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Discussion Starter · #1 ·
Hi everybody, I recently bought a Supercharged 1989 MR2, and I'd like to do some mods/tuning. Previously I've only worked doing minor stuff on carbureted engines, so I figured it would be best to talk to you all about where to start. I would like to try tuning the engine to begin with, and in doing research on previous posts I've heard that the Megasquirt is a good option. Is this true? If so, is there anything else I need to buy to tune it?

Apologies if I come off as a novice tuner, I'm not very experienced in modding, although I do understand how engines work and everything, so I'm not a complete idiot.

Attached below is a picture of a list of mods I'd like to do eventually (and I'm aware not all of them can be applied at the same time, these are just ideas), Im curious for any feedback on it
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I think you'd be best off changing to a smaller pulley and an intercooler upgrade. If you can find a tuner I would use whatever ecu they prefer, the megasquirt ecus are very DIY and require a lot of knowledge to setup troubleshoot and tune. I honestly wouldn't recommend doing all of that yourself having no prior knowledge.

I would also skip the stroker kit. All that work into a 4agze and you still won't make a lot of power. I would look at an engine swap before I spent thousands in machining costs.

A project that might hold you over for now is changing the supercharger oil, if you don't know when it has been done last assume it is long overdue.
 

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Discussion Starter · #3 ·
I think you'd be best off changing to a smaller pulley and an intercooler upgrade. If you can find a tuner I would use whatever ecu they prefer, the megasquirt ecus are very DIY and require a lot of knowledge to setup troubleshoot and tune. I honestly wouldn't recommend doing all of that yourself having no prior knowledge.

I would also skip the stroker kit. All that work into a 4agze and you still won't make a lot of power. I would look at an engine swap before I spent thousands in machining costs.

A project that might hold you over for now is changing the supercharger oil, if you don't know when it has been done last assume it is long overdue.
Thank you for the info, I do have my dad available to help me, and he's been a mechanic for decades, he can help teach me how to use a Megasquirt. also the reason I'd like to get the stroker kit is since it's billet so it'll be stronger and can handle more power, which I figure would help if I twincharged it
 

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If you truly got your hands on an 89 SC and its in decent shape..... you have one of the rarest mr2's out there. any modification will only devalue the car.
If its in so-so shape, Im with J. 4A not worth chasing as a power performer. Many cheaper and easier ways to get power. Megasquirt not recommended for beginners. Not a bad product but does require a fair amount of know how... at least from my research.
 

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Discussion Starter · #5 ·
If you truly got your hands on an 89 SC and its in decent shape..... you have one of the rarest mr2's out there. any modification will only devalue the car.
If its in so-so shape, Im with J. 4A not worth chasing as a power performer. Many cheaper and easier ways to get power. Megasquirt not recommended for beginners. Not a bad product but does require a fair amount of know how... at least from my research.
that is true, modding can devalue it, and it is in amazing shape, that's why I plan on keeping the stock parts so I can change it back, and won't do any permenant mods like boring out or bodykits or whatever, however I don't plan on ever selling the car since it's one of my dream cars. I may just end up doing an engine swap, but ideally I'd like to try to get ~250hp out of the stock engine, does that seem possible with the mods I've listed, if not, what else would you suggest.
 

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Keep the SC stock, or mildly upgraded (such as smaller SC pulley or larger crankshaft pulley). Appreciate it for what it is. If you want a MK1 with 250hp then get a clean MK1na and do a MK1.5 or 2AR swap.

If it's really in "amazing shape" (and reasonable miles) then you should be able to sell it for enough to fund the purchase a clean MK1na AND the engine swap project for that car.

And please, no scissor doors.
 

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Getting 250 from a 4a possible but it won't be a car you'll be driving everyday and will probably cost a pretty penny to get there. I have a NA 4A that the P/O put $10k into so that it would be a reliable 160-170 at the crank. Thank kindo money can get you just about any swap thats common and known to be reliable 250hp+ all day long.
 

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Discussion Starter · #8 ·
Keep the SC stock, or mildly upgraded (such as smaller SC pulley or larger crankshaft pulley). Appreciate it for what it is. If you want a MK1 with 250hp then get a clean MK1na and do a MK1.5 or 2AR swap.

If it's really in "amazing shape" (and reasonable miles) then you should be able to sell it for enough to fund the purchase a clean MK1na AND the engine swap project for that car.

And please, no scissor doors.
alright, well I guess I'll just do the pulley swap, intercooler fan, and potentially the Megasquirt down the line, and Id really rather keep the car as is with only the minor improvements instead of buying an na model. I already have a jag with a 69 Camaro engine for racing, Ill just keep this as my daily driver.

Also the main reason I want the scissor doors isn't for the flashyness, I just am always worried about scraping my doors on curbs since it's so low, and it's just more convenient. Plus I've already got the passenger door messed from my friend opening it without seeing if anything was in the way.

Also here's a pic of the car for everyone asking what condition it's in
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Suggestion for the first thing to do with your MR2, hmmmm, learn to drive it as is. Then, get into the suspension and tires. After you survive that, then think about bumping up the power. These things aren't your typical car.
 

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Discussion Starter · #10 ·
Suggestion for the first thing to do with your MR2, hmmmm, learn to drive it as is. Then, get into the suspension and tires. After you survive that, then think about bumping up the power. These things aren't your typical car.
I've gotten used to driving it as it is, and I should also mention the previous owner installed Street Technique sway bars, Koni adjustable shocks, TRD springs, and a racing clutch
 

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alright, well I guess I'll just do the pulley swap, intercooler fan, and potentially the Megasquirt down the line, and Id really rather keep the car as is with only the minor improvements instead of buying an na model. I already have a jag with a 69 Camaro engine for racing, Ill just keep this as my daily driver.

Also the main reason I want the scissor doors isn't for the flashyness, I just am always worried about scraping my doors on curbs since it's so low, and it's just more convenient. Plus I've already got the passenger door messed from my friend opening it without seeing if anything was in the way.

Also here's a pic of the car for everyone asking what condition it's in View attachment 77432
Gorgeous. Don't change a thing. Find friends that can open car doors properly :sneaky:
 

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Sure, you think you're used to the little beast, but just wait! There's more! Just when you think you got it down, surprise!

Not being a jerk, just giving a heads up. The little MR2 can be a big handful without any notice. Even the most seasoned owners get a taste of that now and then.
 

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... most problematic aspect of AW-11 performance: suspension set-up.

The most adjustable suspension Toyota ever made, even level V drivers, seasoned race engineers found themselves hopelessly lost optimizing an IMSA or SCCA AW11 set-up (e.g., narrow up on your caster; start soft with your shock settings up front; start full-firm with your rear shock settings; dial out from there; that will give you an indication what's needed cambering your alignment).

Lack thereof, there is no substitution, for weight. A plague upon the MR2 fraternity, stupid people doing stupid mods, adding weight to a lightweight vehicle. Rule of thumb in race car fabrication, whatever weight you've added must be offset, taking weight from higher up the vehicle.

Which brings us to the AW11's principle shortcoming: glass weight. It's not that our AW11 carries excessive glass weight, relative to other vehicles. Short wheelbase mid-engined vehicle, exactly the same dimensions of Ford's 1966 GT40, nine inches taller, it's that our AW11s carry a greater ratio of glass weight, concentrated, up high. Which implies a weight transfer issue; imperative of a disciplined driving style, no flinching.

Any sudden movement by the driver when transitioning between maximum tyre adhesion and incipient torsional side-slip, can toss an AW11 into yaw.

At the limit with your AW11, never (NEVER) miss your 5th to 4th. One of the highest femur ratings in insurance industry risk assessment, implication of a missed 5th to 4th downshift at maximum tyre adhesion is typically, a pair of broken legs (or, worse). Good news, the AAR people (e.g., Dan Gurney, himself) did the development on Toyota's AW11 OEM set up. Unlike snap over-steer plaguing the later Mk II variant, when the back end of your AW11 steps out, it's a cinch to catch (provided you haven't done something stupid, fitting 16" diameter wheels).

Brakes and tyres are everything. The most significant upgrade you could ever make to an AW11, paring down reciprocating mass. Lightweight wheels transform Toyota's AW11, from a perky, playful chihuahua, to a snarling wolverine ready to take off somebody's ankle.

AW11 hubs unique, ensuring hub-centrics for aftermarket wheels is a real challenge. OZ people were very good about hub-centrics when I ordered up my Superleggeras. First AW11 guy ever to pony up for a set of OZ wheels, the Tire Rack people were asked to forward my Rolodex info along to the OZ people. And brrrr-ring, I got a call from the Italians, asking if I could please prop the vehicle, mic the hub, so they could make up a decent set of hub-centrics (free!).

Terrific people. Working quick as I could, the guy patiently waiting on hold, the entire time! The real McCoy, real racing wheels, 8 pounds a corner. Shot-peened. To die for. 4th gear apex, my AW11 is 22 mph faster than it was on its OEM wheels. Lightweight wheels, now I'm going 4th gear down straightaways, freewheeling 5th in high speed turns.

What few souls in the Milky Way Galaxy will ever live, to drive a lightweight, short wheelbased mid-engined vehicle? Welcome to the club.
 

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At the limit with your AW11, never (NEVER) miss your 5th to 4th. One of the highest femur ratings in insurance industry risk assessment, implication of a missed 5th to 4th downshift at maximum tyre adhesion is typically, a pair of broken legs (or, worse).
Sorry, I'm new here, and awaiting delivery of my first MR2, a 1988 SC I recently won at auction. Broken legs from missing a downshift? Can you expand on that a bit, please?

As for the original poster, my personal recommendations would be to keep things as stock as possible. Maybe a pulley, lighter wheels, good sticky tires, and avoid changing the doors. If you want to do some big mods on something, or go for big power, maybe go with a car that's more common rather than changing such a rare car that much. My personal opinion.
 

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Discussion Starter · #15 ·
... most problematic aspect of AW-11 performance: suspension set-up.

The most adjustable suspension Toyota ever made, even level V drivers, seasoned race engineers found themselves hopelessly lost optimizing an IMSA or SCCA AW11 set-up (e.g., narrow up on your caster; start soft with your shock settings up front; start full-firm with your rear shock settings; dial out from there; that will give you an indication what's needed cambering your alignment).

Lack thereof, there is no substitution, for weight. A plague upon the MR2 fraternity, stupid people doing stupid mods, adding weight to a lightweight vehicle. Rule of thumb in race car fabrication, whatever weight you've added must be offset, taking weight from higher up the vehicle.

Which brings us to the AW11's principle shortcoming: glass weight. It's not that our AW11 carries excessive glass weight, relative to other vehicles. Short wheelbase mid-engined vehicle, exactly the same dimensions of Ford's 1966 GT40, nine inches taller, it's that our AW11s carry a greater ratio of glass weight, concentrated, up high. Which implies a weight transfer issue; imperative of a disciplined driving style, no flinching.

Any sudden movement by the driver when transitioning between maximum tyre adhesion and incipient torsional side-slip, can toss an AW11 into yaw.

At the limit with your AW11, never (NEVER) miss your 5th to 4th. One of the highest femur ratings in insurance industry risk assessment, implication of a missed 5th to 4th downshift at maximum tyre adhesion is typically, a pair of broken legs (or, worse). Good news, the AAR people (e.g., Dan Gurney, himself) did the development on Toyota's AW11 OEM set up. Unlike snap over-steer plaguing the later Mk II variant, when the back end of your AW11 steps out, it's a cinch to catch (provided you haven't done something stupid, fitting 16" diameter wheels).

Brakes and tyres are everything. The most significant upgrade you could ever make to an AW11, paring down reciprocating mass. Lightweight wheels transform Toyota's AW11, from a perky, playful chihuahua, to a snarling wolverine ready to take off somebody's ankle.

AW11 hubs unique, ensuring hub-centrics for aftermarket wheels is a real challenge. OZ people were very good about hub-centrics when I ordered up my Superleggeras. First AW11 guy ever to pony up for a set of OZ wheels, the Tire Rack people were asked to forward my Rolodex info along to the OZ people. And brrrr-ring, I got a call from the Italians, asking if I could please prop the vehicle, mic the hub, so they could make up a decent set of hub-centrics (free!).

Terrific people. Working quick as I could, the guy patiently waiting on hold, the entire time! The real McCoy, real racing wheels, 8 pounds a corner. Shot-peened. To die for. 4th gear apex, my AW11 is 22 mph faster than it was on its OEM wheels. Lightweight wheels, now I'm going 4th gear down straightaways, freewheeling 5th in high speed turns.

What few souls in the Milky Way Galaxy will ever live, to drive a lightweight, short wheelbased mid-engined vehicle? Welcome to the club.
Thank you for all the information, I should have mentioned in the original post, the previous owner has done a number of modifications, street technique sway bars, Koni yellow adjustable shocks, Toyota TRD Springs, brand new azenis street slicks, and a racing clutch. furthermore I forgot to add this to the list I posted, but I do plan on getting a fiberglass or carbon fiber hood. Also with what you said about the glass up top, would you recommend I simply leave the glass t-top panels out of the car when I go to the track?

Aside from that, new wheels are definitely something I'll look into, however if I take it to any shows I'm definitely putting the stock wheels back on, they look so amazing imo.

Again, thanks for all the advice!
 
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