I've got a BT block EFI engine and an A20A3 EFI, I know they're basically the same thing, but are there any key differences between the two that make either more valuable than the other? Besides mileage and age I suppose
I've got a BT block EFI engine and an A20A3 EFI, I know they're basically the same thing, but are there any key differences between the two that make either more valuable than the other? Besides mileage and age I suppose
Originally Posted by Fixedit
The '88-'89 EFI engines had slightly higher compression and a little better performance than '86-'87 EFI engines.
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Okay, that explains the ~20HP difference Wikipedia claims. As in, I'm assuming my 86 "BT" EFI is just an A20A3 with a different name. I have an 89 A20A3 that I'm trying to figure out whether I should sell or swap in, but I'm thinking a 22HP gain isn't worth the time of the engine swap, plus my 86 has almost 100K less miles. Thank you!
It's closer to 10 horsepower, and it's more than just the long block. The intake and exhaust manifolds are vastly different, with the early models coming with a single runner intake manifold and a 4-1 exhaust, while the later models came with dual length runner intakes and a decent 4-2-1 manifold design that closely mimics a header's shape. The computer control systems are different as well.
Good to know, thank you! Would it be beneficial to put the intake & exhaust manifolds from the 89 on my 86? I imagine if the exhaust pattern matches then it goes right on but what will I run into putting the intake on? Visually it looks like the Injectors will work just fine but it doesn't have the same vacuum ports (A/C Idle up valve, etc.)
The exhaust manifold, sure. You'll get better gains out of a header, though. As for the intake, don't bother. The ECU is what controls the opening of the secondary runners, so without changing everything over, there's really no use. You'll get more gains going with an aftermarket intake manifold.
Okay, thanks. Haven't been able to find a source for aftermarket N/A intakes but I'm sure it'll turn up with more searching. And yeah a header setup would be so much better, just thought about it since I already have the 89 parts.
Probably going to put the A20A3 up for sale soon, once I pull it.
I've thought about doing a 88-89 LXi A20 block and 4-2-1 exhaust swap into my 86 DX. I'm carubrated and was told my intake would fit onto one. Just don't know if I would gain much from it, but even a little gain is a gain when your under 100 Hp. My Weber carb might even like it a bit better lol
Are the heads any different/swappable? Wondering if the combustion chamber is a little smaller or anything that would benefit the early engines
I think the cam is slightly different but not enough to matter by itself. The difference in compression is from the piston tops.
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Ah I see, thank you. Think I'm done with asking dumb questions! Off to the 5 Speed swap
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