is a 3.0 a smaller bore 3.1?

[v8dats]

just wandering because if thats the case why dont more people build a 3.0 with z pistons instead of worrying about having to use the ka pistons and boring the hell out of it.

am i missing sometging or am i on the right path.

according to the z engine chart thing i have .........if i was to take an l28 and use the diesel crank with stock l28 rods and .040 overbore with a p90 head and 2mm head gasket i would get a 2960cc engine with 8.63:1 compression. is this right. now i see that in order to make the 3.1 people use the 240 rods. if i add those rods to my equation above it would put my compression up to 11.16:1.

are the 240 rods the only rods that can be used on the diesel crank?

back to my question is a 3.0(2960cc) a smaller bore 3.1?

am i a moron?

[technicalninja]

Length of rod has nothing to due with total swept volumn of engine(what we call displacement). The only factors which affect displacement are the size of the bore,length of the stroke(crank) and the number of cylinders. Using the longest rod possible in an engine has been proven time and time again to assist in making power(long rods good!) but they are not always necessary.

If you are reusing pistons then the rod length is dependent on the pin height in the pistons. An area of concern is what is called the deck height of the piston (how far the piston sticks out or is below the top surface of the block). This can be the most critical parameter of the engine. If the pistons stick to far out of the block they could hit the head (just because you can turn it by hand doesn't mean you have proper clearance- rods streach at high RPM). If the pistons are to shallow the the squelch area is negated (you end up with a low compression motor which detonates like a high compression one.)

Reusing the 280 rod and a stock pin height 280 piston will put the piston 2mm higher (1/2 the stroke of the LD crank) which equals .080 inch. the 2.0 mm HKS head gasket takes up some of this distance but the stock gasket is approx 1.2 mm thick thus 2.0 mm gain - .8 mm head gasket increase in thickness= 1.2 mm effective deck height increase. it would be like assembling a stock L28 and leaving the head gasket out! Pistons will hit the head without modification. You could have the tops of the pistons flycut or milled but now you have as much money in it as the KA pistons and you do not have the longer rods. Could be done but why?

If you use the Z22s standard pistons with the 280 rods and the LD crank you end up with the pistons 1.2 mm lower in the bore than stock and the HKS 1.0 mm gasket and a N series head will put you at approx 8.4:1 This set up lowers the piston more than I like but will work with no modifications to the pistons.

My information shows that to use the KA 24 pistons, the 240z rods, and the LD crank the KA 24 pistons have to be machined anyways. I am building a LD stroker but am using J&E custom pistons which negate the height issue.

Hope this answers some of your questions.

[z-ya]

I think you are better off raising the CR, than boring and stroking and ending up with a relatively low CR (unless it's going to be turbocharged).

 

I'm building a 0.04 over L28 with flat tops and an N47 head. The CR will be 10:1, and the displacement will be just over 2800cc (a real 2.8L!). I'm using stock L28 crank, and rods.

 

It's a budget motor, that I think will be a real screamer.

 

Pete

[v8dats]

yeah all that is cool but the question is if i can use everything thats in my l28 and stick a diesel crank and a 2mm headgasket and make it all work for a turbo engine?

i know that by using the ka pistons i would hafta bore the hell out of the engine just wondering if i can just use l28 pistons withe diesel crank

[z-ya]

If you want to build a budget turbo motor, just get a low mileage short block and put a fresh head on it. Don't waste you time and $ trying to make a stroker. It's not really worth it. The stock turbo pistons are stronger than KA24 pistons. To build a stroker turbo motor you really need forged pistons. There are people getting over 300HP at the wheels running junkyard motors with big turbos and aftermarket engine management. And they are very relaible.

 

Stick with the stock turbo long block, put a fresh head, and metal head gasket on it. You'll be surprised how much power you can get out out of the stock long block reliably.

 

If you want an NA L28, then a stroker will definitely give you more power, but then it all going to cost you some $$

 

Pete

[z-ya]

Sorry missed your question.

 

No, you cant use the LD28 crank and L28 rods and pistons. The pistons will be sticking above the deck 2mm (will hit the head, no pun intended). What pistons will you be using? If they are flat tops the resulting compression ratio would be around 10.2:1. Not good for a turbo.

[Guest norm[T12SDSUD]]

HHmmmm.......... People say you can't do it, and yet I have been running one of the fastest known SU carbed N/A Z motors with just that setup for the last 4 years!!

 

LD28 crank with stock L28 pistons and rods in a stock bore block with over 300,000 miles !!

 

I run two stock headgaskets and shaved the pistons .015" on my garage floor with emery paper and used a vernier caliper to keep the heights exact and then balanced every thing to within 0.1 gram.

 

Best run with regular street tires netted a 12.804 @ 107.26 mph with a race weight of 2410 lbs.

 

 

Later,norm