Low Dyno.. What's Wrong?
 

Ok, so the crate motor was supposed to make 620 hp/tq crank...

http://i156.photobucket.com/albums/t...9b/fayl002.jpg

Block
4 Bolt Main .060 over block
Two piece rear seal, drivers side dipstick
Square and parallel decked
Align honed main bearing bore
Cylinders honed on computer controlled machine to within .0002
straightness and roundness
Cylinders are sonic tested for thickness

Rotating Assembly:
New SCAT forged steel crankshaft internally balanced
New SCAT 4340 forged H-beam connecting rods
150,000 psi rod bolts
Probe forged flat top pistons
Hastings moly rings
Rotating assembly balanced to within 2 grams
Melling high volume oil pump
Hydraulic roller cam
Jesel shaft rocker system

Cylinder Heads:
AFR aluminum rectangular port cylinder heads
305cc runners and 119cc chambers
1.509 dia. Valve springs w/ damper Hardened retainers & keepers
2.25 swirl polished intake valves
1.88 swirl polished exhaust valves
Comp cams hardened push rods
Jessel rocker arm system

Edelbrock performer RPM airgap intake manifold
10.0 to 1 compression
Milodon cad plated oil pan
Brass freeze plugs
Professional Products harmonic balancer


TRANS is a Th400 with 2300 Holeshot converter
REAR is a 12 bolt with 3:08s

3rd gear at 6000 RPMs was 139.1 mph, so I would figure it's about 8% slippage on the converter. I plan to have an FTI custom built, but could this converter really be the reason for me being so low on power?

All input welcome :chug:

Man, you need to know one thing, a automatic can give some WAY off readings, i have seen cars make 450 RWHP out of a big block but still nail down low tens to the wall, meaning the readings were fals, only use the dyno for maximum tuning purpose and not for the actual power read out, use a calculator and the track to get the estimate with your MPH and race weight, ti is WAY more accurate for me.

-Z

Thanks, I realize that automatics dyno low and all just figured this was way low and maybe something was wrong. Car needs to go to the track.

Yea, the numbers look low to me, but dynos do crazy things, so i dont trust them.

But at the same time I lost to a bolt on + MS4 ls1 camaro, so i feel like i really make low 4s when i wanted high 4s and almost 5xx whp

Have you tuned it?

two things stand out to me. the first is the flat top pistons, flat top pistons and open chamber heads at 119cc usually result in low compression. i would think it needs a small dome to achieve 10:1. second is the rpm i would think an AFR headed big block with a roller cam would turn 6500-7000 rpm and the pull stopped at 5800. i would double check the timing and look at all eight plugs for clues. hopefully someone with more knowledge will chime in here.

It is a hydraulic roller cam that is the reason for the 5800 rpm stop. The valvetrain is really heavy when you go hydraulic roller in a big block. It needs to go solid. The jesel system helps out but its only minimal compared to a standard rocker.

To the OP your A/f is way down dipping below the 12's in the middle of the pull and barely above 12 at the peak of the pull. It needs to be a bit leaner and you might see more power.

Flat top with a 119cc head is around 9:1 throw a blower or a hair dryer on it now.

Yea, a flat top is 8.8 or so, my old mini domes were 9.7.

The motor is a crate motor. (Mostly wanted a warranty honestly..)

http://www.blueprintengines.com/popu...specs&pc_id=64

The motor is a crate motor. (Mostly wanted a warranty honestly..)

http://www.blueprintengines.com/popu...specs&pc_id=64

Well, i am sure they dyno with zero accessories and a huge ass set of headers, but still seems low, like i said, dont trust the dyno, but you got drug by a cam car...maybe the weight would be a factor but damn.

496 chevy, 8-71 blower, 12 psi, 4l80e, 3.50 rear gear, heavy tires, steel wheels.

disappointing chassis dyno #'s = 520 rwhp, 580 rwtq

3800# (plus driver) => 10.62@127 (foot brake, 91 octane, hacked stock converter)

I don't claim to be any sort of chassis dyno expert, but I have a suspicion that if you put the same setup with 4.56 gears would see significantly higher numbers.

sorry if i missed it, but what carb? is it included with the engine kit?

wow, that is a small cam.

Dont put much stock in the rwhp dyno numbers....A TH400 is a horsepower killer, as is the mechanical accessories etc...All that really matters is how it runs....

When I dynoed my 496", we gave it the best possible conditions to make good power....(no accessories, no water pump, hot oil temp, cold water temp, big 2" shop headers with no exhaust, dyno carb hat, well ventilated dyno room etc...) mine made a corrected 657hp/675q.

But in the car I have full mechanical accessories, smaller headers, full exhaust, no carb spacer etc, Th400 w/10" converter, IRS rear end etc...so I only expect about 430hp to the wheels or so....a total turd right???

Last weekend I made one soft pass and it ran 11.14@122 with only a 1.69 60' at 3730lbs then got restricted to 1/8 mile....I made 3- 1/8 mile passes and it kept getting quicker...ended up at a 7.05 1/8 at 99.36mph....

This is a heavy, stock suspension, highway geared, weekend cruising 71 Vette with AC on a 255/60 drag radial..... No one would suspect it being even remotely fast....yet if I was to dyno it I would have been very disappointed with my low-mid 400s.....


Get it to the track....you'll be happy if the motor really made 620hp at the crank...:nod:

I doubt that thing is 10:1 with flat tops and open chamber heads. your lucky if its 9:1 really. (not trying to be a dick)

I dont understand why they have all that duration and then a 112 LSA on a carbed motor...no sense except to have a smoother idle....dumb.

What size are the headers and carb?

I'd like to see some 2" headers and a nice 850 DP Holley on there.

Carb is a 750 DP, need to measure the headers and see

With a 1/4" dome and 119 heads, it works out to about 10.25. At least that's what my wifes 489 is. She has a 1000 Holley, TH400, 3200 stall and 3.90 gears with a small mech flat tappet and in runs 10.80's with mid 1.5 60' times. Weight with her is 3200.

http://cambirdracing.com/myPictures/suni_2-28-09_1r.jpg

your right about the compression...he is lucky if hes 9:1, that'll hurt power for sure, I still think it will do well with a bigger carb and headers, and a bigger bump stick.

and some gear.

Chad