Is my hp/tq outputs correct?

[silvermonte]

I got my engine put on the dyno the other day. I followed an engine build from one of the Chevy mags from the internet. I cant find the article anymore but I swore their motor made over 400hp and 430tq if i remember correctly. I understand dynos will not match each other but I was a bit off from what I expected. Anyways Ill tell you the parts and let me know if there is something that I did wrong or missed something. I was looking for a strong DD motor that would get in the low 20s for mpg in a 2800# truck, I think this will do that but I would like to hear some other peoples thoughts.

350 block bored .60

Pro Comp Aluminum heads 210cc valves are 2.02 and 1.60 and I think the chambers are 58cc. The machine shop assembled them and made sure everything was good as Ive read these are hit or miss when it comes to quality

Compression is 10.1

Comp Cam CS XE268H-10
Advertised Duration: 268 int./280 exh.

Valve Lift with Factory Rocker Arm Ratio: 0.477 int./0.480 exh.
Lobe Separation (degrees): 110

Rockers arms are 1.6

Intake is Edelbrock RPM Air Gap with a Holly Ultra 650 DP

MSD street fire distributor is used for the ignition

Here are the dyno print outs

[IronChevy]

Many little different things put togheter can make a big difference on power numbers, like:

-The engine was tested with accessories? like alternator, mechanical fuel/water pump, this can make a big differece, the wather pump can take more than 15 hp.

-Ignition timing.

-Carburetor tune, including carburetor spacer and air filter.

-Exhaust headers.

The torque numbers are good in low rpm, maybe this its better if you want to use it as DD.

There are a lot of factor that can influence power numbers.
(sorry my bad english )

[Ron Sutton]

Hi Miles,

No one wants to hear this, so please don't shoot the messenger, but the combination is not in harmony. Specifically the heads, cam & intake.

The Pro Comp 210 Aluminum heads ... with large 210 cc runner sizes ... work well in engines running hard up to 7000-7500 rpm. But are too large for a good daily driver, low rpm torque, fuel mileage objective on a 360" engine.

The Comp Cam CS XE268H ... Advertised Duration: 268 int./280 exh. ... has 224°/230° duration @ .050" ... and .508"/.512" lift with the 1.6 rockers is a good low to mid-range camshaft.

The Edelbrock RPM Air Gap intake manifold is a "tweener". Edelbrock gave up low end power for more top end by making the runners larger, but as a dual-plane design, it's still not the best manifold from 4500 rpm & up. A single plane manifold like an Edelbrock Victor Junior would be superior from 4500 & up.

The cam & heads are the farthest apart ... with the intake in the middle. Obviously it will run ok and can be tuned for optimum performance, but it won't be as good as other combos because of the mismatches.

I don't know your goals, priorities, budget & sacred cows, so I can't advise you with any specifics yet. But in general ...
* If you want low 20's for fuel mileage, the heads are too big to be efficient in low rpms.
* If you want maximum power, it would require a larger cam & different intake.

P.S. If you want some specific advise, I'll also need to know what transmission you have (converter if it's an automatic) ... rear gear ratio & header specs (tubing diameter & length).

[sam 74]

I agree with Ron, it sounds mis matched, I'll also add that if your actual compression ratio is 10 to 1 that may be a bit much for that cam also, it'll run but If you want it to run well something will need to change, personally since you have the heads and they can get pricey and the compression, I'd match everything up to the those a bit better. I usually hear people getting disappointed after Dyno runs, it happens almost all the time. Matching up your parts will get everything working together well and your numbers will improve, what magizne did you get this combo from?