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Discussion Starter · #1 ·
I am getting ready to build by 385 sbc. parts will be as follows

040 over late model block will be custom bored and honed for each piston.
RHS alum heads 200cc intake and 64cc chambers with 202 and 160 valves
10.7 probe forged pistons flat top and 4 valve releifs
cam is a lunati hyd roller with 509/[email protected] with 227/[email protected] with 112 lsa
right now I have a pro products victor jr copy but think I may go to an rpm air gap intake, that seems to make more sense at this point.
the pistons in the mock up are 006 down the hole.
and the carb is up for debate as I will have to purchase that when the time comes.
any ideas as to what hp and torque will be available would be greatly appreciated.
 

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I took some liberties. I used 800 CFM carb to be sure there was enough, but you'll actually only need about 600-650. I also used large tube headers with mufflers. If you're using smaller tubes like 1-5/8, drop down about 15 hp.

Here you go. This simulation will be a touch optimistic since the lunati lobes aren't quite as aggressive as this program simulates, but this will get you started. I also accidentally used 2.08" intake valves but at this flow level it only made a 2-3 hp difference.
 

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EA3.2 isn't as generous as Desktop Dyno. Since the details you provide are fairly sketchy, I assumed the following:
water pump and clutch fan for accessories, typical windage, standard rings, 5.7" rods, standard bearings, 10.77:1 compression ( very high ), dual plane reduced heat intake with 5" runners, 750 cfm carb, 1-5/8" x 30" headers with 8" collector, 850 cfm exhaust system, ICL at 107°.
Cranking compression will be about 207#, quite high for anything you want to run on pump gas. Idle vacuum is predicted at 15-16".

RPM···········2000····2500····3000····3500····4000····4500····5000····5500····6000····6500
Brake_Tq······323·····358·····405·····432·····444·····438·····411·····386·····356·····301
Brake_HP······123·····170·····231·····288·····338·····375·····391·····405·····407·····373
Exh_Pres······.1······.2······.4······.6······.8······1.0·····1.2·····1.4·····1.6·····1.7
Int_Vacuum····.4······.6······.6······.6······.6······.7······.9······1.0·····1.2·····1.3
Vol_Eff_%·····71.1····76.5····83.8····90.0····94.1····95.8····94.4····93.3····91.6····88.1
Actual_CFM····170·····229·····301·····377·····451·····516·····566·····615·····658·····686
Fuel_Flow·····62.2····83.8····110·····138·····165·····189·····207·····225·····241·····251
A/F_Mix_Qal···100.0···100.0···100.0···100.0···100.0···100.0···100.0···100.0···100.0···100.0
BSFC··········.507····.492····.476····.479····.487····.503····.529····.555····.591····.672
BSAC··········6.354···6.169···5.973···6.003···6.115···6.307···6.630···6.966···7.411···8.427
Friction_HP···22······32······44······59······76······97······122·····150·····184·····236
Mach_#········.167····.208····.250····.292····.334····.375····.417····.459····.500····.542
Piston_Spd····1250····1563····1875····2188····2500····2813····3125····3438····3750····4063
Piston_Gs·····283·····442·····637·····867·····1133····1433····1770····2141····2548····2991
Overlap_%VE···-3.2····-2.1····-.1·····1.1·····1.6·····1.3·····-.4·····-.7·····-.9·····-.9
Int_AvgVel····115·····144·····172·····201·····230·····259·····287·····316·····345·····373
In_InertiaPrs·.2······.7······1.3·····1.9·····2.3·····2.6·····2.6·····2.6·····2.3·····2.1
In_ResTunPrs··0.0·····.0······.0······.0······.0······0.0·····0.0·····0.0·····0.0·····0.0
Ex_AvgVel·····145·····182·····218·····254·····291·····327·····363·····399·····436·····472
ExTun_Prs·····1.0·····.4······-.7·····-.9·····-1.2····-1.5····-1.5····-1.3····-1.1····-1.1
Lifter_Pump_UpNone····None····None····None····None····None····None····None····None····None
Spark_Adv·····25······28······28······30······31······32······33······34······34······35
 

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dejo said:
.. is low 400's an unrealistic number for the crate motors, with the vortecs.
It depends on which horsepower world you live in. There's Desktop Dyno horses, Engine Analyzer horses, magazine test horses, "my mechanic told me" horses, Westech Dyno horses, other dyno horses, rear wheel horses, and elapsed time horses, etc. Modern horses seem to be slower than old-time horses, given the proliferation of 500 hp 13-second cars....
 

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onovakind67 said:
It depends on which horsepower world you live in. There's Desktop Dyno horses, Engine Analyzer horses, magazine test horses, "my mechanic told me" horses, Westech Dyno horses, other dyno horses, rear wheel horses, and elapsed time horses, etc. Modern horses seem to be slower than old-time horses, given the proliferation of 500 hp 13-second cars....
Amen to that... take you 400-hp engine from the Mustang dyno to the dyno across the street and suddenly its a 419 hp engine.... but is that measured in the new SAE, the old SAE, gross, net, with what accessories and exhaust?
 

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Discussion Starter · #12 ·
I hear you on the mags. I just figured that what I am building would at least exceed what the gm crate motors would do. and also figure them to be rated in a sane manner.
 

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In the grand scheme of things, your motor may not outperform the same motor with vortec heads. For flow , .400 lift and below, the vortecs scream. Yours may flow a better peak number, but if from 0-.400 lift the vortec heads are flowing better and at .500 yours start to flow better, the vortecs could do about the same as your heads. Another thing to consider is that the vortecs are doing all this with a 30 cc smaller runner. More velocity with equal flow usually means more hp. If you had a cam with ~.600 lift that could take advantage of the ~260 cfm your heads flow there, it may be a different story. Your heads only flow as well as the max lift of the cam your are using. Also, I could just be being pessimistic, and if so someone correct me, but those numbers you gave seem a little high for an unported head.

Here are the vortec flow numbers. Click on GM L31 Vortec heads.

http://www.sallee-chevrolet.com/frame.html?/Cylinder_Heads/Vortec.html

Here is a 355 to look at with the RHS 200cc heads. It is not a 385 like yours, but it should give you an idea as far as hp/ci goes. This one has a bigger solid flat tappet cam which will make some more hp, but if you assumed the same hp/ci as this motor in a 385, you would be looking at ~470. Yours will probably not make hp at quite that rate because of the smaller cam, but I still think you will see around ~420-440 hp.

http://www.chevyhiperformance.com/t...evy_engines/henrys_engine_specifications.html
Adam
 

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dejo said:
I hear you on the mags. I just figured that what I am building would at least exceed what the gm crate motors would do. and also figure them to be rated in a sane manner.
Your making a huge and incorrect assumption that what onovakind modeled and how GM dyno tests their motors are one in the same. They are not.

onovakind simulated power much closer to an as installed engine. Most all GM ratings are not.
 
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