Hypereutectic Pistons for 3.1 in a 2.8 (Page 1/1) Josh86gt FEB 07, 04:51 PM I found Hypereutectic Pistons for the 3.1 at summit racing and from what I have heard the 3.1 is a stroked 2.8 so would they work? sleek fiero FEB 07, 08:46 PM They will with a 3.1 crankshaft. You will also need a neutral balanced flywheel . Josh86gt FEB 07, 08:47 PM quote Originally posted by sleek fiero: They will with a 3.1 crankshaft. You will also need a neutral balanced flywheel . Why is the 3.1 crankshaft required will it not go on the stock rods? 82-T/A [At Work] FEB 07, 09:31 PM quote Originally posted by Josh86gt: Why is the 3.1 crankshaft required will it not go on the stock rods? It's been a while since I did this (the motor currently in my Fiero is a 3.1 rebuild), but it's the crankshaft that essentially makes the engine a 3.1. You need 3.1 pistons and a 3.1 crank. The rods are exactly the same. Josh86gt FEB 07, 09:32 PM quote Originally posted by 82-T/A [At Work]: It's been a while since I did this (the motor currently in my Fiero is a 3.1 rebuild), but it's the crankshaft that essentially makes the engine a 3.1. You need 3.1 pistons and a 3.1 crank. The rods are exactly the same. The reason I'm getting the 3.1 Pistons is because I can't find them for the 2.8 I am just wondering if they are compatible armos FEB 08, 01:11 AM quote Originally posted by Josh86gt: The reason I'm getting the 3.1 Pistons is because I can't find them for the 2.8 I am just wondering if they are compatible The wrist pin height of the 3.1 pistons is different. If you use 3.1 pistons with a 2.8 crankshaft, the pistons will be way down in the hole. You'll have no compression. Likewise if you use 2.8 pistons on a 3.1 crank, they'd hit the head. The connecting rods are the same, so the pin height of the pistons is what compensates for the different length of the crankshaft. So the pistons have to match the crank. I've never done this but that's always been my understanding about 2.8L vs 3.1L on these engines. Josh86gt FEB 08, 01:13 AM quote Originally posted by armos: The wrist pin height of the 3.1 pistons is different. If you use 3.1 pistons with a 2.8 crankshaft, the pistons will be way down in the hole. You'll have no compression. Likewise if you use 2.8 pistons on a 3.1 crank, they'd hit the head. The connecting rods are the same, so the pin height of the pistons is what compensates for the different length of the crankshaft. So the pistons have to match the crank. I've never done this but that's always been my understanding about 2.8L vs 3.1L on these engines. Okay then I will probably just buy the stroker kit for the extra power fieroguru FEB 08, 09:17 AM quote Originally posted by Josh86gt: Okay then I will probably just buy the stroker kit for the extra power You might just want to get a 3.4 pushrod engine. Drill the starter holes and it is largely plug & play. Going with a neutral balance 3.1 or 3.4 would allow you to use the stock 3.9 flywheel and clutch for the F40 too. 82-T/A [At Work] FEB 08, 09:37 AM quote Originally posted by Josh86gt: Okay then I will probably just buy the stroker kit for the extra power Just an FYI... these guys (ARI Racing Engines) are a known commodity here on Pennock's Fiero Forum. They've been around for decades, and the dad who originally owned the business was really into helping the Fiero community by offering all these kits and components. The father has since passed away, but the son is continuing the business. He has to focus on other areas of course, but still has the expertise and support for our engine: https://engine-parts.com/online-store/ Lots of awesome parts for our V6/60 on there... including stroker kits, and even short blocks already built up.