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Old 10-04-2012, 03:43 AM   #1
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So i have a '92 model with a 1.6 that is getting closer and closer to death, ive got a '99 bp motor that is going to replace it. My plan is to build the bp to help support a turbo conversion. I am currently on my p plates in australia so im restricted to no forced induction for another 12 months. my power goals are around the 300hp mark, maybe more, maybe less, ill see what i can get.

From what i can figure, i have several options:

1. Swap the bp in now as is to replace the dying motor and build/turbo in 12 months.

2. Build the motor now to turbo spec i.e.: lower compression forged pistons and rods etc. i do understand that you can run a turbo setup without building the engine, but for safety and a bit of piece of mind im choosing to.

3. Hope the 1.6 lasts for another 12 months while building the 1.8 and put it in with the turbo once i get my full license.

Im leaning towards option 2 because it means i can diagnose problems with the engine swap separately to the conversion to FI and i wont have to rip the motor out again for the foreseeable future. My question is this, will i be able to run the motor without a turbo with the lower compression ratio, probably 9.0:1, by compensating for the lack of compression via ECU tuning?

sorry if this has already been answered or the answer is blatantly obvious.
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Old 10-04-2012, 03:53 AM   #2
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prepare for butt rape?

Last edited by bmxfuel007; 10-04-2012 at 05:37 AM.
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Old 10-04-2012, 05:35 AM   #3
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yes you can run 9.0:1 but on a n/a lower compression = less power.
i would honestly post this on mx5cartalk instead of here. people dont like noobs here aha.
so how is your 1.6 about to die if you dont mind sharing?? these motors are tough as f#ck maybe its an easy fix
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Old 10-04-2012, 12:33 PM   #4
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I ran 9:1 naturally aspirated for 2 years before I got my **** together and boosted it. And I'm pretty sure the 94's have 8.8:1 (i think).

You'll be fine.
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Old 10-04-2012, 12:55 PM   #5
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Build the motor now, drop it in, tune NA, then boost it so hard its mother screams.

Last edited by skidude; 10-04-2012 at 03:17 PM.
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Old 10-04-2012, 01:12 PM   #6
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Quote:
Originally Posted by skidude View Post
Build the motor now, drop it in, tune NA, then boost it so hard it's mother screams.
+1, don't be a ------ about it.
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Old 10-04-2012, 11:55 PM   #7
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thanks guys that answers my question. anyway, previous owner was useless and managed to flatten one side of the keyway on the crank :/ its loc-tited back together now but every now and then it still feels like its slipped out of timing a bit and then comes good again. it just doesn't feel right anymore.
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Old 10-05-2012, 12:56 AM   #8
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build the motor now to turbo spec.

when my turbo broke my car basically became a N/A intercooled 1.9. even with all the intake restriction (85kpa under WOT, lol) etc etc it was a bit faster than a stock 99 with super-healthy engine.
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Old 10-05-2012, 01:00 AM   #9
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Quote:
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build the motor now to turbo spec.

when my turbo broke my car basically became a N/A intercooled 1.9. even with all the intake restriction (85kpa under WOT, lol) etc etc it was a bit faster than a stock 99 with super-healthy engine.
Megasquirt FTW!
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Old 10-05-2012, 05:04 AM   #10
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cheers guys, thanks for the info, megasquirt is the plan too
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