HP estimate...opinion needed.

[Dm1pfoy1]

So have been posting alot on here and got another question thought some one must be good at this. Based off your knowledge of set ups and this truck given my setup whats a ballpark for my hp and tq at the wheels,brakes whatever you choose. I have not run a quarter in it just looking for idea. Dont want to be that guy that says he shot the 16 point buck but come find out i only got 8 lol.
Engine
Stock 350 bored to 383 around 8.5 compression
Stock heads
RV cam or 3/4 cam for you old timers lol
long tubes to muffler dumps after cab before rear
Rest of info is in sig with anything else not mentioned being stock
Transmission turbo 350 assuming stock stall
Stock driveshaft
10 bolt 3.73 rear with stock tire

If you need more just ask. Otherwise appreciate the help. Also if you guys have some good upgrades let me know i like the old school hot rodding style and thats the style its in. If you guys know good upgrade rockers, also what head combos from other gen small blocks can be used on this. just any good feed back you guys got.

Thank you

[67_C-30]

First of all a 350 cannot be bored to a 383. It has to have a totally different crank, special pistons, and be be bored .030" over to acheive 383 cu in.

Secondly a 3/4 cam and a RV are two totally different things. A RV cam is a smooth idling torque cam, and a 3/4 cam is a rough idling, high performance cam that needs way more than 8.5 : 1 CR.

[mmiddle]

Assuming your cam peaks at around 5500-6k and not knowing what heads you have, I would guess maybe 300ish.

If your heads are the crappy "light weights" This will kill HP. This set up with say good Vortecs or doublehumps, roller cam and rockers and HEI dizzy you could be in the 400+ range. With only 8.5 CR I would be inclined to think you have 76cc light weight heads. CID=HP, but crappy heads kill that HP.

[cool68]

do not know what you really have in your engine to figure horse power but, 3:73 gears with a turbo 350 and stock (?) tires is too low for trans/engine to function properly. don't go racing with this unless you want to break something

[67_C-30]

Originally Posted by cool68

do not know what you really have in your engine to figure horse power but, 3:73 gears with a turbo 350 and stock (?) tires is too low for trans/engine to function properly. don't go racing with this unless you want to break something

Huh? 3.73's a TH350 is great street/strip set-up.

[Dm1pfoy1]

Originally Posted by 67_C-30

First of all a 350 cannot be bored to a 383. It has to have a totally different crank, special pistons, and be be bored .030" over to acheive 383 cu in.

Secondly a 3/4 cam and a RV are two totally different things. A RV cam is a smooth idling torque cam, and a 3/4 cam is a rough idling, high performance cam that needs way more than 8.5 : 1 CR.

I appreciate feedback. Dont know if you intended it to but reply came across a bit stern. I know a 383 needs but i guess i was assuming that was understood and that i ment cast not forged and the most basic needs for a 383 were met.

On the cam i really didnt know i was going off of that based on other threads i read awhile back when looking at what a rv cam generally means. So thanks for clearing that up

[Dm1pfoy1]

Originally Posted by mmiddle

Assuming your cam peaks at around 5500-6k and not knowing what heads you have, I would guess maybe 300ish.

If your heads are the crappy "light weights" This will kill HP. This set up with say good Vortecs or doublehumps, roller cam and rockers and HEI dizzy you could be in the 400+ range. With only 8.5 CR I would be inclined to think you have 76cc light weight heads. CID=HP, but crappy heads kill that HP.

It does have HEI dizzy. I believe they are the"light weight" heads you are talking about and i am at peak dead balls on 5500 to 6k.

[sublime1996525]

If you're doing a basic 383 setup with stock heads and a mild cam I'd guess around 350ish maybe a little more.

[Dm1pfoy1]

Originally Posted by cool68

do not know what you really have in your engine to figure horse power but, 3:73 gears with a turbo 350 and stock (?) tires is too low for trans/engine to function properly. don't go racing with this unless you want to break something

Reason i mentioned no 1/4 time is because i know some people like to go off trap and 1/4 mile info to figure hp and wanted to let people know that right off.

I do have to agree from what i have seen an learned 3.73's and a turbo 350 is a strong street strip combo. I was always under the understanding a 350/350 combo is the street rodders go to and use to be as common in ford and chevy hot rods as leaves are to trees.

[Dm1pfoy1]

Originally Posted by sublime1996525

If you're doing a basic 383 setup with stock heads and a mild cam I'd guess around 350ish maybe a little more.

Thank you. "Ish" is all i need appreciate it.

[Dm1pfoy1]

Anyone else feel free to comment.

[67_C-30]

Originally Posted by Dm1pfoy1

I appreciate feedback. Dont know if you intended it to but reply came across a bit stern. I know a 383 needs but i guess i was assuming that was understood and that i ment cast not forged and the most basic needs for a 383 were met.

On the cam i really didnt know i was going off of that based on other threads i read awhile back when looking at what a rv cam generally means. So thanks for clearing that up

I didn't mean it to sound that way, I was making sure somebody didn't tell you that. (I didn't know if you built it or not).

If it is a 8.5 : 1 CR 383 with a small RV type cam, I'd agree with mmiddle and say about 300 - 320 HP tops. Should be 400 or little more TQ though. Stock heads really limit airflow on a 383, but the 3.75" stroke makes a lot of torque.

[Dm1pfoy1]

Originally Posted by 67_C-30

I didn't mean it to sound that way, I was making sure somebody didn't tell you that. (I didn't know if you built it or not).

If it is a 8.5 : 1 CR 383 with a small RV type cam, I'd agree with mmiddle and say about 300 - 320 HP tops. Should be 400 or little more TQ though. Stock heads really limit airflow on a 383, but the 3.75" stroke makes a lot of torque.

Thank you didnt want to jump to conclusion and assume you were coming off that way. You seem very savvy and well informed on this set up. What is your personal reccomendations for heads and anything else i could do to improve the output. Thank you again. I like the torque it makss and i personally am a torque minded person but posted hp because thats the term most people speak in.

[67_C-30]

Originally Posted by Dm1pfoy1

Thank you didnt want to jump to conclusion and assume you were coming off that way. You seem very savvy and well informed on this set up. What is your personal reccomendations for heads and anything else i could do to improve the output. Thank you again. I like the torque it makss and i personally am a torque minded person but posted hp because thats the term most people speak in.

I have built several 383's, and I am big fan of them. Do you know if your pistons are dished or are they flat tops? To get 8.5 : 1 with what I'm assuming is stock 76cc heads, I assuming they are flat tops.

A good set of heads will really wake up a 383, but if you have to be careful about getting the CR too high for pump gas with a 383, and most aftermarket heads have smaller cc chambers than 76cc. If you have dish pistons, you have a lot more options.

If you can afford aluminum heads, you can get away with higher CR with pump gas.

[Dm1pfoy1]

Originally Posted by 67_C-30

I have built several 383's, and I am big fan of them. Do you know if your pistons are dished or are they flat tops? To get 8.5 : 1 with what I'm assuming is stock 76cc heads, I assuming they are flat tops.

A good set of heads will really wake up a 383, but if you have to be careful about getting the CR too high for pump gas with a 383, and most aftermarket heads have smaller cc chambers than 76cc. If you have dish pistons, you have a lot more options.

If you can afford aluminum heads, you can get away with higher CR with pump gas.

I will be honest. I did not build the engine. The infomation I have i from owner whom I still have been able to stay in touch with. The engine is built with flat tops. Its got to be the 76cc heads. I really don't have the cash for alu heads. Are these heads as really hopeless as they seem? I had hoped to hear that some mill work, port and flow would do them good maybe a old fashion 3 angle valve job. Sounds like im not going to be that lucky. If you know a few sets of heads that can keep me on the pump it would be welcomed. Also i know 0 about tbe vortec stuff i know there are differences on the ports is it worth doing? I know ill need new intake to match. Again thank you for all your help so far.

[67_C-30]

Originally Posted by Dm1pfoy1

I will be honest. I did not build the engine. The infomation I have i from owner whom I still have been able to stay in touch with. The engine is built with flat tops. Its got to be the 76cc heads. I really don't have the cash for alu heads. Are these heads as really hopeless as they seem? I had hoped to hear that some mill work, port and flow would do them good maybe a old fashion 3 angle valve job. Sounds like im not going to be that lucky. If you know a few sets of heads that can keep me on the pump it would be welcomed. Also i know 0 about tbe vortec stuff i know there are differences on the ports is it worth doing? I know ill need new intake to match. Again thank you for all your help so far.

If they are flat tops, you're probably closer to 9.5 : 1, which raises your power level higher than I originally thought. Here is a few examples of manufacturer's CR info:

383 Chevy DSS E Series Forged Piston (For use in 3.75" stroke x 5.700" rod) -5cc Flat Top with two valve reliefs, 1.425" comp hgt, Includes .927" full floating pin with double True Arc pin locks, 5/64 5/64 3/16 ring groove, Approximate Compression Ratio: (58cc Head = 11.94 to 1) (64cc Head = 10.81 to 1) (76cc Head = 9.50 to 1).

MADE IN THE U.S.A.

Keith Black Performance Pistons are offered in Hypereutectic 390 alloy and Forged 4032 low expansion alloy. Their 4032 alloy is preferred for high performance / high compression applications. They offer offset wrist pins for a quiet engine and most have coated skirts. The low expansion alloy allows for a tighter piston to wall running clearance.

Compression Ratio with 64cc Heads 11.1:1
Compression Ratio with 76cc Heads 9.7:1
Advertised piston weight 505 grams, 145 gram wrist pin.

As you can see, the extra cu in from the longer stroke makes the CR higher with 76cc heads it does for a 350. You are squeezing more swept volume in the combustion chamber. The bigger the cu in, the more CR it will have. That's why BBC heads are generally 98 - 119 cc.

With all that being said, you can modify those for performance, but you would be better off modifying a set of early 70's 76cc heads. Castings like 441's. 487's, 993s, and even common 882's are better than what you have, if your's are thin later castings.

The first thing you need to do is identify what you actually have. Does it have a casting mark on the front of the head, and what is shaped like? Are your heads center bolt or old style perimeter bolt heads?

The worse heads you could possibly have is '87 - '95 TBI heads. They are the swirl port heads, and would REALLY choke a 383. Here are some guides to ID your heads, but later don't always have these marks.

[Dm1pfoy1]

Originally Posted by 67_C-30

The first thing you need to do is identify what you actually have. Does it have a casting mark on the front of the head, and what is shaped like? Are your heads center bolt or old style perimeter bolt heads?

The worse heads you could possibly have is '87 - '95 TBI heads. They are the swirl port heads, and would REALLY choke a 383. Here are some guides to ID your heads, but later don't always have these marks.

I am trying to get picture uploaded but the casting mark is the first in the group of 3 in the second row. Like i said i will get picture up so you can see.

[Dm1pfoy1]

Originally Posted by 67_C-30

The first thing you need to do is identify what you actually have. Does it have a casting mark on the front of the head, and what is shaped like? Are your heads center bolt or old style perimeter bolt heads?

The worse heads you could possibly have is '87 - '95 TBI heads. They are the swirl port heads, and would REALLY choke a 383. Here are some guides to ID your heads, but later don't always have these marks.

Here is link its on my google drive so dont know if this will work but it should be high res enough for you to zoom in and see.

https://lh5.googleusercontent.com/eq...Bi-PSW7Rw=s400

[Dm1pfoy1]

Got it to cooperate

[67_C-30]

Well that's good news! That is the head I was recommending earlier. The 441, 487, 993 casting are the best of the factory 76cc castings. They are heavy castings unlike the later lightweight castings, and flow comparably to the 1.94/1.50" valve 462, 492, 186, double hump heads and the 041 performance heads. These are decent heads have the potential to make a lot more power. I had a set of ported 441's on a 350 in my '82 Z28 that ran 12.50's on motor at one time.

Here is an excerpt from John Lingefelter's Modfiifying SBC's book:

http://books.google.com/books?id=GUC...20flow&f=false

I'd put your power level more in the 350 - 360 HP range, depending on what your cam actually is. Can you get those specs from the guy who built it?

[Dm1pfoy1]

Originally Posted by 67_C-30

Well that's good news! That is the head I was recommending earlier. The 441, 487, 993 casting are the best of the factory 76cc castings. They are heavy castings unlike the later lightweight castings, and flow comparably to the 1.94/1.50" valve 462, 492, 186, double hump heads and the 041 performance heads. These are decent heads have the potential to make a lot more power. I had a set of ported 441's on a 350 in my '82 Z28 that ran 12.50's on motor at one time.

Here is an excerpt from John Lingefelter's Modfiifying SBC's book:

http://books.google.com/books?id=GUC...20flow&f=false

I'd put your power level more in the 350 - 360 HP range, depending on what your cam actually is. Can you get those specs from the guy who built it?

The very close estimate i have constucted from info I could get
204/214 @ .050 .420"/.440 112 lsa i was told intake and exhaust could be as high as 224/234 but i could not find a grind profile to match that without it being custom and this sounded very off the shelf.

[Dm1pfoy1]

Originally Posted by 67_C-30

Well that's good news! That is the head I was recommending earlier. The 441, 487, 993 casting are the best of the factory 76cc castings. They are heavy castings unlike the later lightweight castings, and flow comparably to the 1.94/1.50" valve 462, 492, 186, double hump heads and the 041 performance heads. These are decent heads have the potential to make a lot more power. I had a set of ported 441's on a 350 in my '82 Z28 that ran 12.50's on motor at one time.

Here is an excerpt from John Lingefelter's Modfiifying SBC's book:

http://books.google.com/books?id=GUC...20flow&f=false

I'd put your power level more in the 350 - 360 HP range, depending on what your cam actually is. Can you get those specs from the guy who built it?

Posted cam specs would love to get rest of your opinion.

[67_C-30]

Originally Posted by Dm1pfoy1

The very close estimate i have constucted from info I could get
204/214 @ .050 .420"/.440 112 lsa i was told intake and exhaust could be as high as 224/234 but i could not find a grind profile to match that without it being custom and this sounded very off the shelf.

There would be a noticeable power difference between 204/214 cam vs a 224/234 cam. If it idles very smooth and pretty much sounds stock, that would be more in line with the 204/214 cam. If it has a noticeable lope at idle it would more in line with the bigger cam. I am running the Summit CS-1014 cam in the 383 in my ramp truck that sounds to be pretty much identical to the first cam you posted. It is .420/.443 - 204/214 - 112 LSA. That's a very common grind that is made by GM, Summit, Sealed Power, Wolverine, and probably many others.

If it has this cam, the peak power is made before 5000 RPM, so you are probably a little short of 350 - probably 335 - 340-ish? If it had a cam with 224/234, you'd be looking at at least 350, maybe a little more. A cam with that duration would make power to at least 6000 RPM, where the 204/214 cam will be all done at around 4500 or so.

Either way, it should be a very stout engine, and make tons of torque.

I have a 383 in my '69 C-30 ramp truck that has the CS-1014 cam, 80's 76cc stock heads, a '65 stock cast iron square flange carb, basic 600 cfm Holley single line 4BBL, and I estimate at around 310 - maybe 320 HP based on a similiar build I read about years ago. This engine makes more power at every RPM range than the 396 that was originally in the truck, and is better on fuel too.

[67_C-30]

To give you an idea between of the differences in the cams, here are some real dyno tests I dug up comparing the cam in question.


Chevy 350 .030" over, stock 186 heads, 9.73 : 1 CR
Performer manifold, 600cfm, 1 5/8" headers

CS1014
204/214 @ 050 .420/.443 112 LSA
302 HP @ 4800 RPM
364 TQ @ 3400 RPM

CS1013
214/224 @ 050 .443/.465 112 LSA
315 HP @ 5200 RPM
355 TQ @ 3600

As you can see, the extra duration makes a lot of difference in HP numbers, but comes with a loss of torque numbers.

Here's another build showing the difference in what you gain with a bigger cam, porting and bigger valves. The 441's are basically the same heads you have, and this is a flat top 383 with 76cc heads that came out to 9.3 : 1 CR. This cam would be a little bigger than you'd want in a daily driver, but you get the idea.

Displacement: 383 cu. in.
Carburetor: Holley 750 double pumper
Heads: GM #441 castings, 76cc chambers, 2.02/1.60 in. valves, pocket ported
Intake: Edelbrock Performer
Camshaft: Comp Cams 280° Magnum hydraulic, with 280/280° of duration, 230/230° of duration @ 0.050 in. lift, and 0.480/0.480 in. lift
Rockers: 1.5:1
Headers: 1 5/8 in. street
Pistons: TRW forged
Rods: 5.565 in.
Crank: cast
Comp. Ratio: 9.3:1

MAX HP: 382 @ 5300
MAX Torque: 400 @ 4500

[Dm1pfoy1]

Originally Posted by 67_C-30

To give you an idea between of the differences in the cams, here are some real dyno tests I dug up comparing the cam in question.


Chevy 350 .030" over, stock 186 heads, 9.73 : 1 CR
Performer manifold, 600cfm, 1 5/8" headers

CS1014
204/214 @ 050 .420/.443 112 LSA
302 HP @ 4800 RPM
364 TQ @ 3400 RPM

CS1013
214/224 @ 050 .443/.465 112 LSA
315 HP @ 5200 RPM
355 TQ @ 3600

As you can see, the extra duration makes a lot of difference in HP numbers, but comes with a loss of torque numbers.

Here's another build showing the difference in what you gain with a bigger cam, porting and bigger valves. The 441's are basically the same heads you have, and this is a flat top 383 with 76cc heads that came out to 9.3 : 1 CR. This cam would be a little bigger than you'd want in a daily driver, but you get the idea.

Displacement: 383 cu. in.
Carburetor: Holley 750 double pumper
Heads: GM #441 castings, 76cc chambers, 2.02/1.60 in. valves, pocket ported
Intake: Edelbrock Performer
Camshaft: Comp Cams 280° Magnum hydraulic, with 280/280° of duration, 230/230° of duration @ 0.050 in. lift, and 0.480/0.480 in. lift
Rockers: 1.5:1
Headers: 1 5/8 in. street
Pistons: TRW forged
Rods: 5.565 in.
Crank: cast
Comp. Ratio: 9.3:1

MAX HP: 382 @ 5300
MAX Torque: 400 @ 4500

I appreciate all the help I really do, thank you. It is a noticable lope at idle. Thank you for the additional build info. Truck is not a dd so i may look more into upgrading cam similar to your above post, I will at least getting port work done with valve work as well.Your numbers posted are what im kind of shooting for. Not to many places to lay it out and get to 6k aside from on ramps lol. Again thank you for your help its been very valuable if you do know of any othe cam #'s that you can think of i would love to know. Thanks again im going to take what you gave me and dig a bit more.