OK guys I have a 03 1500 RC with 5.7 that has 334000 miles on it. Only wrench ever put on it was waterpump change at 200k miles. It now smokes on start up and just doesn't have power it use to have plus it pings like crazy if I don't run 93 octane now. I bought a 6.1 SRT8 engine 06 I think and I want to build the bottom end of the 6.1 install the 260 comp and mildly port my stock 5.7 heads and reuse my 5.7 manifold. I know the 6.1 pistons are flat and 5.7 are crowned so im guessing compression will drop to around 9:1. I have the 6.1 heads but would rather have the smaller runner 5.7 with a good port job to keep runners small and torque up throughout range. Im not building a race engine just a torque engine. I plan to use my stock ECM as well. Anybody see any issues with my thinking here? 6.1 block is already at machine shop. Also would a set of headers be worth the effort and are they prone to leaking. Im too old now for the loud exhaust stuff. Thanks
03 1500 rc 6.1 i think!!!
- Thread starter dynobo
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usaf2006
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Killer! Love to see that mileage haha! Pics of the motor when and if you can. Been thinking about doing something like this in the distant future myself.
Welcome!
Welcome!
If you got the 6.1L exhaust manifolds they are really a pair of shorty headers and with the right gaskets and an EGR delete they will bolt up to the 5.7L heads. Pretty popular swap with the LX car crowd.
I'm not sure you can use the stock program as the sensor suite on the 6.1L may be a bit different but you might be able to get a custom one done to use with a DiabloSport Predator or InTune programmer.
One other thing to give a good close look at port matching the heads to the 6.1 block.
Lastly be dang sure about the compression ratio. The 5.7L heads on a 6.1L block means you better select the right pistons and head gasket.
Good luck. Sounds like an awesome build!
I'm not sure you can use the stock program as the sensor suite on the 6.1L may be a bit different but you might be able to get a custom one done to use with a DiabloSport Predator or InTune programmer.
One other thing to give a good close look at port matching the heads to the 6.1 block.
Lastly be dang sure about the compression ratio. The 5.7L heads on a 6.1L block means you better select the right pistons and head gasket.
Good luck. Sounds like an awesome build!
dynobo
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I wasn't able to get the exhaust manifolds and I know the manifolds I have now will bolt to the heads fine but didn't know if power gained from headers would be worth extra time and money spent. I plan to use the 6.1 head gasket as im sure the 5.7 would probably be too small ( kinda like using a 318 gasket on a 340 if you're old enough to remember the old school engines) I don't understand what you mean by port matching head to block. Are you meaning the open chamber of combustion chamber being smaller than the 4.06 bore of the 6.1?? Also the 6.1 had a smaller combustion chamber than the 5.7 up to 2009 so im just assuming ( possibly wrong) that the 10cc bigger chamber of the 5.7 heads will put compression ratio back down on the big bore 6.1 block. I have all the tools to measure it ( have been building race engines since the mid 80's ) but my block is at machine shop and not having knowledge of piston deck height and gasket thickness and actual combustion chamber cc I am just guessing at approx. compression ratio.
Unfortunately they won't fit 3rd gens. SRT Grand Cherokee manifolds are different and they have been successfully installed in 4th gens but I haven't heard of anyone doing it in a 3rd gen.
Since it's just a 6.1 short block with the original 5.7 heads, intake and front cover/accessory drive he'll be able to use the stock harness and sensors. Custom tuning will be very limited with the 03 PCM/TCM setup but can be done, especially since it's only a slight displacement increase with a fairly mild cam. A 260 in an otherwise stock 5.7 will run off Superchips canned tuning. To truly take advantage of it custom tuning would be better.
Port matching the head to the block?
Yeah because I don't think the bore size of the 6.1L and the head of the 5.7L matchup that well. But then again it may be so close as to not make a difference.
Once you get the engine back you can get the measurements on deck height and what gasket you need.
Once you get the engine back you can get the measurements on deck height and what gasket you need.
dynobo
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I do not know the deck height of the stock 6.1 engines but I seriously doubt it will have a positive deck height ( such as the early model 340 LA engines). If the combustion area of the 5.7 head is smaller than the 4.06 bore diameter AND there aren't any interference issues with piston to head clearance then I probably wont worry with it and just use the 6.1 head gasket and call it a day. Does anyone know where any published BLUEPRINT DATA is for the 6.1 engines? I mean specs such as piston pin height, piston deck height, combustion chamber volume etc. Not looking for generic specs such as compression ration, bore size etc. Thanks
Sounds like a lot of headache to up the block size to just go with the smallest cam available for these motors. With a stock 5.7 block you can go all factory everything from gaskets, bolts, heads, ecu, intake exhaust(or upgrade to pacesetter long tubes) and have just as much of a beast with a lot less headache. And do it all on a canned superchips hand held tuner with no custom tuning needed. If you can get your hands on a stock 5.7 block, slap a custom cam in it with some headers, do some 4.10 or 4.56 gears, a 3000 stall and full exhaust and you will be sitting pretty. Just my opinion. Good luck brother
dynobo
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Hemi 8073
You are probably correct in what you say but here is my deal. I picked up the 6.1 for about the same as a stock rebuildable 5.7. I have the 6.1 heads, cam etc but I'm not looking for horsepower as much as im looking for the maximum amount of torque that I can get from the least expense. REMEMBER THIS TRUCK HAS OVER 335000 MILES ON IT NOW WITH THE STOCK 345HP HEMI. I am gaining a steel crank, piston oilers, 25 cu/in. I have been building performance race engines (dirt track) for 30 years and actually have my own engine dyno and I build several engines each year in the 900hp range normally aspirated so the actual designing and building are the easy part. The dilemma I have is I am a carburetor guy ( old school) and these computer controlled processor tend to be much smarter than us old school engine builders. My goal is to use more cubic inches with nominal compression (9:1), the small runner heads ( ported to flow 300+ cfm with 2" valve) and also to keep low end port velocity maximized and decent fuel economy. I have looked at several cams and for what im doing I think the 260 comp is best suited for me. I want to keep stock manifold( injectors) torque converter etc etc. I should have about 12-1300 dollars in this build when Im done and the cam is 1/3 of that. Who knows it all may not work but im gonna give it a try and see how it falls. I really do appreciate all you guys input good or bad.
You are probably correct in what you say but here is my deal. I picked up the 6.1 for about the same as a stock rebuildable 5.7. I have the 6.1 heads, cam etc but I'm not looking for horsepower as much as im looking for the maximum amount of torque that I can get from the least expense. REMEMBER THIS TRUCK HAS OVER 335000 MILES ON IT NOW WITH THE STOCK 345HP HEMI. I am gaining a steel crank, piston oilers, 25 cu/in. I have been building performance race engines (dirt track) for 30 years and actually have my own engine dyno and I build several engines each year in the 900hp range normally aspirated so the actual designing and building are the easy part. The dilemma I have is I am a carburetor guy ( old school) and these computer controlled processor tend to be much smarter than us old school engine builders. My goal is to use more cubic inches with nominal compression (9:1), the small runner heads ( ported to flow 300+ cfm with 2" valve) and also to keep low end port velocity maximized and decent fuel economy. I have looked at several cams and for what im doing I think the 260 comp is best suited for me. I want to keep stock manifold( injectors) torque converter etc etc. I should have about 12-1300 dollars in this build when Im done and the cam is 1/3 of that. Who knows it all may not work but im gonna give it a try and see how it falls. I really do appreciate all you guys input good or bad.
Redtruck-VA
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03 PCM unfortunately was the first NGC PCM for the hemi and has limitations. The 03 has a single cat and starting 04 they went to dual cats, this affects the wiring and piping configuration. There is no idle control with SuperChip or Diablo. My recommendation is to swap to a 05 PCM and that will open the door for custom tuning. Any of this will blow your current budget. I'm a stubborn old man and still use a 03 PCM that has been reflashed and CMR tuned (tuning continues as it is a test mule) and with the work that has gone into just the PCM also blows your budget. If you want to do this spending as little as possible I recommend putting a stock 5.7 back in it. You will be way ahead of the game. Even buying the hand held tuner will take a serious bite out of the budget. Cut your losses and drop a used 5.7 back in it or rebuild the old engine. Good luck...
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