Are the L48 heads on my 79 Vette 882's? If so, I read that the intake runners are 152cc and the flow is 205cc sounds pretty good for a street head. Do you think these heads would support 300hp? I have a rebuilt engine w/ flat tops, a Isky cam with 204/214 with 425/440 lift, 882 heads w/ three angle valve job, aluminum intake, qjet and Hooker super comps. Thanks, Al

 

Yeah you should have 882 heads and I don't think you'll get 300 HP from them.

They just don't flow very well, and are even prone to cracking.

 

Al: If it's tuned right, your combo's making at least 300 hp at flywheel right now ... maybe as much as 320.

 

No problem making that power with those heads, I agree with Jacksons post as well. Check out this site for some good info on flow capabilities and potential HP http://users.erols.com/srweiss/tablehdc.htm

 

That is an extremely mild camshaft (204/214, 425/440 lift). I doubt you can make 300HP with it.

 

You think so? Even with flat top pistons, those heads wouldn't give him more than 9.0:1 static compression. Even with that mild cam, a set of 64cc heads and a 9.55:1 static CR would get barely get him to 300 HP.

I could be wrong...I'm working backwards from a combination I know works using a set of 64cc Vortec heads, which flow great, a slightly more aggressive cam, and that would give an L48 with flat tops about 300 HP at the wheels.

I just don't think the lesser flowing heads, with a smaller chamber, a mild cam, in that combo, would get 300 HP even at the crank. Anyone know for sure?

 

Would be inclind to agree. Super Comps 1-5/8 on these or 1-3/4?

 

I ran your combo on EA3.0 and the SIM shows it to be making around 315 flywheel HP.

 

I just ran your combo on compcams simulator, using a very simular cam I came up with 296HP As it is now.
And that was using mufflers!!!

 

Why is it the guys at the dyno shop always say they see 10% less on a real dyno compared to the desktop software?

I have also heard from a few guys here that that software is rarely accurate within 15 - 20 HP.

Anyone used BOTH and have documented success?

 

Are the L48 heads on my 79 Vette 882's?
The easyiest way to find out is pull a valve cover, You"ll see the head # on top of the head. The last 3 digits would be 882, You can also look that # up here: http://www.mortec.com/ to find out a little more about them. pick the easy side

 

I used Comp Camquest and was accurate as I could possibly be.
Motor dynoe'd 60 hp less.

Word of warning on that program it can be very difficult to uninstall also.
Wouldnt download it again.

 

Wow, haven't looked at that site for over a year. Everything has been updated to todays head availability and information. Bookmark it!

 

Checked out the website that was posted by SStocker & 63 Mako. How is this site coming up w/ these hp numbers, looks to good to be true? What cams are they using ect?

 

Those are potential HP numbers using the flow numbers. Those heads will fit on a high performance 427 small block with a solid roller as well as a docile 350. Wouldn't be a good match but the numbers posted would be close to the maximum hp you could possibly pull out of those heads under ideal conditions.

 

My EA software has been tweaked using multiple actual dyno results. EA also tends to be more conservative than DD out of the box and with the data provided, one has to make several assumptions but given that two of us are in the same ballpark, the results are pretty close.

 

This is very close to your combo and my DTD comes up with 290 hp and 362 trq.
This is the 260 / 350 Goodwrench engine with a slightly larger camshaft.
This engine comes with a warranty from Gilbert Chev.
Off Of their website:
GILBERT CHEVROLET’S PERFORMANCE 285HP, 5.7L (UNIVERSAL ENGINE) SPECIFICATIONS
Horsepower¹: 285 HP @ 4,600 RPM Torque¹: 355 FT/LBS @ 3,600 RPM
Redline: 5,200 RPM Comp. Ratio: 8.50:1
Heads: Cast Iron, 76 cc Valves: 1.940” I, 1.500” E
Rocker Arms: 1.5 ratio Camshaft Lift: Hydraulic; 0.420” I , 0.442” E
Crankshaft: Cast Iron Nodular, 3.480” Stroke Duration @ 0.050”: 204° I, 214° E
Block: 4 Bolt Main, 2 Piece Rear Main Seal, 4.000” Bore
Spark Plug: R44TS, Gap @ .035 For Points Distributor or .045 For HEI Distributor
Ignition Timing: For most applications it should be 10 to 12 BTDC°, Total timing, which includes base setting plus centrifugal advance, should not exceed 36° @ 3,000 rpm.
Note¹ - Numbers are for a engine that had an Edelbrock Performer intake manifold, 1904 Edelbrock Q-Jet Carb., HEI distributor, 1-5/8" headers and open exhaust installed prior to dyno testing.
For the person who wants just a little more power than stock, we installed a GM Performance camshaft kit P/N 12353917, a Performer intake manifold, and an damper ( 8” HD Balancer).
Warranty Note: The GM Goodwrench warranty applies only to the base long block engine (P/N 10067353) for P/N SC285GW. Upgrade parts, other parts, and optional parts are only covered by a 12 month parts only warranty.
Additional Options To The Basic Goodwrench Performance 350:
1) Chrome - valve covers, timing cover, damper pointer, dip stick, breather, and valve cover spreader bars. Also included are: Stainless - ARP timing cover bolts and intake bolts. $85.00
2) Proform HEI Dist. $125.00

 

I would say it's because the program isn't aware of the fact that the motor and all the components of the drive train is 30 years old....

 

Precise timing curve and exact A/F ratio to get maximum power is part of the reason.