Warning. This is long and tedious - even by my standards.
Fox bodies are the arch nemesis of my favorite turbo car, the Buick GN.
Because I drove a GS I went to all of the Buick Vs Ford drags growing up. Buick didn’t have much, but they did have the Grand Nationals. It always came down to which Fox body was going to beat what GN. Ford beat Buick most years but it was still fun.
GNs are sexy as shit tho. I love a good Fox for the simplicity and enormous potential, the EECIV cpu/ecu system they run makes life a lot easier when building something you want to still be able to drive day to day... But a Fox can't touch a GN in style, and for those that know what GNs are (sadly, not many do it seems like, at least around here), the pure street presence of a GN can't be touched by a Fox.
I have never had the pleasure of working on a GN. I almost "bought" one YEARS ago, but it been stripped completely down to the shell for a restoration, and was literally the body without a bolt or single thing attached, and the entire rest of the car was in almost individual pieces, in tubs, wrapped up on pallets.
The car would have been payment for actually building an oddball project I had been researching for a guy, he'd owned rx7s for years, and had a pair of FDs, one beautiful, pure stocker on its third fucking motor, and one mostly complete in primer, sans drivetrain. He'd asked me about options to ditch the rotary engine* in a rebuild because he was SUPER tired of their shit, but he wanted to keep as much of the character they gave the car as possible. I'd hunted up info and looked in to other projects and spent a couple months compiling info. Ls1 swaps are a thing with the FD guys, and its something in the neighborhood of practical. This was more than 10yrs ago, and there were some kits and prefabbed stuff floating around.. but I've driven, worked on and yelled at more ls1s than I can hope to remember and it's an AMAZING motor. Hell, it's predecessor, the Lt1 was a solid engine if you didn't want to mod the damn thing.. but LS1s bleed power. Great head design. Easy to work with.. but part of what makes them so great, is exactly what he didn't want.
If you've ever driven or ridden in a rotary car, a rotary motor makes all it's power right up front. They don't make torque with two shits (it's part of why they love boost so much) , but they are basically single stroke motors. A 4 stroke - every automobile engine ever - doesn't create power on every stroke (a ToD event), but rather every fourth. It's why the power builds with the RPMs. More RPMs, more ''puts", or ignition events, ie, more power. So your 400hp engine makes 400 @ a specific RPM. And less below that. Rotary engines don't do that.. sorta. No one wants me to explain this in more depth, and I've been SUPER light so far (if any engineer is reading this, don't hang me for being extremely imprecise in my explanation). Anyway. They have an ignition event every stroke, so if a rotary makes 200hp, it makes that power practically off-idle. Same thing if it makes 400hp (lollerskates). There IS powerbuild, but it's nothing like a piston/standard engine. So when you hit the gas, regardless of rpm, you GO. It's an interesting illusion of torque.
So, an LS series motor won't work. Not without extensive mods, and ultimately you'd be fighting the character of the engine, which is kinda stupid. They are meant to wind out, they have an AMAZING mix of muscle car and sports car feel. But, this guy wants off-idle power that doesn't build so much as it's just 'there'... Welppp, after a bunch of research and such, I out together a detailed parts/work/fabrication list for.. well, an LS series motor, but a little different. Cost was a factor here as well. So, enter one of Chevy's least appreciated engines. The LS series 5.3 v8, found in a bajillion trucks from.the early 2ks. That was my solution. Part of it. Truck engines make power low for obvious reasons, so the character was right. A 5.3 is about a third the cost of the LS performance series motors, and still makes respectable power, with the ability to squeeze more out without breaking the bank, but it's two bigggest selling factors were it's somewhat low-ish compression and it's tank reputation. It can take a LOT of abuse. Low compression means boost is easier. High comp boost is a beautiful thing, buts it's tricky. All said and done, a low-psi, small turbo'd 5.3 v8 swapped in would meet his budget and come as close as possible to the off-idle power he was looking for. The turbo system would be designed to spool VERY early, running sub 10-psi. Oh, and the 5.3 has an aluminum block w/ iron sleeves version that's a little harder to find, but costs about the same.. so we'd be saving some weight.
Ultimately his offer of payment wasn't worth the effort though, I'd have been 6mos building the FD, only to have 6mo of work rebuilding the GN, with who knows how much money thrown at putting the engine back together and such.
This has been long even by my standards..sorry. Im sitting in the waiting room at a Drs office while my niece waits to get her yearly checkup and physical.
