Quick Buggy question. If you put 5x5 arms on the rear do you need to move the motor/Tranny back more? We have 3x3's on the back of the manx and I was thinking of going bigger but wondered if we had to move the drivetrain at all.
Depends on your back angle of the CV's at full droop. Ideally, you want no back angle when the suspension is at full droop to help gain down travel and keep CV angles respectable. If the trans/engine are in factory spots, you may run into CV bind sooner than on the 3x3 arms because you have more back angle. I would certainly do it if you are the fence about it. you will gain more from it and keep CV's happier. I know there are guys who have put 5x5 on cars with the engine/trans in the factory spot, gained travel and say CV's are happy but ive never seen them give the full story as too how much cv angle they have/had, dont know how to measure the back angle, swapped to micro stubs from type 1 (you gain travel from that alone), and other things. Mine was already moved back parallel to the hubs when i bought the car. it was actually too far back, cups were in line with each other at ride height but the hub was farther forward at full droop. with the 5x5 arms, i now have only 1* of back angle (hub is now behind the trans cup) when at full droop.
i think im a glutton for punishment. Sand car is all ready but still need to work on my daughters quad a bit, change generator engine oil and filter x2, daughters b-day party next weekend and now im working on this. I wrench/rebuild/ or just build duramax engines on the side..... well use to do it alot but slowed up on it to work on my house, toys, kiddo time, etc. Buddy of mine cracked cyl 5 piston in his LMM so i told him id help him out. This is will be bare bones fix IF the cyl is hone-able, other wise its trash and hes getting a JY engine so he can sell the truck off.
Momma has been gone all week so kiddo hits the sack at 8-8:30 and then i bring the monitor in the garage with me and work on shit till 11-11:30ish. back up at 5am and off we go for the day. its been a long week.... i like my god damn beauty sleep, you cant keep this sparkling face with those kinds of sleep hours!!!
last nights work
fucking hate emissions bull shit, pile would be half this size
ive got tons stashed away in my phone of different builds. when you get down to the short block, they look just like a big block other than no distributor hole and no timing change, they are all gear driven. its not till you look at the pistons, heads, and up that you really see the difference.
There is the problem child. Nice little hole just over the wrist pin, weakest point of the lbz/lmm pistons. Normally there is a big crack right across the middle of it but since the owner wasn’t pounding on it, he lucked out. Saved the bore of the cyl. There is aluminum stuck to the bore but it’s not scarred. Easy fix.
Notice the star pattern on the pistons?
That’s like reading a trees age with its rings accept we are seeing how big of a tune is being ran and how often. Spraying outside the bowl of the piston is not ideal for cyl pressures nor for engine health. It means the injector duration is starting and spraying fuel before the tip can aim it into the bowl and continues to spray fuel as the piston moves away and goes outside the bowl. This can super heat the top edges of the piston marking them more brittle over time and crack or in the lbz/lmm case, do that to the piston it’s self just over the wrist pin where it’s thinnest. If you see the rings closer to the bowl edge, that’s due to the owner running smaller tuning for extensive periods of time over the larger tune. Flat out, these pistons suck major ass and Gm can shove them up their ass. The lb7/lly pistons are way stronger and if you take 1/8” off the radius of the bowl, they are known to hold 800rwhp. LML are a toss up but are an improvement over lbz/lmm. L5p is anyone’s guess till they push big power or cut one up.
Now that said, common rail diesels do not have combustion chambers in the heads. It is literally perfectly flat here. The chamber is all consisted in the bowl of the piston. Quench area and piston protrusion out of the block are big things to measure to ensure you run the right head gaskets and Taylor the engine to the performance you are after.
And this is why egr’s and pcv routes back to the intake are a fucking terrible idea on diesels. This shit can get up to be 1/2” thick in areas on 100% stock trucks. If you own a diesel, please relocate or delete one..... unless you live in commifornia, then your fucked
Yes sir! the points almost at the cyl wall are from the large tune and/or aggressive timing (diesel timing is based on when the injector fires, not when spark fires since there is no spark plugs). the smaller lines are from stock/very mild tune. A stock tune will have the rings on edge or close to it. it can vary as again, timing factors in here too. outside the bowl does not let the fuel swirl to help with atomizing and mixing with air. They already run 23-26,000psi of fuel pressure to help atomize diesel fuel but you want the fire to take place in that bowl. This helps with lessening fuel in the quench area as well (quench is the area between the head and piston at TDC that fuel or air is trapped in but the flame front can not burn in). This is why you see guys run bigger injectors (well atleast the guys that are in the "know" do, not just for more power) so that the big shot of fuel is done quickly and within the bowl. You can technically run a very high duration on the injector and get power from it but there is a point of diminished return and decrease in reliability as well as increase in cyl pressure and egt's. On our race cummins, at 1000uS (microseconds) we make 1600hp to the crank and all fuel is in the bowl with only 10* of timing. at 1500uS and 15* of timing, we make 2200hp at the crank but fuel is now starting to go outside the bowl. At this point, we are getting suspension dialed to hold the 1600hp so we have been turning up the power but we plan to go to a bigger injector to get the uS down more. we will drop cyl pressure, drop EGT and increase power. it sounds counter intuitive that less cyl pressure and egt = more power but its due to an over abundence of cyl pressure currently and starting the injection event earlier in the cycle.
Now my buddy is swearing his heart and soul it has a mild tune only which i didnt believe till he told me he has a H&S tuner for it.... that tuner is very crude. they run high timing in them and only marginally more fuel at WOT than stock. His truck also being an 09 means that instead of GM using a 9th injector to shoot fuel into the DEF filter to heat it up and burn off soot, GM has the truck do whats called "post injection" where on the exhaust stroke it shoots a high duration of fuel to be ran out the exhaust and down into the DEF to burn on regens. terrible fucking idea cause it can cause cyl wash downs and again lead to piston issues. this truck had 100k of its life 100% stock like that, then add in the tune and the possibility that a piston oil squirter may have popped out and it was just a matter of time. im pulling the pan off tonight and ill see if all the squirters are there.
btw, im a duramax/chevy guy at heart but to go fast and be semi reliable, cummins takes the cake here.
I’ve not played with them but they are very similar to the Dmax other than they have reverse flow heads (exhaust is the intake, intake is the exhaust). Still only 4 bolts per cyl though compared to Dmax and cummins that are 6. Also uses a CP4 high pressure pump which is weak on volume but can push 34k psi.
Like to hear the stuff about the Dmax trucks too, as that is the next planned vehicle. Planning to stay stock with a cold air intake on an LML, and looking for one in the 40-80K mile range. I was reading that when the CP4 goes out, it wipes out the entire fuel system costing 7K+ in repairs. Is that true? and if so, is it possible to replace it at a certain mile interval for a cheaper price and save the rest of the fuel system?