extremecorvette

Any downside to f/i on a darton resleeved Block? I know there is a cost diffrence but what is the best? I can get a darton 4.125 block for around $2k and the Iron block is around $600 I think? What is the bore on the block, what does it take to make one a 402,408, and can you make a 427?

Do I have to change or mod the car to make the iron block run in my car?

Pro Stock John

iTrader: (34)

A resleeved block might be riskier yes.

sb427f-car

There's a thread about iron blocks in the LS1/LS6 section about bore/stroke and displacement. Check there. As far as strength and $, you really can't beat the iron block.

SStolen

iTrader: (22)

Yes you can do a 427 with a resleeved block, you would have to change from the stock crank though. 4" crank + 4.125 bore = 427ci.

extremecorvette

I know that but what do I get with a LS2 4.00" bore with 4.125"

sb427f-car

Displacement formulas are in the interanal engine section. So look there in the future. But to answer you question, it works out to be 415. It's my personal opinion that if you can avoid going out of square (stroke > than bore) I would. What are your plans anyways? If you're on boost the extra 13 or so cubes wouldn't be of much concern (as 402 or a 4x4 bore stroke) should be pleanty to spool an 88mm turbo. Also, fitting in rods to maintain a a good rod ratio at that length stroke would require some clearing where the 4" stroke is more workable. I'd definately be more leary about spinning an out of square motor, JMHO.

extremecorvette

I'm planning on a stage 2 turbo kit with two 57 turbos or 6X haven't picked yet.

Thinking of a 4.03 bore in LS2, witha 4.125" stroke for a 422 or a 4.03 bore with 4" stroke for a 408? It comes down to the crank which ever one I get get the best deal on at this point. I was told both work great with and don't need any machining but the 4.250 crank does.

What do you think about the LS2 with 16lbs boost?

Nate_Taufer

iTrader: (1)

4.0 x 4.125 is 427ci no matter what type of block it is in.

Nate

sb427f-car

Incorrect. Increasing the bore will exponentially increase the cubic inches where the stroke will only change it linerally (sp?) (multiplier instead of a square).


Cubic inches formula.

(Bore / 2)^2 x (22/7) x Stroke = Cylinder displacement x # of Cylinders = Engine displacement.

22/7 is an approx. for Pi, and thus area of a circle.


4.125 bore x 4.00 stroke would give 427" where the reverse only nets ~415.


Again extreme, what is the application? Street/strip? Pure strip?

10.5 Dave

iTrader: (5)

I wouldn't use a 4.125 crank in a FI application.

Camaro_Zach

iTrader: (19)

i agree.

i hate to point out the obvious (but i will anyways) if you insisted on a 427, the smartest way would be to get a c5r block and use a 4" crank. i said smartest, not cheapest.

Got Me SOM

iTrader: (2)

Go with a 408, its a proven engine.

extremecorvette

I was thinking a 422 or a 408 same bore 4.030"

So why not a 4.125" stroke?

gnx7

iTrader: (28)

Guys are making 1000rwhp with 346ci shortblocks..... Just do an LS2 402 stroker. No resleeving needed (get a better reciprocating assembly with the money saved).

sb427f-car

Number one, 402 or 408"s will spin most any turbo just fine (unless you get in to thumpers where a solid roller cam would probably be nessecary to actually have useable boost).


I'm definately not the expert on this, but with throws that long on a crank, you'll have to do a some amount of clearencing on the bottom of the cylinder liners to get it to work. With a 402 (4.0x4.0) or 408 (4.030x4.0), no or minimal clearencing is required, so you save yourself cost in block prep. Also, to keep the pistons in the block, you'd need to run a shorter rod, which doesn't lend itself well to being able to take shock from already increased cylinder pressures from a blower or n2o application. A stroke that big doesn't lend well to a good rod to stroke ratio, which can be important for piston speed and detionation (of course the motral enemy of forced induction).

HotRod just did an article in the lastest issue (which I got yesterday and haven't read yet) but they did two identical cubic inch SBC, one with more bore, one with more stroke. Power ratings? Virtually the same. I glanced over the dyno sheets quickly and found it rather interesting. Both motors appeared to be within 5~6 hp of each other. Longer stroke had TQ peak quicker, but it appeared as though the bore motor had more avg. tq. The bore motor had HP peak a bit quicker and again appeared to have more avg. HP. I'll dig into the article a little more this evening and post up later.

One of the things to keep in mind is that depending on turbo size (if that's the route you're going) you really don't need to worry about displacement too much as you'll build pleanty of TQ with it and the abilty to have it rev a bit more freely (with a square or under square motor) should give you more curve and more useable RPM (which if it is a race car is a good thing).

The are only two reason imo to build a really long stroke. Extended, constant RPM load (read boats, trucks and heavy machinery) where you can tune the HP with the air in and out via cam, heads, et al. and use the mechanical advantage of the long stroke to get the peak tq. into the RPM range needed. The second reason is in a pure race sense when you can simply not build more cubic inches into a motor via increased bore (read mountain motors in IHRA Pro Stock where there is an 800 cubic inch limit, correct me if I am wrong, or in the new NHRA Pro Mod rules where there isn't a cubic inch limit).

sb427f-car

And this is the other reason. Is there anyone out there in FI land that is running a true LS1/6 block stroked to 382? I don't think anyone is though I could be mistaken.

extremecorvette

I think your right, 4" x 4" 402 should be fine for my needs. I had just found a guy that had a 4.125" Callies crank for sale for $1.1K but sold it from under me for a extra 200. I was going on cost. I'm keeping my eyes open for a 4", and if I'm right you use a 6.125" billet rods? If you know any one trying to get ride of a LS2 cheap let me know

sb427f-car

That sucks, but I'd consider my self lucky on that one.


Ok, so I read that article, and it was very interesting. In fact, even some of the assumptions and "myths" of years of bench racing were implied in my above post. All I can say is, get the June issue of HotRod and read the article yourself, as it will fully explain a lot of what I was trying to explain (and it even discants some of the things I mentioned.) The short version of the article is that, do your best to find heads, cam, and then build displacement around it, or in this case the displacement and the turbo around it. However, due to modern cylinder head design and intake valve size, Big bore x Short stroke does tend to win out.

2001WS6Vert

If I were doing it over again I would do a 402 LS2. No sleeve issues or special cooling requirements + you still have pretty decent displacement. Even though the smaller cubes can make the big power the big cubes still feel a lot better in the 1000 to 3000 rpm range which is where most street driving is.