Thread: 390 Turned 445 Stroked Mudder Project

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Awesome! Thanks Barry! I'll probably be getting a hold of you soon

Well, i guess teres the answer tech, so no higher than 6500 i suppose? or 6000 if you think that would be better.

As far as available fuel, I would love to run premium. Love love love... But i think JP5 is available. My friend uses a 25 JP5 / 75 premium mix when he races. At least i THINK that's what he uses.

Anyone have Any ideas?

Personally I would just build the 390 to run on pump premium. With gearing you should be able to run around 10.8:1 with flat tops. A decent big solid flat tappet and a bit of head work to the Edelbrocks and you're around 550HP on an honest dyno.

The 390 block will become marginal around the 600 HP mark - so there is no reason to push much higher - it's not really cost rational to add cros bolts to a 390. RPM is not a problem - we've run the stroker stuff past 6700 and up to 7000 with regularity. Its just that most of my 390 builds don't ned to "go there". These are generally pretty torquey and peak around 5700-6200 in street combos.

I can be a challenge to get on the phone sometimes. Kind of a "one man band"...but busy is good. Woodward Dream cruise this weekend...

I wouldn't worry so much about the cam lope though it sounds nice in a hot rod.
They usually don't preform well in the mud where you need that grunt power.
I would quite worrying about rpm's so much and focuse on torque.
You start turning 7,000rmp's and then hook up with those big tires, I don't care what you got under it, your gonna be making some trips to the parts store for some new stuff.
I used to go mudding all the time and help plenty of my friends out with thier stuff.
I would see these guys in giant trucks go out in the mud spinning their tires at big rpms
and get stuck every time. Then this little Isuzu would creep out with some tow straps
and pull these giant trucks out at no more then 3000rpm's. We would all sit there and laugh because these big trucks would be sunk to the tops of their fender with 44's under them. Here is the kicker the Isuzu was running a Toyota R22 4 cylinder motor.
Pulled them trucks out every time, never once seen him get stuck pulling those other guys out in years. Kurt

Thanks Barry! I completely agree with you. Premium all the way. Flat tops sound good as well. And you are completely right, I don't think i should run past 6000-6200, since i SHOULD be aiming for torque. What kind of work do you recommend to the E-brock heads?

That's why I'm asking the experts :P

And don't worry Barry, I know you're busy. I'm not exactly on a time schedule, So I'll get a hold of you sooner or later.


Vara, You are absolutely right. I've re-read a few of my posts, and i make no sense . Lately I've been way too stressed getting things together at work, and on personal projects. My bad. You all keep me sane, because i forget issues and start thinking Toys

I'll aim for torque, and forget about the lope. Though i think it will be a nice rough idle anyway, at this point.

Thanks so much to both of you!
Dave

Dave, I'll fiddle around with the DynoSim later today for you. 390 +0.030", worked over Edelbrocks, 10.8, solid flat tappet.

Awesome, Thank you very much Tech, Much appreciated!!!

I feel kind of silly putting together a combo, when Barry could just pull parts off the shelf and make more power or a better combo. He's the FE expert here and could make me look like a dunderhead.

Irregardless of that, I do like putting parts together on the DynoSim, so will do my best to assemble a 396 torque motor.

I built this one at 10.3:1 static compression ratio. It worked out that way with 0.030" overbore, 72cc heads, flat-tops with 5cc reliefs, zero deck and Fel-Pro #1020 0.041" gasket (10.2cc's) recommended by Edelbrock. Only way I could see to get more scr with flat-tops would be to cut the heads and/or go bigger on the overbore. I didn't want to do that, so settled on less scr. Rotating assembly stack 10.155". Block cut for zero deck.

I figured that a professional porter could get another 10% over the Edelbrock published flow figures, so that's what I used for the Sim. Here are the flow figures I used....
0.100 97 70
0.200 168 124
0.300 215 163
0.400 256 188
0.500 292 201
0.600 297 220

If this is unrealistic, I'll cut back to the published figures and re-run the combo.
http://www.edelbrock.com/automotive_.../6000/6007.pdf

Forged pistons, Ross #99601 flat-top, 5cc valve reliefs cut by Ross for Edelbrock heads.

Comp doesn't have a real good selection of solid flat tappet cams for an FE, so I had to make do. Given more time, I could sort through some of the other manufacturers offerings and come up with a better choice....I'd like to see the intake closed a little later to lower dcr for use on pump gas. I extended the close 5 degrees after I had already run the Sim and made 583/555 with a 8.25:1 DCR....
http://www.compcams.com/Cam_Specs/Ca...?csid=946&sb=0

I ran this with a 750 carb, RPM intake and open small tube headers.....

RPM HP TQ
2000 161 422
2500 203 426
3000 262 458
3500 335 503
4000 406 534
4500 474 554
5000 527 554
5500 561 536
6000 576 504
6500 567 458
7000 539 404

Static compression ratio 10.3:1
Dynamic compression ratio 8.55:1 on Keith Black's calculator
Max volumetric efficiency 103.2% @5000
BMEP 211.3 @5000
Squish 0.041" with zero deck

Dyno programs are great directionally, but tend to be off from dyno numbers for any of a million reasons. I like to use the data, and it is really helpful to define the build, rather than determine the result.

The below is based on data from the local SuperFlow 1020 flow bench. Every bench seems a bit different - use the data for direction rather than for absolute comparison. Same situation really - more like a compass than a map. You need both to get anywhere.

Edelbrock's flow data for the unmodified heads is -ahem - "optimistic". The peak number they give is obtainable on our bench but only at a really high lift - well beyond the cam's range. We generally see around middle 250's at .600 lift.

Moderate bowl & detail work and a slightly larger valve will get you into the lower 270s - closer to the advertised numbers @ .600 lift. It takes a pretty nice porting job to hit 300 cfm onn these. We get to the middle 320s with extensive work - but that is cost prohibitive for a build at this level.

Based on my dyno testing - and dynos are like flow benches - the combination listed above will get around 475 horsepower with a 272 cfm head. Assuming a similar flow/horsepower relationship the additional port work could get to around 520ish. The next cam up is the 294S with 248 @ .050 and .605 gross lift - it will get you closer to that 550HP mark. Jay used the even larger 306S cam is his Car Craft article engine to get the "Hollywood" number for the magazine - but that'd cost torque downstairs and idle like a can fulla rocks....