1986Z28OWNER

iTrader: (1)

Dynoed my vortec headed 383 this weekend. Specs are as follows:

- 383ci
- Compstar 6" h beam's
- Wiseco forged pistons
- 10:1 CR
- Comp hydraulic roller (224/229 duration @ 0.050", 0.598"/.544" lift w/ 1.7 int and 1.6 ex rockers, 110 LSA installed on a 108 intake centerline)
- Production vortec heads with 2.02/1.60 valves, Intake port as cast(other then bowl work to match valve job) minor porting on the exhaust.
- Peformer RPM air gap, no port work other then a bull nose plenum divided
- 1.5" carb spacer, (1" open and a 1/2" nitrous plate)
- AED 750 HP-HO (74's primaries & secondaries, 4.5" PV's)
- MSD pro billet locked out at 36 degree's
- 1 5/8" - 1 3/4" step header
- Moroso 4 vane vac pump pulling roughly 11-12" of vacuum at 6500RPM


The results: 481HP @ 6000rpm 487ft-lbs of TQ @4700 RPM.

AutoRoc

iTrader: (1)

That will get out of its own way! Congrats, i'm sure it was a fun, nail biting experience.

Those are impressive numbers for a cleaned up vortec head aren't they? I've been out of the loop on magazine SBC builds in the last few years.. Haha

86LG4Bird

iTrader: (1)

Very decent for near-stock heads and mild CR!
I'm glad to see you made a sensible cam choice to match the rest of the combo

1986Z28OWNER

iTrader: (1)

Ive never been one to over cam a engine.

ASE doc

Nearly 500hp on nearly stock Vortec heads. Very good. People choosing Vortecs will be happy to see this. It's also cool to see someone else using vacuum evacuation. Would be interesting to know how much of a gain this provided.

1986Z28OWNER

iTrader: (1)

It netted roughly a 4Hp gain, but the ring is just a standard tension 1/16"-1/16"-3/16" mahle, Gains would have been much higher with a ring combo better suited for vacuum like a 0.043"-0.043"-3.00mm low tension ring pack. but when I built the engine I didnt intend on running a vacuum pump.

ASE doc

Still the 1/16 rings will be happier down the road with added evacuation. They do pass more gas but also reduce friction. The only down side of the vacuum pump is that it needs to be rebuild about every 5,000miles. Moroso does it for a $125 flat fee including return shipping. I take it that this motor won't be a daily driver so like me, you can handle these things in the off season. Ive thought about having a front cover machined for the pump that takes a sealed ball bearing to increase service life.

Orr89RocZ

iTrader: (20)

Surprised to see power go that high with such mild cam and stockish port vortecs. Very solid numbers.

1986Z28OWNER

iTrader: (1)

We stock the kit's here and I have rebuilt so many I can do it in the dark.

ASE doc

Right on. So you work at the machine shop. Experience building HP small block chevys I'm thinking has more than a little to do with those unusual results.

Orr89RocZ

iTrader: (20)

I see the ultra high intake valve lift. That would help explain the power peaking high. Who says vortec heads dont work with over .550" cams because flow backs up? Lol

1986Z28OWNER

iTrader: (1)

Our flow bench begged to differ on that one. These didn't see any significant gains, but didnt fall on there face as everyone always makes it sound like they do. Not bad for a head with a 173 cc intake port. Even though certain member's on this site insist you need a minimum of 195 cc for a 383ci engine.

Orr89RocZ

iTrader: (20)

Yeah perhaps the valve job and bowl worked help stabilize airflow and allowed gains above .500"?

I would be one of those who insist a 383 receives 195cc but usually because rpms are over 6000. Lol Port those heads out some to a larger csa and pour 190's cc and i bet numbers go up. Or atleast has potential for more rpm and power with more cam. Seen a 580 hp 383 with vortecs that poured 190's cc and flowed 280-ish cfm. 2.050 valve. 230 deg hyd roller under .600" lift . Above 6000 rpm 383 needs some airflow. For street, lower rpm range, this combo you have kills! Very solid

1986Z28OWNER

iTrader: (1)

I dont reall intend on turning it past 600-6200, I wanted a torque monster and thats what I got. I have already got the ball rolling on the new engine. A local drag radial guy is helping me out with it. I have most of the engine pieces, going to start putting it together this summer. The plan is a 370ci 6.0L, GM LSA heads, Twin magnum 76mm's, A2A, HP EFI. I want to make 1100RWHP. which seem's to be do-able.