Tell me what one you like

[trowa47]

Engine 1

 

l28 block

0.040 over

 

with Flat top pistons

l28 crank and l24 conrods

p90 head

 

2mm head gasket

 

 

engine 2

l28 block

0.040 over

flattop pistons

l24 crank and l20a conrods

p90 and 1mm head gasket

 

tell me what you guys think.

[Challenger]

So engine 2 will be a destroked and bored L28?

[RTz]

With no more data than that, the only response I can give is the advice of a good friend... "Always build as much displacement as you can afford".

[BRAAP]

If it were me building either of those combinations, because you are using flat tops with quench style head, I would not use the 2mm gasket as it adds just that much more clearance between the piston top and head deck, effectively eliminating or at least greatly reducing the affects that good squish delivers. For Turbo engines that are using stock style dish pistons, this is of no consequence as the dish doesn’t’ allow for any squish to begin with, but for flat tops…. If the reason for choosing the thicker gasket is to keep the static compression ratio closer to your desired goal, I’d suggest trying make use of the thinner gasket and through creative valve unshrouding, you can gain some chamber volume that way.

With the OE L-28 flat tops on OE L-28 rods, the pistons pop up OUT of the cylinder bore at TDC approx .021”-.025” and with a 1mm gasket this offers pretty much “perfect” squish. The pistons come so close to the head deck surface that if the pistons has its oversize stamped in the right area, that stamping will ghost imprint on the head deck surface, yet the pistons do NOT actually contact the head. I used to have a picture of this ghosting from a mild Race N/A L-28 that I built an MN-47 head for some years back, but can’t seem to find it.

 

As for the combinations you posted, not knowing more details about either one such as induction, valve train specs, intended usage, intended RPM range, possible class rules dictating displacement limits, etc, you’ll be well served by building as much displacement as your budget can afford. If having 2.8 liters wont cost any more than 2.4 liters, you are far better off with the 2.8 liter engine. With both engines built with the same induction, valve train, and exhaust system, the bigger engine will deliver more torque and more HP within the same RPM range, (as long as the bigger engine can rev to the levels the smaller engine revs to...)

 

So what are building and how are you going to use it? We’re all curious to see new projects…