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L18 8.1L swap resource thread
- Thread starter Larry
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I can't remember, I looked at a bunch until I found one to suit my needs, The one you have is for rear air.
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The plugs it calls for
..... no, I don't buy into that theory of reducing the gap. High RPMs aren't really what big blocks are about anywayAC Delco Double Platinum 41-983..... or 41-805. Don't gap these! These are already pregapped at .060
Or if on a budget a regular ole R44LTSM6 conventional plug will do. Gap these to .060
I have never heard of smaller gaps but did read that bigger gaps with hotter coils get better burn, never cared to test that.
I run stock everything. I just try to find bigger stock engines
Question for all
I will be installing my workhorse 8.1 in my k30 soon and I am trying to see what the masses are thinking about the timeless question
Return or returnless on the fuel rail?
To catch all you up on the project
I purchased a 8.1 workhorse and it was running on cng.
I will be converting it over to gas and so here is what I was thinking
1st option:
Run a returnless system and adapt either a new tank with sending unit pump package so the regulator is in the tank with the pump on a dual tank setup
2nd option:
Do stock tanks with ep381 pumps and then either a vette return style filter
Running dual factory selectors wired in series
That way the second selector also selects the tank the return fuel goes to.
Thoughts?
I will be installing my workhorse 8.1 in my k30 soon and I am trying to see what the masses are thinking about the timeless question
Return or returnless on the fuel rail?
To catch all you up on the project
I purchased a 8.1 workhorse and it was running on cng.
I will be converting it over to gas and so here is what I was thinking
1st option:
Run a returnless system and adapt either a new tank with sending unit pump package so the regulator is in the tank with the pump on a dual tank setup
2nd option:
Do stock tanks with ep381 pumps and then either a vette return style filter
Running dual factory selectors wired in series
That way the second selector also selects the tank the return fuel goes to.
Thoughts?
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Personally, I cannot think if a single good reason to use Returnless type fuel system other than it is one less fuel line to run up to the engine. The only reason why the industry went way from Return Type fuel systems around 2004 was due to Evaporative Emissions rule changes where the purpose was to reduced EVAP emissions by stopping the flow of warm fuel back to the tank allowing fumes to be stirred up and belched out the fuel cap, etc. The change to returnless was not implemented to improve performance, durability or anything, just make the Feds happy. Two big downsides to Returnless are the lack of an easy method to adjust fuel pressure (fuel regulator right on the fuel rail and easy to adjust fuel pressure with a turn of a screw) and Returnless systems are more susceptible to vapor locking.
Personally, I remove Returnless fuel systems on 8.1Ls since there is a return type rail that drops right in place. Later GM engines like Gen IV “LS” engines do not have a return type rail that will bolt on so you’re stuck with returnless, but if one has an engine family that had return type available at some point….that’s the rail I’d personally use.
If you use the return type fuel system with an adjustable regular on the fuel rail there is no need to add a Corvette style filter. There are tons of write ups on various ways of running dual fuel tanks with LS or 8.1Ls swaps. I found the OEM GM type TBI type dual tank switch valve made by Pollock was too restrictive on the return side which drove head pressure through the roof. In the end I ditched the idea of running a switch valve where my Left tank is the primary tank that feeds the engine and the Right tank (also fitted with an EP381) transfer fuel straight into the left tank.
Are you sure you have an actual “Workhorse” engine running on CNG? CNG wasn't quite as popular as Propane on the 8.1Ls. Never heard of such a machine although there were a few conversions going on back in the day after the chassis was built and gone that we never heard about. I was at Workhorse from the begging to the end.
Below should help clear up confusion as to what a Workhorse actually is… Many people keep referring to Workhorse engines but I suspect they are really GM Medium Duty engines.
Official Company Logo. Workhorse was not part of GM. Workhorse was basically born when GM decided to exit the stripped chassis market and a private individual purchased the GM P-Chassis plant in Detroit then moved production to Union City, IN in 1998 and became an independent manufacturer of stripped chassis until 2005 when Navistar (International Truck and Engine Company) bought us. Even after Workhorse became an independent manufacturer we still maintained closed ties to GM, which was evident by the powertrain, steering columns, wiring, etc. Pretty much just about everyone at Workhorse were Ex-GM people including me and Zoomad75. This logo was also on the steering wheel
This is a Workhorse stripped chassis. This is all that Workhorse made….just a motorized stripped chassis
Then we sold them to companies that turn them into these…..
Workhorse with a Step-van body. This one happens to be Utilimaster body
Workhorse with a Winnebago Adventurer RV body
This is not a Workhorse. This a GM Medium Duty truck. Schwan’s Foods was the primary upfitter that converted the majority of 8.1Ls to propane. They actually engineered and built their own fuel system at this corporate headquarters in Minnesota. Most people that are acquiring propane 8.1Ls are getting them from these exact trucks. Schwan's converted a TON of 8.1's from gasoline to propane between 2001 and 2009. Ironically, the same propane system that was on the Schwan's trucks has been slightly updated and is now on the PSI 8.8L in the International school buses still to this day.
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Once again Larry your wealth of knowledge on these is mind boggling!!
OK so I guess it is a medium duty since I pulled it out of a Schwan truck
So what I was thinking was if I used to selectors I could reverse one back meaning I would use the feed side to return the fuel back to whatever tank I switch to
Because I figured that if it didn’t have a problem supplying the fuel to the engine it wouldn’t have a problem returning it back with that same set up but using the feed side going back to the tank from the secondary switch
If I’m thinking about it correctly Hell who knows I was laying in bed trying to figure out how to overtake the world and that’s why I was wondering
The only reason I’m considering using the returnless is really not because I want to it’s more based off of the fact i have a brand New one in the box and I wouldn’t have to hunt down another return style and spend $300.
Since this engine is starting to get pricey on me
Since mine came out of a schwan truck it’s got the giant bathtub oil pan so I tracked down an oil pan dipstick tube and a dipstick and oil pick up tube recently
So I can convert it over to fit in the K30
OK so I guess it is a medium duty since I pulled it out of a Schwan truck
So what I was thinking was if I used to selectors I could reverse one back meaning I would use the feed side to return the fuel back to whatever tank I switch to
Because I figured that if it didn’t have a problem supplying the fuel to the engine it wouldn’t have a problem returning it back with that same set up but using the feed side going back to the tank from the secondary switch
If I’m thinking about it correctly Hell who knows I was laying in bed trying to figure out how to overtake the world and that’s why I was wondering
The only reason I’m considering using the returnless is really not because I want to it’s more based off of the fact i have a brand New one in the box and I wouldn’t have to hunt down another return style and spend $300.
Since this engine is starting to get pricey on me
Since mine came out of a schwan truck it’s got the giant bathtub oil pan so I tracked down an oil pan dipstick tube and a dipstick and oil pick up tube recently
So I can convert it over to fit in the K30
I'm using the Holley set up that is preset to the Larry recommend 59 PSI it has a replaceable 10 micron filter and for overkill I added a Fuelab 6 micron filter. I also have a 25gal tank in the rear running the ep381 pump and my saddle tanks feed to it with a frame mounted pump.
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The more I think about what you’re saying about running two switch valves the more it makes since. Use one for the feed side switching (big ports) and use the other (big ports) to handle the return side switching and wiring them in parallel where the work together. That would solve the problem of the tiny 5/16 ports on the switch valve return side that are too small and restrictive. The only other thing I would worry about is the clamped connections on a high-pressure system, although I have one spot on my K10 where there is a clamped connection as well. I used hi-tach cement on the barbs then slid the hose over and used to EFI hose clamps. At one point a few years later, I tried to pull that hose off and it wouldn’t budge even with the clamps loose. Hi-tach holds it tight! If you try it let us know how it works!
I hear you on not wanting to spend the money on a fuel rail but check eBay. Ironically, Schwan’s was selling fuel rails with injectors that came off those exact trucks many moons ago. I bought a rail from them for my Suburbans 8.1 swap as recent as 2015. I think it was around $100 for the return type rail with 8 injectors. BTW, the injector part numbers are the same on return type and returnless.
I doubt that pan will fit a K30 unless you make some very BIGGGG crossmember for it.
I always reverted back to the idea of using a returned system in favor of keeping my stock fuel tank switch valve for the saddles. I ended up just running the ep381 in the driver tank and transferring my passenger tank on its own fuel guage and switch. It works but a dead switch in the stock dash and an extra fuel guage don't give that "factory" feel.
Exactly!!
That’s what I was thinking on the port issue and solving an issue with factory parts working together at same time.
I will try it and let y’all know
It’s going to be a little bit before I get to it due to another project bleeding me dry
so if someone else wants to try let us know if you do.
Is there supposed to be a heat shield over the PS knock sensor? On the DS there are two threaded bosses on both sides of the sensor (and I have that shield). On the PS there is only 1 hole.
I had only one heat shield on ds
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Exactly, there is only a shield on the drivers side, which doesn’t really mater as that Knock Sensor location doesn’t work there when installed in a squarebody anyway and a different hole (and sensor part number) have to be used.
So I'm considering tig welding my three inch V bands on the factory manifolds. Seems these are ss I am a bit worried about the heat cycles between the two parts being different.
The El cheapo ss ebay long tube headers are in a bad spot as usual. The front shackles are wearing through the collectors causing the o2s to read higher o2 and dump fuel causing the popping issues under acceleration.
New headers are 600$ in ceramic coat. I feel this may be the way to go, has anyone tried welding these manifolds?
The El cheapo ss ebay long tube headers are in a bad spot as usual. The front shackles are wearing through the collectors causing the o2s to read higher o2 and dump fuel causing the popping issues under acceleration.
New headers are 600$ in ceramic coat. I feel this may be the way to go, has anyone tried welding these manifolds?
Keep putting oil it it
Think there's any merit to this vent tube extension idea?
Were there any actual changes to the oil pan for light trucks between '01-'06? Part numbers 12560248 and 12559764 are discontinued and superseded by 12574833, which is also discontinued (don't know if that one has the oil level sensor hole or not). Is there any oil pan available besides Spectra GMP75A?
The weird thing is wherever I search, the Spectra pan does not fit Suburban, but it does fit Avalanche, Yukon XL, Sierra and Silverado. Possibly the difference is the oil level sensor hole and Suburban is the application that didn't use it.
The weird thing is wherever I search, the Spectra pan does not fit Suburban, but it does fit Avalanche, Yukon XL, Sierra and Silverado. Possibly the difference is the oil level sensor hole and Suburban is the application that didn't use it.
I just bought one off of eBay, and it worked. I didn’t do much research.
