power and torque estimates?

[redtruck75]

hi guys im looking for input on what my motor makes.

360 block stock bore
2u 390 crank
360 rods with arp studs
3/4 groove bearings
speed pro forged pistons with 4 valve reliefs (compression height cut down for longer rod)
pistons pop out .010 should be 9.71:1
C4aeg heads with little clean up on intake and exhaust runners
edelbrock performer rpm intanke
comp cam .494 lift 268 int./268 exh 110 lob separation
stock rockers
comp springs that match the cam.
600cfm holley/summit brand carb
6al2 ignition system.

my guess is high 300 low 400 hp

[Nightmist66]

Welcome. I can't say for sure on torque what you are making, but you may be just under 400hp.

I have estimated my combo to be around 415ish hp from some passes down the track. I am usure what my torque is too. Maybe someone can help you and I better. Here's my combo:

Factory 390 block bored .030 over, flat-top pistons for around 10.2-3:1 compression, windage and valley trays, factory heads with mild port and valve job, hyd. flat tappet cam- .536int/ .562exh 224°int/ 234°exh @.050" 110° lobe sep., 1.76 adjustable rockers, Performer RPM intake, mildly worked 650dp from the stone age, stock dist. upgraded w/Pertronix ignitor III and matching flamethrower III coil w/timing set at around 40°.

[chilly460]

360hp/420ftlbs

Very similar combo with more cam made 390hp, along with a few other examples.  Stock head combos with street cams are going to struggle to hit 400hp on 390ci unless they've been rubbed on quite a bit.

https://www.youtube.com/watch?v=PjxO7sND__Q

[Royce]

I built a 390 many years ago: .30 over C2SE heads with just a valve job. A cam one notch smaller than yours.. A little bit more compression 10.5. and a G code intake and carbs.. Made 340 horse 440 ftlb. but was all done at 4800. I think that 360-375 horse estimate is pretty close maybe 425-430 on torque

[fryedaddy]

any guesses on mine,428,30 over,internal balance, speed pro pistons-11 to 1,cj heads with good valve job,pi intake port matched,565-292, 244 at.050 comp cam,hamburger true roller chain,msd box,coil,dist,950 ultra hp holley,hooker long tube headers,3 inch exh.arp studs in rods and mains,melling pump,oiling tricks,windage tray,

[Royce]

I will say 465 to 475.. I built a 30 over 428  unported edelbrocks about same cam and compression. Made 488 with a performer rpm and just tickled 500 with a Victor

[fryedaddy]

i was trying for 500hp,you say 465-475.how can i gain 25-35hp without tearing it down?

[Royce]

Boy that's a tough one.  The only area that I see it could improve without going after the heads is the intake..  the Performer RPM will get you some extra horsepower.  Another Intake manifold option would be a ported StreetMaster...With iron heads you are maxed out on compression for pump gas. cam is plenty big.  Carb is fine, headers good. .  Take a look at Jay's manifold book and look at his slightly warmed 428 build,  that will give you some idea how your engine might respond to a better manifold..   Time spent on the dyno might get you some incremental gains from timing, fuel curve optimization, and spacer testing.. You might get pretty close.. It takes a very careful build to get 500 hp with un-ported CJ heads. 

Then there is always that hidden 75 hp shot of nitrous

[fryedaddy]

thank you Royce,i have been wanting a modern intake.my heads and intake have been gasket matched,so i have some slight porting and a good valve job on the heads and the intake has been ported out alot.

[Royce]

Your ported PI intake might flow all the air the heads can use.. Joe Craine would be the guy to ask about that..He can also tell you what to expect out of un-ported CJs power wise

[fryedaddy]

Your ported PI intake might flow all the air the heads can use.. Joe Craine would be the guy to ask about that..He can also tell you what to expect out of un-ported CJs power wise

how do i go about asking Joe about it.i dont think i know him.i only know who a few people are on here.im fairly new to the site. if the ported pi flows good enough,ill just leave it on for now,and get new heads and intake combo for christmas

[Royce]

Just send Joe a private PM on here he is  Joe-JDC He is a very experience head porter and racer

[Joe-JDC]

A gasket matched PI with porting into the runners for three or four inches will average around 300-305 cfm average airflow.  A stock set of CJ heads with excellent valve job will flow in the 255-260 cfm range.  Gasket matching CJ heads doesn't net much, the real work is in the bowl and short turn to gain any real airflow.  Any intake manifold that flows 110% or 115% of the head will work fine on the street or occasional drag racing.  To do an all out porting on a set of CJ heads, a person would need larger intake valves with 45ish* seat, and 1.665-1.680 exhaust valve with lots of port work.  A PI intake can be ported and balanced to ~360 cfm average airflow with the right carbides and long mandrels for cartridge rolls.  Joe-JDC