Newbe saying hello and requesting help (Kinda Long)
09-04-2001, 08:58 AM
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Newbe saying hello and requesting help (Kinda Long)
Hi,
Just wanted to say hello and thanks for all the help you've provided through the existing posts. I don't have a thirdgen car, yet, but I am very interested in burning my own proms for my 1991 C2500 heavy duty pickup. I plan to eventually get more appropriate street machine, but can't afford that right now. I'm using this truck as a kind of test vehicle so I'll be ready.
I've got a few questions and sure would appreciate any help. I new to this so please be patient.
This truck has a 5.7L HD motor, which means it has less compression (8.3:1), less HP and less torque than the normal 5.7L of that year. It does have a 4 bolt main, 4L80E tranny and 14 bolt rear. I've added a modified air intake, a little hotter cam, and headers.
My next engine modification will be a better set of heads. The original heads are what GM called "High-swirl" which means they have a ramp in the intake side that causes the air/fuel mixture to swirl. Supposedly, this helps torque. What it really means is that the engine just doesn't seam to get enough air to make any power.
With all that said, what should I look at in changing the program in my existing prom with my current mods? In the old days, adding a cam and headers usually meant that you advance the timing throughout the rpm range, does that still hold true with computer controlled engines?
When I put on a new set of heads I'd like to increase compression ratio to around 9:1. What will I need to look at in programming another chip for this mod?
Thanks and cheers,
Davidjon
Just wanted to say hello and thanks for all the help you've provided through the existing posts. I don't have a thirdgen car, yet, but I am very interested in burning my own proms for my 1991 C2500 heavy duty pickup. I plan to eventually get more appropriate street machine, but can't afford that right now. I'm using this truck as a kind of test vehicle so I'll be ready.
I've got a few questions and sure would appreciate any help. I new to this so please be patient.
This truck has a 5.7L HD motor, which means it has less compression (8.3:1), less HP and less torque than the normal 5.7L of that year. It does have a 4 bolt main, 4L80E tranny and 14 bolt rear. I've added a modified air intake, a little hotter cam, and headers.
My next engine modification will be a better set of heads. The original heads are what GM called "High-swirl" which means they have a ramp in the intake side that causes the air/fuel mixture to swirl. Supposedly, this helps torque. What it really means is that the engine just doesn't seam to get enough air to make any power.
With all that said, what should I look at in changing the program in my existing prom with my current mods? In the old days, adding a cam and headers usually meant that you advance the timing throughout the rpm range, does that still hold true with computer controlled engines?
When I put on a new set of heads I'd like to increase compression ratio to around 9:1. What will I need to look at in programming another chip for this mod?
Thanks and cheers,
Davidjon
09-04-2001, 02:26 PM
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Car: An Ol Buick
Engine: Vsick
Transmission: Janis Tranny Yank Converter
<font face="Verdana, Arial" size="2">Originally posted by davidjon_99:
Hi,
Just wanted to say hello and thanks for all the help you've provided through the existing posts. I don't have a thirdgen car, yet, but I am very interested in burning my own proms for my 1991 C2500 heavy duty pickup. I plan to eventually get more appropriate street machine, but can't afford that right now. I'm using this truck as a kind of test vehicle so I'll be ready.
I've got a few questions and sure would appreciate any help. I new to this so please be patient.
This truck has a 5.7L HD motor, which means it has less compression (8.3:1), less HP and less torque than the normal 5.7L of that year. It does have a 4 bolt main, 4L80E tranny and 14 bolt rear. I've added a modified air intake, a little hotter cam, and headers.
My next engine modification will be a better set of heads. The original heads are what GM called "High-swirl" which means they have a ramp in the intake side that causes the air/fuel mixture to swirl. Supposedly, this helps torque. What it really means is that the engine just doesn't seam to get enough air to make any power.
With all that said, what should I look at in changing the program in my existing prom with my current mods? In the old days, adding a cam and headers usually meant that you advance the timing throughout the rpm range, does that still hold true with computer controlled engines?
When I put on a new set of heads I'd like to increase compression ratio to around 9:1. What will I need to look at in programming another chip for this mod?
Thanks and cheers,
Davidjon</font>
Hi,
Just wanted to say hello and thanks for all the help you've provided through the existing posts. I don't have a thirdgen car, yet, but I am very interested in burning my own proms for my 1991 C2500 heavy duty pickup. I plan to eventually get more appropriate street machine, but can't afford that right now. I'm using this truck as a kind of test vehicle so I'll be ready.
I've got a few questions and sure would appreciate any help. I new to this so please be patient.
This truck has a 5.7L HD motor, which means it has less compression (8.3:1), less HP and less torque than the normal 5.7L of that year. It does have a 4 bolt main, 4L80E tranny and 14 bolt rear. I've added a modified air intake, a little hotter cam, and headers.
My next engine modification will be a better set of heads. The original heads are what GM called "High-swirl" which means they have a ramp in the intake side that causes the air/fuel mixture to swirl. Supposedly, this helps torque. What it really means is that the engine just doesn't seam to get enough air to make any power.
With all that said, what should I look at in changing the program in my existing prom with my current mods? In the old days, adding a cam and headers usually meant that you advance the timing throughout the rpm range, does that still hold true with computer controlled engines?
When I put on a new set of heads I'd like to increase compression ratio to around 9:1. What will I need to look at in programming another chip for this mod?
Thanks and cheers,
Davidjon</font>
91 with a 4L80E?.
Your running a PCM?.
BTW, thought it was 4L8E.
If a 77R4 with an ecm it should be a 1227747. there is a ton of info on that ecm at www.tunercat.com from links there, and at DIY_EF.Org, under gmecm
09-04-2001, 03:46 PM
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<font face="Verdana, Arial" size="2">Originally posted by Grumpy:
91 with a 4L80E?.
Your running a PCM?.
BTW, thought it was 4L8E.
If a 77R4 with an ecm it should be a 1227747. there is a ton of info on that ecm at www.tunercat.com from links there, and at DIY_EF.Org, under gmecm</font>
91 with a 4L80E?.
Your running a PCM?.
BTW, thought it was 4L8E.
If a 77R4 with an ecm it should be a 1227747. there is a ton of info on that ecm at www.tunercat.com from links there, and at DIY_EF.Org, under gmecm</font>
Yep, the 4L80E transmission (MT1 RPO code) was introduced in '91, there is some confussion about this, but I got it verified by GM.
The codes I have on my ECM are:
16147060
AWBK 4329
I think the big difference between mine and the 1227747 is the transmission. I really don't know though. Still not real sure what it all means, but I'm learning. I am about to buy an ALDL cable from Andrew and get a copy of DataMaster so I can see what the engine and tranny are doing. Then I plan on trying my hand at burning proms.
I tried going to TunerCat homepage, but they went over their traffic limit and are shut down for now.
Cheers
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