bfreema4

I just recently found out i have a L-48 making 180hp. I think it needs to make more hp to be a corvette. anyone have any ideas to boost the hp on a reasonable budget?

Ganey

Exhaust. See what many refer to it as my Exhaust topic. http://www.corvettefaq.com/c3/ganeyexhaust.htm
Headers rec., however are optional.

Cam. Another cam which L-48 needs badly.
AL. intake can be done at same time as cam. The Q-J works well for many. Heads can be done later if wanted.

Tuning & Timing are basic & should go w/o saying.

gerry72

What's a reasonable budget? Exhaust, heads, and tune will be your biggest bang for the buck.

RonR80

Real easy and pretty cheap, a few years ago I replaced the intake with a eldebrock performer, true dual exhaust and a camshaft L-82 I think . I had the car dyno'd first and the rear wheel HP was a whopping 119, after the mods I pulled at the wheels 221HP . I got rid of the converter
and the car is a little better on gas and pulls pretty good , mine looks pretty stock , you can't even notice it! Ron
I can send you a pic of the dyno sheets!!!!

TedH

I started with a 160rwhp baseline on my '80 L48. That was AFTER I had rebuilt the engine, added Jet-Hot coated Heddman headers, 2.5" duals with h-pipe (no cat), Crane Energizer cam (.454/.454), and flat top hypereutectic pistons.

The greatest, least expensive improvement I can recommend does not require new exhaust or that the engine be opened (with exception of carb and distributor removal).

Your 180hp L48 is tuned for emissions. Have it tuned (re-curved) for performance. Have an adjustable vacuum advance canister added to the distributor in place of the non-adjustable that's on the distributor. Have the distributor rebuilt with that recurve.

Then, have your carb rebuilt/re-jetted by a reputable tuner in tandem with 2-3 dyno pulls to dial it all in (A/F mixture, jetting, timing).

Your low-compression L48 will like ALOT of initial advance. I think I have close to 12 degrees advance at idle, 25 at 1500rpm and about 34-35 at 2500rpm. My L48 is very happy with this.

I recall there is also a vacuum line change you can make to feed the distributor vacuum advance off ported or non-ported vacuum.

Distributor advance and carb are the two single biggest improvements you can make and normally for the least $$$.

Remember, your car has the '300hp cam' (.390/.410) from the factory so it isn't getting the full benefit of it with tuning for emissions.

Also, with proper setup, you can get a better 3-way cat converter that allows greater flow and results in better emissions controls and still pass emissions with these adjustments. My bet is if you have the orig or an old converter, you can do better with a Dynomax or Magnaflow hi-flow, 3-way (3rd-treats for NOx also... augments what your EGR valve does recirculating unburnt hydrocarbons from exhaust into your intake).

After the carb and distro, if you still aren't happy, add the better exhaust system. You'll likely have to adjust the carb jetting so perhaps a good idea to do it WITH the carb/distro. Leave the intake manifold alone unless it is defective. I'd not swap the intake unless you are also stepping up to a new cam/lifters.

Enjoy! And share your results!

P.S. I added a K&N filter to the OEM ram air system. ALSO, I rebuilt the OEM ram-air system (new radiator shroud seals, hood to air chamber seals, etc.) and replaced ALL vacuum lines/connectors on the car to ensure I got maximum benefit of the vacuum the engine produces and that I wasn't losing any to rotted lines or cracked/degraded connectors (Cruise, EFE, EGR, Headlights, internal heater/ac controls). Dr Rebuild sells the most comprehensive vacuum line kits in my opinion. Most competitor products likely started with his designs (some copied and paid for it $$$ in litigation... see his website).

I've since added:

Edelbrock Performer #3701 (EGR) Intake
Dart Iron Eagle heads. 180cc intake runner, 72cc combustion chambers
700R4 Bow-Tie Overdrives trans conversion
3.54 DANA/Spicer gears

7T1vette

No need to change the intake manifold if you don't change the heads, too. Low dollar method: improved exhaust system, good set-up on the distributor mechanical advance system and timing (per Lars recommendations), and fine-tune the carb jets/rods. After that, go to different heads, cam, intake, etc.

Reggie Dunlop

Agreed. No reason to change the intake or carb with stock heads and cam. Your engine can be made to pull strong right to 5,000 rpm. The exhaust should always be the first thing on the list. Going from single w / cat to duals & no cat is worth 30 HP. Second would be to optimize the spark curve - a low compression engine with an automatic trans can tolerate a quick curve and 38 degrees total mechanical timing. Make sure the vacuum advance is functioning. Third change the secondary rods to something in the .052 range and dial in the opening rate on the q-jet, and fourth, swap the stock rocker arms for some 1.6:1 roller tips. These are all proven, simple, and cost effective improvements that will make your car fun to drive and more efficient too.

justanotherdoe

Agree with the others - timing and carb tuning are the cheapest hp increases. Distributor shim, spring and bushing kits cost more to ship than buy. The timing light is the most expensive piece needed for the process.

Barryk's library has lots of articles with part details under timing and advance:

http://lbfun.com/Corvette/Tech/vettetech.html

Skyhorse

More power from a good running L-48 on a budget?

My suggestions:

1) remove the EGR valve and place a shop fabricated blocking plate made from 16 ga. steel and re-install the EGR over it.
2) Rebuild the Q-J carb
3) set the timing at 5(ish) before
4) 1.6 :1 rocker arms


A little more money:
Dual exhaust.

Enjoy!


I thought about what Ted said above back in 2009 ( wow this is an old thread) I had an old spare adjustable vacum advance in the shop. I installed it and man what a difference. I'm still playing with it, but that was some good advice