Loss of HP? Help!!

Old 08-25-2008, 09:05 PM
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Midgetmouse
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Default Loss of HP? Help!!

I went to the track this past weekend for test and tune and my car was way slower than expected. Here are the specs. 3550 lb car, 350 chevy w/Dart 64cc 215 heads, comp roller cam xr288hr, performer RPM air-gap intake,Holley750 double pumper, MSD ignition, headers w/3 inch exhaust,3000 stall,TH350,4:11 rearend 28 inch drag radials. This thing runs super strong on idle and revs like crazy sitting still. It only ran a 13.50 and had no pull under a load. It's okay on the street but I don't stand on it much. Plugs look great. Played with the timing from 36-40 but it didn't help. Could this be a fuel delivery problem during wide open throttle? Timing? Should I run a different carb? Electric fuel pump? Any suggestions are greatly appreciated. :?
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Old 08-26-2008, 01:22 AM
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cepx111
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Have you run it before? If so what are the numbers?

Does it feel like its missing?

What type of fuel are you running?

Was the weather a factor, I.E> HOT and HUMID
Is it spinning? Maybe you need slicks.

Are you getting full wot? With the engine off, have someone push accerator pedal to the floor and then you can check to see if your carb is at WOT.
Your heads are pretty big for that bumpstick, alittle more agressive cam profile and a open plane intake like a Victor Jr would really wake that thing up.
Goodlcuk,
Cp
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Old 08-26-2008, 06:48 AM
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SST4530
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What's the compression ratio?

Deffinately need more gear and converter to get that thing off the line.
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Old 08-26-2008, 01:47 PM
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ARUSSELL
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That air gap manifold is very restrictive go to a Victor Jr or a Super Victor
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Old 08-26-2008, 01:48 PM
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hammertime
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Originally Posted by blittle

Deffinately need more gear and converter to get that thing off the line.

x2

Have you raced this car before ? its heavy and has no gear/converter to help it.
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Old 08-26-2008, 03:09 PM
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dparker
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Default Re: Loss of HP? Help!!

Originally Posted by Midgetmouse
I went to the track this past weekend for test and tune and my car was way slower than expected. Here are the specs. 3550 lb car, 350 chevy w/Dart 64cc 215 heads, comp roller cam xr288hr, performer RPM air-gap intake,Holley750 double pumper, MSD ignition, headers w/3 inch exhaust,3000 stall,TH350,4:11 rearend 28 inch drag radials. This thing runs super strong on idle and revs like crazy sitting still. It only ran a 13.50 and had no pull under a load. It's okay on the street but I don't stand on it much. Plugs look great. Played with the timing from 36-40 but it didn't help. Could this be a fuel delivery problem during wide open throttle? Timing? Should I run a different carb? Electric fuel pump? Any suggestions are greatly appreciated. :?
13.50 isn't that bad for a 3500lb car. Thats about the the horsepower that combination is going to make. To go faster you'll need to get a 4500 to 5000 stall converter, but your camshaft and intake are maxed out at 6000 RPM. Horsepower is all about combinations! To go faster you'll need a bigger cam, higher stall, more compression, better performance intake, and maybe a lower gear. Your cam is maxed at 6000 rpm and is made for 9 to 1 compression. Its going to be real hard to get 355 cu inches to put out big HP with that combo. I don't think you have a real problem, your engine will probably have a cealing in that weight of car at about 12.80s. Doesnt mean you cant upgrade and go faster though. I don't think changing your stall and gear without changing some of the components in your engine will be much help to you.
Good Luck
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Old 08-26-2008, 06:37 PM
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Midgetmouse
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Thanks everyone for the help. I checked WOT and it was about 1/4 inch from all the way open on the linkage arm. It is the first time this combo was at the track. It's about 10:1 compression. 92 octane gas. No missing, just no "pull". Weather was sunny and mid 70's. Good air. Was expecting 12.80's but didn't happen. Thanks again.
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Old 08-26-2008, 10:05 PM
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sds10racer
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keep the intake. that thing is better than a victor jr. it will work better with a 1-2" spacer tho. mine revs just fine past 6000 and it is macking power up there also according to my et slips. chevy power mag did a test on this intake and made more powerit. check out the sept 08 issue for details on this one and others. just thought i'd share.
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Old 08-27-2008, 01:59 AM
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cepx111
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That 1/4 off of WOT will make a difference.

Another thing that will give you slow et's is to make sure your not rolling into the stages beam too far.
An inch or two deep can slow your ET big time.
Heres some pointer's on staging.
After the burn-out dont rush up to stage, take your time it's your turn they can wait.
Look at where the staging beams are at before you go in so you'll know exactly when you need to start easing in.
Ease up slowly breaking the first beam, then stop, gather your thoughts, take a couple big deep breaths and double check to make sure everything is ready to go I.E> shifter in low, carb not loading up, oil pressure is good etc. Then with yoru foot on the brake torque the motor up just a tad to "BUMP IN" by pumping the brake pedal ever so slightly with firm braking pressure till the second beam just comes on, that way you'll know your as shallow as you can be which will net you the fastest ET and make all your runs and reaction times much more consistent.
Goodluck, Charles
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Old 09-02-2008, 08:13 AM
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SST4530
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A 355 with 10 to 1 comp unfortunately isn't going to do much better than that in 3500 lb car.
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