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1991 Toyota MR2 Turbo Custom Amp/Subwoofer - Questions on Electrical System Upgrades
1991 Toyota MR2 Turbo Custom Amp/Subwoofer - Questions on Electrical System Upgrades
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Old 25th September 2004, 11:18 PM   #1
newsystem is offline newsystem  United States
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Question 1991 Toyota MR2 Turbo Custom Amp/Subwoofer - Questions on Electrical System Upgrades

Hello everyone,

I currently own a 1991 MR2 turbo which was passed down to me through the family. It presently contains two mediocre 8" drivers in sealed boxes behind each of the two seats, and a small amplifier under the passenger seat. While adequate, I've been waiting for something better and have finally found myself with an Earthquake PH3 3000wrms amplifier as well as two no longer commercially available Eclipse 8" drivers.

My main concern here is with the MR2's electrical system. I know that being such a small vehicle, the alternator and such must be appropriately sized on a small scale. Thus, I have come to the conclusion that I will likely need to buy a new high capacity battery, in addition to a high output alternator.

Now the question is, does anyone have experience with upgrading the electrical system in the 1991 Toyota MR2s? It is a small mid-engine car, and the engine compartment is a very tight squeeze. I want to make sure I'm going to get an alternator and battery that is compatable and as easy to install as is possible in my current situation.

Can anyone here recommend specific HO alternators and/or batteries that I should consider, given my vehicle? Any tutorials or personal advice with respect to my specific installation would also be greatly appreciated!
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Old 3rd October 2004, 06:11 AM   #2
mista2 is offline mista2  United States
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hey newsystem --

it seems you and i have (had?) similar problems! i too own a 1991 mr2. unless you're looking to run this thing at full power all the time, the stock electricals should be just fine. i installed a 1000wRMS, a 300wRMS, and a 150wRMS amp in mine (mounted in trunk x_x) on the stock electricals, and have had no problems thus far. i can also play the thing at moderately high volume for about 3hrs w/o engine running and then crank the engine no trouble.

is your mr2 a model with t-tops? if so, how do you store them having the two 8's in boxes behind the seats? (i have two 6.5 TB subs in the stock subwoofer areas behind the seats and am still able to store the t-tops, but would love to do 8's instead!)

hope i helped *shrug*...also, how (and where?!?) in the world are you gonna mount that 3000w beast of an amp?

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Old 7th October 2004, 04:25 PM   #3
SupraGuy is offline SupraGuy  Canada
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Toyota alternators aren't bad, and are usually of adequate capacity for a reasonable system.

I don't know offhand what the current capacity of the MR2 turbo's alternator is, but I know that the '87-92 Supra Turbo's alternator is 100A. I would think that it would be a reasonably simple job making one of these fit, provided that it is a signifigant upgrade. (My guess is though that with power windows and door locks, the MR2's alternator will be at least 80A. -- Toyota doesn't like to current starve their cars. Even an Echo has decent alternator capacity!)

Of course, I'm nowhere near the 3kW mark in my car, but then I want to be able to hear in 10 years.

mista2: I've seen a system in an MR2 with a pair of 10" subs mounted in the front. The car in question had an amp rack where (I think) the spare tire would have been and a pair of 10" subs firing into the leg area of the passenger compartment. Full storage for the T tops in the back, and IIRC, about 145dBA SPL. Just not a car that I'd want to get a flat tire in. I don't know what amount of fabrication that took to do, but it sure seemed like a good idea.

I have been considering getting an MR2 turbo as a "fun car." I'm just waiting for the right deal to come along.
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Old 8th October 2004, 09:52 PM   #4
newsystem is offline newsystem  United States
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Thanks for your responses! I've looked into the parts for my car with my mechanic and found out that all 1991 Toyota MR2 turbo's manufactured outside of Canada come with a 100A alternator .. those manufactured in canada can get as low as 70A on their alternator.

Now that I know this, I think I won't even bother isolating a second battery, however I will be replacing my current battery with an Optima Yellow Top since mine is pretty old and I've heard good things about the Optimas.

SupraGuy, I was actually considering having some drivers mounted under the front hood and firing into the passenger footwell, but after reviewing the space situation up there I resolved that it's just too much of a hassle for me to undertake at this time. So I'll just drop my new 8's into the enclosures which already reside behind each of the seats.

mista2, I do have T-tops on my car, and their storage is a bit of a pain. There is still enough room to store them behind the seat.. but there won't be after I mount my Earthquake PHD3 amp on the wall behind the passenger seat! Fortunately I rarely drive with the tops off anyway, and if necessary I can just wrap them up in a towel and keep them in the trunk.. or rig up some type of harness system but seeing as I hardly ever take 'em off I think I'll stay with the former option.

I suppose I could attempt to mount the amp under the passenger seat, but I'm not convinced that there is enough room for it there even though one of my associates has told me that there should be.. only time will tell. I'm also thinking of expanding my enclosures and venting them just so I can have a beastly showmobile. My own listening tastes are somewhat conservative so I wouldn't worry about myself going deaf.. just trying to put together a demo system to show to others interested in the hobby.

Thanks again for the feedback.. if anyone else has anymore to give, by all means I'm listening!
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Old 4th November 2004, 01:34 PM   #5
klm1 is offline klm1  United States
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i don't like being a spoil-sport, but here goes...
100 amps @ 12 volts is only 1200 watts, right?
so,1200(say, even 1500) watts for short time is no problem.

3000 watts is a heck of a drain on any car system.

I'd suggest a battery charger, OR
another complete alternator; OR
only play the amp @ lo power levels regularly.
hi levels for short time(<15 min. tops);

OR ,one more battery in parallel w/ 0 gauge wire(read,battery jump cable or equivalent).

Please don't take me as being critical-I have seen too many
destroyed alternators in my time.
some like it hot;"the biggest mistakes are made by those who make assumptions!" Graham Maynard
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