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Old 02-17-2011, 05:44 AM   #1
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Default My mx5 turbo to be

Hi there,

I am currently looking at buying another mx5 but with a turbo fitted. I have found one but I am wanting some input from some experienced guys about what the conversion and car looks like...so here it is...

2002 mazda mx5

550cc injectors
forged pistons
h beam rods
fully balanced
Garrett T25 A/R.48 internally gated running 0.7bar
front mounted intercooler
Spitronics Piggyback ECU
all the usual parts ceramic coated
o2 sensor
Exhaust is 2" stainless 304 front to rear

The car is putting down about 149kw and 270nm with a safe street tune and on a conservative dyno. Does not have a BOV or bypass valve, does that seem to be a problem at these levels?

Car has 65 000km on the odo. Not sure what else you need to know but iv posted some pics 2. i hope i will have some good advice on this soon, cheers
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My mx5 turbo to be-img_0001.jpg   My mx5 turbo to be-img_0002.jpg   My mx5 turbo to be-img_0007.jpg   My mx5 turbo to be-img_0005.jpg   My mx5 turbo to be-dyno.jpg  


Last edited by MrStevo; 02-17-2011 at 02:02 PM.
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Old 02-17-2011, 10:12 AM   #2
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what engine management are u using?
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Old 02-17-2011, 10:36 AM   #3
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its a locally produced product here in South Africa. its a Spitronics ECU - http://www.spitronics.co.za/cms/enginemanagement.php

Im not sure which model of it but enough to get the car working with no problem for 5 years now.
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Old 02-17-2011, 11:11 AM   #4
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Wow, those are cheap < $400 USD for the 'ECU Advance Kit'.
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Old 02-17-2011, 11:19 AM   #5
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The tuning company that did the conversion is quite experienced now and used the product a lot, even on high powered drag rotaries so it must have the power to control it all. Local stuff here is cheap for you, but if you are over hear the prices of things can be quite hectic, thats why I'm looking at changing to an already turbocharged mx5. Just needing some help from you guys to see if this one looks good
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Old 02-17-2011, 11:22 AM   #6
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just got some more info, the exhaust is a stainless 2'', isnt that a little small for a turbo? I know this turbo is small but wouldnt a larger one improve spool quite a bit? Any improvement in the pre and post turbine pressures is better i guess
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Old 02-17-2011, 11:26 AM   #7
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Your steering wheel is on the wrong side I would not get it.

Just kidding.

looks like a nice setup.
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Old 02-17-2011, 11:32 AM   #8
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haha I should have seen that one coming! What do you think about the lack of a BOV? its not upping power too much but still...
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Old 02-17-2011, 11:44 AM   #9
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Easy enough to add, you have a lot of space to the left of the cold side intercooler pipe (directly off the throttle body).

Buy a $20 ebay plastic unit, they're better than you think. Might leak a little at your boost levels though.

Biggest problem is that you're putting a lot of stress on the turbo from what I understand. Every time you close the throttle, the pressure between the turbo and the butterfly valve in the throttle body backs up and stops the compressor wheel. After you open up the throttle again (like after a shift), it has to spool up yet again.
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Old 02-17-2011, 11:52 AM   #10
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I don't think the surge is that high though due to the rate of volumetric flow from the turbo but I do believe that it is how ever much being unfriendly to the turbo in terms of stress. The extra rpm of the turbo after shifts would also be nice so adding a BOV would be top of my list.

Would a BOV or bypass valve be better for this application? Im not sure where the air flow readings are coming from so I don't know if a bypass would be needed to drop the chance of rich fueling and even stalling at shifts.
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Old 02-17-2011, 12:01 PM   #11
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BOV is a important aspec for drivabilty and longevity of the turbo. I would install one, also the exhaust may be little on the smaller side. Depending on the price of the car, it may be worth to upgrade.

Read some builds on here and you will get a good ideal what you have and what you would need.
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Old 02-17-2011, 12:24 PM   #12
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thanks for the tip, I'll go read some now
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Old 02-17-2011, 12:49 PM   #13
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just did the KW to HP conversion and for all the engine mods, it is rather low.
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Old 02-17-2011, 12:55 PM   #14
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As I have been told everything is conservative, remember that it is a small turbo too with a small exhaust, with a little work it would be up to where i want it. Plus the internals have been upgraded for safety, not a high power build in mind.
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Old 02-17-2011, 01:01 PM   #15
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A Bosch recirculating valve (black plastic one) would work fine for what you are doing. They are common to many OEM turbo cars. Is there still a stock MAF somewhere in your inlet tract? If so, the recirculated air needs to come back into the system after the MAF.

Yes, going up to a 3inch exhaust would make a big difference.

The valve cover breather hose going to the inlet pipe for the compressor is probably not helping things. You are probably sucking a lot of oil vapor into the compressor.

The gear-type hose clamps on the pipe before the throttle body are not going to be as robust as we typically prefer. "T-bar" clamps or whatever other name they are listed under are better.
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Old 02-17-2011, 01:16 PM   #16
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I'm not sure if the MAF has been located out of sight or what is being used. Will find out though because the bypass valve/BOV would be at the top of my list.

Would a straight filter on the valve cover breather be fine with the exhaust there? Iv seen a few melted before...

The plumbing just before the throttle body also doesnt look straight, maybe its the angle but id sort that out at the same time, would probably keep it in place better and the new clamps would be 100% then
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Old 02-17-2011, 01:24 PM   #17
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The TPS is unplugged.
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Old 02-17-2011, 01:35 PM   #18
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you are right, it is...can't a reading for the throttle be taken in another way though?
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Old 02-17-2011, 01:44 PM   #19
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Quote:
Originally Posted by MrStevo View Post
you are right, it is...can't a reading for the throttle be taken in another way though?
Map based but u want throttle input for many reasons. How does it run? Videos?
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Old 02-17-2011, 01:51 PM   #20
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The throttle position can be estimated by the ECU, early Miatas have on/off switch TPSs. It just means the ECU has to be reactive rather than proactive in accel enrichments.

BTW, standalone tied in to stock ECU doesn't make sense. It's either standalone or piggyback.
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