What can I get away with on a stock PROM

[vetteboy86]

What can or cant I get away with using the stock, or the hypertech prom that is in the car now. I understand that tuning can optimize performance if hours on a dyno are spent, but are we talking about 10 hp or so.

Thanks,
Craig

 

[Edmond]

Short of a cam or more cubes, I think the stock prom will work fine.

 

[MPoore]

I assume you are talking about a 1986 with a MAF system. The short answer is quite a lot. MAF systems actually measure the air entering the engine and calculate injector pulse width. On speed density systems vacuum is measured and air flow is estimated. The problem with speed density is that any modifications that alter the flow characteristics also make the vacuum/air flow calculation inaccurate. There are problems with MAF systems, but in general, they are much more adaptable to modifications. A new chip might eek out a little more power, but this isn't where you will see noticable improvements.

The problem is that L98's have such a restrictive intake system you have to deal with that before you will see a substantial power increase. Add up all the little tricks and you might get an extra 50 hp, but until the intake is addressed things like headers, head porting, and a hotter cam will not make a worthwhile difference because the intake can only flow so much.

Mike

 

[vetteboy86]

How much of a cam are we talking? I was informed that a mild cam would not add any driveablity problems associated with the prom.

Edmond, I dont know if the computer would know if there were more cubes. I guess that would mean that the flow of air into the engine would increase, but wouldn't the computer compensate for the increase?

 

[Edmond]

If you were running more cubes, you'd definitely have some hotter mods on there like a cam, intake, CR, headers, a whole boatload of stuff.

And if you did a cam that the stock prom could run on very well, I think you just wasted your money because it was basically no different than stock. You're not going to feel 10hp.

I don't know about the TPIS Big Mouth. They do say that it's better than a fully ported stock intake. Then again, they're trying to sell those $400 pieces so they'll probably say anything.

 

[tigmaned]

so is a after market prom worth the money if my engines is pretty much stock? will i see a inprovement from one?? only thing i have done it what is called the free mods.

 

[vetteboy86]

What does the computer do on our cars, other then measure the incoming air. I have the mass air flow setup, so it is my understanding that all the computer sees is the amount of incoming air. Am I wrong in thinking this? If you have more cubes, you will have more power and torque regardless of the rest of the engine, and the computer has no way of knowing how many cubes you have.

 

[Edmond]

so is a after market prom worth the money if my engines is pretty much stock? will i see a inprovement from one?? only thing i have done it what is called the free mods.

No, you will not see much of an improvement over the stock prom on a pretty much stock car. You could get the car running cooler. I think the mass burned chips like Hypertech are a waste of money, it's just a generically burned chip.

 

[MPoore]

Save your money for a new intake and throttlebody.

 

[MPoore]

What does the computer do on our cars, other then measure the incoming air. I have the mass air flow setup, so it is my understanding that all the computer sees is the amount of incoming air. Am I wrong in thinking this? If you have more cubes, you will have more power and torque regardless of the rest of the engine, and the computer has no way of knowing how many cubes you have.

It measures air passing the MAF, air temp., vehicle speed, O2 in exhaust, and coolant temp. More cubes does not affect the accuracy of the above readings.

 

[vetteboy86]

This is kind of what I thought.

 

[Mad-Mic]

you don't need a new chip even with a wild setup like a heads cam intake and stroker combo. i know guys running mid 11's with super ram, heads, ZZ9/LPE 219 cams, and running stock chips that are daily drivers.


what will a chip do for you? make that nasty cam more streetable. after recurving the fuel curve and spark advance you can make the car more managable and more of a daily driver. on a stock chip you might be running rich on the low end and lean on the high end with a wild setup like i just described. this is where streetability comes into play. this is where a new chip would come into play also. to get the fuel and spark with in managable settings so it's safe to run on. i doubt you have to worry about fuel mapping as our chips are pretty good as they are from the factory. you might eek out 10-20 more hp from a factory stock chip. oh yeah your fans can come on earlier and TCC can activate at a lower speed also. instead of 43 mph it will come in around 38 mph. thats about it. what a chip burner would do for a stock or close to stock application is lean the low and mid range parameters out alittle and add timing to the overall curve, turn the fans on earlier, and for auto cars make the tc lock up at 38 mph.

 

[Mad-Mic]

Save your money for a new intake and throttlebody.

werd to yo mutha

 

[Edmond]

I think a 48mm TB is plenty enough for a 350 or even a 383, isn't it?

 

[vetteboy86]

That I am not sure off. What is the flow rating of the 48 MM, compared to the 52. Gosh that is another expense I have not taken into account.

 

[Mad-Mic]

That I am not sure off. What is the flow rating of the 48 MM, compared to the 52. Gosh that is another expense I have not taken into account.

roughly 650 for a 48 mm 750 for a 52 mm and 900 for a 58 mm. remember the good ole days of the 650 double pumper? flowed good and put cars in the 10's back in the day . unless your running a big lift cam stick with the 48 mm. throttle response will stay crisper and you'll probably actually make a few more ponies with it. once you go with a big cam then go with the 52 mm.

 

[vetteboy86]

Well this is kind of where I dont know which setup is better. I think going with a slightly milder cam now, with the head work, and the new intake, and maybe just maybe a rotating assembly would make the car more of a street rat.

From my gathering, a wilder cam will benefit you at a higher RPM, not giving as much low end and torque. If the cam is somewhat milder, the cylinders fill better at a lower engine speed there for making the car have good low end grunt. This is kind of what I have read out of the various books. Most say that for a street car, you want more low to mid torque and hp opposed to high end, because you need to build the motor to produce power in the RPM band it will live in most of the time.

I think the 48 will be fine for now, although I am going to put the 1.6 rockers on. If I need to update I will, if I see a reason to. It isn't that hard to switch.

 

[Mad-Mic]

Well this is kind of where I dont know which setup is better. I think going with a slightly milder cam now, with the head work, and the new intake, and maybe just maybe a rotating assembly would make the car more of a street rat.

From my gathering, a wilder cam will benefit you at a higher RPM, not giving as much low end and torque. If the cam is somewhat milder, the cylinders fill better at a lower engine speed there for making the car have good low end grunt. This is kind of what I have read out of the various books. Most say that for a street car, you want more low to mid torque and hp opposed to high end, because you need to build the motor to produce power in the RPM band it will live in most of the time.

I think the 48 will be fine for now, although I am going to put the 1.6 rockers on. If I need to update I will, if I see a reason to. It isn't that hard to switch.

you don't know much about cams do you? you can get a cam to do what you want where you want and for how long you want. if your gonna do a cam now don't go for a weak @ss mild cam that you'll hate later when a stock C6 blows your doors off. get something with atleast .525 lift and around a 226 or greater duration on a 112 lobe seperation. with that being said and with those numbers that cam will start making torque down low around 2500 rpm and make peak HP around 5500 rpm. idea for the big mouth setup you are thinking about IE ZZ409 camwill be perfect for what you are doing.