|07-17-2008 11:39 AM|
start a new thread????....
title it something like "how to build a mega TQ 451 mopar street beast motor for my Dakota"....
I have never built your particular motor....
there are lots of (mopar experienced) members better qualified to help you pick a combo....
more general food for thought:
the very general rules "key" for getting the max TQ possible at the lowest rpms possible is getting max A/F velocity possible at slow piston speeds (low rpms)....
that's what the 4x4 and RV cams are all about (excellent A/F mix quality and chamber fill to make best power possible at low rpms)...
what I don't know at all is how your heads are biased for intake versus exhaust ratio which you need to consider when selecting a cam...
and using a intake with relatively small runners (like a performer) and a wee bit small cfm rated carb to help keep up the velocity does help ....
(trivia, 383 roadrunners only had about a 450cfm carb to help make TQ)
deeper gears does make a world of difference for TQ "wow" factor....
450ft-lbs x 3.55 gears = 1597 ft-lbs
450ft-lbs x 4.56 gears = 2052 ft-lbs twisting the hides=25% more acceleration force
but try to be sensible for how deep the ratio is versus how you use the truck!
your truck is heavy so deeper is better but 3.55=roughly 3,000rpms at 70mph and 4.56=4,000(? calculator not handy) at 70mph
I'd leave the 3.55's in it and gut every last extra once of weight possible out of the truck, (performance results are the same)
4000lb truck/1597ft-lbs 3.55 gears=2.5lbs of weight per ft-lb of TQ force
5000lb truck/2052ft-lbs 4.56 gears=2.5lbs of weight per ft-lb of force
(trivia: 98%? of all of the muscle cars had deep gears standard and that's why they were a blast to drive...big cubes TQ and low gears..)
build it with about a 9.3CR so you can use 87octane and full best timing for the cam (450cubes+4,000lbs="not great"mpg)
more compression does add some to the HP "at" the HP rpms peak but adds very very little at street rpms and smaller cams don't need it
drive safe, have fun
|07-16-2008 10:11 PM|
|SSedan64||Hiway, what crank & rods are you going to use? 440 crank & BBChevy rods?|
|07-16-2008 10:08 PM|
I appreciate everyone's feedback, thank you.
RedMustang, would you suggest I go with the set up I described earlier even if it doesn't meet my goal for HP? This will be a weekend cruiser with a visit to the drag strip maybe twice a year.
|07-16-2008 01:37 PM|
just some food for thought:
unless the main major goal for the build is to hit a specific strip et and mph you can honestly ignore the HP number....
(the HP number is basically applied TQ measured over distance and time)
what makes a really fun to drive street car is all about max TQ possible available over the WHOLE rpm range....
it's the TQ rotational acceleration force that pushes you back in the seat and gives "instant" gas pedal response and wicked quick mph and rpm's increase passing somebody .....
when you build up the HP to 1HP per cube, you don't gain much more TQ (if any) and usually have alot less at street rpms due to the cam (that's why a big HP cam needs very low gears and a convertor swap, no low rpms acceleration force TQ available to move the car weight)
(very very roughly motor cubes=max TQ ft/lbs....)
with just a stock 87 octane 451cu/in motor your 450ft/lbs x 3.55 gears in high gear (1:1) = 1597ft/lbs of force available twisting the hides at roughly just 3400rpms!!!!
due to poor weight distribution in a PU it's gona be a challenge to get the tires to hook up at all in first gear (and not break lose on a wet road) with that much flywheel TQ!!!
a favorite Max Keith (a member) saying that's so true so often: "ALOT more gooder isn't necessarily more good"
|07-16-2008 01:02 PM|
I'm building a 400/400 right now with ported 915 closed chamber heads.
I don't think that stock open chamber 452's will do it. You need template porting and big valves. Modifications for valve lift will be necessary because you need as much lift as you can get. Stock rockers are fine up to .525. Most testers agree that the big valves without porting is a waste of time.
I suggest the new cams designed for Mopar lifters, roller preferred, solid roller the most preferred which requires a new valve train.
Something as mild as a Purple Shaft flat hydraulic 292/.509/108* I don't think will get you to your goal, but it is a nice street cam in 440s. (we run it in our long cross ram 440s) The LSA is most important. 112*and more sucks.
Pistons with a mild dome to fill the open chamber will be a benefit, keeping the compression about 10.0 for 91 octane.
You will also need a Performer RPM. Avoid single plane intakes.
I'd plan on keeping it under 6,000.
|07-16-2008 11:48 AM|
|babygene41042||You are not going to make 450 horsepower with 451 cubic inches and a cam that small.Plus you want to shift at 5500 rpm.You are going to need better heads,bigger cam,and about 6000 to 6500 rpm depending on the heads.Or just get a 440 and stroke it.Then it would be a lot easier.I don't know much about the 452's.But you will still need to look for a bigger cam IMHO.|
|07-16-2008 07:05 AM|
|Highway||Yes, I already have the 452's. They were on the 400. For my 450hp goal, 452's should work fine.|
|07-15-2008 09:09 PM|
|slowturbo||Do you already have the heads (or any of the other parts)? If not, I'd consider running either stock or the MP HD rockers, and put the money saved toward a set of aftermarket heads like the Edelbrock Performer RPMs , or the Stealth heads from 440Source (though I am personally biased against the Chinese 440Source castings).|
|07-15-2008 01:57 PM|
engine build - 451 stroker
Guys, let me know what you think. This will be my first engine build.
85 Dodge Ram D150 - short bed
450hp - Power band between 1800 to 5500 rpms
Weekend cruiser and sometimes drag strip
400 B block .40 over
crank - 3.75 stroke
Rod length - 6.760
pistons - KB 215s (10:1 FT)
Heads - "452"
valves - 2.14int - 1.81exh.
3-angle valve job
Intake - Eldebrock Performer Jr - dual plane
carb 750cfm - make/model undecided
Camshaft - .480-.485 lift