Thread: Hot Street 396 build, dyno numbers?

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Ok, just put the engine in my car, it's going in my '69 El Camino with a Muncie M-20 4speed and 3.90 gears.

Here it is...
-396 Big Block Chevy bored .030, makes 402ci.
-Small domed pistons, 17cc.
-Edelbrock Air Gap RPM intake manifold, port matched.
-750cfm Holley carburator
-Doug Thorley headers, 1.75" primaries with 3" collector. Open Exhaust.
-10.4-1 compression
-Heads are 1967 GM closed chamber oval ports- 255cc intake port, pocket ported, chambers polished, flowed 271cfm at .500 lift. 2.065 intake valves, 1.72 exhaust valves. Combustion chamber size is 96.4 cc's.
-Comp 1.72 roller rockers

Camshaft Specs:
-Iskendarian Z-45 camshaft, solid flat tappet, 240 degrees duration @.050 on both intake and exhaust.
-with a 1.72 ratio roller rocker makes .503 lift at the valve. This already has the .018 lash taken out.
-Cam Timing @ .050----Intake opens 12 degrees Before TDC, Intake closes 48 degrees After BDC. Exhaust opens 48 degrees Before BDC, Exhaust closes 12 degrees After TDC.
-108 LCA

I get something like this ...............

Nice, over 500 pounds/feet of torque from 2,000 to 4,000. Great street motor.

Doesn't sound right. Considering the head flow and the cam, it should make peak power at about 6000-6300rpm's. That dyno shows it topping out at 5000. Anybody with a desktop dyno professional that you can put head flow numbers in? I edited my first post, the cam timing I listed is @ .050 lift, I didn't specify. That may have been the problem.

Originally Posted by 69elko

Doesn't sound right. Considering the head flow and the cam, it should make peak power at about 6000-6300rpm's. That dyno shows it topping out at 5000. I was hoping for about 480+ horsepower. Anybody with a desktop dyno professional that you can put head flow numbers in?

To make 480 + hp you will need a hyd. roller,mech. or a mech. roller cam.

Originally Posted by erik erikson

To make 480 + hp you will need a hyd. roller,mech. or a mech. roller cam.

It is a solid lifter cam. Isky high rev series on a 108 LCA.

what are you trying to get for hp the TQ is what will move you i was thinking 400 to 430at the best.but the tq is fine it will move with that

Just enter the flow numbers under the cylinder heads / custom port flow.

Best list out there I know of...............


http://racingfeed.com/downloads/chevy_flow_data.pdf

This was one of my first port jobs, the exhaust didn't turn out quite as well as I'd hoped for but I did it without a flowbench. This flowtest was taken at GrommRacingHeads.

intake/exhaust flow @ 28 inches
.100 lift- 67/63.39
.200 lift- 153/108
.300 lift- 213/130
.400 lift- 252/149
.500 lift- 271/165

Closed chamber 96.4cc
255cc intake runner

Sounds like a good motor to me,low rpm power means less engine wear and every time you shift it will drop down into to torque band. 500 + torque is good stuff
Keep in mind thats only a estimate from one simulation,real world results may differ
I am with Pat,I thought less on torque, just from other hp to torque build specs I have seen.Maybe the HP is close to 450 + ? Which would mean less low rpm torque.
From the page Viking posted it looks like about 250-260 on the inkake about 170-185 exaust are what flow numbers it takes to make close to 500hp.Your pretty close on the exaust ,maybe some ratio on the exaust rocker ? ...Or a split duration cam that is going to make up for the exaust and take advantage of those good intake numbers.

Originally Posted by shawnlee28

Sounds like a good motor to me,low rpm power means less engine wear and every time you shift it will drop down into to torque band. 500 + torque is good stuff
Keep in mind thats only a estimate from one simulation,real world results may differ
I am with Pat,I thought less on torque, just from other hp to torque build specs I have seen.Maybe the HP is close to 450 + ? Which would mean less low rpm torque.
From the page Viking posted it looks like about 250-260 on the inkake about 170-185 exaust are what flow numbers it takes to make close to 500hp.Your pretty close on the exaust ,maybe some ratio on the exaust rocker ? ...Or a split duration cam that is going to make up for the exaust and take advantage of those good intake numbers.

Ya, I was thinking about running 1.8's on the exhaust to see if it might help power. But I want to run this cam for now. If I really wanted to, I could have ported the exhaust a little more after I got the heads flowtested but I guess I got lazy.

I did do a desktop dyno before and put all my specs in, except it was a regular version of desktop dyno. It didn't have the headflow feature. Made 480 horsepower/490 torque. That sounded about right to me. I wouldn't think a 240 duration at .050 would make 500+ torque and only 415 horsepower. But I think I will be satisfied with 450 horsepower, considering I built the whole engine for about $4000. That was including the $500 March serpentine pulley kit. Can you say budget big block? I'm sure Pat can probably match that though. The more work you do yourself the cheaper it gets.

Originally Posted by 69elko

This was one of my first port jobs, the exhaust didn't turn out quite as well as I'd hoped for but I did it without a flowbench. This flowtest was taken at GrommRacingHeads.

intake/exhaust flow @ 28 inches
.100 lift- 67/63.39
.200 lift- 153/108
.300 lift- 213/130
.400 lift- 252/149
.500 lift- 271/165

Closed chamber 96.4cc
255cc intake runner

The heads I used in DD have higher flow than what you posted .............

Kitz

Originally Posted by 69elko

Ya, I was thinking about running 1.8's on the exhaust to see if it might help power. But I want to run this cam for now. If I really wanted to, I could have ported the exhaust a little more after I got the heads flowtested but I guess I got lazy.

I did do a desktop dyno before and put all my specs in, except it was a regular version of desktop dyno. It didn't have the headflow feature. Made 480 horsepower/490 torque. That sounded about right to me. I wouldn't think a 240 duration at .050 would make 500+ torque and only 415 horsepower. But I think I will be satisfied with 450 horsepower, considering I built the whole engine for about $4000. That was including the $500 March serpentine pulley kit. Can you say budget big block? I'm sure Pat can probably match that though. The more work you do yourself the cheaper it gets.

I am sorry I miss read your post about the mech. cam
At 450 hp that is more than 1.1 hp per cubic inch and that sounds very good when using stock heads.
I like the March products but they are very slow.
Over a month a go I ordered a serpentine pulley kit for a customer and he is still waiting on it.
Now today I hear they are shipping everything but the bottom crank pulley.
They say I should get that in another few weeks.
What can you do??

Originally Posted by erik erikson

I am sorry I miss read your post about the mech. cam
At 450 hp that is more than 1.1 hp per cubic inch and that sounds very good when using stock heads.
I like the March products but they are very slow.
Over a month a go I ordered a serpentine pulley kit for a customer and he is still waiting on it.
Now today I hear they are shipping everything but the bottom crank pulley.
They say I should get that in another few weeks.
What can you do??

Yeah when I ordered the kit from Summit they took a little longer than usual. Wasn't a month, but was about a week. Was missing the allen screws for the alternator pulley cap.

Well, maybe I'm wrong. I guess I had higher hopes for this engine. There wasn't any other head I could use without the use of a massive dome piston which they don't make for a 396. All aftermarket heads are in the 113cc-119cc chamber range and would give me 8-9 compression with my 17cc dome piston. After all the hassle I've been through, I think I'm gonna build a 468 as my next engine.

Originally Posted by 69elko

Yeah when I ordered the kit from Summit they took a little longer than usual. Wasn't a month, but was about a week. Was missing the allen screws for the alternator pulley cap.

Well, maybe I'm wrong. I guess I had higher hopes for this engine. There wasn't any other head I could use without the use of a massive dome piston which they don't make for a 396. All aftermarket heads are in the 113cc-119cc chamber range and would give me 8-9 compression with my 17cc dome piston. After all the hassle I've been through, I think I'm gonna build a 468 as my next engine.

just go to a 496 they are not that much more and from there rigth to 565