New 331 dyno #'s poor!! Help!!
 

I recently ran my new 331 set up on the dyno the yesterday and was VERY dissappointed. My car made 270rwhp@5500 and 291tq@5400 I believe (forgot the sheet at work). My engine is basically the complete edelbrock performer package (except with RPM intake) stroked to 331 cubes with the heads and lower intake ported. To summarize:6037 ported edelbrock heads(1.60/1.90), e-303 cam, performer rpm intake with ported lower, 1 5/8 shorty headers, x-pipe with 40 series flowmasters and turndowns, 24lph injectors with 75mm matched mass air meter, 70mm trottle body, 190lph fuel pump, and underdrive pulleys. Anyhow we took off the mufflers and only gained 4hp, and tried taking off the airfilter (gained 2hp). I put it on the scope today and no cylinders were dead although the voltage was low. I tried my buddys blaster coil and it didn't make much diff. either. Whats wrong here??? I e-mailed one guy and was told my heads are too small, my headers suck, my trottle body and mass air are too small and my cam is too small. OK fine but my car without the stroker kit and head/lower manifold porting made 250rwhp and 270tq last year. It's just very hard to believe stroking the engine and porting the heads and lower intake would only net me 25 more rwhp. My dyno guy tunes many 5.0's and thinks output should be at least 300rwhp so were is my problem??? I don't have thousands of dollars more to put into the car. Could it be the cam? The stock igniton system?? What gives? The dark side is looking really tempting right now because a stockish LS-1 car makes about 300rwhp and my big expensive 331 can't even come within 25 ponies!!! Help me.

Re: New 331 dyno #'s poor!! Help!!
 

When you built the engine, what was your ring end gap? Have you run a compression test to see what the static compression is? Was the engine overbored (God I hope so), and if so, were the cylinders checked afterward for the correct finish and straighness? Was the overbore done with torque plates?

Just a bunch of questions I'd like to know the answers to. I'm assuming you were running FRESH high-octane gasoline with the timing set correctly, and all the usual other dumb stuff that SHOULD be taken care of. :p

FYI, I used the E303 camshaft in my mostly-stock LX, and it actually went SLOWER in the quarter-mile.

I'm writing this @ 4am so if I'm missing anything, it's cuz I can barely hold my eyes open. :(

Re: New 331 dyno #'s poor!! Help!!
 

Although the parts may not be optimum, they don't "suck" and I agree you should be making more power. Did you degree the cam in? Did you check for proper pushrod length/rocker tip travel? The little things can make a BIG difference.

Re: New 331 dyno #'s poor!! Help!!
 

The short block was built by a reputable builder who has been in business for quite awhile, but I have not done a compression test yet and I highly doubt compression is low but I will check anyways. I believe he said 10.4 to 1 with my alum. heads. My valve train is exactly the same as it was with the last setup (stock rockers), my timing is at 14 degrees. I also run the same premium fuel I always have. My cam was installed stright up, and my valve train was set up with proper clearances. My exact dyno numbers are 267.7rwhp@5500 and 291.1tq@4000rpm

Re: New 331 dyno #'s poor!! Help!!
 

OK, you have the stock pedistal rocker set up. With 10.4:1 compression I'd have to ask if the heads were milled - if they were and your running the stock length pushrods, your may not running the best length pushrod or have the optimal valve train geometry.

Re: New 331 dyno #'s poor!! Help!!
 

I do have one ineresting trinket of info. I just came upon. a friend had his stroked LS-1 car to the same dyno yesterday and was told he is only making 360rwhp, this is very hard to believe because it is a 408cid and although it is lower compression for the blower (20-30psi)(the blower belt snapped on the dyno so they ran it with just engine) I would think it should make at least 400rwhp even without the blower running (mind you it is a chevy though) if I factor 10% low readings I would be making around 300rwhp and he would be at 400rwhp. I guess I'll just have to get it to the track and let the drag strip tell me for sure what I have before I go ripping my new engine apart.

Re: New 331 dyno #'s poor!! Help!!
 

You don't say what your A/F ratio was on the dyno. What timing are you running? Without knowing what the PCM was doing, there's no way to know for sure where the problem lies.

Re: New 331 dyno #'s poor!! Help!!
 

A/F hangs right around 13 to 13.3 and timing is 14 or 15 degrees intial. We played with both to find optimal settings, my guess (although not a guru by any means) is that my problem does not lie in either timing of A/F ratio. My dyno guy runs a 9 sec twin turbo LX and I am very confident in his tuning abilty.

Re: New 331 dyno #'s poor!! Help!!
 

your 302 made 250rwhp, that's 0.83 rwhp per cubic inch. You only added 29 cubic inches, it's not like you stroked the crap out of the thing, so there's no reason to expect much more than 24 more horsepower (29" x .83).

Was this on a mustang dyno or a dynojet? Mustang dyno's, while more accurate in simulating real world conditions, will give you a lower hp number.

Have you had it on the track to compare times at all? How does it feel? Can you post up the dyno graph with the AF curve?

My advice would be, if you don't want to spend a ton of money on a new set of heads (which would really help it out) then focus on the cam. Call up Jay Allen, Ed C, or any of those guys, and they'll be able to help you out.