Stroked 2.3L Quad 4 - Performance Forum

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Stroked 2.3L Quad 4
Friday, November 26, 2021 5:15 PM
I've got 3 high output Quad 4's in the garage and a W41 on the way. So I've got plenty of parts and want to do something exotic. I have seen a couple of threads that talk about stroking the 2.3L Quad with the 2.4L Twin Cam crank but haven't seen many details. The engine would go into my 1984 Fiero. The engine would be N/A and hoping for about 230 HP. The Quad4forum appears to be defunct so I thought I'd post here.

Based on dimensions it appears that custom rods would be needed to keep the pistons in the block with stock Quad 4 pistons. The Twin Cam rods appear to be too long by about 0.016". Can anyone confirm this? Is there any place to get customs rods that don't cost $250 each?

I have found some hypereutectic 93mm pistons (0.040" overbore for the 2.3L block) with a compression height of 1.1". These would work with stock Twin Am rods. The only catch is that they have a 0.090" dome which makes the compression ratio crazy high. The stock Quad 4 HO pistons have a dish with 7.5 CC of combustion volume. The 086 head has combustion chambers that are 48 CC. I have an inquiry into Silvo-O-Lite to see if there is enough meat on top of the piston to machine off the dome and take an additional cut 0.080" deep by 70 mm diameter cut to get the desired 7.5 CC of combustion volume. This still results in a compression ratio of 11.5:1. Definitely going to need 93 octane and maybe a 55 gallon drum of toluene.

Now the question of the crank. I have read that there are two ways to install the 2.4L Twin Cam crank. The first is to grind down the main journals on the cranks to fit the smaller 2.3L Quad 4 bearings. The second method is to leave the crank alone and align bore the block. The bore needs to be opened about 0.213". Can half come off the block and half off the bearing caps to keep the crank center line the same?

Hope there are some still around who are interested in these old engines!

Re: Stroked 2.3L Quad 4
Saturday, November 27, 2021 10:13 AM
Opps, I forgot to divide the stroke in half when calculating piston height. This means that both the 2.3L and 2.4L blocks are about 8.75" from the crank center line and the deck. Thus, stock pistons and the 2.4L rods will work in the 2.3L block with the 2.4L crank. However 2.3L HO pistons even in std bore do not appear to be available.
Re: Stroked 2.3L Quad 4
Saturday, November 27, 2021 8:29 PM
I think that Cadillac Northstar pistons will work.

However I have not been able to find 2.4L TC connecting rods anywhere. Anybody have some laying around they would like to sell. Also a 2.4L TC crankshaft
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