getting started on my 03 8.1L 3500
11-30-2015, 05:41 PM
#1
getting started on my 03 8.1L 3500
So I've been reading up on all that has been done to several trucks posted on the forum. Thanks to all of those who have been sharing.
This truck will be used mostly for towing (big gooseneck enclosed race car trailer), I'm not too concerned about low speed torque (under 2000 RPM), I don't think we can hurt low speed torque enough to worry about unless we get truly stupid, and I'm not going there. The truck has a 4.10:1 rear gear.
I have access to a chassis dyno, and the guy who owns it is an experienced tuner. I think we're going to just do a baseline pull with only a new 180 thermostat, a K&N filter, a fresh tune up (AC Delco double platinum professional plugs), and a set of Taylor 10.5 plug wires. Then we'll see what we have to start with. Then he's going to tune it, and probably delete the EGR, as well as the part of the map for keeping the converters hot.
The first serious modifications will be some air box and air duct work. Followed by a set of 1-7/8" headers with 3-1/2" collectors, and a true dual 3" mandrel bent exhaust system, probably with 3" DynoMax mufflers. I've been looking and haven't found a set of tail pipes I know will fit (I want side exit style, behind each pair of rear tires) so it may require some custom work. The converters are getting tossed, I do not have to have them. Then we'll go back to the dyno for another tune.
I'm picking up an extra intake manifold, the plan is to cut the bottom off, and do a full porting job, removing the baffle, and correcting air flow. I also plan to put the bigger throttle body on it, 90MM or 92MM should be plenty. I'll solve the PCV problem, too. I'll have some help from the guy who does the cylinder heads, intakes, and carburetors for my race engines, and for my customers engines, he has a flow bench, but I'm not real sure if we'll get that serious. He's got 50 years of experience, and everything he does for me is killer, so his guidance and my 35 years of experience should get me there.
I had not originally intended to change the camshaft, I was just going to put adjustable rocker arms on it, probably 1.8:1. But since I have seen how bad the intake is, and I plan to fix that, I will probably change the camshaft, valve springs, pushrods, and rocker arms. I'm thinking some where around 220-224 @ 0.050" on the intake and 226-230 @ 0.050" on the exhaust, either a 114 or 116 LSA, and 0.510"-0.520" lift at the valve, I'll have Comp or Lunati grind me a custom cam, and provide the valve springs etc.
It has well under 100K easy miles on it, great oil pressure, and decent power, the oil consumption is not bad, and I think most of it is PCV related.
I'm not planning to pull the heads, or go past the camshaft into the short block. I'm keeping the truck, if it does get tired, it will likely get bored and stroked then.
I'm hoping to see what would be over 400 HP at the flywheel, and over 500 ft/lbs. I don't really think 60HP and 60 ft/lbs is too much to expect from all of that, and I don't think any of that will do anything but help for towing.
This truck will be used mostly for towing (big gooseneck enclosed race car trailer), I'm not too concerned about low speed torque (under 2000 RPM), I don't think we can hurt low speed torque enough to worry about unless we get truly stupid, and I'm not going there. The truck has a 4.10:1 rear gear.
I have access to a chassis dyno, and the guy who owns it is an experienced tuner. I think we're going to just do a baseline pull with only a new 180 thermostat, a K&N filter, a fresh tune up (AC Delco double platinum professional plugs), and a set of Taylor 10.5 plug wires. Then we'll see what we have to start with. Then he's going to tune it, and probably delete the EGR, as well as the part of the map for keeping the converters hot.
The first serious modifications will be some air box and air duct work. Followed by a set of 1-7/8" headers with 3-1/2" collectors, and a true dual 3" mandrel bent exhaust system, probably with 3" DynoMax mufflers. I've been looking and haven't found a set of tail pipes I know will fit (I want side exit style, behind each pair of rear tires) so it may require some custom work. The converters are getting tossed, I do not have to have them. Then we'll go back to the dyno for another tune.
I'm picking up an extra intake manifold, the plan is to cut the bottom off, and do a full porting job, removing the baffle, and correcting air flow. I also plan to put the bigger throttle body on it, 90MM or 92MM should be plenty. I'll solve the PCV problem, too. I'll have some help from the guy who does the cylinder heads, intakes, and carburetors for my race engines, and for my customers engines, he has a flow bench, but I'm not real sure if we'll get that serious. He's got 50 years of experience, and everything he does for me is killer, so his guidance and my 35 years of experience should get me there.
I had not originally intended to change the camshaft, I was just going to put adjustable rocker arms on it, probably 1.8:1. But since I have seen how bad the intake is, and I plan to fix that, I will probably change the camshaft, valve springs, pushrods, and rocker arms. I'm thinking some where around 220-224 @ 0.050" on the intake and 226-230 @ 0.050" on the exhaust, either a 114 or 116 LSA, and 0.510"-0.520" lift at the valve, I'll have Comp or Lunati grind me a custom cam, and provide the valve springs etc.
It has well under 100K easy miles on it, great oil pressure, and decent power, the oil consumption is not bad, and I think most of it is PCV related.
I'm not planning to pull the heads, or go past the camshaft into the short block. I'm keeping the truck, if it does get tired, it will likely get bored and stroked then.
I'm hoping to see what would be over 400 HP at the flywheel, and over 500 ft/lbs. I don't really think 60HP and 60 ft/lbs is too much to expect from all of that, and I don't think any of that will do anything but help for towing.
11-30-2015, 10:18 PM
#2
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cool, nice to see another 3500 on here, is yours 4wd? post some pics up in the "post pics of your truck" thread in the show n shine section. I'd like to see more 8.1 builds, all those cubes there has got to be much more potential in it.
12-09-2015, 12:15 PM
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This truck will be used mostly for towing (big gooseneck enclosed race car trailer), I'm not too concerned about low speed torque (under 2000 RPM), I don't think we can hurt low speed torque enough to worry about unless we get truly stupid, and I'm not going there.
The first serious modifications will be some air box and air duct work. Followed by a set of 1-7/8" headers with 3-1/2" collectors, and a true dual 3" mandrel bent exhaust system, probably with 3" DynoMax mufflers.
I'm picking up an extra intake manifold, the plan is to cut the bottom off, and do a full porting job, removing the baffle, and correcting air flow. I also plan to put the bigger throttle body on it, 90MM or 92MM should be plenty. I'll solve the PCV problem, too. I'll have some help from the guy who does the cylinder heads, intakes, and carburetors for my race engines, and for my customers engines, he has a flow bench, but I'm not real sure if we'll get that serious. He's got 50 years of experience, and everything he does for me is killer, so his guidance and my 35 years of experience should get me there.
I had not originally intended to change the camshaft, I was just going to put adjustable rocker arms on it, probably 1.8:1. But since I have seen how bad the intake is, and I plan to fix that, I will probably change the camshaft, valve springs, pushrods, and rocker arms. I'm thinking some where around 220-224 @ 0.050" on the intake and 226-230 @ 0.050" on the exhaust, either a 114 or 116 LSA, and 0.510"-0.520" lift at the valve, I'll have Comp or Lunati grind me a custom cam, and provide the valve springs etc.
I'm keeping the truck, if it does get tired, it will likely get bored and stroked then.
I'm hoping to see what would be over 400 HP at the flywheel, and over 500 ft/lbs. I don't really think 60HP and 60 ft/lbs is too much to expect from all of that, and I don't think any of that will do anything but help for towing.
The first serious modifications will be some air box and air duct work. Followed by a set of 1-7/8" headers with 3-1/2" collectors, and a true dual 3" mandrel bent exhaust system, probably with 3" DynoMax mufflers.
I'm picking up an extra intake manifold, the plan is to cut the bottom off, and do a full porting job, removing the baffle, and correcting air flow. I also plan to put the bigger throttle body on it, 90MM or 92MM should be plenty. I'll solve the PCV problem, too. I'll have some help from the guy who does the cylinder heads, intakes, and carburetors for my race engines, and for my customers engines, he has a flow bench, but I'm not real sure if we'll get that serious. He's got 50 years of experience, and everything he does for me is killer, so his guidance and my 35 years of experience should get me there.
I had not originally intended to change the camshaft, I was just going to put adjustable rocker arms on it, probably 1.8:1. But since I have seen how bad the intake is, and I plan to fix that, I will probably change the camshaft, valve springs, pushrods, and rocker arms. I'm thinking some where around 220-224 @ 0.050" on the intake and 226-230 @ 0.050" on the exhaust, either a 114 or 116 LSA, and 0.510"-0.520" lift at the valve, I'll have Comp or Lunati grind me a custom cam, and provide the valve springs etc.
I'm keeping the truck, if it does get tired, it will likely get bored and stroked then.
I'm hoping to see what would be over 400 HP at the flywheel, and over 500 ft/lbs. I don't really think 60HP and 60 ft/lbs is too much to expect from all of that, and I don't think any of that will do anything but help for towing.
The intake manifold modification will increase both horsepower and torque but you're still going to see pretty dramatic falloff after 4400rpm as the heads can't support the air flow. The cylinder heads on the 8.1L are the biggest limiting factor when it comes to making power with these motors. More info here: Performance Cylinder Heads - Raylar Engineering
Don't waste your time porting the stock heads. Its 12-14 hours of grinding cast iron for about 15hp. Below is a comparison with the same motor with ported stock heads and a set of our aluminum cylinder heads. Dart also sells new iron castings, but they come bare, so you'll be buying valves / springs / etc.
Good plan to step up to a larger cam, something in the range you're talking about is very similar to our BP202 camshaft which is going to provide you with plenty of power in the bottom end and mid range. With that cam on stock heads, I'd expect to see around 390hp / 485ft-lbs. Here's a dyno of the 202 with aluminum heads:
Lots more to read on the stroker kits (and general 8.1L modification) in Car Craft's 8.1L 540 stroker build up here:
http://www.raylarengineering.com/pdf...-of-torque.pdf
12-13-2015, 11:41 AM
#6
The stock heads with the bowls blended, the short turn radius worked, the correct valves, and a 5 angle Super Stock valve job will be completely adequate for what I'm doing so long as this thing keeps the short block stock, or a mildly modified short block (it might get a set of forged pistons and nice Total Seal rings later). I'm pretty sure that I can easily reach the same power level as the normally aspirated marine HO version, and possibly exceed it, without going further into the engine than the camshaft swap, the valvetrain, and the intake. I'm not even going to pull the heads unless and until I need to go into the short block.
All of that should be fine for this truck. It is a tow vehicle, not a race vehicle. It will haul the race car and trailer.
If I were going to go past that, I'd just build a Dart head and block (I'm a Dart dealer) based 4.5"x4.5" engine, and for a 572, I'd just carry the Dart heads to the guy who does my Super Stock cylinder heads, and turn him loose. Considering what we can do with our other stuff, we should do okay. I might do that sort of work for a customer if they want it. But I really don't need that much power, or to spend that much money, on the tow vehicle.
All of that should be fine for this truck. It is a tow vehicle, not a race vehicle. It will haul the race car and trailer.
If I were going to go past that, I'd just build a Dart head and block (I'm a Dart dealer) based 4.5"x4.5" engine, and for a 572, I'd just carry the Dart heads to the guy who does my Super Stock cylinder heads, and turn him loose. Considering what we can do with our other stuff, we should do okay. I might do that sort of work for a customer if they want it. But I really don't need that much power, or to spend that much money, on the tow vehicle.
12-15-2015, 05:05 PM
#7
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The stock heads with the bowls blended, the short turn radius worked, the correct valves, and a 5 angle Super Stock valve job will be completely adequate for what I'm doing so long as this thing keeps the short block stock, or a mildly modified short block (it might get a set of forged pistons and nice Total Seal rings later). I'm pretty sure that I can easily reach the same power level as the normally aspirated marine HO version, and possibly exceed it, without going further into the engine than the camshaft swap, the valvetrain, and the intake. I'm not even going to pull the heads unless and until I need to go into the short block.
Sorry about the rough cylinder pics, with the popularity of aluminum units in the aftermarket we never thought this many people would be interested in porting the stock iron cylinder heads. I think the guys at Rehr Morrison said it best:
"The stock heads are JUNK with a capitol "J"! Don't even think about trying to step the stock heads up with port work. The castings are thin, the short side radius is way to high and the combustion chamber is a total joke. The stock version of these heads are the worst I have ever seen come out GM... Raylar cylinder heads take less timing, gain over 65 horsepower and improve gas mileage tremendously!! With the new intake manifold that Raylar designed the engine gets even more efficient. The stock cylinder heads were so bad that making them better was a snap. Better in every single regard, I might add."
As a Dart dealer, you may be interested in the cast iron aftermarket heads they sell. They're great parts, they just weigh a ton.
Most of your gains will be from the intake manifold modification and the 496HO cam swap. I'd expect if you tossed a set of 2 inch headers on your engine with the planned mods you'd come in right around 430-440hp. Primary size is the only real limiting factor when it comes to comparing marine and street engine output. We'd love to see dyno sheets as you build it up. Always good to see another 8.1L build being documented!
Last edited by Raylar Engineering; 12-15-2015 at 05:14 PM.
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12-16-2015, 01:55 PM
#8
I just responded to your post in another thread about electric fans. I see here that you tow close to limits and are looking for more power.
My advice is DO NOT pursue electric fans for this rig. They absolutely will not work for your application and would be a regrettable nightmare.
My advice is DO NOT pursue electric fans for this rig. They absolutely will not work for your application and would be a regrettable nightmare.
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