How can I make my 1977 L48 4 speed faster?

[leeboy66]

Evolution, what's your opinion on a chambered exhaust system? A lot of people on this forum seem to like it.

 

[Evolution1980]

Evolution, what's your opinion on a chambered exhaust system? A lot of people on this forum seem to like it.

Can't say I have any first hand experience with 'em. I don't know if I've ever even heard 'em! But like you, the general concensus appears to be favorable. (BTW, with regards to the gearing question above, the 200R4 will give the same mph/rpm as the 700R4 in every gear except first. I point this out just in case you get wondering about transmissions... There's been plenty of talk about the 700R4 -vs- 200R4 in the forums here.)

 

[leeboy66]

Thanks for the valuable info. What brand of exhaust system/muffler do you suggest? By the way, Is the 700R4 a 5 speed manual transmission?

 

[Evolution1980]

Thanks for the valuable info. What brand of exhaust system/muffler do you suggest?

Exhaust preferences vary based mostly on what the intended application is, what is allowed by your county (in terms of requiring emission checks and all that stuff.), and sound levels. I'm running straight pipes from the headers and ending in 'glass packs', which are now just essentially empty shells/tubes since the fiberglass packing is pretty much gone. It's kinda llike having almost no mufflers at all anymore :L

By the way, Is the 700R4 a 5 speed manual transmission?

Nope. It's a 4 speed auto w/ overdrive. Introduced for the '82 model year and used through the early 90's. Because GM is good about backward compatibility, it's used on a lot of older cars as a bolt in replacement for other/older transmissions. You can get your fill of 700R4/200R4 information here and here.

 

[Art Jett]

Evolution, What stall speed converter do you have? I'm going to have a 700R-4 with a 383 TPI stroker, 3.08 gears

 

[Evolution1980]

Evolution, What stall speed converter do you have? I'm going to have a 700R-4 with a 383 TPI stroker, 3.08 gears

I have a 2200RPM stall. This one specifically...Click Here

 

[Art Jett]

Perfect! That's the one I was leaning toward. It ought to make a nice combo. The block builder estimates the engine at 425+ hp.

 

[Evolution1980]

Perfect! That's the one I was leaning toward. It ought to make a nice combo. The block builder estimates the engine at 425+ hp.

Sounds like he's building the ZZ383 engine. Nice...

 

[Art Jett]

Basically yes but instead of a carb I'm going to use a new TPI system from Affordable Fuel Injection w/ Edelbrock performer rpm heads. Hope it turns out like I think it will. Hope I live long enough to finish it!

 

[glen242]

- open element air cleaner (purchased out of Mid America Corvette catalog) with K&N air filter
- roller tip rockers
- synthetic oil
- stainless steel braided, silcon wrapped plug wires
- Bosch Platinum plugs
- high flow cat
- enlarge pipes from 2 1/4" to 2 1/2"
- DynoMax mufflers
- Edlebrock 795 CFM carb
- aluminum intake manifold

These are almost all easy bolt ons - and I kept all of the original pieces just in case...car really came alive and feels quick and sounds quick. I gained real speed and documented most of it on my G Tech meter.

I've played with suspension as well - composite rear leaf spring takes huge weight out and gets power down better - aluminum manifold is big weight savings - remove air pumps, etc.

Mine has 51,000 original and documented and is a blast!

I would also like to put in an electric fan to reduce engine drag, and install a lightweight flywheel and performance clutch - but won't do that until it pitches...

Have Fun!!!!!!!!!!

What are your before and after G-Tech numbers?

 

[glen242]

If you MUST do something, do the intake and exhaust. (Make sure you don't need to pass emissions!) Not much else will be worth the time and investment.

Dump the single or dual snorkle intake, go with an open-element as already suggested. Get rid of all the emissions BS, such as the air-pump and all that other stuff. Get rid of the cast iron headers and the front & rear Y-pipes.
Put on some Hooker Comp Headers, and run some exhaust straight back into some free flowing mufflers.
Don't replace your stock Q-jet 750, but have it tuned ("rejetted") by someone that KNOWS Q-Jets. Rejetting a Q-jet is cheap, but unless you have a dyno, it's a trial & error process.

Now, the BEST thing you can do... save your pennies for another year (or just don't do anything else to the car). When you have the funds, buy a crate engine ZZ4. Then you'll be happy. The reality of the situation is that with the L48 engine, it just isn't going to be much of anything without an entire rebuild from top to bottom. And by then, you are into crate engine prices. Take it from someone that's been there / done that.

The exhaust and intake mods you do (if you do it) this year will easily transfer to the new crate engine. So that'll be one less thing you'll need. When it comes time, the crate engine will just about be a plug-n-play upgrade. You'll be happy you waited. But in the meantime, the power increase AND more exciting sound of the intake/exhaust will help you get by.

Why dump the dual snorkle if it was set up for cold air induction? Are you saying you will make more power with an open element sucking in hot under hood air?

 

[Evolution1980]

Why dump the dual snorkle if it was set up for cold air induction? Are you saying you will make more power with an open element sucking in hot under hood air?

Good question. I never much thought about it until now. I don't have any before & after numbers to back it up. However, I would say that without all the other stuff under the hood anymore (intake pieces, emissions, etc.), while the car is moving there's enough fresh air being drawn in from the lower front air-dam under the car. Also, my cowl is taller, allowing for more air-circulation.
Look at what the stock setup looks like and then with the original hood closed as well. If you were to put an open-element filter in there, it would be terror trying to draw fresh air to it. Not to mention it's also a smaller air filter (to fit under the hood). You pretty much HAVE to have the air snorkels.

The one thing I have yet to determine after 10 years of asking...why did some models have dual and others have a single??? It's not based on engine nor year it seems. So what was the determing factor??? I dunno!


PS - Open air elements just look cooler anyways...

 

[zachh]

Mine, I have:
-hooker headers/ sidepipes
-mallory 50,000 volt distributer(HEI)
-rebuilt carb
-new valves/ springs
-open air cleaner (muscle car style)
-Super coil plug wires
-owner before me put in new cam shaft
all of that, except the sidepipes cost about 2,500$, the sidepipes cost about 1,500. In my view, money well spent. Gos much faster and produces about 340 hp. Hauls ass! Also, I removed all the emissions eqiupment. Be sure, though if you do all this work, make sure you don't have to passs an emissions test! Good Luck,

zachh

 

[leeboy66]

Thanks, Zachh. What type of carb do you have?

 

[zachh]

original Rochester quadrajet 4 barrel

 

[Dave L.]

78 - 80 L82's had dual aircleaner snorkel as well as all 81's.

 

[Evolution1980]

Mine, I have:
-hooker headers/ sidepipes
-mallory 50,000 volt distributer(HEI)
-rebuilt carb
-new valves/ springs
-open air cleaner (muscle car style)
-Super coil plug wires
-owner before me put in new cam shaft
all of that, except the sidepipes cost about 2,500$, the sidepipes cost about 1,500. ...produces about 340 hp.

I'm not trying to a be a complete dick and rain on your parade, but I highly (x20) doubt cam & headers is going to get your L82 engine up to 340hp. Did you leave something out of your list, such as "heads"? If the sidepipes were $1500 (which would be chromed ones), where did the other $1000 go???

 

[Jack]

Zach may well have 340HP@flywheel

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.

I'm not trying to a be a complete dick and rain on your parade, but I highly (x20) doubt cam & headers is going to get your L82 engine up to 340hp. Did you leave something out of your list, such as "heads"? If the sidepipes were $1500 (which would be chromed ones), where did the other $1000 go???

 

[Glensgages]

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?????

 

[zachh]

340 hp at flywheel, I think, the guy who dynod it said, it was engine only. Not sure what that means. not sure what owners before me did, all I know is tune- up and replacement of the cam, I know the guy, and I'll see if he did anything else

...sorry, only 1,500$ in parts other then sidepipes, wrong number. All in All, what I did cost about 3,000