wfot

Does anyone know where to buy the big bore 4.125 liners? Pete & todd will only provide the finiche block and I can't see spending 5k for 25 CID.
Thanks

ccmano

Dominic Sorresso

Polo-1

You could get the LT5RW from LA sleeve these will go safe @ 4.030 You will have to hone the block they don't just drop in.
After that, it's not an easy job. I think Pete and Todd are using Darton. A sh#$ ton of block work is needed for these 4.100 -4.250? liners to work. It will be a closed or almost closed deck.

Rkreigh

I don't mean to burst your bubble but the 5k for the closed deck block might just be the start of that party and is pretty good deal

is the juice worth the squeeze? Well seeing is I'm flow limited at 390 cubes I don't think so. It's some pretty expensive ponies and the block needs some work

I don't know the "raw cost" of the liners but I think it's around 2200 or so, and putting them in isn't drop in at all.

Sure if you have the $ to get those expensive few ponies go for it I'd spend that money on good head porting and cams IMHO.

I'd love to get a drop in closed deck liner that doesn't need the block work for 1300 and I'd be good and buy some today!!!

tpepmeie

You mean a drop in closed deck 4.000 bore? That is something I might consider. But...… why? I'm not seeing the need for the closed deck unless you're doing something very radical like extreme boost.
On the big bore liners, the closed deck was intended to compensate for the reduced support on the bottom of the liner, because the block has to be bored, reducing rigidity.

wfot

OK, I wanted to follow up on my question and thank everyone for their input. As stated, I am on a 402 build and I wanted an extra 25 CID with the 4.125 bore and found the pricing to be very high. So I asked and asked and asked and got some good information, I think.

First, I want to acknowledge Todd, Pete and Marc because they are by far the best around and are that because they have done so much development on the LT5. I have found each of them to be very helpful and answer all my questions. Thank you.

A few things that I have discovered. 1) The 4 inch liners are spun cast and are fairly straight forward to produce. The 4.125 are a different animal. Because they have the integrated lip on top, they have to be machined out of a solid 6 inch diameter piece of iron. This requires a lot more man hours and physical manipulation to produce and the end result is they are about 3 times the cost to produce. Hence the much higher cost to go past the 4 inch bore. 2) The 4 inch liners weight about 3.5 pounds each, the 4.125 liners weight about 7 pounds each. So there is a 28 pound increase in engine weight to go to the 4.125 liners. Removing weight is equal to adding horsepower, so something to consider. 3) as Todd just pointed out, there is considerable block machining to be done to add the 4.125 liners, they do not just press/drop in, they are thicker at the bottom and the block needs to be milled to receive them. 4) You should consider the bore and stroke that you want to have. A 390 inch motor can have a 3.7 stroke and a 4.125 bore or a 4 inch bore and a 4 inch stroke. They will feel different when you drive them. Longer strokes typically have more torque/rev lower and shorter strokes typically have more HP higher in the rev band and rev higher. Figure out what you want and work with the builder that likes to build the motor that you want. Each of them have their favorites. A particular builder will have a better way of doing specific combo and be able to tune it better and recommend matching parts to get the most out of it.

For me, if I were starting from scratch and wanted more cubes, a 4.125 bore might be the way to go. For about 5k in block work you get a big bore, stock crank, 390 inch motor and a reasonable turn around time say 2 months. If you wanted a stoker crank, the crank alone would be about 5k and take about 6 months to get if you are lucky. For Me I like the longer strokes and already have a 4 inch crank, so I am going to work with that and focus on cams and intake mods to get the most out of it. Anyway my 2 cents …….and about 3 weeks of research, lol

John

Rkreigh

closed deck liners, 4.00 bore, twin turbo

the lt5 is not ideal platform for this but I'm a turbo junkie and want to do one using vband stock manifolds, modern turbos, and e85

I have a haltech platinum that could do the deed for the engine management with dual wb and 8 channel egt to help with tuning

my engine is apart right now and I have a good set of new liners, but if "I had to do it again" I would stay stock bore to keep the block strength and liner thickness

I don't need to worry as much about unshrouding the valves and this displacement would make all the HP and trq needed


my little c5 tt does 800 at the tire "without a sweat" and with the iron block 4.8 020 overbore "junkyard warrior" build I'll be up over 1k hp for not a lot of $$$

Not easy or cheap on the lt5 but here would be my approach

stock crank, good oliver rods, 10 1 so you could run "flex fuel" with the haltech or MS3 pro (ecm of choice)
closed deck liners, MLS hg from Marc, head studs if I can afford them but stock bolts probably fine there

remove flappers (done on my engine) don't need them.

tranny becomes and issue as if you aren't doing 8-- hp "why bother" with turbos

1k plus gets pretty easy with the e85 secret sauce as long as the lt5 can hold the cyl pressure


LPE and others did much more exotic setups, that were "worth it"

but based on what we have now it can be done at a bit lower price point by cutting back on some of the high end parts


I'd like to build out a "proof of concept" stock block car like Wayne did at SGC and then run it on E85 and you might be surprised what a "stock block" LT5 could do on boost with the right tune and fuel.

by eliminating the "engine build" part of the project and retaining the stock 93 exh manifolds as the starting point for the fabrication, and minimizing the porting cams and other costs, I think the stock block LT5 could comfortablly hold 800 hp of cyl pressure as long as detonation is held at zero with e85 The lt5 heads are very stiff and don't flex like the LS heads but the lt5 still has the 4 bolt lilmitation

I have a solution for that issue as well but that will take a bit more R&D for folks that want to crest 20 psi or so of boost

the lsx has a 6 bolt head clamp solution that is all so possible with a deck plate and stretch liners similar to what fastlane did on the 421 builds

this will require a different intake or spacers which can be a hassle, but the increased head clamping is important to keep the engine together at higher cyl pressure.

tpepmeie

Hello, John. Very good research into the salient differences between the open deck and closed deck configuration. Please know that none of us who build these engines are getting rich at your expense. Machining the block for the oversize sleeves is non-trivial. The sleeves themselves, as you noted, are very difficult to produce because of the 5.200" top flange--that means you have to start with a 6" casting. Not many companies can do that. As I'm sure Dave from LA Sleeve told you, anything in small batches is going to be very expensive. As it stands today, if a client wanted a closed deck solution, I would refer them to Pete to get the Darton/RED configuration. There simply isn't a business model there to duplicate what they've done, and they've amortized the R&D cost over the initial batch.

I have convinced myself that the 4.000 bore is simply fine for most extreme LT5's. Dollar for dollar, the power differentiation comes in the induction system and cams. An economical 4.125 bore would be nice, but to really take advantage of that you need to increase the inlet valve size and run more lift on the camshafts. With stock size valves, a big bore engine will make excellent torque but won't match the specific output of an engine with at least 32% intake valve-to-bore area.

Good luck with your build, and do let us know what it ultimately produces.
Todd

Rkreigh

yes, I know the liners would be expensive, but eliminating the machining and making a "drop in" liner with 4 bore and the superior closed deck definitely appeals to a boost junkie like me.

I looked at doing a closed deck block with a deck plate with "ears" on it so I could make a 6 bolt lt5 implementation.

Fastlane did deck plates and stretched liners a while back. it requires custom chains and it's a pita but it produced 900 hp na so I know I can do a bit better with boost

he used solid cams and revved up to 9k as I remember hearing that lenco bang off shifts those were the good days.