Does this HP guess sound right for this combo?

How can you have '68 351W heads? Anyway, with headers and a excellent tune, I could believe 280 or so. I would have chosen a different carb/intake personally, I'm assuming you already had the setup you have listed.

Stock mainfolds? What's up with that ? And 68 351W heads ? The Windsor didn't come out til 69, so if you've got 68 castings, then they're 302 heads. You've got your cam specs off. It should be 280 degrees ( advertised) on both intake and exhaust with a .512 lift on both. The 280-90 HP estimate isn't unrealistic.Why'd you go with the 84 crank ? Those are known to break easily. Seen two of them myself personally. The earlier 28oz ones are fine, and so are the later 80's on up to the end of production ones. Hope you're gonna have the rotating assembly balanced too, otherwise you'll regret it.

I was kinda wondering about the crank and rods myself. Nothing wrong with the rods, its just that there is absolutely no point in using boss rods compared to using stock rods with arp bolts. That engine definately needs headers asap.

On the contrary, the Boss rods are much stronger than the stock rods. A 3/8 ARP bolt is much better than a 5/16 one too.

Excluding complaints about specific parts strength or availability...
That sounds like a strong combo... except for the manifolds.
That is my worry. You have strong performing parts trying to push waste gasses through restrictive manifolds.
If the heads are 351w, then you have strong breathers mixed with other good breathing parts.
Get some LT headers on there!
My .02
Dave

D.Hearne said:

On the contrary, the Boss rods are much stronger than the stock rods. A 3/8 ARP bolt is much better than a 5/16 one too.

Click to expand...

unless I'm forgetting something(and its possible right now), the only difference between regular rods and boss rods were the bolts. The 3/8 bolt takes up room making the cap/rod weaker. Best solution was to use good ARP's(either 5/16 or 11/32) on a stock rod. Whats the casting number on the boss rods?

its a moot point on a <300hp street engine anyway.

Analysis Report for Street/Strip Engine with Desired HP Peak at 6000 RPM

Peak Tq =298. @ 4500 RPM .97 Ft Lbs per CuIn
Peak HP =279. @ 5500 RPM .91 HP per CuIn

Maximum Exhaust System Backpressure 'Exh Pres' is 1.1 PSI.
This is typical for a street/strip vehicle with a free flowing,
full exhaust system. To simulate open headers, select the
'Open Headers' from the Exh System Type combo box.


Maximum Intake Manifold Vacuum 'Int Vacuum' is 1.1 ''Hg.
This is somewhat high and is limiting air flow and HP.


Maximum Fuel Flow 'Fuel Flow' is 183 lbs/hr GAS.
This is equal to 31.3 gallons per hour of fuel flow.
For an injected engine with one injector per cylinder, you will require
at least 23 lbs/hr injectors.


Mechanical Efficiency 'Mech Eff' is 69 %
at the current Peak HP RPM of 5500 RPM.
This is Very low and represents a real power loss in this
engine's current operating range. This can be improved by paying
close attention to details in the Short Block Specs menu.



The Maximum Average Piston Speed 'Piston Spd' is 3000 ft/min
at the Performance Calculations Maximum RPM of 6000 RPM.
This is somewhat high (if you want to run this entire speed range),
requiring light, high strength reciprocating components.

A street/strip engine should limit Piston Spd to a range of 3000-4000
ft/min. However, even to run at 3000 ft/min or higher, you will need
'better than production', high quality reciprocating components
(connecting rods & bolts, pistons, etc.).

Maintaining low Piston Spd and Piston Gs are critical for 'keeping the
engine together'. OVER-REVVING PARTS BEYOND THEIR INTENDED LIMIT IS
UNSAFE FOR THE ENGINE, YOURSELF AND BYSTANDERS.


Maximum Contribution to VE During Overlap 'Overlap %VE' is 0 %.
This is Very low for street/strip engines which typically show
3-8%. Low Overlap %VE will limit Tq & HP and is most likely is caused
by high exhaust backpressure, high intake vacuum, exceptionally poor
intake and/or exhaust tuning or too little valve overlap.

It is normal for Overlap %VE to dip (even go negative) at some RPMS.
You will not be able to eliminate these dips and still maintain high
Overlap %VE at other RPMs. However, you may be able to move the dips
outside your desired RPM band.


The Intake Runner Velocity 'Int AvgVel' is 363 ft/sec
at your 'Desired HP Peak RPM' 6000 RPM.
This is somewhat high and indicates you will need a larger Intake
Runner Diameter or larger Intake Port Diameter for less
restriction and stronger intake tuning.

For these engine specs, an 'Int AvgVel' of about 260 should work well.
If the 'Int AvgVel' is approximately 30-80 Ft/Sec higher than this,
you will likely improve torque below this RPM, but lose some HP.


The Inertia tuning of this intake is tuned to 5222 RPM,
which is close to your 'Desired HP Peak RPM' of 6000 RPM.
Since this RPM is about where the HP peak should occur, peak HP
should be good. If you specify longer and/or smaller diameter intake
runners, you will likely gain Peak Torque and lose some Peak HP.


The Exhaust Runner Velocity 'Ex AvgVel' is 425 ft/sec
at your DESIRED HP PEAK RPM of 6000 RPM.
This is somewhat high and indicates you will need a larger Header
Primary Diameter for less restriction and stronger exhaust tuning.
Exhaust tuning is usually best with 300 ft/sec 'Ex AvgVel'.


The % Exhaust to Intake Flow Capacity 'Total Exh/Int %' is 67.9 %.
This is somewhat low, and indicates you could improve performance
by improving exhaust valve flow and exhaust cam profile. The most
common 'rule of thumb' is to design for around 75% EXH/INT flow
capability.

End of Analysis Report

Fwiw:
No changes other than 1.625" LT headers...
Peak tq: (298) 343
Avg tq: (231) 264
Peak hp: (279) 317
Avg hp: (178) 203
Vol eff: (91%) 99%

Iron manifold numbers in ()

302 coupe said:

unless I'm forgetting something(and its possible right now), the only difference between regular rods and boss rods were the bolts. The 3/8 bolt takes up room making the cap/rod weaker. Best solution was to use good ARP's(either 5/16 or 11/32) on a stock rod. Whats the casting number on the boss rods?

its a moot point on a <300hp street engine anyway.

Click to expand...

The Boss rods are different forgings. They're the same length as the 289 Hi-po rods, but the bolt seats are spot faced instead of square cut. You'd need custom pistons to use them in a std 302. The pin height needs to be 1.55 with them.

stephen4785 said:

Thanks for the power estimates. I couldnt get it pluged in right for my desktop dyno.
I know it sounds like Iv got a bunch of hosh posh of parts put together but when I built the motor alot of these parts were brand new and free.I figured that I would install them now so I didnt have to swap things later.I think itll all work fine once I get everything setup the way I want.Headers,stall convertor,heads,AOD tranny(with better internals),new rear end with limited slip-3.55/3.73 and disc brakes,electric fuel pump water pump and fan,better alternator,and all new suspension.

Click to expand...

Well, good luck with that crank, I hope it holds up. Like I said, I've seen two of those break, back in the mid 80's when they first went to the 50 oz/in balance weight. And both were in stock applications. One was in an F150, the other in a Crown Vic. Neither was "hot rodded" or had high mileage. If you want a better crank, I've got two 90's castings that are vastly improved over the mid 80's ones ( $50 each) I also hope you had everything balanced as well, if not then you're really asking for trouble with that mix of parts and that crank.