minor mods

[94HeavyChevy]

lookin to do some minor mods over the summer to my 94 caprice 350...was thinking about thermostat swap...does it make a legitamit difference? and should i go with the 160 or 180 degree one? also i was thinking about taking the cat converters out to get a better tone from the exhaust...does the 350 need the cats to run properly, will it mess up the backpressure?? anyone else got a few decent little mods??? let me know

[400sbc_guy]

oooo do i......if u pull it put a big ass cam. but either way snatch that intake off and put a power plus typoon intake w/ a decent sized carb stay under 800 if you want gas mileage at all. replace stock 1.5 rocker wit 1.6 roller tip rocker.hi voltage coil and hei distributer w/ vacuum advance and curve kit......but if u dont want a carb- get a stage 2 chip ,1.6 roller rocker,bigger injectors 4 efi/bigger tbi 4 tbi,and maybe a small shot of nos or small blower

[silicon212]

1994 350 = LT1. Sequential port injection, carburetors need not apply.

400sbc_guy - Do not just go and tell him to throw a 'big ass cam' in it. The camshaft is but a part of a larger system in which all parts work in harmony for maximum performance and driveability, including heads, valves, intake, exhaust, etc. Do some research on how you're going to drive a car and build your engine accordingly. Sometimes a SMALLER cam gets you better performance in a street car. The biggest mistake most rookie car guys (I am not saying you are one, but there are bound to be some reading this) can make is to mismatch performance parts on an engine. In a worst-case scenario, you can have an engine that has a cool (read: rough) idle to it due to cam, but completely falls flat on its face because either the intake, the exhaust, or what have you, could not keep up. In another worst-case scenario, you could have piston-to-valve interference or spring bind - either will have disastrous results for the engine - if you go and throw a 'big ass cam' in an engine without ensuring the rest of the engine is up to it.

I'm not taking this out on you specifically, but I do have a fundamental problem with those who give out bad advice (ignorance is no excuse).

[Blue Bowtie]

FWIW, the factory thermostat on a '94 L1 is 180ºF. If you change to a 160ºF thermostat, you will have to reprogram to assure full normal operation.

There are several significant PCM functions reliant upon the coolant reaching a minimum temperature of very near 160ºF or above:

Coolant Temperature Sensor Related Parameters
BLM enabled between 50ºC (122ºF) and 140ºC (284ºF)
Cold spark advance disabled above 56ºC (133ºF)
Highway Mode spark advance > 59.8ºC (140ºF)
Knock sensor disabled below 66.5ºC (152ºF)
Power enrichment at base A/F ratios > 56ºC (133ºF)
Target IAC idle RPM >80ºC (176ºF)
IAC multiplier at 1.0 (base) > 32ºC (90ºF)
Knock Control enabled > 67ºC (153ºF)
EGR Duty-cycle enabled at 56ºC (133ºF)
EGR Duty-cycle at MAX >80ºC (176ºF)
Diagnostic communication enabled at 70ºC (157ºF)
DTC 43 enabled > 90ºC (194ºF)
Cooling fan duty cycle at 100% at 80ºC (176ºF)
Acceleration enrichment multiplier at 1.00 below 80º C (176ºF)
Acceleration enrichment multiplier at 0.75 above 80º C (176ºF)
Acceleration enrichment decay factor at 25% below 80º C (176ºF)
Acceleration enrichment decay factor at 40% above 80º C (176ºF)
Acceleration enrichment decay factor at 50% above 104º C (220ºF)
Fuel limiting factor timer at 217 counts below 80º C (176ºF)
Fuel limiting factor timer at 169 counts above 80º C (176ºF)
Code 13 (oxygen sensor fault) enabled above 70ºC (157ºF)
EVAP canister purge enabled above 70.3ºC (158.5ºF)
Hot closed-loop timer enabled above 70.3ºC (158.5ºF)
Rich/Lean O2 offset at 16 counts between 20ºC (68ºF) and 92ºC (197.5ºF)

As you can see, power enrichment is no better at 160º than at 180º.

[400sbc_guy]

just for silicon212 i go into detail bout cam. make sure ur pullin range of cam is what u want . bigger cams will need beter valve springs. and some require high compression. or a stall for automatic. head change are not required but for massive hp gain get a good set of alum heads but remeber that alum exspands fastier than cast therefore causing head walking...... and to fix ecm problems with temp stage 2 chip will change these setting for ur low temp therm. if u go with a cam an keep the computer controlled efi then u must have chip. stage 2 chips are custom made to specs of motor cam injectors therm ect.

['97ventureowner]

Originally Posted by Blue Bowtie

FWIW, the factory thermostat on a '94 L1 is 180ºF. If you change to a 160ºF thermostat, you will have to reprogram to assure full normal operation.

There are several significant PCM functions reliant upon the coolant reaching a minimum temperature of very near 160ºF or above:

So much stuff relies on temperature on computer controlled vehicles today, that the practice of putting in a lower temp. thermostat does more harm than good. That was done "way back" in the '60 and '70s but as the '80s vehicles started to become more complex, certain things that we got away with back then no longer applied. I've seen many cars in the shop where the customer had driveability issues and many times it was found that the vehicle had the wrong temp.rated thermostat.

[silicon212]

Originally Posted by 400sbc_guy

just for silicon212 i go into detail bout cam. make sure ur pullin range of cam is what u want . bigger cams will need beter valve springs. and some require high compression. or a stall for automatic. head change are not required but for massive hp gain get a good set of alum heads but remeber that alum exspands fastier than cast therefore causing head walking...... and to fix ecm problems with temp stage 2 chip will change these setting for ur low temp therm. if u go with a cam an keep the computer controlled efi then u must have chip. stage 2 chips are custom made to specs of motor cam injectors therm ect.

I know what you are saying, but remember that every cam has an operating range of RPM - larger cams tend to send this up on the scale which is fine if you have 4.11 or shorter gears, but no torque on a street car at road speeds equals no performance, I don't care who you are. And to have a cam that comes alive at 3500RPM while the valves only breathe to 3500RPM is a performance crisis waiting to happen, no matter how you slice it. Yes, I am exaggerating, but this is the way things go.

Just to let you know, I've been building performance small blocks since 1986. :P

[94HeavyChevy]

ok so the thermastat is a no go...what about the cat converters? will the engine run okay without them and will it make a difference in sound...i got a 350 engine and i have duel flows out the back...also by minor mods i was thinking of things such as an intake, msg ignition box, and headers...i cant find headers anywhere...anyone know a place? im not pulling the engine anytime soon..just lookin for those little things that make a difference

[400sbc_guy]

u can put your low temp therm. in but u must have a superchip. but this is eazy to install and 25 or more hp. this would be the first mod id do. and dont let the talk of cam keep u from ever getting one cause u can go as big as u want if the rpm range of the cam is say 4000-8000 just instal using a degree kit and dail in the came this will bring down the pullin range but u still have the duration of cam. the duration is what produces extra hp. but any way www.dougherbert.com they have everything for chevy ford dodge and a lot of import junk. ive bought a lot through them. get the superchip for ecm and do away with cat. and install headers and that where id start.

[silicon212]

<shrug> Some people just don't understand. Much like neutered dogs, they just don't get it!

[400sbc_guy]

oh i get it ok .......just come 2 nc rr 27870 and u get some of this s10 or my camaros since u know everything there is to know.......and bring me some of ur money with u.

[silicon212]

sigh

There's nothing wrong with a big cam if a) it's going to work with your driving profile and b) you don't negate it somewhere else.

As I stated before, the cam is but a part of the chain, albeit an important part. Some consider the cam to be the 'brain' of the engine, since its profile determines more than anything else that engines' power profile. In order to maximize power potential, you need to make sure that the induction and exhaust system are capable of handling and delivering the extra power.

You have to plan the powerband you're going to be running in before you go around and buy go-fast parts for the engine - things such as transmission ratio, final axle ratio, tire diameter and vehicle weight, and intended driving mode (full-out race, grocery-getter i.e. daily driver, etc) all weigh into this.

If you have a car with large tires and a highway/economy gear ratio (2.56, 2.73 etc), an engine built to have a power band off 1000 to 4500 RPM makes the most sense, conversely a car with small tires and a short performance ratio (4.11, 4.52 etc), it makes sense (from a performance standpoint) to have an engine with a power band off 2500 to 6500 and higher. This is simplistic - there are more factors that weigh in but suffice it to say these are some of the decisions that must be made when selecting a cam or anything else for a particular engine.

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I used to run a COMP 260H grind cam in my car, and it was a great cam but when I switched to a Crane Powermax 2030, I picked up a little bit more as it was more designed for the car it's in.

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Basically, you're going for the angle of high-RPM use with your selection of cam, intake and carb (I don't know what your exhaust is) and this may be just fine for YOUR car. To me, it sounds like you race your car at the local strip (hopefully). It may or may not be what someone else has or wants their car set up for. ... My issue with you is that you are recommending a certain setup without asking information on how 94HC wants to run his car. Due to this, I consider it bad information.

I can take you up on your offer, but instead of an all out drag race, let's fill up our tanks and see who hits 400 miles without stopping for fuel.

[GreyGoose006]

400 miles... really?
i dont get nearly that good mileage with a 3.8 v-6

[evildragon]

im gonna be putting an LT4 knock sensor in my Caprice Classic LS (94), with it's L99 engine..

Supposedly it gives a big performance boost, from NOT counting false knocks all the time...

[silicon212]

Originally Posted by GreyGoose006

400 miles... really?
i dont get nearly that good mileage with a 3.8 v-6

Theoretically, with its 25 gallon tank, 20MPG will get you 500 miles. My car gets a little less than that, but will do at least 400 miles easy. I can drive from Phoenix to L.A. and then back to San Bernardino before my car starts sucking fumes!

If it was level ground, I could probably give the 500 mile mark a run, but there are more than a couple of 6% grade stretches along that drive.