More power!

[justin 620]

hello there! i have a 79 620 with a stock l20b and i'm looking for inexpensive ways to boost the performance of my lil truck. i'm already getting a brand spankin' new weber for it sometime this week, with plans to run a 3in exhaust system. but i need more ways to get more power, without having to break the bank, cause i'm 16 and my funding is really tight.

 

any help or ideas would be very appreciated, thanks!

[Pumpkn210]

Take your cam out and have it reground, cheep easy power!

[nismo dr]

cheap, fast, reliable - pick 2

 

3 inch is way too big, you will have no backpressure and it will run like a dog. 2 1/4" is about as big as you want to go on a built L4. Normally aspirated.

[Mini-L320]

3 inch is Fine, as long as you have a Cat or a Muffler.

Intake Ported, Get a Cam, MSD Ingition(MSD 6A Box with Blaster 2 Coil)

[datzenmike]

Doubling a pipe's diameter increases it's size by FOUR TIMES!!! This is total waste of money and time. Going from 2" to 3" almost doubles it's cross sectional area. This is a stock L20B not a V8. 15% or 20% is plenty. Adding a 2" low restriction muffler will be the cheapest. You'll gain a couple of hp at RPMs you never drive at. Do the math.

 

Stock EI distributor does a good enough job. The same unit will run a six cylinder 280zx to 7,000RPMs. That's the same as 9,000RPMs on a 4 cylinder. Can't beat it with a stick. Why spend hundreds for the same thing???

 

You got a standard? and want more snap? Get the rear end out of any other year truck except '79. You have a 4.11, get rid of it and run 4.375.

 

Weber 32/36 with auto choke and idle cut is best. Don't buy someone else's trouble, get a new replacement one for your year.

 

Best bang for the buck (as mentioned) is a MILD cam.

[metalmonkey47]

And yet again, Mike delivers to the fullest

[datzenmike]

OK.... i got carried away.

[Pumpkn210]

OK.... i got carried away.

Ev-Er-Ey Time, and were

[datsunfish]

I had 2 1/2" with a cherry bomb on an L18 once. Just as a temporary and it was terrible. Had to shift down on hills even at highway speeds. Replaced it with 2" and a free flow borla and it made a smooth ride with way more power. Go 2" or 2 1/4" with a free flow muffler. Cam grind will run 80-100$ resurfaced rockers about 80$ new lash pads to set it all right 80$ damn near $300 for about 5-10 hp. Ive done all this and its fun but have driven a 620 with stock L20b with exhaust upgrades and weber 3838 dges that was faster.

[datzenmike]

but i need more ways to get more power, without having to break the bank, cause i'm 16 and my funding is really tight.

 

any help or ideas would be very appreciated, thanks!

 

I would spare him spending on stuff with little gain. The MSDs are dress up items... would love to see a dyno of with and without it. Can or red spray paint is cheaper. A mild cam will move more air and should perk it up even with the stock carb. A Weber would complement the cam. A 4.375 would rev the motor faster in all gears and is a simple 'bolt in' job and not rocket science.

[Skib]

with plans to run a 3in exhaust system.

 

 

dont.

 

 

its going to hurt performance.

 

 

 

find a peanut head and get a mild cam.

[Z-train]

3 inch is Fine, as long as you have a Cat or a Muffler.

Intake Ported, Get a Cam, MSD Ingition(MSD 6A Box with Blaster 2 Coil)

 

 

NO,going to a 3 inch system is not fine.It will kill the performance and ruin milage-but it'll sound bitchin'.Do not port the intake as it will ruin port velocity(cylinder filling).Cam-yes.Weber-yes.MSD will provide no benefits over a PROPERLY working ELECTRONIC distibutor.However,it will clean up your idle,promote easier starts and be cheap "over-rev" insurance.

[datzenmike]

He may have meant port matched to intake? P-nut is a good idea too.

 

What you don't spend on 3" pipe and MSD would get you a head and cam easily maybe a rear end too.

[banzai510(hainz)]

I find that a 38/38 is the Ezest power upgrade esp if one had a 32/36 already on there so you already have the carb adapter.

Just bolt it up. But dont expect V 8 power!!!!!!!!!!

 

SUs are a close bolt on but may have water/heater line issues. Thats if the SUsa are any good.

[Z-train]

He may have meant port matched to intake?

 

Port matched is a good idea but porting is not.

[Spades]

Ok, time to discuss exhaust. There is more to exhaust than just the diameter. If large tubing was all that mattered, every V-8 muscle car you see would have dual 12" exhaust...however, this is reality, and it doesn't work that way.

 

When dealing with the physics involved with exhaust gasses leaving your engine, one thing that people forget about is velocity. You are dealing with not only expansion but also the escape velocity. A larger pipe diameter doesn't mean that exhaust will automatically exit any faster than the appropriate size of pipe for your displacement of engine.

 

What exhaust velocity means when putting in a exhaust system is actually simple. Use the same size pipe, never expand the pipe diameter, then run a smaller diameter pipe behind it. Never run a glasspack or other muffler with a louvered core....for example, don't run a exhaust header with a 2.5" out into a 2" louvered glasspack, then to a 2.25" tail pipe. As the gasses expand and then compact back down, the exit speed is slowed.

 

As far as what mufflers are the cheapest and best for HP? Non-louvered glasspacks. There are very few glasspacks on the market that are a true straight through design, and the louvered glasspacks have little bits of metal jutting into their tubes, which slows exhaust velocity far more than just reducing the pipe size. Louvers are excellent sound absorbers, which is why companies use the technology, but the reality is that almost any muffler will outflow a louvered glasspack.

 

Do some research, most car magazines have done a muffler test at some point in their issues, and a straight through glasspack will flow better than anything else(including straight pipe).

[Braden]

3 inch is Fine, as long as you have a Cat or a Muffler.

Intake Ported, Get a Cam, MSD Ingition(MSD 6A Box with Blaster 2 Coil)

msd 6a box will nto boost performance enough for him to tell a difference, after 2500 rpm there is no multiple discharge anyways

[Mini-L320]

msd 6a box will nto boost performance enough for him to tell a difference, after 2500 rpm there is no multiple discharge anyways

 

Its always good to have that quick starting power :P. and your right it makes no difference in performance, Cause i have it in my 210.

if you want power go with TURBOCHARGING IT!!!!!! :hyper:

[justin 620]

dont.

 

 

its going to hurt performance.

 

 

 

find a peanut head and get a mild cam.

 

ok, so 3in is a bad idea. ha.

 

i'll just go with the new carb, mill the cams, and just rebuild it. i still want to increase the exhaust diameter, but i won't go with 3, probably just 2-21/4, with a decent muffler. and i might have guy with a peanut head, but hes not fersure if it is or not yet. i'm not going to drop a 4.375 in it tho, i want to actually be able to go over 65, and i'm probably going to get small wheels and tires for it anyway, and that would make it worse.

if you have any other ideas or methods...

[]2eDeYe]

You can't get over 65?

 

I could do 90 with 4:375's all day long at about 4500 rpm in 4th gear (give or take about 500 or so, haven't drivin that truck in a while) :lol:

 

Redline is 7000 rpm on a stock L20.

 

Have you done a regular tune up on the truck?

[datzenmike]

Agreed!

[justin 620]

2eDeYe' date='08 September 2010 - 05:22 PM' timestamp='1283995378' post='349378']

You can't get over 65?

 

I could do 90 with 4:375's all day long at about 4500 rpm in 4th gear (give or take about 500 or so, haven't drivin that truck in a while) :lol:

 

Redline is 7000 rpm on a stock L20.

 

Have you done a regular tune up on the truck?

 

i actually have no clue how fast i'm going, my speedo is broken : / the only good reading i got was when my truck was running like shit, and that was only 65-70. and mine has the 5 speed (yes, it's the 79.5 : D) when get the new carb, i'll be able to get more speed. and i don't have a tach either, i just go by the sound of the engine... ha, i'm planning on getting a tach soon tho.

 

and no, i have yet to take it in and get it done by somebody who actually knows their s@#$. i do some stuff here an there, but i haven't gone too deep into it.

 

i might just stay with the rear end i have now until i lower it, and see if i wanna go lower, cause if i do i need smaller wheels/tires. and if i don't i might get the 4.375 off this guy who has a truck, but i have no idea what year or model it is : /

[ggzilla]

First, tune the engine, fix the speedo and fit a tachometer (about $100 for a used tach).

[justin 620]

First, tune the engine, fix the speedo and fit a tachometer (about $100 for a used tach).

 

i'm waiting for the new carb to tune it, and i don't really know how to tune an engine, i've never done it before : / and i'm in the process of fixing the speedo actually, and a tach is close to the top of the list of things to get. after the carb and if need be, a new speedo as well.

[Skib]

get a factory service manual or a Haines/Chilton manual

 

 

 

 

that needs to be be step one if you dont know what your doing