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Discussion Starter #1
Need some help to figure out what's wrong.

Fresh 383 stroker. Made 481 horsepower at the crank on the local dyno. Put it in my 3600 lb Chevelle and can only get 107 mph (1/4 mile) out of it?? :confused: According to the calculators, it should be around 115-117mph. Best ET so far is only 12.45...I built it shooting for 11.50.

We dyno'd it with my carb, distributor and headers. Only thing different was, we used an electric water pump on the dyno and I run a mechanical pump, fan, power steering and alternator.

I have checked for full throttle and also tried 2 convertors.
Tight 3000 - 10" and loose 4500 - 8". No change in MPH and only a slight change in 60'...which suck :(

I did notice my front brakes had quite a bit of drag and could barely turn the wheels by hand, so I adjusted them and it made no difference :smt102

Car specs are....
3600 lbs
TH350 rmvb w/brake
4.10 gears
29x10 goodyears
Holley 750 with proform main body (72 f 84 r)
Holley black pump - stock tank and lines to regulator. -6 to carb. Fuel @ 6psi
Digital 6 box
Mallory dist locked @ 36 degrees

Thoughts please??
 

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What are the 60. I would run a 456 gear with those tires. Your mph and et match decently so just need to get it out of the hole.
 

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Discussion Starter #5
I've only got 7 passes on motor. Best 60' was 1.81 with the 8" convertor.

I know the tires aren't ideal, but shouldn't the mph be alot higher regardless?

If I can get it to 60' in the 1.60's will that pick up the ET a 1/2 second?

Motor made 466 torque @ 5000 rpm
 

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not enough jet, gear or timing. tires are to tall. stock fuel line aint helping. where are you shifting this thing? are you spinning the tires leaving?
 

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Discussion Starter #8
Motor made max power at 5800 rpms. I have tried shifting anywhere from 6000 - 6500. Best pass was at 6200 and it always crosses the stripe right around 5800.
Yes, I have some traction issues that will be addressed over the winter.
 

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Discussion Starter #9
There are a bunch of cars at the track with a lot less motor in similar weight cars that are going just as quick or quicker?? Everyone I talk to says it should be deep into the 11's.
 

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Butch
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Need some help to figure out what's wrong.

Fresh 383 stroker. Made 481 horsepower at the crank on the local dyno. Put it in my 3600 lb Chevelle and can only get 107 mph (1/4 mile) out of it?? :confused: According to the calculators, it should be around 115-117mph. Best ET so far is only 12.45...I built it shooting for 11.50.

We dyno'd it with my carb, distributor and headers. Only thing different was, we used an electric water pump on the dyno and I run a mechanical pump, fan, power steering and alternator.

I have checked for full throttle and also tried 2 convertors.
Tight 3000 - 10" and loose 4500 - 8". No change in MPH and only a slight change in 60'...which suck :(

I did notice my front brakes had quite a bit of drag and could barely turn the wheels by hand, so I adjusted them and it made no difference :smt102

Car specs are....
3600 lbs
TH350 rmvb w/brake
4.10 gears
29x10 goodyears
Holley 750 with proform main body (72 f 84 r)
Holley black pump - stock tank and lines to regulator. -6 to carb. Fuel @ 6psi
Digital 6 box
Mallory dist locked @ 36 degrees

Thoughts please??
Rundown on the engine? Cam? Heads? Compression? Intake?

You can try 5 5000rpm stalls and everyone will react different. It needs more gear in my opinion for starters.

My old 331 has been in the 1.5/1.6 range when it hooked leaving at 3600rpm with 6200rpm stall and 5.38's at 4080 race weight, several high 1.6's and low 1.7's when it didn't hook, 94-96mph at the 1/8.

With a small block, everything you gain in the first half, even if you loose a hair on the big end, will carry to a lower ET due to the weight and being a small block

That thing should be in the 10's or low 11's assuming its not a hydraulic roller with GM heads
 

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I agree with what was said about needing more gear. Tall, heavy tires on a slow car need A LOT of gear. Once you get your traction issues figured out, try to borrow some shorter tires from a buddy for a pass or two. The shorter tire will be just like going to a higher gear. I'll bet you could pick up .2 or better with some 27" or 26" tires.

Also, I wouldn't put a whole lot of faith in the dyno numbers. Especially if the guy running the dyno is the same guy who built your engine. All dynos are different and some tend to be VERY loose. I would only trust it if you have references from quite a few people who say their car made a certain number and then performed exactly as expected based on that number once on the track.

The next concern would be your shift point. You said you shifted between 6000 and 6500. Is that taking the shifting delay into account, or is that the rpm you have your shift light set at? It can make a big difference. Say you set your shift lite for 6000. By the time you react, pull the shifter, and the trans shifts, it could be 6500rpm or even higher. If your peak hp is 5800, I would be setting that shift light for 56-5700 or perhaps even lower.

But the most important detail is your traction issue. That should always be the #1 priority when dialing in your car. You can't be repeatable if you can't get repeatable traction. You can't even begin to address anything else until the traction issues are settled.
 

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Beer me!!
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I agree with what was said about needing more gear. Tall, heavy tires on a slow car need A LOT of gear. Once you get your traction issues figured out, try to borrow some shorter tires from a buddy for a pass or two. The shorter tire will be just like going to a higher gear. I'll bet you could pick up .2 or better with some 27" or 26" tires.

Also, I wouldn't put a whole lot of faith in the dyno numbers. Especially if the guy running the dyno is the same guy who built your engine. All dynos are different and some tend to be VERY loose. I would only trust it if you have references from quite a few people who say their car made a certain number and then performed exactly as expected based on that number once on the track.

The next concern would be your shift point. You said you shifted between 6000 and 6500. Is that taking the shifting delay into account, or is that the rpm you have your shift light set at? It can make a big difference. Say you set your shift lite for 6000. By the time you react, pull the shifter, and the trans shifts, it could be 6500rpm or even higher. If your peak hp is 5800, I would be setting that shift light for 56-5700 or perhaps even lower.

But the most important detail is your traction issue. That should always be the #1 priority when dialing in your car. You can't be repeatable if you can't get repeatable traction. You can't even begin to address anything else until the traction issues are settled.
Totally agree with all of this!! ^^^^^ Especially the issue of gearing, and tall tires. Like Greg said, try a shorter tire first, and if that doesn't get you closer to where you wanna be, then it's gear time. I made this same mistake with my Nova, am running 4.10's, because we run 1/8 and 1/4 mile, so I wanted something in between, plus this car will see plenty of street time, so I didn't want too much gear. If I had it to do over again I would have gone with a 4.30, or a 4.56. My 5.3 makes decent torque for what it is, but it's no monster, could definately benefit from more gear. It's amazing how much gears, converter, and chassis tuning effects a car, I honestly believe more than the engine.
 

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Discussion Starter #16
Thanks for all the responses so far.

Motor - 10.5 compression, Aluminum Dart Pro1 - 200cc, Lunati Solid Roller #60131 - 237/243 @ 50, 566/578 lift, Victor JR, 1 3/4 headers, with 2 1/2 inch exhaust with 2 chamber Flowmasters.

Builder did not dyno the engine. It was dyno'd by a local shop that is highly recommended and know for real world power. So I am not too worried about the numbers not being accurate.

Good point on the shift rpm Greg. I did not take that into account. The lowest I set the light was 6000. Based on the tach recall, it sees another 300 rpm before it shifts.

I did want to try a set of shorter tires, but I only managed to get 2 tnt nights and now the tracks are closed for the winter:mad: I am not sure if I want to go to more gear, or shorter tire??? It is a street car, but for the next couple of years it will be 95% strip only. The local bracket guys here are telling me to do the tall gear (4.88 or 5.13) and big stall convertor too.

Suspension updates are on the Christmas list :)

Suspension is stock in front with cheap 3 way Comp Engineering drag shocks.
Rear has air shocks :( (I know, I know) and stock boxed arms with urethane bushings.

Even if I was spinning to half track...doesn't anyone think the MPH is still too low?
 

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cam is too small, if youre running with the exhaust on, its choking the motor, if you stay with the 29" tire go to a 4:88 gear. first thing you need to do is stop it from spinning, and throw the air shocks in the garbage
 

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I think it has to do alot with your shift by the time it shifts you are out of the power range and starting to fall off shift earlier when it is still pulling hard like 55 to 5700 this should help out alot.As far as air shocks i have been 1.47 60'with a 347 making 475 hp on a 29x10.5 with 4.56 gear weight 3550 but these small blocks have hell with getting these heavy cars moving torque kills us
 

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as far as any engine tuning device i have said very often, one of the best tools you can buy is an air\fuel gage! dial your carb in, it may seem lil rich on idle, may be lean somewhere else in the throttle or vise versa. i dont think your far away on jets, i think your prob close.i do think cam is small, so thinkin perhaps your better short shifting it. agreed too that launch needs big time attention.good luck
 

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Butch
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I agree with what was said about needing more gear. Tall, heavy tires on a slow car need A LOT of gear. Once you get your traction issues figured out, try to borrow some shorter tires from a buddy for a pass or two. The shorter tire will be just like going to a higher gear. I'll bet you could pick up .2 or better with some 27" or 26" tires.

Also, I wouldn't put a whole lot of faith in the dyno numbers. Especially if the guy running the dyno is the same guy who built your engine. All dynos are different and some tend to be VERY loose. I would only trust it if you have references from quite a few people who say their car made a certain number and then performed exactly as expected based on that number once on the track.

The next concern would be your shift point. You said you shifted between 6000 and 6500. Is that taking the shifting delay into account, or is that the rpm you have your shift light set at? It can make a big difference. Say you set your shift lite for 6000. By the time you react, pull the shifter, and the trans shifts, it could be 6500rpm or even higher. If your peak hp is 5800, I would be setting that shift light for 56-5700 or perhaps even lower.

But the most important detail is your traction issue. That should always be the #1 priority when dialing in your car. You can't be repeatable if you can't get repeatable traction. You can't even begin to address anything else until the traction issues are settled.
Very true, with our gears and converter 7600rpm provided a 8000rpm shift. The delay is usually 200-400rpm on most cars
 
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