How can I make my 1977 L48 4 speed faster?

[Evolution1980]

340HP at flywheel L82 quite possible with a good cam, headers & right tuneup. Evidence by: our "lift rule" circle track motors ... 355" 10:1 CR (flattops, NO vortec, only shaved plain jane 76cc production NONported heads), untouched eb 2101 intake, solid cam .480" valve lift EASILY make 370HP at flywheel on engine dyno w/ 110 gas ... with a TWO barrel carb ... ours & many others in the same ball park. Real engine dyno ... not that DD2K stuff.

EASILY???
(background info) The L82 had an additional 30hp over the base L48 in 1979. The bore and stroke were the same, so I don't know if the heads were different or intake manifold was different, or a combination of things.

What's the breakdown on getting 115 HP just from a cam & headers? Let's say that ya gain 20hp by just removing all the smog stuff. You're left to making an additional 95hp. Where does it come from? 50hp from headers, 45hp from cam? 35/60??? I'm not an engine builder, but from my past non-technical experience, those numbers sound generous.

 

[Jack]

Jack:

I believe you may-be correct..... a buddy builds motors for a local track that make in the area of 330-350 HP w/ a 'spec' head, intake, and 2-bbl carb, but I have a question.....

I'm not sure, but I don't think his track allows/permits 110 octane fuel:
why use that fuel with such relatively-low CR?????

Our local tracks have and require cars to use tracks' only fuel (110) ... you must show track fuel receipts to get your win money & points ... sometimes they actually test fuel from carb bowl against their fuel .... no receipt or fail test & you're DQ ... there are hotter fuels/additives. More octane makes some difference... even at 10:1CR ... even a hundredth of a second on a short 3/8 mile circle track is the difference between hero & zero.
JACK:gap

 

[Jack]

EASILY???
(background info) The L82 had an additional 30hp over the base L48 in 1979. The bore and stroke were the same, so I don't know if the heads were different or intake manifold was different, or a combination of things. (/jack: it had a little more CR and a little more cam & a little bit better intake)

What's the breakdown on getting 115 HP just from a cam & headers? Let's say that ya gain 20hp by just removing all the smog stuff. You're left to making an additional 95hp. Where does it come from? 50hp from headers, 45hp from cam? 35/60??? I'm not an engine builder, but from my past non-technical experience, those numbers sound generous.

Simply as a point of reference you MIGHT find credible:
88958602 GMR 350/350 Circle Track Engine
Great racing power at a reasonable cost (350 HP at 5000 RPM _ torque 390 @ 4000 RPM)

This is a factory sealed crate engine package, complete from high rise dual plane intake manifold, stamped steel valve covers with racing style breathers, and 8 quart single kick-out circle track racing oil pan.

The 350 engine is a great value with the nodular cast iron crankshaft, iron vortec heads with 1.94"/1.50" valves, flat tappet hydraulic lifters, and HEI distributor.

The base engine is a 330 HP 350ci, with the following parts: P/N 10105123 4 bolt iron block
P/N 14088527 Nodular cast iron crankshaft
P/N 10108688 PM rod
P/N 12361371 Cast aluminum piston
P/N 24502476 Camshaft with hydraulic flat tappet lifters
P/N 12558060 Iron vortec head
P/N 12366573 High rise dual plane intake manifold
P/N 1104067 HEI distributor
P/N 25534353 8 quart circle track oil pan (with oil filter)
P/N 25534359 Valve cover kit with breather tube
P/N 25534355 Valve cover breather kit
P/N 25534352 Special rocker arm nut "kool nut design"
Technical Notes: These engines are sealed at the intake manifold, cylinder head, front cover, and oil pan with special twist off bolt heads. The 350 HP @ 5000 RPM was derived from a superflow dyno using a 4 barrel 650 cfm Holley carburetor P/N 80541-1, 32" long by 1 5/8" to a 1 3/4" stepped header with a 3" collector, and 92 octane unleaded gasoline. This engine package DOES NOT include a water pump. Oil pan clears most GM rear steer chassis with stock engine location. Oil pan is 8" deep at sump.

The above GMPP "SEALED" 602 is virtually same motor as 12486041 and sells for under $3K ... but more importantly it is a 9.1:1 CR 350" w/ hydraulic flat tappet cam valve lift .435"/.460" duration @0.050" 212/222, iron vortecs, dished pistons & a thick gasket that's makes a published 350HP on 92 gas w/ 4 barrel. Some of the locals are running those ... they dyno about 360HP w/ 2 barrel & 110 gas & tracks give 'em a 100 lb weight break ... even so, our built motors are still beating them. I have no doubt there're guys all over USA/Canada making as good or better numbers. The 9.1:1 crate 602 EASILY does it with a little cam on 92 ... our built-motor cam is only a bit bigger. So ... even a 9:1 CR L82 w/ a good cam, headers & tuneup can do even more. BTW ... a "good" 2 barrel will supply nearly as much as a decent 4 barrel ... particularly below 7K ... they work real well on < 360" motors ... we spend relatively big$ on "good" 2 barrels ... track rules REQUIRE them on built motors. I recently got a superflow 110 flowbench so that I can do carbs & heads myself ... I'm just now beginning to learn that part ... & have a long ways to go.

For further enlightenment I suggest following: go to local circle track pits ... while there: keep your ears-eyes wide open & comments to a minimum (except to volunteer for grunt work) ... while there: you can learn a lot, have a lotta fun & make good friends ... who knows ... you might catch the race bug to own/drive yourself. Don't believe everything you see on TV or net ... not even this. Nothing, NOTHING beats eyes-on, hands-on proof!

So, in the words of our favorite Clemson Extension Service agent Rowland Wilson "Happy Gardening Everyone!"

Wishing a Happy & Safe Easter Holiday to you & yours!
JACK:gap

 

[Glensgages]

Jack:

both of the local, NASCAR-sanctioned paved ovals are running Late Model classes with the 'sealed' crate-engine this season, and it may help control costs for the racers.....


..... while on the subject of using OEM short-blocks for build-ups, does anybody know if the CompCams' 292H hydraulic cam (.501" lift, 292*, 244* @ .050" lift ) can be used with 2.020"/1.600" valves on an as-assembled L-83 (Cross-Fire ) short-block without piston-to-valve problems (i.e. : will the eyelets in the forged pistons, designed for 1.940"/1.500" valves at .400" lift, "clear" bigger valves at that lift/duration ) ?
;help :confused :ugh

 

[Evolution1980]

88958602 GMR 350/350 Circle Track Engine
Great racing power at a reasonable cost (350 HP at 5000 RPM _ torque 390 @ 4000 RPM)

This is a factory sealed crate engine package, complete from high rise dual plane intake manifold, stamped steel valve covers with racing style breathers, and 8 quart single kick-out circle track racing oil pan.

The 350 engine is a great value with the nodular cast iron crankshaft, iron vortec heads with 1.94"/1.50" valves, flat tappet hydraulic lifters, and HEI distributor.

The base engine is a 330 HP 350ci, with the following parts: P/N 10105123 4 bolt iron block
P/N 14088527 Nodular cast iron crankshaft
P/N 10108688 PM rod
P/N 12361371 Cast aluminum piston
P/N 24502476 Camshaft with hydraulic flat tappet lifters
P/N 12558060 Iron vortec head
P/N 12366573 High rise dual plane intake manifold

So ... even a 9:1 CR L82 w/ a good cam, headers & tuneup can do even more.

For further enlightenment I suggest following: go to local circle track pits ... while there: keep your ears-eyes wide open & comments to a minimum (except to volunteer for grunt work) ... while there: you can learn a lot, have a lotta fun & make good friends ... who knows ... you might catch the race bug to own/drive yourself. Don't believe everything you see on TV or net ... not even this. Nothing, NOTHING beats eyes-on, hands-on proof!

Unless the parts are exactly the same as in the L82 AND all brand new, then I'd give the L82 upgrades credibility. Different heads and intake on the L82 versus the engine above can make that difference in calling into question. Plus, we're talking an L82 engine that likely has some miles on it (being from 1979 and all). Although that's not as big a factor if everything was rebuilt internally (new seals, rings, gaskets, etc.) On top of that, the newer heads even if they are the same design, probably flow better due to better manufacturing abilities and the inherant tolerances that come from that. And the stock L82 intake manifold certainly ain't no big flower of air, at least not compared to a dual-plane hi-rise on the engine above!
I'm certainly not denying that a 350ci can make some power...tons of power! The GM 350 is a killer engine. Note, I have the ZZ4, so I'm not ignorant to the 350's abilities/capabilities with even minor tweaks and mods. But hey, he's got the dyno graph to prove his numbers. Plus, he said there was work done to the engine before he got it. So there could be different heads, pistons, bores, crank, whatever! If the dyno log says 340, then 340 it is! That's really all that matters in the grand scheme of things. I just don't believe that if you take an L82 from 1979 with miles on it (or not!) and simply slap in a different cam and some headers that you are going to generate an additional 95-115 hp as stated. By that point, you're talking the hp of my ZZ4, and that's more than just an L82 with cam an headers (not taking tq spec into account)

As for spending some time at the tracks? Hell, I was just about born into SCCA. I probably spent the first 12 years of my life at Mid-Ohio, Nelson Ledges, and a couple weekends at Sebring and Elkhart Lake. Besides both my grandfather and father being drivers, my father was also a driving instructor for SCCA. We had our own car dealership when we were racing, showroom stock and formula. (At one time, my family had THE ONLY new car dealership in ALL of Cleveland proper!) So yeah, I grew up in the pits and at the track. After SCCA, he got into circle track racing. All paved oval, no dirt. But by and during that time, I wasn't much into the circle track scene, so my interest waned. It wasn't until years later that I really got interested in cars again. So I'm kinda learning all over again.
Peace!

 

[zachh]

I believe the 79 L48 has a 9:5:1 compression and the L82 a 10:5:1 compression, i'm not entirely sure. I asked the previous owner of mine. He said he replaced the pistons and rods with special racing ones. Thats what I was told, didn't know they existed, he did that in late 2004, about a year before he sold it to me. It only has 72,000 miles on it. About 5,000 since the new pistons and cam shaft. Not sure whether the new pistons upped the compression or not. I don't know how to check it to see.

zachh

 

[TJay]

The 79 stock compression is..
L48 - 8.2.1 = 195hp
L82 - 8.9.1 = 225hp

 

[glen242]

What are your before and after G-Tech numbers?

This is for blackandred78:

On 4-08-06 I asked you to post your before/after G-Tech numbers that you said you had documented.

It is now 4-15-06 and still no numbers.

 

[Jack]

EVO:
I may be off by a coupla years ... but I recall it was about 10-15 years ago that the SCCA National Championhips (aka runoffs) were moved to Mid-Ohio ... for some thirty years prior to that they'd been held at Road Atlanta ... The runoffs are nirvana ... and if you didn't make it to them then you hadn't reached the pinnacle of amateur sports car racing ... the same holds true for the runoffs at Mid-Ohio ... but the national championship runoffs weren't held there until about the last 10-15 years or so. I understand Mid-Ohio has lost them & the 2006 runoffs will be at Heartland in KS. I've never even been to Mid-Ohio ... but I've enjoyed many a runoff at RA ... I've never driven at RA ... but I've helped prep & crewed a few cars for RA runoffs. I build motors ... and didn't learn what I know about building motors from owning a crate motor. Asphalt here ... but I'm doing a dirt motor too.

Glen:
The late models & supertrucks at the Nascar-sanctioned track at Myrtle Beach (Myrtle Beach Speedway) are also permitted to run the aluminum head GMPP crates ... MBS' charger series can run 602. The Timmonsville track here is not Nascar-sanctioned but has rules that closely mimic MBS' ... same deal with the crates ... similar situation at Hickory NC & others. Crates are being heavily promoted by tracks for several reasons ... not all is what it seems though ... the tracks themselves are often a source for the crates (track makes money selling motor) ... and ... the track has less hassle at tech shed because the crates are sealed (track saves time/money). So far (until crates' weight-breaks etc get too liberal), a built-motor will usually beat 'em ... but this crate motor thing is really putting economic pressure on guys that build 'em ... true, it's really hard to build that kinda performance & make a dollar ... the sealed GMPP crates are selling for relatively small$. One more thing ... there are sealed ... & then there are sealed. We hear of breakaway bolts (sealed bolts) being black-marketed like crack ... I know of two "sealed" GMPP crates that turn Super LOW times; strongly indicates they've been into ... on one of 'em, a little bird saw the TC off of it and the "tech man" from track was standing over it degreeing in the cam in the owner's shop ... crate owner has the tech man in his pocket I suppose ... I really don't like to think that because, so far, I have respected the tech man ... dunno what to think now ... of course that "bird" may be full of it too. The GMPP crates are good motors ... and they're an excellent choice for those who haven't the time/skill/desire to build themselves or have built. But ... in my corner ... crates are not at the end of my rainbow ... not even ZZ4 ... not yet.
JACK:gap

 

[Glensgages]

... the tracks themselves are often a source for the crates (track makes money selling motor) ...

I don't think the 2 local NASCAR tracks are 'involved' in selling the crate-motors themselves, but I believe I've heard the crate-motors can 'only-be-bought-FROM' certain GMPP dealers in the area, so there might be a 'back-door' thing going-on.....


Both tracks now run 2 seperate 'Late-Model' classes, one for 'built' engines, and the other for 'crate-motor' cars, and I hear the crate-motor class will eventually win-out (via higher car-counts ) over the 'built' classes.....


Jack, any idea on my earlier question regarding big-valve heads/.500"-lift cam/OEM L-83 short-block:
I am thinking about this for a high 12-second/low-maintenance bracket-motor in my '82 Corvette, and would consider using the 25,000-mile O.E.M. short-block as-is, with cam/heads/intake/carb for this application, with a shift-point/trap-speed of 5800 RPM.....
:confused

 

[Bills money pit]

my 81 has the stock stainless headers and I am wondering if I went to true duels, will it affect the ecm or emission parts. I would remove the cat converter. What say you on going to true duel exhaust????

Thanks!
Bill

 

[zachh]

If you have to get it inspected, depending what state you live in, if they check the exhaust system and don't see a cat. converter. They may red flag it, then your screwed. I would check the state rules/ regs first.

 

[Jack]

..... while on the subject of using OEM short-blocks for build-ups, does anybody know if the CompCams' 292H hydraulic cam (.501" lift, 292*, 244* @ .050" lift ) can be used with 2.020"/1.600" valves on an as-assembled L-83 (Cross-Fire ) short-block without piston-to-valve problems (i.e. : will the eyelets in the forged pistons, designed for 1.940"/1.500" valves at .400" lift, "clear" bigger valves at that lift/duration ) ?

It would PROBABLY clear it ... but you should check it with modeling clay. I'm not a drag strip guy ... I think your Q about heads & cam & carb to reach a certain time @ certain shift point would best be answered by someone who's built many combo's for DS ... perhaps you should post a separate thread on this & also state whether the car will be street/strip or just strip.

 

[Glensgages]

It would PROBABLY clear it ... but you should check it with modeling clay.....

We're going to check-it with clay either-way:
I thought that maybe the positioning on the face of the pistons (not so-much the 'depth' ) of the eyelets-THEMSELVES, being cut for the smaller-diameter valves, may-not allow the larger diameter valves to clear, not so-much 'up-and-down', but 'side-to-side' dimensions.....

 

[Evolution1980]

my 81 has the stock stainless headers and I am wondering if I went to true duels, will it affect the ecm or emission parts. I would remove the cat converter. What say you on going to true duel exhaust????

If you have to deal with emmissions, I don't think you'd pass any of 'em without a cat in place.
I don't know the effect it would have, if any, on the components prior to the cats.. I don't know enough about the system.

 

[SPANISHVETTS]

my 81 has the stock stainless headers and I am wondering if I went to true duels, will it affect the ecm or emission parts. I would remove the cat converter. What say you on going to true duel exhaust????

Thanks!
Bill

Stick on a set of Radom 3¨Hi-Flow cats. You will never feel the difference and leave clean air behind.

 

[blackandred78]

Mom always told me that you got more flies with honey...

No problem supplying numbers, but I do have another life and do not spend every waking hour here - would love to mind you but can't.

My pre-mods times, on a cool day (55 degreeF) on a county road - not a track - ranged from 6.89 to 7.11. I did one 7.60 pass but I had loads of wheel hop/spin.

My recent passes ranged from a 5.72 to a 6.42 in warmer conditions on a better road - it was 72 degreesF). I think my clutch is not holding either - it is original - the car is a 51K car and I have been running it a lot harder with the mods and because the open element filter makes it sound like a V12 howl over 4,500 revs...I think 5.5 is well within reach.

My GTech is fairly old - first generation model and I need to recalibrate for weight reduction from the suspension.

 

[zachh]

I believe the cat. converter has a catalyst inside it and it conmdenses methane to a liquid? Not 100% sure.

 

[Evolution1980]

I believe the cat. converter has a catalyst inside it and it conmdenses methane to a liquid? Not 100% sure.

Look here... One of my favorite sites!

 

[leeboy66]

Great site, Evo. I'm getting rid of my cat. converter as soon as I install my true dual exhaust. I haven't decided whether to go with a chambered system or one with mufflers. Right now I am just enjoying driving my car in the great weather we had here in NY the last week or so. Yesterday I noticed a strong fuel smell when I got on the gas pedal. Could my carb need some tuning or a rebuild? It is a stock Q-jet. What do you guys think?