crappy dyno run!
 

i installed a crate 383 with first fuel injection setup. The compression is 10.5 to 1, #24 injectors, pro filer aluminum heads and a comp cams high energy 268h cam. It has 218 duration .454 lift and 110 lobe separation. It came with a dyno sheet showing 384 hp and 486 ftlbs of torque. That seems realistic to me. The car was'nt driving well but pulled pretty hard. I took it to get dyno tuned today at ida automotive in new jersey. He installed a perfect power piggyback module and got the car driving great. The only problem is the dyno results showed 258 hp and 338 ftlbs of torque to the rear wheels! I was shocked to see this! Everything i know about this motor tells me something is off about the numbers. Can anyone tell me what this combo should make? I thought i should be seeing something like 325hp to the wheels. Could something have caused the dyno to show those results? The motor is solid and i got it from precisionautomachine in tennessee. They have a great reputation and are part of the better business bureau. The motor definately feels stronger than that! Any thoughts?

Re: crappy dyno run!
 

I forgot to add that it has 1.6 rockers, so the actual lift is .484.

Re: crappy dyno run!
 

sounds like it needs a lot more cam and more tuning to get better numbers out of it. Did they play with timing and a/f ratio at all?

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i know it's a small cam, but it's still way off. I could'nt afford more time, i was at a thousand bucks already and i was happy with the seat of the pants feel. Like i said, it was a strange result. I took the car there because it had poor drivability. Bad throttle response and a constant surging. It ran really rough. He found it to be really rich on the low end and fixed it. The car is running great now and i should be happy except for the stupid numbers on the sheet. My seat of the pants tell me that the motor is legit, but the dyno is messing with my head. I put the combo together on comp cams engine dyno simulator and even altering the combo for a milder setup shows more power.:confused:

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The exhaust system can really rob HP.If you have shorty headers and a restrictive y-pipe that could explain part of the lower numbers than you expected.

Re: crappy dyno run!
 

the chassis dyno can be a humbling experience.
where did it make peak hp? did you have a wideband on there? if so, it should have plotted an a/f graph...... did it look ok up top?
i am not familliar with those heads. specs?

i can honestly see this motor making what it said it did. im guessing it had peaked by 5000 or so with that cam. and its an automatic, correct?

Re: crappy dyno run!
 

yes it's auto, 700r4 to be exact. The air fuel ratio was perfect throughout. Both hp and torque was as flat as a table. The flattest i've seen. The heads are aluminum and feature 2.02 1.60 valves. Even untouched they should flow enough to show better numbers.

Re: crappy dyno run!
 

I forgot to mention, he did have a wideband on.

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flat hp curve?

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Take it to the track. Dyno numbers should be used as a tool, not the bible. Timeslips don't lie.

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exactly, the dyno is nothing but a tuning tool, take it to the track and it'll tell you the real story. and personally i don't think those numbers are that far off, looks like a 400ish hp combo to me, so with that 700 sucking up power, i'd say its about right

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wow, the 700r4 eats up that much power? i guess i should be around 13.9 to 14.1 at the track? I think i'm going to be sick.:(

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you also have to look at the fact that the engine dyno was probably run with no accessories on the front

Re: crappy dyno run!
 

Just looking at the engine combo it should run an EASY 12.50 at 108-110. I don't know much about your car or gears, etc., but I know it would be faster then a 12.50 in my car.

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yeah the 700 will eat up 20%. So your motor puts out 310 horse and 406 ft lbs of torque. I can't believe that they recommended that cam, its so tiny, but anyways. If your running a 1 5/8 primary header it will robb you of power. Go with a 1 3/4 primary. You will see much better results I did. And for the heads it didn't say much about them other than 2.02 1.60 valves. When I went from my edelbrock performer heads 2.02/1.60 valves to a pair of 200cc Dart heads, I gained 38 more horse. Just proves these engines need to breathe. Any other questions, I would like to help since I was in the same sitation awhile back

Re: crappy dyno run!
 

thanks for the replies guys, i am definately going to run at the track soon. I just thought about something though. What if the plugs are fouled up, that is definately possible since before the tune i ran a new set of plugs for less than a month and they were completely black when i replaced them. I then ran the new plugs for a week before getting the dyno tune, so maybe they are fouled up. I should have changed the plugs after the tune and then pulled on the dyno. Is it possible maybe running on 7 cylinders during the run? I know it's a stretch, i am going to change the plugs today anyway, but if the car was running so rich off idle for a week, i could see losing power on the dyno after the tune if i never changed the plugs. Any thoughts?

Re: crappy dyno run!
 

one of my friends had a set of dirtied up plugs and picked up 5 mph after swapping them out

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Could you post up the dyno graph?

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do you have one in rpms instead of mph?

a/f looks fine, no real power gains to be had adjusting that.

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no that all.

Re: crappy dyno run!
 

if you still have a stock convertor on the car that will hurt you to....but i agree with the cam being way to small...should be up around 230-240 range to make good power and torque with a 383...the more cubes the bigger the cam ya need...hope all works out for ya....watch that weak 10 bolt at the track...

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i'm still looking for reasons for the bad numbers. could the wrong plugs alter the power? I keep plugging different combos into the desktop dyno, all much more conservative, and everything shows i should be at least 50 hp and 50 ftlbs higher. there has to be something i'm overlooking. I know that computer sims are not exact science, but i've used them several times in the past for other engines and found them to be very close in accuracy. I'm stumped.

Re: crappy dyno run!
 

W/o actual head flow numbers the desktop dynos are pretty much worthless. Even then they're best used for tweaking cam specs.

Change the plugs, but before you do run a good induction service on it. If it's been running around rich for a while you likely have some decent carbon build-up in the combustion chambers and on the valves. Past that, what oil are you running? Did you break the engine in with the proper additives for the flat-tappet cam? Whens the last time you checked the valve adjustment? Ignition timing? Full tune-up?

Re: crappy dyno run!
 

flow numbers and stuff should be here http://www.profilerperformance.com/sbc-heads-176.html

Re: crappy dyno run!
 

i had a set of stage II cnc ported patriot 5.3 heads on my LS1 car awhile back.... with a 230/236 cam it put down 376rwhp.

meanwhile, i have a friend with cnc ported TEA heads and a 224/228 cam that layed down 440rwhp.

these cars both have a t56 trans, LS6 intake, dyno tuning, headers, exhaust, and both dyno pulls were made on a dynojet dyno. his heads are great and expensive, mine were cheap and sucked.

i have learned that when a car is running good and pulling hard without missing/smoking/hiccuping/knocking etc, chances are its either the heads or the cam. adjusting the a/f ratio doesnt even affect overall power much. or timing. (within 15-25rwhp or so most likely before the engine is noticeably not running right anymore)
when you are down big on power, it is something major. heads/cam, or you have a hole in a piston or something.
im still thinking your results are probably typical for that cam size, however.

Re: crappy dyno run!
 

:iagree:

I wouldn't use the flow numbers provided off a website. Even flow numbers from the "batch" your heads were cast with can be far enough off.

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i guess i should just accept it and be happy with it. i just ordered a custom 12 bolt rear with 3.55 gears from dts, plus eibach pro kit springs and a set of koni sport shocks and struts, adjustable umi torque arm, panhard bar and lower control arms. I hope the car runs good after all the money i just spent and at least i know i could raise the power level in the future with the setup i'll have. What do you guys think about the stuff i ordered? Will i be dissappointed again?

Re: crappy dyno run!
 

I forgot to mention, my original goal was a daily driver that could hit 12.50 to 12.90 in the quarter. My guess is i'll be in the 13.90 to 14.20 range. pathetic.

Re: crappy dyno run!
 

your just guessing way too much. yes that cam is way too small but even 258 at the wheels would be good for low 13's.

and gauranteed those flywheel hp #'s are with no accesories and longtube dyno headers. add all that junk (alternator, p/s pump, water pump) plus you never mentioned your exhaust setup.

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don't guess don't complain don't get depressed and most importantly don't give up till you go to the track and lay down some numbers

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i know you guys are right, but it's not easy when you've spent a lot of money. I think my goal is pretty modest, i'll be hitting the track within the next couple of weeks. Until then i just can't help worrying about it. maybe now that the car is tuned and i changed the plugs there will be a difference.

Re: crappy dyno run!
 

Who was it over @ Ida Automotive that tuned your car, as I go there all of the time? Either someone gave you a very conservative tune there, or your timing was locked out, and they simply didn't even notice that it was, because it appears as if RPM's did not even exceed 5000-RPM, and that is why your horsepower figures seem low. Are you running an aftermarket igntion system w/RPM limiter by any chance? Same thing happened with Dave over @ Krazy House Customs here in NJ, his ignition was locked out, stock ECM wouldn't advance, and the engine couldn't rev past 5000-RPM. His result was 267HP/370TQ @ 10-psi, but the actual math said closer to 400-RWHP (had it advanced)....

http://videos.streetfire.net/video/T...Day_641050.htm

Re: crappy dyno run!
 

Bob himself did the tuning. I guess i should go again and find out if the timing was off. I did'nt know it could be locked out. Maybe he overlooked it. Is there any other way to know about the timing? All i know is that it's set at 6 degrees initial.

Re: crappy dyno run!
 

I have to speak with him. Remember that torque and RPM are divided by 5252, and torque and horsepower are always equal at 5252 RPM, the lines will always cross. In your graph, the lines never meet, which is why it's important to see it from an RPM scale. Whoever did the tuning, either eased off before-hand, or your timing was locked out. I would highly recommend not to go WOT above 5000-RPM until you speak with him first, because your more than likely not tuned for it just yet....

Re: crappy dyno run!
 

I can't go anytime soon. I'm getting my interior redone this week and i'm just about tapped out. I live in the bronx, are you in the englishtown area? I know very little about tuning, I took the car to bob ida and he installed his perfect power setup. He tuned the air fuel and dynoed it that way . I guess i'll have to save up a bit and when i can take the car back, i'll have him check the timing to see if it's advancing or not. Thanks for your input.

Re: crappy dyno run!
 

is the computer still advancing the timing at 5k? that seems aweful high, but i am unfamilliar with that stuff.
a typical mechanical advance dizzy will be fully advanced by 3k or less, no?

if the dizzy is locked out with no computer control, seems like you could put it around 34 degrees and it should work fine. would be good to have an ignition box pulling timing during startups, though.

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With carbed engines, the vacuum advance will have you fully advanced by around 2800 to 3000-RPM, but with EFI though, the computer will pull timing if something is amiss, and the engine just won't be able to rev, no matter how hard the pedal goes to the floor. Strong possibility. But I keep looking at that graph though, and it's as if the tuner just let off when 5000-RPM was reached, as maybe he assumed TPI + low lift cam, and didn't feel the need to even push it. But then again, that torque figure seems awfully low under the curve....

Re: crappy dyno run!
 

Before you take it back to him, get a timing light, disconnect the EST, and check your base timing. When the motor was shipped from Precision Automotive, it's very possible that they tested it, then shipped it, with 0 degrees of timing. If this is the case, advance it to 6 degrees BTDC for starters, then 8 degrees BTDC, as that will make a world of difference. Although, I'd be shocked if Bob didn't check that beforehand....

Re: crappy dyno run!
 

Actually, it is at 6 degrees. I checked it myself. As for the letoff at 5000 rpm, that was me, i was running the car while bob was watching the air fuel ratio. He spent most of the day installing the perfect power module and welding in the bung for the wide band o2. He also told me that my tach was 200 to 300 rpm higher than on his computer. I guess i backed off around 5000 on my stock tach. Would that kill the numbers?

Re: crappy dyno run!
 

the vacuum advance on a carb engine doesnt come into play unless your puttin' around town at part throttle. the mechanical advance is what fully advances by 2800-3000 or whatever....

looking at the graph, it seems the hp curve had flattened out anyways. thats about all she would do unless there was a huge timing issue or something like that. if it never advanced beyond 6 degrees i would think it would be very obvious the car wasnt running right. it should be pretty easy to see what your total timing is right now. just pop the hood, hook up the timing light, and rev the car to 3-4-5k and watch your timing. im assuming it will pick up 20 degrees or more from the base of 6, and you should be able to see it advance from an idle.

Re: crappy dyno run!
 

EXACTLY!!! dyno numbers are just for bragging rights, get a slip and you might be happier. I had my car out it went 9.83 @ 137 the weekend after I took it to a open house for a couple dyno pulls the guys tells me I layed down 337 HP to the tires, I just laughed and said unhook my car. The guy did just get the dyno and was having problems, it was in the back of this shop with no air movement but still. You have some time left before winter get to a track. Good luck.

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Thats is just funny to say you are only making 337 HP to the tires!! lol Torque converters can do some funky things on dynos too which is probably the biggest problem with the numbers coming out so low. I guess dyno's can be beneficial because if you would have left with anythign more then 337 after tuning then you know you made more power then when you got there. You just cant be concerned about the actual number but just the improvement of it when dynoing your car. The real test is the time slip which I 100% agree with too.

Re: crappy dyno run!
 

Yes, letting off too early will hinder the readings of peak horsepower numbers, especially if your tach was off 200-300 RPM lower than the 5000 you let off from. I'll give you an example, here is a 305 build from Engine masters, compare it to your dyno....;

With their build, the stock 305 fell flat on it's face exactly after the 5000-RPM mark. Peak numbers were 291 Torque @ 3200-RPM, and 221 Horsepower @ 5000-RPM. But after it was modded, it pulled all the way to 6200-RPM, with peak numbers embellishing 350 Torque @ 3500-RPM, and 372 Horsepower @ 6100-RPM....

The 305's mods included;
180cc EQ Heads....
Performer Air-Gap, w/650-Demon Carb....
XE268H Comp Camshaft (click here for specs)....

http://www.popularhotrodding.com/eng...o_testing.html

If you kept on it above 5000-RPM, the dyno would have reflected much higher horsepower numbers. However, they would still seem kind of low though, as your engine should be reflecting higher torque readings than that, which would of course impact horsepower numbers, because horsepower is calculated torque. It sounds like, either, Bob was shooting for 128 BLM's across the board, when your engine might want to run richer, or leaner, or, he simply gave you a conservative tune, or, the ECM wasn't advancing properly. Did he give you, or can you get, any datalogs....?

Re: crappy dyno run!
 

This stuff is a little over my head, i'm gonna see if i can go to the track before they close for the winter. Once i get a couple of runs in, I think i'll have a better idea of whats going on. The last time i ran at englishtown was a year ago on a friday night. I only got 1 run in. There were too many cars. Thanks for the feedback, maybe i'll run into a board member when i go.

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We'll be there this Wednesday and Friday night, just look for about four or five Grand Nationals. You should get quite a few runs in this week, as the weather will be in the 60's and 50's, and it won't be as packed. Just knowing your trap speed will help us determine how much power you should be making....

- Rob

Re: crappy dyno run!
 

Dont think you'll make more power reving higher.. your curve looks very flat. Without knowing what exactly is done to the tune, its hard to say where to make improvements.

I do realize tho that setup should be MUCH higher than that. Torque and hp. My bolt on L98 matched those numbers.

Cam is abit small for that motor but not really causing the low numbers. Make sure there are no leaks at the runners or anything like that.

Good news is I went 12.95 with 254whp :) You may go pretty quick

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Look for these guys, the first one is a burgundy T-Type, the second is a dark blue regal w/LC2 swap, and the third is a black Grand National. You can normally find us in lanes seven and eight.... ;)

-Rob

http://videos.streetfire.net/video/T...ype_705707.htm
http://videos.streetfire.net/video/S...ick_703574.htm
http://videos.streetfire.net/video/P...and_705706.htm

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I honestly think he will though. If anything, we will know for sure if 73Duster posts a picture of the dyno sheet that the engine came with, the one embellishing 384-HP, and 486-TQ. That dyno sheet should show the RPM scale. I know his cam is on the small side for a 383, but I don't believe horsepower will peak at 5000-RPM, not with a FIRST setup....

Re: crappy dyno run!
 

i think it was done by 5k. my 350 LT1 with 230/236 cam and not so great heads peaked at 6000-6100. that cam in a 383 would probably peak at 57-5800. a teeny weenie 21x cam in a 383 would most likely land somewhere around 5k.