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Old 04-25-2013, 06:16 PM
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383 Top end rebuild questions

Hello all !

I'm new on this forum and believe this is the place for some expertise.

Thing is, I bought a SBC 383 crate engine couple of years ago, promised to put out 432 hp at the flywheel. A trip on the dyno revealed a healthy engine, but only 250 hp at the wheels.. So, here is what I have:

Eagle Cast Steel Crankshaft 103523750
http://www.summitracing.com/parts/esp-103523750

Speed-Pro Hypereutectic Pistons ZH860CP
http://www.summitracing.com/parts/slp-h860cp

Eagle SIR I-Beam Connecting Rods SIR5700BBLW
http://www.summitracing.com/parts/esp-sir5700bblw

Lunati Camshaft 60104 : 276/284 .504\.525
Cam Spec Card :: Lunati Power

Holley 750 single pumper
Some china junk Patriot Performance heads, have no spec on these.. Believe 195-200 runner, 64cc

I think that my heads are my main issue here and believe that by adding some quality pieces may change the story (?) I've checked out these:

Edelbrock E-210 Cylinder Heads 5087
http://www.summitracing.com/parts/edl-5087

How will this work for me? May I reuse my old camshaft, carburator etc? I would like to end up close to 500 hp and have seen these heads do the job. Any help would be highly appreciated as this will be my first engine rebuild. The car is for the street use only.

Thanks!

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Old 04-25-2013, 07:22 PM
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Quote:
Originally Posted by Bullseye View Post
Hello all !

I'm new on this forum and believe this is the place for some expertise.

Thing is, I bought a SBC 383 crate engine couple of years ago, promised to put out 432 hp at the flywheel. A trip on the dyno revealed a healthy engine, but only 250 hp at the wheels.. So, here is what I have:

Eagle Cast Steel Crankshaft 103523750
http://www.summitracing.com/parts/esp-103523750

Speed-Pro Hypereutectic Pistons ZH860CP
http://www.summitracing.com/parts/slp-h860cp

Eagle SIR I-Beam Connecting Rods SIR5700BBLW
http://www.summitracing.com/parts/esp-sir5700bblw

Lunati Camshaft 60104 : 276/284 .504\.525
Cam Spec Card :: Lunati Power

Holley 750 single pumper
Some china junk Patriot Performance heads, have no spec on these.. Believe 195-200 runner, 64cc

I think that my heads are my main issue here and believe that by adding some quality pieces may change the story (?) I've checked out these:

Edelbrock E-210 Cylinder Heads 5087
http://www.summitracing.com/parts/edl-5087

How will this work for me? May I reuse my old camshaft, carburator etc? I would like to end up close to 500 hp and have seen these heads do the job. Any help would be highly appreciated as this will be my first engine rebuild. The car is for the street use only.

Thanks!
Chassis dyno numbers by themselves don't tell much (yeah I know what they advertise).

You need a run on an engine dyno, then a run after installation in a chassis dyno.

The difference between these numbers is what's lost to the installtion. Then you need to decide what to do about that. That can range from redoing the engine to make more power to hit some desired outcome between the tires arnd rollers. Or staaying with what you've got then figuring out ways to get more of what you started with to the tires and rollers.

Bogie
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Old 04-25-2013, 09:46 PM
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that 432 hp engine might be losing a lot to your accessories,transmission/diff and most important,,,exhaust system. 250 rwhp is not that bad.and when on the dyno,did you tune the engine or just make 1 pull?
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Old 04-26-2013, 03:17 AM
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Thanks for your reply folks. I was kind of expecting around 350ish hp on the rear wheels. I really can't see how 100 hp may be lost through accessories.. (?) I'm running a manual TKO600 transmission and a 2.5" Pypes performance X-pipe exhaust, no cats. Hooked up to the serpentine system I have only the standard equipment.. I did mulitple pulls and timing and carb were adjusted.

Also, it does not feel like a 432 HP car, not even close.. The dyno run was made when I had an automatic transmission in the car, but I have now swapped to a TKO600 manual, but to be honest I don't feel that much of a power difference...

Last edited by Bullseye; 04-26-2013 at 03:46 AM.
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Old 04-26-2013, 06:55 AM
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That 2 1/2 inch exhaust could be costing 50 hp by itself.Im not defending that engine builder.My 80 Camaro went 4/10s faster just removing the mufflers,,,2 1/2 inch with turn downs before diff.

Even if you find more HP, the exhaust needs to be upgraded for serious power.
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Old 05-01-2013, 09:30 AM
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I see, I'm actually quite confused.. Could I experience some other problem with my motor..? I find the dyno numbers quite strange as the engine does not build any power past 3600 RPMs... I don't think that my 2.5" exhaust system will be a limiting factor with these numbers (?)

RPM RWHP FlyWHP RWTRQ (Nm)
3500 192,8 233,3 392,3
3600 216,3 261 427,8
3700 218,4 264,1 420,2
3800 222,4 269,3 416,7
3900 225,5 273,7 411,8
4000 227,3 276,4 404,6
4100 228,5 278,5 396,8
4200 223,4 273,4 378,8
4300 222,8 273,3 368,9
4400 230,6 283,2 373,2
4500 233,6 287,4 369,6
4600 236,8 291,8 366,5
4700 239,8 296,1 363,2
4800 243,3 301,1 361
4900 244,9 303,7 355,7
5000 242,5 301,8 345,4
5100 237,9 297,4 332,2
5200 233,7 293,4 320
5300 233,8 294,5 314,1
5400 235,2 297 310,1
5500 193,8 250 251,6
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Old 05-01-2013, 10:45 AM
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Could it be my vacuum secondaries on my Holley not opening? Any way to check this?
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Old 05-01-2013, 11:53 AM
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What intake do you have?
What do your ignition system and timing curve consist of?
What grade of gasoline did you use?
What headers do you have?
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Old 05-01-2013, 12:33 PM
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My headers is by Flowtech, 31106FLT I believe
HEI distributor, total timing 36 degrees in at 3000 rpm, curve has not been adjusted and vaccum advance is not used.
The grade of the gas here in Norway would be 98, but converted to US rating I believe 93.

I'm not sure what brand or specs my intake is, no markings on it. It's a dual plane though..

NOTE: The heads have 185cc intake runners.
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Old 05-01-2013, 01:05 PM
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OldBogie didn't post the info that he wrote on another thread, but I'll post it for him because it makes perfect sense.....

"Since you have a timing slip, if you know the weight of the car the horsepower can be calculated for another data point. I'm not much of an acceptor for chassis dyno data is a solid indicator of crankshaft horsepower. Bach when I was a young man in college, I accepted a couple summer intern jobs at Ford and as super good luck would have it ended up in the dyno rooms. What I discovered was that there can be as much as a 50 percent difference between the crankshaft power outputs as the engine is configured on the engine dyno compared to how it is configured when installed in a chassis on the chassis dyno. So when I hear chassis dyno guys talking about a 20 percent loss in the driveline, I just hold my nose and leave the room to find a place to puke.

You are going at the exact spot these guys want you to attack which is pour more money and technology into the engine. Don't get me wrong this will work; you can jack up the power till it overwhelms the installation losses. The problem is you have half a piece of information. From my reckoning by their formula to my experience you have an adjusted horsepower at the crank from 408 to 508. That's a huge spread and raises big questions in my mind as to whether the engine is down on power or whether that power is disappearing in the various installation losses. The installation is inclusive of ancillary drives such as the water pump, fan, alternator, power steering pump, possibly AC. Losses in the exhaust system. Losses in the torque converter, these can be significant as well as the transmission, drive shaft and rear end. Also the tires can eat a lot of power, especially when turning fast as they develop waves that move through the tire structure absorbing energy as they go.

So my opinion is that without a dyno run on an engine dyno, you're just pokin' at a pig while blindfolded.

Bogie"

I have learned over the years that whatever OldBogie says, you can take it to the bank. He does not blow smoke.
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Old 05-01-2013, 02:17 PM
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In my opinion, the Edelbrock heads will not make the 500 hp you are looking for.

Here's a recipe that will do it.......
Keep your same cam.
Air Flow Research 195 Street heads, part number 1036 with 75cc chambers.
With a piston deck height of 0.025", gasket thickness of 0.028" (GM 10105117), static compression ratio will be right at 10.0:1 and squish will be 0.053". A tighter squish would require complete disassembly of the motor to cut the block decks. The 10105117 will work with aluminum heads. Use of a shim gasket with aluminum heads is not recommended. I would use 1 3/4" long-tube headers with an "X" or "H" pipe installed before the mufflers. 1 5/8" long tube headers will not make quite the power on a 383 that the slightly larger diameter units will show.
Use a 750 carb on an Edelbrock Performer RPM intake manifold. The same design manifold can be had in the Holley 300-36 or the Weiand 8016 manifolds. Both are no longer in production, but may be sourced used. Any of the 3 will produce the same following results.....
Use plenty of air filter area, like 14" x 4". Don't tell me that it won't fit under the hood. Never let sheet metal get in the way of performance. Cut a hole.

RPM....HP....TQ
2000....154....404
2500....201....422
3000....257....450
3500....321....482
4000....387....509
4500....446....521
5000....501....526
5500....532....508
6000....549....480
6500....548....443
7000....509....382

Peak volumetric efficiency 101.8% @5000 rpm's
Peak BMEP 207.4 lbs @5000 rpm's
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Old 05-01-2013, 03:24 PM
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Thanks for the recipe techinspector1, appreciate it ! I've been playing around with a simulation software with different combos (Desktop Dyno), including the AFR 195cc and same cam,
but the numbers I get from this is nowhere near the ones you listed (?) I've read that this program would give a good indication of which numbers to expect, can't I trust it?


From simulation (10.22:1 CR):

RPM HP TRQ
2000 153 402
2500 195 409
3000 243 425
3500 294 442
4000 344 451
4500 387 451
5000 416 437
5500 424 405
6000 408 357
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Old 05-01-2013, 10:18 PM
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Quote:
Originally Posted by Bullseye View Post
but the numbers I get from this is nowhere near the ones you listed (?
Are you using the current flow numbers on the AFR195 street heads. The flow is insane compared to what it used to be. I don't know how AFR did it, but they sure hit a home run with that head. I had to go into the software and change the flow to the new numbers.
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Old 05-01-2013, 10:31 PM
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Afr's if the funds allow it, or take a look at the pro-filer 195 head. The flow numbers are outstanding and the price is shocking for what they are. The following is from one of the best head guys in the business.

First, I'm not here to sell anything. I've done an independent flow test on both cylinder heads. I thought I would post because there are many SBC guys and these heads are extremley good! One of the untold stories at looking at raw flow data is the hidden aspect of velocity. These heads are dead nuts for there flow!They were designed by Darin Morgan, enough said. The beauty in the 210cc head is the*flexability. You want a non-raised runner you have it. Want to use that core to make a raised runner, it has enough material. You want a 2.5 inē choke, you have it. Want to use that same core and get a 2.95 inē choke, you can do it.. Or you can run them in out of box shape.The 195cc head has very good off throttle and drivability on street strip engine of small displacement and allows the engine to accelerate quickly. Guys put these mild performance engines in these heavy street cars. Darin wanted to give them something that flowed well but had air speed out the butt. They can drop that 195cc port head on a 305 or a 383 with street gearing and a mild cam and feel the TQ in there ***.*195cc out of box. 2.055 valve 45š valve job. This same head will flow 300+ at .500 amd 307 at .800 ported..200/156.2.300/216.6.400/262.8.500/277.3.600/282.5.700/284.7.800/285.2
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Old 05-01-2013, 11:17 PM
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not sure how well a 2.05 valve works on a 305?
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