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300 HP/ 383...naw!

10K views 31 replies 8 participants last post by  spinn 
#1 ·
Gents; After 2 years of gathering dust I finally completed freshening up my 383 Chevy engine that's in my 1980 4 speed Camaro. I had the home ported 993 heads gone thru with new seals by a local machine shop. I installed zero gap (cheap "claimer" style) rings and a XE268 cam. The engine makes 195 to 200 lbs. of cylinder cylinder which is more than it did before (170-175). I am running cheap cast flat top pistons (again "claimer" parts) and 1 5/8" headers. I am at a loss as to the higher cylinder pressure other than the XE cam's ability to trap more cylinder pressure because of it's fast acting lobes...Harold Brookshire apparently, really does know what he's doing. The best I've seen for my combo on the net is maybe 320 horsepower and 390 lbs of torque. Anyway, that auto runs like a scalded dog and will break loose and go sideways if I'm not careful shifting gears...heck my wife makes me sleep on the sofa if I open it up with her in it....300 to 320 horsepower would not do that! Am I getting old and becoming overly easily impressed or do I have more horsepower than the desktop dyno's describe??
 
#5 · (Edited)
I ran the combination on my Desktop dyno since I've been running various combinations of 350/383 Chevy prior to my build (check my gallery).
I got 344 HP @6000 and 326 Torque @5000
I think the cylinder pressure is about right for 10.0 to 1 (or higher)compression
I think the problem is the heads flow too poorly to take advantage of the larger displacement and bigger cam. I Plugged in my AFR 195 street heads and it jumped to 375 HP @ 6000 and 342 ft lb @5000
Just for fun I ran one of the cams I'm considering, a Howard Hydraulic roller #111145-10 and my AFRs and got 496 HP @ 6000 and 498 Ft lb @ 4500. Cool also was the 402 Ft lb of torque at 2000 RPM. I'll bet that would REALLY chap your wife:D
I've been studying "dynamic compression" and it's pretty interesting and applies to some of your questions. Google it.
After learning to input data properly, I have found that Desktop Dyno and Desktop drag to be dead on with all my cars for the last 15 years from Stock Mustangs to my big block Chevy T-Bucket to my 9.20 @ 149 Mustang drag car. Use the drag strip to verify your Desk Top Dyno results. If you are careful to input accurate data you will be pleased if you don't have to sleep on the couch too much.
 
#6 ·
Very interesting and informative reply Choctaw Bob! I also listened to the other gents and called a "dyno shop" in the town next to mine concerning having my ride dynoed. When I told the shop gent (Jim) about my engine he laughed and said all of the guys with a car like mine think they have a Melrose Rocket but leave the shop with their tail between their legs! Well, according to Mr. Chactaw I have about 345 horsepower which is most the most I've seen so far and I have to believe it but frankly I think the motor has around 375HP. I remember when I first rebuilt the engine (1994) I followed David Vizard's book very closely. In his book he did not like 993 heads but he stated they could be made to run with some port work which I did. Next week or so I will belly up to the bar with 80 bucks in hand and go see Jim at the dyno shop. Of course I will state my figures on this site and we will see how close Mr. Choctaw is!
 
#8 · (Edited)
My neighboor did a nova with a 383. He had it limited to 5500rpm , but still was not impressed. It has the summit street strip heads, 3000 tci stall, etc. It had a 350 similar build before and it was not all that different.

Now In July, my buddy out of town, had me rebuild a $800 144 roots bm blower. We used a 114lsa blower cam on his 350 camaro. After installation it was so impressive, imediately I knew that was the way. So I cashed in a mature CD bought the new Edelbrock E force for vortec engines and did my c10 305. It was a new design eaton impeller with sneeze valve and better streetability. A 5.0L makes about 600hp with thier kit and a 8 psi pulley. Even a old BM style roots makes plenty and they are comonly under 1000 to buy it now. If you put that on a stock roller cam 350 from a truck and 800 cfm It would beat those 383 numbers and cost under $15-1600 total runner.

Mileage , power, cool factor, blowers have it all. Just consider it next time you think about stroking it, and get someone to blow it.
 
#10 ·
Going to Comp Cams website and using CamQuest and dyno results a 383 cid with 993's ported with 1.94 and 1.5 valves put out 346 hp @4500 rpms and 436 lbs torque @ 2500 rpms. If you have 2.02 and 1.6 valves the results are 370hp @ 5000 rpms and 440 lbs torque @ 3500 rpms. This is with the XE268H cam.
 
#16 ·
Here in lies the problem of dynoing my ride. As you all know it will show rear wheel power which is not something I can relate to. However, that said, for 80 bucks, it will be interesting to see where I stand next to the new rides which the dyno shop will tell me. As for the misses, when we were 1st married I would suffer a heart attack when she stepped out of the shower for she had a body that rivaled Kim Kardashian's. Now, I have a heart attack when she steps out of the shower but not for the same reasons!
 
#18 · (Edited)
I can relate, I'm 66 years old and have been married to this one for 15 years. She used to complain when I would smoke some kid on the street in my T Bucket or one of the Mustangs. I have some hope because the other day we were watching Stallone in the Avengers drive that 56 Ford truck in the chase scene she said "Listen to that thing wind up". You can have hope in any woman who recognises a great sounding engine like that.
The dyno guy can tell you but I usually add 50 to 75 HP to whatever they say to cover parasitic losses. Horsepower ratings are more for bench racing bragging rights, anyway most people lie about them. I used to carry the dyno print out with a 9.26 1/4 mile timing slip to show anyone that needed convincing. We have an outlaw 1/8 mile strip 15 miles away where this kind of stuff gets settled.
It just occurred to me that I drive through Richmond every time I take my wife to see her family in Flemingsburg.
 
#17 ·
The total horse power an engine makes is a moot point at best. By the time you factor in the horse power robbers like Ps/Ac,the charging system,the transmission,drive line,differential,over sized tires,what you have left is for the ground.Next you will deal with the tub you are pushing around,how straight the wheels are when you push it,the aero dynamics of a barn door or w/e.
Assuming the tune is perfect,,,,
maybe post some stats on the wife and what you have to work with and we can have fun with that too?

good luck with both
 
#19 ·
The drag strips are fun, but a race car and road car are different. A built machine screaming at 7000rpm is not going be fine in traffic. In town a 5500rpm machine will be more fun. Case being when are you going to wind up 7k rpm going to work to get that peaky power. It is time and place. Work or play.

Yeah the built woman look good in the beginning, then gravity pulls it down. Then there is the charge bill they have no idea how to budget. What is a outfit good for if you can only wear it once.
 
#20 ·
That used to be true in the old days when to make horse power you had to wind them up. Since an engine is an air pump the way to make power is to pump more air. With the advent of modern head air flow technology and hydraulic roller cams everything changed. A roller cam opens the valves quicker and obtains higher lifts than is possible with a flat tappet cam. Thus, the air pump achieves the same air flow at a much lower RPM than before. The famous Chevrolet 350 HP 350 cam had 290 degrees duration and .460 lift. This is a very streetable cam for a factory muscle car and needed to be wound over 6500 RPM. to make full power. My 350 Howard hydraulic roller has 288 degrees and 530 lift and makes over 500 HP @ 5500.
 
#21 ·
Reading between the lines that U gents wrote I'm envisioning some monster yet very streetable high horse power machines out there...I'm envious! As for the misses...I'm also seeing that I'm not the only one who's crying for the old days. Yes, the misses has changed with gravity taking it's tole. However, if I squint my eyes and catch her in just the correct lightning I can still catch a glimpse of a gorgeous lady. I was certainly lucky then and I'm lucky now....I just wish she'd let loose of some extra cash so I could make some real power with my ride!!
 
#22 ·
A roller cam is not magic. The small amount of return you get under the curve is not worth the price to convert. Half a inch lift ,is a half inch of lift. The spring pressures are there. You can reduce them with multiple valves like modern 4 valve engines.

The edelbrock crate 420hp RPM or the Mopar crate 380 HP 360 both have roller cams. Both are well designed and not for heavy vehicles. Neither make a great road engine. To go bigger heades and cam only makes driveability worse.

A roller cam is not magically have 5000rpm powerband. No carbureted build is. A built hot small block usually doesnt get organized till 3-4 k rpm.

It is getting easy to spot the experienced.

Important* Nothing wrong with good love at 5'3" 160 36 x 26x 46 !
 
#23 ·
D, why not get 2 things you want? Send the old girl in and get the filling removed,iron out the wrinkles,lift the suspension and get a new paint job.Wait a week for it all to cure.The cost is maybe 10k ish. The return is obvious,you get a new toy to play with that looks updated and great.She will be so happy with the mirror and attention you give her,Im sure she would reciprocate and let you spend a bit on the car. You win twice.
 
#24 ·
As far as roller cams not being magic,thats true,lol. I have 3.5 gears a 5 spd and I can plod along in 5th at 2,000 rpm doing 60 mph with no problems.My power starts under 2,000. If Im in 1st gear and use more than 1/2 throttle at or before 2,000 rpm the tires break loose.If Im in second gear and plant the throttle anywhere near 3,000 rpm the tires break loose. I know my engine will rev to 6500 rpm but I put a 6k chip in the ignition to keep the car controlled easier.Its a small block and n.a.
 
#25 ·
Nah, not the way it works. clutch out at 2000 rpms and you floor it with 3.5 gears and good tire, it does not have the intake velocity to spin them. The engine has to increase piston speed rapidly. Only way is to slip the clutch at that rpm. Who you kidding.
 
#27 ·
V, think about the physics of motion. You are moving forward at 2000rpm locked up drive train, and have traction. You have no from a stop launch impact at the tires. Just the pump shot.

You are proud of what you built and that is awesome.

When my cuda had the 4.10 gears in it 1st gear clutch out at 2000rpm, it would not spin them with cheap 265/60 15 street tires. That roller 440 makes 550hp/550 TQ. Dyno sheet in photos, car in journal.
 
#28 ·
You had a heavier car with less power.My car breaks the tires loose from the carb being yanked open.Ill give you all the details on the engine down to the plug wires if you want. My car is not a fast car compared to a lot around here. There are also some very slow cars here that should run better.
 
#29 ·
Not to rob this post but talking about the Cuda reminded me back of in the 70's. I had a 67 Barracuda 2dr coupe. It was a Formula S 383 4 speed with 3.90 gears. Now that was a fun car to drive. The only thing that was frustrating I couldn't keep a clutch disc in it. Even a Hayes racing clutch I shifted about 5Gs and it would blow.
 
#30 · (Edited)
Rob it, of what. Not possible its just poeple talking , taking it in all directions with a nice even flow. Youre staying right with the current. Dont get sucked under when youre to the drain.

Cuda's were fine. My 71 440 convert has been in the family forever. Money does not have enough value to buy it. The 83/4 rear can swap gears in the same time it takes to change the oil. ceramic material lasts a lttle longer than organic clutch wise. If you know how to drive it can last a while. My girlfriend fights the garage door return spring to press the clutch, and hates it. To used to her civics hydraulic.

 
#31 ·
Spinn, nice car. I don,t blame you for not wanting to get rid of it. It would be an insult if someone made you an offer! Yeah, lookin at them old Plymouths get my heart to pumpin. Back in the day I started with a 1968 Super Bee 383/auto, 323 posi gears. Turned 15's in the 1/4 mile but that was fast to me. Next two were Barracudas, a 1967 Formula S 383 4-speed. I wrecked it and was totaled. I was walkin by the Chrysler dealer a few months after and saw a 1968 convertible Barracuda. I popped the hood and low and behold it was the motor out of my 67. I bought the car for $700. Swap the motor to a 68 Dodge Coronet and drove it for 3 years before I spun a bearing coming home from work. In 1977 I bought a 1967 GTX. By that time a neighborhood friend had opened a machine shop. He gave me all the info on what block to get. I took him the 69 block, heads, and crank. He built me a .060 383 motor. I bought a Fairbanks 727 and a 3600 stall, a B&M flexplate. I installed a 4.30 posi, i think I used all Chrysler parts. That was my last Chrysler product. At age 27 I got married and had kids, you know the sad story after that. Fast forward to 1997 I found a 1967 RS Camaro that I still have today. A 496, Th400, and 4.11 gear. Like you it will be passed on when I'm gone.
 
#32 ·
You have to keep that kind of stuff, and that camaro sounds like a treasure. Kids sitting on the fenders handing you tools, like your father when you were young. You cant replace the memories with money. You do what you can and have fun.

15 seconds is fast for me too.

Thanks.
 
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