Hot Rod Forum banner
1 - 20 of 32 Posts

·
Registered
Joined
·
53 Posts
Discussion Starter · #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??
 

·
Hotrodders.com moderator
Joined
·
9,581 Posts
Only way I know to know for sure is to get the car on a dyno..that will tell the tale..Desktop dyno has it's use but it is real world that counts..

Sam
 

·
Registered
Joined
·
179 Posts
X2 take it to the track wiegh it and you should be able to calculate hp also remember not all 300hp are created equal depending where you make the power changes how it feels when u smash on the go pedal
 

·
Registered
Joined
·
380 Posts
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.


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??
 

·
Registered
Joined
·
53 Posts
Discussion Starter · #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!
 

·
Registered
Joined
·
380 Posts
Great, I'll be looking forward to hearing about it.

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!
 

·
Registered
Joined
·
2,538 Posts
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.
 

·
Registered
Joined
·
1,684 Posts
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.
 

·
Registered
Joined
·
380 Posts
I think we are all in the same neighbourhood. The differences are in precise inputs.



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.
 

·
Registered
Joined
·
380 Posts
Thats why I'm building mine with all forged bottom end. I plan on a turbo charger next year.

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.
 

·
Registered
Joined
·
53 Posts
Discussion Starter · #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!
 

·
Registered
Joined
·
12,338 Posts
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
 

·
Registered
Joined
·
380 Posts
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.

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!
 

·
Registered
Joined
·
2,538 Posts
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.
 

·
Registered
Joined
·
380 Posts
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.

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.
 
1 - 20 of 32 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top