The time has come to consider new motors for my ae86. The k24 intrigues me because it makes the power I want, suits the car's personality and is cheap(ish). Only downside I can see is that it requires subframe spacers to clear the hood. What kind of negative effects can I expect and can they be mitigated?
Camber curve/roll center will be altered due to lowering the inboard pickup points.
The bumpsteer may not be ideal afterward as well.
Mitigtion can be as simple as ballpoint spacers to lower the outboard pivot point the same amount as the inboard points. bumpsteer correction typically requires similar spacers for the outer tie-rods. All of which may be available for your vehicle, given its popularity.
Hold on... you're going to prioritize hood clearance over suspension geometry? Put a bump in the damn hood and don't worry about it!
In reply to Stefan :
Already running 25mm balljoint spacers. Tie rod spacers are readily available so thats not an issue thankfully.
In reply to ¯\_(ツ)_/¯ :
Id like the car to stay sorta nice looking. Plus lowering the subframe helps add some clearance for the oil pan.
In reply to Fitzauto :
Is it totally stock appearing? The common aftermarket AE86 option looks like it would buy you some clearance, especially if you tweaked the inner section a bit:
I'd much rather solve cosmetic problems than create geometry problems.
In reply to ¯\_(ツ)_/¯ :
Thats actually the exact hood I have. It has spacers on the hinges to allow more airflow through the bay.
In that case I would measure to see whether bumping up the section in the center of the "U" shape would get the clearance you'd need. Moving that part of the hood, maybe by cutting where it meets the bump and epoxying back together, would be nearly invisible after the fact if done decently.
Are any of these (or combination of) a possiblity?
• Rerouting the oil pickup to the side of the crank
• Redesigning the oil pan for less depth and more width to retain capacity
• Modify the subframe to allow a lower engine position
I used all three to get a much larger Mazda F engine in my Miata. The front of the bigger F engine now sits just a bit further back than the stock 1.8 and the hood closes with plenty of clearance. I ran subframe spacers on a prior swap and it was never an issue for the car, just for me. 
¯\_(ツ)_/¯ said:Hold on... you're going to prioritize hood clearance over suspension geometry? Put a bump in the damn hood and don't worry about it!
THIS!
One of the worst mods I ever did with respect to handling was to put an FC RX-7 subframe in my FB. The control arms mount lower, so the roll center gets dropped. To get the same handling that I used to get with 175lb springs, I had to go to 250lb springs, and it still doesn't feel as good under certain conditions. Were I to do it again, I'd cut and section the chassis rails so the subframe could sit an inch higher in the tub.
As an expedient, I raised the front of my car an inch, which gave me a bunch of cooling system issues (air wants to go under the car instead of through the radiator) but I got some semblance of handling back.
With an AE86, you have strut housings that bolt to steering arms, yeah? At a minimum, I'd space the arms away from the strut as much as you space the crossmember from the body. That should help things tremendously. SA/FB RX-7s are built with this setup and spacers that exist to do this are on the market and called "turn-in spacers", to give you an idea of what you will lose if you go the other way by dropping the crossmember.
In reply to Knurled. :
Ive got spacers already since the car is lowered a good bit.
What about a cowl-induction style hood?
In reply to pres589 :
Hadnt thought on that. At this point I may just rebuild the 4a and put a turbo on it. Should maintain handling and get me a bit more power.
How much power do you need in an AE86?? Do you know how much you have now??
While I can't build you a 4AG equivalent to a K24, I can build a 4AG that will make an AE86 hustle... OR build a 7AGE that will make it fast.
oldeskewltoy said:How much power do you need in an AE86??
https://www.youtube.com/watch?v=osJSoen8hxQ
Huh. It's left hand drive.
More realistically, the videos of S2000-engined AE86s look enticing. Like a low budget version of a Millington Diamond engined Escort. (The only time when "low budget" can be applied to "S2000-engined" or "AE86", sadly)
Fitzauto said:In reply to ¯\_(ツ)_/¯ :
Thats actually the exact hood I have. It has spacers on the hinges to allow more airflow through the bay.
Fyi- those spacers aren’t doing you a DAMN bit of justice. It doesn’t work that way, and has been proven many times, in wind tunnels, that hood spacers actually make the engine bay hotter. Take them out. Remember- form follows function.
Side note- I’ve read that the Lexus v8 can be done cheaply, and puts out decent enough power (300hp in a 2400lb car ain’t slow.)
_ said:Fyi- those spacers aren’t doing you a DAMN bit of justice. It doesn’t work that way, and has been proven many times, in wind tunnels, that hood spacers actually make the engine bay hotter. Take them out. Remember- form follows function.
Must be an AE86 thing. With the rear-latching hood on my SA RX-7, if I opened the hood on the highway, it would rise up a couple inches from the underhood pressure. Spacing the latch up an inch did wonders for keeping my much-higher-powered FB cool, it allowed the air to escape. (For some reason, the SCCA frowns on competing with an unlatched hood...)
In reply to Knurled. :
Per the internet: “It can have the opposite effect. You get high pressure air at the base of the windscreen so if you lift the rear of the bonnet it forces air down. This creates a high pressure zone and can slow down air flow through the rad. The only reason to to this would be to get extra cool air into the induction system.”
In reply to _ :
Again, it must be an AE86 thing. Every car is different, aerodynamically-speaking. Where the edge of the hood is in relation to the base of the windshield would also play a huge role. If the hood goes all the way to the glass, then I can see it being a negative if you don't block the base of the hood so high pressure windshield air can't come in, while still letting air escape out the sides.
In reply to _ :
I do it because it works. Without the hood spaced the car runs very hot.
In reply to oldeskewltoy :
Right now I have a 4agze pushing 11psi or so post intercooler. Bone stock besides the grunt box and pulley.
If your car is lowered, riding on bigger tires, has coil overs, or any other number of things, you have already messed with the geometry. Do what you gotta do and adjust things afterward. Its not an F1 car! Its a street track car. Lets not loose perspective. I space u[p the hood on the rear of the TR8 race car as well. According to the above picture, it should be a high pressure area. I can tell you its not on a TR8. You can see the fumes plume out if a breather or something else comes loose. It helps greatly in keeping under hood temps down, and lets the air passing thru the radiator escape over the top of the car and not under it.
Keep in mind, while the base of the windshield may be a high pressure area, on cars with poor engine bay exit airflow and good airflow in through the grille / radiator, it's quite possible for the engine bay pressure to be even higher (meaning air will still flow out of the engine bay). Plus, just how high pressure the base of the windshield is will vary a lot between cars.
In reply to Fitzauto :
Bone stock 4AGZE (8.0:1) is leaving a LOT on the table.
As to what is possible with an SC12, I built a 4AGZE a couple of years ago that planted over 200hp, and 200#/ft @ the wheels... so there is a LOT you can do with an "A" block Toyota.
In reply to oldeskewltoy :
Im leaning towards a 7a at this point. While I like the grunt the GZE has, with two drivers it gets heat soaked fast. I also like the idea of going simpler with the car.
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