift on a 114 LSA in a 390, and everything you said is spot on as far as the torque goes.
It runs great N/A, and makes gobs of torque across the entire band, and when I spray it, it's just insane. I have hit it with a 150 shot on a forged bottom end, and the block half-filled, but the tires wouldn't hold it.

My compression is sitting at 11.0:1, and it doesn't like pump gas, though."
 
Upon tear down I found some .005 chips out of the #8 and #6 bores, scratched and worn cam bearings, good news I turned 4 corners of the heads and did a visual inspection of the bore depth at TDC, looked .070 in the hole consistently no real deck level issues. That bastard piston came back to bite me, wiped the rod bearing.

Ordered the in-house balanced rotating assembly from CNC-motorsports, thanks DrEamer for piston recommendation.

$200 for gaskets, head bolts, cam degree wheel, filters etc.

Block is going to the machine shop in the AM. Looks like I'm in for a hot tank, freeze plugs, cam bushing install, .030 over bore, check the deck. $400

Looks like about 3 weeks on the block and 2 weeks plus shipping on the rotating assembly. I'll update when I get going.

Total:
$1,498.00
$450
$200

sca-1-40005bl.jpg

SCAT 1-98113BI
 
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I'm re-using my cam for now:
.005 @ 292 dur
.050 @ 226 dur
.200 @ 141 dur
.328 x 1.6 = .525 lift
112 LSA
108 Intake CL

I found out I have a 3 keyway crank, any thoughts on the effect of advancing or retarding it 2 degrees being helpful?
 
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put it in straight up
whose cam
.325 duration? :)
you can change it
do a compression test after break in for your records
 
Sounds good, it's a Bullet cam re-grind. I can't seem to find the damn cam card, doing a search on the way back machine to when I bought this cam in 2010, I found a cam with similar specs. Card said HR292 226 @ .050 .525 lift with 1.6 rockers.

I got to thinking about keeping a budget, honestly I need tires more than a cam to hold this beast. I smoked them to the damn lug nuts with the 360; I can't imagine what a broadsword swinging, dragon killing, pussy tamer it's going to be afterwards. $20 says I turn white as a ghost first time I take it out.

I found this little rig that sent me over the edge on running what I brung.

BluePrint BPF4084CT Ford 408 Stroker, Base Engine, Alum Heads, Roller Cam

My intake duration stomps all over it. Still makes over 450 ft/lbs.
 
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