93Euphoria

So once again im making a thread on info on builds. So I havent called Ellwein yet But anybody running a 4 Inch stroke on an LT block? Id like to keep the Cyl walls thick. Why not 402 over a 396? Compression could do some good on a 4 inch stroke. Single plane, Nice high flowing AFR or TF Ai ported heads, and a good lift, duration cam, how bad can it be? Im surprised I haven't seen that many 400ci+ LT's. Im assuming reliability issues but how bad are those issues if you add some block filler? I mean Dart isnt making SHP blocks for LT's. So I can stop hoping for god to send an angel from heaven to make a Big Inch LT1. Though its always a good thing to have something thats rare. I remember reading about some guy having a 414 LT1. Now thats maxing it with a .06 bore. Thats about as much as your going to get out of the LT block. With enough money you think by bribing Dart or Donavon thell make a big inch block? or do they not have the right machinery and computers to make that happen. I know expense it this biggest issue. Dart Needs to Have a meeting about this one. then making the deal

Puck

iTrader: (17)

Dart already had the meeting, sold us the dream, then bailed on us. It is very unlikely to happen anytime soon, but I would buy a big inch LT block for sure as long as its around the same price as the SBC ones. My heads are too small IMO, so I'd have to sell my topend too but it would be worth it. I would go straight for 18* brodix or even SB 2.2 heads on a big bore 434+ LT1. Lots of $$$ for that type of build but it would be nasty.

Joelster is the one with the AFR headed 414 you probably saw, he just went bottom 10s with it NA and the car will do 9s with a few more tweaks and better air(he was over 1000 DA IIRC).

ReggieWarrenJr

iTrader: (11)

I don't see how Dart couldnt have made some money doing the aftermarket blocks. I think Circle track guys would have even bought them because of the reverse cooling. And there are plenty of people on here willing to shell out the cash for one.

Valkyn

iTrader: (8)

There was a guy on camaroz28 that converted an aftermarket SBC block to reverse flow cooling. That would probably be cheaper than trying to get Dart or someone to make a one off block for you.

At that point, I would just run an aftermarket big bore SBC block with whatever badass heads you want and a single plane, then a 24x ignition setup and tell people its an LT1 lol.

93Euphoria

Cant be a true LT1 without the gear driven water pump and atleast the reverse flow cooling Because Chevy Enthusiast will know what it is once you pop the hood. heck id take a Big Inch LTx 454 over an LSX 454. Just my Opinion. With reverse flow cooling it should make as much Horsepower NA as a NA LS454. Correct me if im wrong but who will know really until a Big Inch LT comes out. I will be saying then on the 7th day god created a big busty Angel of LTx's.

BTW id love to hear more about this guy converting a SBC block into reverse flow. Id certainly give him a call. Was it an SHP block by any chance?

bufmatmuslepants

iTrader: (3)

You can also make a 402 with a 3.875" crank and 4.060 bore. The problem with the 4" crank joelster pointed out was the need for a small base circle cam, which isn't a huge deal but it is a couple hundred more than normal.

The side loading would also be higher as it's almost a square motor (4" stroke 4" bore) without a tall deck to allow longer rods. There is an eagle 4" crank 1pc rms on here for sale cheap if your serious about this. I would LOVE to see a brodix 18 or 15 degree headed 396, 402 or 414 13:1 compression single plane pump gas motor, I think it would dominate all other pump gas similar cubic inch motors due to the high compression the reverse flow allows.

Rob94hawk

iTrader: (1)

Yup. I was one of them.

Puck

iTrader: (17)

It was an aluminum Donovan block.

Our bore size is what really kills us, not just the cubes. All the hardcore SBC race heads require a larger bore then we can run since we can barely get 4.060.

noice

Puttin a .060 over piston will likely put the cylinder walls .080 thick between cylinders. With the right parts lots of clearancing will be needed but you should be able to run standard base circle cam. Problem with our engines is we can't compete with the sbc guys that all run 4.125" bore and larger. With large intake runners, better heads, and better intakes.

If you want to be the best get some SB 2.2 heads, make sure they aren't restructure plate heads or buy the unfinished ones and adapt them to a max bore size lt1. Run all the compression you can and that engine will be the one of the most powerful NA LT1 engines ever.

Or get a turbo and go crazy.

z_speedfreak

iTrader: (3)

like mindgames old sbc2.2. LT1
when going .60 over I cant remember the aprox # but allot of the blocks wont pass sonic testing

joelster

I have the 4" stroke crank and it requires a few keys things done to get it to fit. You can't run an h-beam rod. The bottom ends are simply too big, the block would need a ton of machining. My rotating assembly is a 1-piece rms Eagle crank, Scat Pro-Comp I-beam rod, and Mahle flattop pistons. No way in hell a regular cam will fit. A .950" base circle cam clears but it is pretty tight. If the lobe lift on it is kept under .415" then it "should" be fine, but I went with a .900" base to be safe. I have plenty of room with the .900" base. The crank requires a lot of machining to get it to balance. Not a big deal, any competent machine shop can handle it. Combine a light I-beam rod, with a super short piston, and the bob weight is really light. The block requires no more clearancing than any other 383 that I've seen. The rods are the key. If you go with a 4.030" bore and a 4.000" stroke you have yourself a 408. Grab your wallet when it comes time to buy the camshaft as it will have to be custom made. I got mine from LSM and it was $572, Comp was a joke to deal with. As far as "accelerated bore wear from piston speed", lol there are pluses and minuses with every engine design. That is internet speak. A fast piston speed also has a few good benefits too like getting the piston up to tdc and then back down without the piston hanging at the top. This supposedly allows far less time for detonation to occur, but these are theories. There are many people that have no fear taking an LT1 block out to .060", while there are others that want to see a certain wall thickness, and say that .030" is the max. I bought the shortblock assembled, so I didn't really have a choice.

Puck

iTrader: (17)

Was waiting for you to chime in, thanks.

I didn't know you needed a custom cam. The price isn't a big deal since a billet grind is already at or over 300, but .9 core seems skinny. How much spring pressure are you running, and are you worried about the cam distorting at high rpms?

1slow94z28

im happy with the 383 karl ellwein built me. bigger cubes would be nice, but if i were to do it all over again... LS power would be my choice. btw, my motor on his page is ese #33

joelster

I don't recall exactly what the springs are but they are around 225/525lbs. Give or take 4 or 5lbs. My lifters are pretty beefy but the rest of the valvetrain is light. I could have gotten away with a spring around 190/475, but the p-to-v clearance was on the tight side so I wanted to have a spring that was more than capable.

I went on yb and asked about .900" base cams, and nobody had any failures, and there were guys running way more spring pressure for circle track sprint cars.

Puck

iTrader: (17)

Oh, you got a light spring on it . Must be a real nice valvetrain or gentle ramps to keep the valves happy with that little spring! Makes me feel like I have a race car .

Sick combo, the numbers are proof its working and I can't wait to see a 9 from you.

93Euphoria

Nice man. So hows the motor doing now? Im Assuming its running like the day you picked her up. And whats it going to take LSM to build a big inch LT block? I called ellwein and they said they have done several motors in the 400ci+ range so im pretty confident on my build.

97Z28SS

iTrader: (5)

Didn't GM build a limited number of big bore LTx raceblocks, I remember seeing one on ebay, iirc it sold for like $3500. And as for the LSx engines their advantage over the LTx is the far superior flowing heads and availability of a 4.125 bore block. As others have stated I would just buy a standard sbc shp, motown or dart big bore block then top it with whatever head you want and call it a day if you don't want to go LSx.

djjab57

iTrader: (17)

Yes they built 10 for a race team that never took them. so there is 10 and go for @ 10k IF you can find someone to sell it to you. The one from ebay was bought by someone on here just dont remember his Screen name

Dave357LT1

You would have thought one out of ten would have been used!

djjab57

iTrader: (17)

you can look in this thread, there was a couple more
https://ls1tech.com/forums/lt1-lt4-m...hop-block.html

http://s553.photobucket.com/albums/j...%20LT%20block/