Not too bad but there is a problem after 5500rpm. The curve hits a flat spot (at 5500) and then drops off around 6500. When I say flat, this thing doesn't fluctuate more then 5hp over 1000rpm. I'm also losing 100lbs of tq in 200rpm. Could be valve float or someone had mentioned that the valves could be too tight. One more thing, not sure if its related, the tq curve was shifted to the left (lower rpm) more than what the dyno guy was used to seeing. Long story short here's the build, 355 holley stealth ram and 58mm TB 30# injectors at ~41psi (the needle was bouncing very fast) Protopline 200cc comp cams @ 0.050 230/244* and .544/.576 commander 950pro. 10.18:1 c/r dynamic is around 7.58:1 (low) and the numbers 355rwhp and 357rwtq I was hoping for closer to 380+. A/f was close to 13:1 I have the dyno files but don't know how to read them. I can send the files to someone if they want to post them for me. I would GREATLY appreciate it.

You can send them to me MaxxMitchell@kc.rr.com but i wont beable to check my email till after 5 or so, but i could upload the pics tonight, unless you can get someone else to get it for ya.

Are you sure 41 PSI is enough? How much was it bounching, a 1-2 PSI or more? Sounds almost like you where running a little too lean at WOT. Might need to recheck your fuel system, sounds like either a pump or a filter/lines might not be up to par. Checking out the graph will help alot.

I still think you needed to jack up the FP and lean out the tables...JM2C! Although I still wouldnt rule out the mechanical side of things!

I agree, I think the pressure is too low. It was bouncing violently about 4-5psi never dropping below 39. I didn't want to waste dyno time going thru the tables again. Anyway I figured out something, here's the graph. I still can't get the hp & tq va rpm.

That's going through a T-56 and a 9"

definitely a fuel pressure problem if its bouncing around that much, but just out of curiousity, what does the ignition map look like.

Dang, that thing fell on its face...

Working on the spark map.

Too bad there was not a widebanc O2 sensor available. Looks like pretty good number to me. Get that problem solved and it will be better yet.

There was a WBO2. It was reading 13.1:1
We played w/ the timing and fuel tables but not the pressure.

If you can post the O2 readings vs the RPMs with the HP & TQ graph it might be a little easier to see where theres more power. But i would deffinitly work on your fuel system first and get the pressure evened out. What are you using as a pump, lines, regulator? If its an external pump, did you remove the intake and make a pick up?

Getting some knock retard maybe? 13.0-13.1:1 afr should have been pretty good if it's stable. 355rwhp isn't out of line IMO, the Protoplines are unported right?

If it's not weak springs yeilding some valve float I'm wondering about some knock retard w/ that wavyness going on if the AFR was steady, the C950 show you KR during the run?

Not running a knock sensor. Thinking too much timing?
Here are some runs w/ the A/F ratio.

Unported off the shelf. They still advertise flow number up there w/ AFR. And according to all the calculators I've seen they'll support 544hp (in theory). 355 +15% = 408hp @ crank.

Today I drove the car and it's now breaking up real bad above 5500. I'm pulling some springs this weekend to check install height and pressure, see if they're the culprit.

Do you think that the motor itself my not like the 14* split in dur. from the intake to the exhaust?

One more thing, doing some math ( i know, more bench racing) the car (3440#) went 7.78 @ 89mph. That works out to around 375rwhp.

which is about right if you're making 410 crank HP, considering frictional losses through the transmission & diff.

what kind of dyno were they using?? Dynojet? Mustang??

Dynojet dyno.

That's what I thought 375rwhp sounds right, it make sense. 355 OTOH seems low. I'd be happy w/ another 20rwhp.

fuel pressure...

What kind of fuel pump do you have? Sounds like its time for a better one that can keep up if your having pulsations.

been there done that. What's in the tank??

if your using hydraulic rollers its likely valve float, there have been many posts dealing with this. I have afr 190's with the upgrade springs with a comp 224/230 roller and i set my rev limit at 6000 to avoid any chance of float. My power should peak around 5500 with a 383. i think you should peak around 6000 so i can see wanting to get to 6500. I was told by Rick Spearling (owner of afr) that the bsaic spring they sell would float by 5500-6000 with the hyd roller i chose the upgrade i have is good to 6000-6500.

don't rule out FP but its common to have these problems with hyd rollers and off the shelf heads

If the Top line and the Pro Action heads are the same heads, the CHP flow numbers are a good bit lower than the advertised. If that's the case, your numbers look really good to me.

You posted SAE numbers with a smoothing factor of 0. Most magazines and a number of people post the "standard" HP numbers which would probably boost your HP by at least 15 horses. They typically do not use the smoothing factor of 0 either,,, 3 usually, sometimes 5 which typically drop your peak HP by a few horses, but literally smooths the fluctuations in the graph. So, make sure you note those when comparing your numbers.

Your A/F looks good, nothing to suggest you had a fuel problem,, your gauge jumping around could be the gauge. I'd check it out though, because if the fuel pressure really is jumping around you'll need to correct it. Although it might not have any real significant impact on HP, it could extend the life of the engine if the pump is going bad and craps out on you.

The curve is shifted a little more to the left as I would have expected myself. It looks like there might be more than 4 degrees advancement on the cam. Did you degree the cam? If you have the cam advanced more than 4 degrees and throwing a lot of timing at it, it could break up at the top end - backing off the timing would let you know if too much timing is a problem.

More than likely you're getting into valve bounce or float due to the springs - a tell-tell sign is if the rpm it starts to break up keeps getting lower and lower. Try adjusting the lifters to 1/8 turn - if that,,,, and the timing drop doesn't cure things, my bet it you'll need to replace the valve springs.

I pulled off a couple springs and will be taking them to get tested today. If that's not it, I'll bump up the FP and adj. the valves 1/8 turn or less.

Thanks for everyone's help.

fuel pump is an intank walbro 255.

BTW, these are none corrected #s. "standard" and there is only a difference of about 8 hp versus the SAE corrected #s. Remember, this was with less timing IIRC, the 6th pull you added timing and a little fuel where you were lean from the 005 pull, and your numbers dropped...correct!?


DYNORUN.005: 102.64°F 30.09in-Hg Humidity:8% STD:1.02 Average Gear Ratio:N/A

s mph hp Air/Fuel
0.18 59.00 N/A 11.71
0.34 60.00 198.60 11.88
0.45 61.00 205.58 12.31
0.56 62.00 210.88 12.53
0.67 63.00 216.88 12.61
0.78 64.00 221.92 12.60
0.88 65.00 226.49 12.55
0.99 66.00 231.60 12.52
1.09 67.00 236.13 12.51
1.20 68.00 241.47 12.48
1.30 69.00 246.33 12.46
1.41 70.00 250.73 12.44
1.51 71.00 255.39 12.41
1.61 72.00 260.58 12.39
1.72 73.00 264.77 12.38
1.82 74.00 267.81 12.35
1.92 75.00 271.66 12.32
2.02 76.00 275.60 12.32
2.13 77.00 279.88 12.37
2.23 78.00 284.15 12.43
2.33 79.00 288.71 12.48
2.43 80.00 292.42 12.52
2.53 81.00 296.21 12.57
2.64 82.00 300.68 12.61
2.74 83.00 304.23 12.62
2.84 84.00 307.58 12.62
2.94 85.00 311.59 12.64
3.04 86.00 314.50 12.67
3.14 87.00 317.34 12.69
3.25 88.00 321.13 12.69
3.35 89.00 324.26 12.69
3.45 90.00 326.89 12.69
3.55 91.00 329.08 12.69
3.66 92.00 331.74 12.68
3.76 93.00 333.94 12.68
3.86 94.00 336.60 12.66
3.97 95.00 338.20 12.68
4.07 96.00 340.88 12.73
4.18 97.00 344.38 12.79
4.28 98.00 347.10 12.83
4.39 99.00 350.02 12.87
4.50 100.00 353.27 12.91
4.60 101.00 356.65 12.96
4.71 102.00 357.74 12.99
4.81 103.00 360.88 13.02
4.92 104.00 361.98 13.03
5.03 105.00 364.04 13.03
5.14 106.00 363.21 13.02
5.25 107.00 363.29 13.00
5.36 108.00 363.49 13.02
5.47 109.00 363.10 13.05
5.58 110.00 363.50 13.09
5.70 111.00 364.51 13.14
5.81 112.00 364.10 13.15
5.93 113.00 364.64 13.13
6.04 114.00 364.00 13.02
6.16 115.00 361.55 12.89
6.28 116.00 360.61 12.83
6.40 117.00 359.38 12.74
6.53 118.00 356.01 12.55
6.65 119.00 355.08 12.01
6.78 120.00 347.78 11.38
6.92 121.00 313.37 10.93
--------- --------- --------- ---------
MAX: 6.92 121.00 364.64 13.15
MIN: 0.18 59.00 198.60 10.93


DYNORUN.006: 102.06°F 30.10in-Hg Humidity:8% STD:1.02 Average Gear Ratio:N/A

s mph hp Air/Fuel
0.22 51.00 N/A 10.90
0.44 52.00 153.23 10.72
0.57 53.00 160.27 11.31
0.69 54.00 166.29 11.84
0.80 55.00 173.80 12.14
0.92 56.00 179.16 12.30
1.04 57.00 183.45 12.33
1.15 58.00 188.31 12.31
1.26 59.00 192.91 12.27
1.38 60.00 198.06 12.23
1.49 61.00 204.14 12.21
1.60 62.00 209.06 12.20
1.71 63.00 214.39 12.21
1.82 64.00 219.56 12.24
1.92 65.00 224.17 12.26
2.03 66.00 228.94 12.26
2.14 67.00 234.19 12.22
2.24 68.00 238.55 12.22
2.35 69.00 243.48 12.28
2.45 70.00 248.22 12.31
2.56 71.00 252.67 12.27
2.66 72.00 257.18 12.24
2.77 73.00 261.91 12.24
2.87 74.00 266.24 12.25
2.97 75.00 270.89 12.28
3.07 76.00 274.83 12.31
3.18 77.00 278.75 12.33
3.28 78.00 282.55 12.35
3.38 79.00 286.88 12.38
3.48 80.00 290.89 12.42
3.59 81.00 294.61 12.48
3.69 82.00 298.78 12.55
3.79 83.00 303.11 12.58
3.89 84.00 307.17 12.57
3.99 85.00 309.93 12.58
4.10 86.00 313.03 12.62
4.20 87.00 316.79 12.65
4.30 88.00 320.56 12.66
4.40 89.00 322.22 12.66
4.51 90.00 323.69 12.63
4.61 91.00 326.33 12.60
4.71 92.00 329.03 12.59
4.82 93.00 330.71 12.59
4.92 94.00 332.76 12.62
5.03 95.00 336.04 12.64
5.14 96.00 339.37 12.63
5.24 97.00 341.40 12.64
5.35 98.00 344.02 12.68
5.45 99.00 346.52 12.74
5.56 100.00 348.78 12.77
5.67 101.00 352.41 12.79
5.77 102.00 354.50 12.82
5.88 103.00 356.08 12.84
5.99 104.00 358.13 12.82
6.10 105.00 359.71 12.79
6.21 106.00 360.39 12.77
6.32 107.00 360.08 12.78
6.43 108.00 359.94 12.82
6.54 109.00 360.16 12.86
6.66 110.00 359.91 12.86
6.77 111.00 360.37 12.83
6.89 112.00 359.82 12.80
7.01 113.00 360.58 12.76
7.12 114.00 357.82 12.71
7.24 115.00 356.48 12.67
7.37 116.00 356.71 12.66
7.49 117.00 354.27 12.59
7.61 118.00 351.67 12.45
7.74 119.00 351.93 12.20
7.87 120.00 347.17 11.80
8.00 121.00 333.71 11.13
8.15 122.00 298.87 10.60
8.31 123.00 275.90 10.45
8.48 124.00 263.95 10.89
--------- --------- --------- ---------
MAX: 8.48 124.00 360.58 12.86
MIN: 0.22 51.00 153.23 10.45

You didn't mention it being 102* when you were dynoing. I'm sure that's good for 1-2% more power.

Something seems off with that fuel pressure still. Why do you have it set to 41psi anyways? I'd set it to at least 43, maybe something more like 45-47, and then just raise the injector constant in the chip, see if that fixes anything at all.

It seems to be running a tad rich the way it is across the whole board.

Id hold off raising the pressure untill there is a good reason to raise it, like very high injector duty cycles.

I agree, I'd rather see 13.5:1, I don't like the 12.X:1. Loads up my colder plugs to much.

FP, I think I am going to set it at 45psi even though it isn't going lean. Piece of mind.

Poorboy8, Yes. On run 6 we tried adding a bit more timing and the numbers did go down, not much, but they sure didn't improve. I don't think we changed the fuel from dyno 5-6.

I'm running a C950 ECU from holley which doesn't recognize injector size. There is no place in the ECU to change the constant. It's all done w/ the fuel table.

YES! Which is fine by me Although do you remember weither or not you can your duty cycle on your injectors?

I didn't see any, I'd have to check again.

Got the springs checked out,
130# on the seat
325# over the nose.

Damn near coil bind though, less than .080". Any votes on valve float? My machinist said I should be looking at something w/ around 380# open.

Problem is finding a spring w/ an install height of 1.750

According to comps catalog, for your cam you should be using a 987 dual spring: 121@1.800, 388@1.200. Your machinist can probably get an offset retainer or whatever is needed to get these to fit. This is also a 1.430" spring, what size is in there now? I would call comp and get their opinion.

Comp keeps telling me to go w/ the 918's which is 130 and 318. That just doesn't sound like enough to me at open.

The springs I have cam on the heads from summit and were supposed to rated to .600 lift but didn't give me any pressures at open and close.

Will running a different retainer like that screw w/ my valvetrain geometry? Would it req. longer pushrods?