Estimated Horsepower and Torque?

[timsullivan]

I'm building the following motor. What would you guess the horsepower and torque specs will be?

351W bored and stroked to 408"

10:1 compression (based upon dished pistons and 60 cc head chambers)

Edelbrock Performer RPM Alum cylinder heads with the larger 2.02" intake valves, 60 cc chambers, 170cc intake runners

Comp Cams full roller rocker arms

Edelbrock Performer RPM Air Gap intake

Holley 750 CFM carb

Superformance headers and side pipe exhaust

Cam specs as follows: Hydraulic Roller: Lift: 510/534, duration at .050 222/232, 114 LC

MSD Pro Billet Street distributor

Milodon Windage tray and 8 quart pan


What's a wild guess on torque and horsepower?

[Gunner]

I have a very similar 302/347 that was software dyno projected at 430/430. You have 18% more displacement and a slightly more radical intake. I'd guess 500/525.

(I have yet to get the engine installed and chassis dynoed, so I have to trust the software numbers from a very experienced builder.)

[Mark O'Neal]

I don't know.

But the heads, the cam, and the manifold are all too small.....and that motor doesn't need a 114* LS.

[Gunner]

Originally Posted by Mark O'Neal

But the heads, the cam, and the manifold are all too small...

It's a fairly mild build but not a bad one... maybe you could explain "too small" WRT heads and intake?

[vector1]

ford crate 392 with gt40 heads and more lift/same duration, vic jr intake makes 430 hp/ 450 tq.

[Hotfingrs]

You're adding cubic inches, and not enough parts to match. The more inches, the more it tames down the parts. 170cc intake runner is too small, 114 LC is way too much, probably should be no more than 110. Not knowing what you intend to use the engine for, you've basically got a grocery getter engine here.

[Gaz64]

As others have said, a mild combo for over 400 cubes.

I'd be going for more compression into the high 10s, single plane intake, 850 DP and about 245-250 @ .050 lobe centre of 106-108.

[bermblaster41]

As everyone has said.....a mild motor. If you are going thru with the expense of stroking you should bump up your top end. I have a 408 with afr 205 heads,, cam with .600 lift duration in the 250ish, vic jr intake with 850dblpmpr. I dyno'd at 437hp at the rear wheels corrected at the flywheel 555hp. If you want a mild cobra stick with a 351 and save yourself the bucks . Not a slam by any means just giving you my2 cents. Berm

[Three Peaks]

Two things jump out at me- the RPM heads don't match up with the rest of the engine, flow- wise. And the Superformance sidepipes have a reputation of being very restrictive.
A set of Vic. Jr. heads or AFR 185/205's would really wake up this engine. The cam is fairly mild, with that displacement a cam in the .550 lift range would be better suited. However, you should easily be in the 400-430 range at the flywheel, which isn't too shabby in a Cobra and will be more than enough horsepower to be entertaining.

Bob

[Mus408]

Amazing how things change with time! I remember when a 230/240 degree cam was rather wild for a 400+ cube engine...remembering the old RA IV Pontiac engines.
Depends on how wild a combo you can tolerate down below 3000 RPM,for street use. I have found a 231/239 hyd. roller is working well as an all around cam for a 427 stroker. 234/242 optimum.
I tried a larger 242/249 hyd. roller and it was giving 9-10 inch idle vac. and a bit rough for use below 2000 RPM.
Look how small the duration is in some of these 400 inch LSX strokers,and they're making 550-600 HP. They have great flowing heads to make it work.
Use a good head and cam for RPM range of power.

[jdean]

Yes not enough heads or cam for the cubic inches. It will make great low end torque though.....in fact it specs out more like a truck engine as it is.

[timsullivan]

Here is what Mike Forte says about a very similar engine running this EXACT camshaft:

I just dynoed a 408 that produced 491 hp & 515 ft lbs. It's a real workhouse with a mild custom grind hyd roller, Edelbrock heads, 10.4:1 comp ratio forged Eagle rotating asm & Edel Air Gap intake & Holley 750 dp. This engine produced 400 ft lbs below 3000 and peaked at 515 around 5000.... I use this custom grind camshaft on smaller engines with fantastic results. This would work fine in any car and run below 2000 rpm in 5th gear with np problems.

[Three Peaks]

Check which Edelbrock heads he is running on this combo. I'm betting they aren't the RPM heads...

Most of our answers are speculation based on some real world experience and anecdotal evidence. Not really scientific. If Mike says it is a great set up, it probably is.

Depending on your purposes, you won't know for sure what you're going to get until you have someone do a calculation on one of the many computer engine calculators available. Or, you cand build the engine and find out for yourself. Either way, I think this cam will make more than enough horsepower to be fun/dangerous in a Cobra.

Bob

[olddog]

I have Edel performer RPM heads on a 347 (5.0 stroker). I'm running .555/.575 lift and 236/242 duration. I think the LSA is 106 or 108 - I'd have to find the cam card to be sure. It depends on what you like, but vacuum at idle is low and idle is a bit knarly. I feel these heads limit the engine. The heads have been port matched to the gaskets.

Power is all about breathing. I would put better heads on the 408. Look at Keith Craft's web site and check out his head section. For about the same money you can step up to better heads.

If you like good low rpm torque, your cam will work. I would go higher on the lift, to take advantage of the heads. Another 6 deg on the duration would help, and still give good manors.

Just one more opinion.

[PDUB]

I am planning/building a similar 408, with the Eagle forged rotating assembly. I checked with KC about what he uses, and it was Vic Jr. heads, RPM air gap intake, and the DaVinci 750HP carb, which I got from Kieth.

He builds this engine, and I saw a dyno sheet (I'm guessing you could get a copy from him) that said 524.7 Hp @ 5500rpm and 541.0 ft-lb torque @ 4600 rpm. The hydraulic-roller cam he used is the Comp Cams 35-426-8, which I had ground to use the retro-roller lifters, so no reduced base-circle... At .050 lift, the in. and ex. numbers are 236 240, with .555 .576 lift and a 110 degree separation angle.

The RPM heads won't develop as much, since they don't breath as well, but that does'n mean that they aren't a good choice for you.

If I remember correctly, in one of the Ford engine rebuild books they do a 408W based on the bolt-on performer RPM package (heads, cam, intake, and carb) and it produced 410hp and around 430 torque at the crank.

Hope this helps...

[Mus408]

Did some carb tuning on my combo today...427 Dart with TFS Highport heads,ported, Super Vic intake with my latest 900 wetflow Holley,and a weeny 231/239 Lunati hyd. roller.
In my 3000 lb,with driver '85 Mustang,5 spd with 3.50 gear,1st and 2nd gear at any hard throttle is useless on the street tires,and 3rd gear at around 4000
RPM,at WOT at speed is also useless on the street tires. Tires are somewhat
sticky Potenza R1's 245x45x17.
In a lighter Cobra,that would be a plenty of power!
I do have a larger cam on the shelf,but it kills the idle vac. down to 9 inches.