MrStevo

Hi there,

I am busy looking at buying a turbocharged mx5 and I am concerned about how the engine would hold up and how it would change costs if things go wrong? Obviously maintenance would be more frequent.

The car is a 1990 with 140 000km before the conversion, so obviously a 1.6 and it was rebuilt completely when the conversion was done to the car. The crank was replaced but I believe the rods etc are the same, I could be wrong but lets assume only the crank was replaced with a standard one. The custom conversion was done by a reputable performance company.

A t3/t4 hybrid turbonetics turbo was used along with an evolution external wastegate, BOV, front mounted intercooler and all the usual plumbing, boost controller and engine management system, full stainless steel exhaust and centerforce clutch. At the moment the engine has done 30 000km after the turbo conversion and is running at 0.9bar and pushing about 210whp. I would like to know if this would be all okay on the engine as a daily driver assuming the car has been looked after??

Any other information would be much appreciated

http://www.cardomain.com/ride/2242796

above is a link to a profile of the car

Thanks

kotomile

iTrader: (24)

Power seems a bit low at first glance, considering the large-ish turbo and 13-14 psi.

Is there a bottleneck somewhere? Conservative tune?

Assuming the car is quality (I can't see your link, firewall > me), it should be fine as a DD. The only thing here that scares me, since I'm going to assume the tune was done by someone competent, is the engine. What, exactly, was done to it? Something about a custom crank??

rider384

iTrader: (3)

0.9 bar is around 12.xish psi. A t3/t4 hybrid is a giant turbo. It should be making that power at half the boost. Something is wrong. If you're going to get a turbo Miata, build it yourself.

MrStevo

the early cars, 90 and 91, had a short nose crank which was not that great and in the end it would usually be a problem so the crank was replaced with a stock one. The guy who had the car when the conversion was done payed quite a lot and it was done by a very reputable company here. besides that I think the engine was just overhauled. Maybe the tune is very conservative to save the engine? how would a tune be limited that much though?

I wish I would do my own build but I simply dont have the money to do so...Could the T3/T4 maybe be fitted with a smaller turbine or something? The owner said it was custom

rider384

iTrader: (3)

I doubt a tune could be so conservative as to take a giant turbo @ 13psi down to 210hp. 13psi from a much smaller turbo has netted people more than that. It could be very simple (A boost leak, stuck open WG, that sort of thing) But it could be much worse.

kotomile

iTrader: (24)

Between that and the "custom" this and "custom" that on the car, I'm going to say pass too. Just too many unknowns.

MrStevo

you say much worse, can you give some examples?

MrStevo

the guy who did the conversion said the turbo was sized for 200whp, could that mean that its not a usual T3/T4?? He could have been aiming for a particular output and limited things to stay there?

rider384

iTrader: (3)

No offense man, but if you need examples of the problems that turbocharging a non-turbo car may cause, you really shouldn't be buying this thing. They're maintenance heavy beasts once they're turbo'd, and it sounds like you don't really have the know-how. I don't mean it badly, I'm just offering my advice.

MrStevo

No offense taken, you have a good point and I have just been looking into it. I'm not set on getting anything but I have just been trying to get information, you have to start somewhere i guess...

Braineack

iTrader: (62)

looks well built, turbo is just way too big to be efficient on that tiny motor.

wittyworks

iTrader: (6)

it also looks like the boost controller is reading off of the compressor housing pre intercooler, so the .9 bar it says it sees might be closer to .7-.8, making the 210 more realistic.

Braineack

iTrader: (62)

if the boost GAUGE is reading off the manifold, then you go buy that.

wittyworks

iTrader: (6)

I know that lol, just presenting a possible reason, so this begs the question, is the gauge reading off the mani

MrStevo

the boost controller was added, then taken off again, the owner said he had the overboost function taken off so maybe the reading was moved to the mani?

user 8392

I think that sound about right. 0.6 bar for me is about 170whp

rider384

iTrader: (3)

What's your setup?

Red94

I have also seen some pretty small T3/T4 hybrids, T3/T4s are pretty large family of turbos.

Braineack

iTrader: (62)

His compressor wheel is huge, his inducer looks larger than my exducer at 60mm. I bet that's the T3/To4E, so a 58.2mm/75mm wheel, which is about the size of the GT3076 compressor wheel. So that in itself will make the turbo produce zero boot until about 4K, where it will spike up fast. Then since it's a Turbonetics it's probably a Stage III or Stage V turbine in a .63 turbine housing, so the thing is never spinning as fast as it should, and completely out of it's efficiency window. So it will never make good torque and have relatively low output.

Much like this 3076 on a 1.6L:


This run was at 13psi.



The car looks clean and the setup looks well made, I like the manifold. I'd simply replace the T3/T4 with a 60 trim standard T3 with a .48 A/R housing.

MrStevo

ya it sounds like the turbo is way too big for the car to be efficient at all, the owner said boost starts kicking in at 3000rpm so it could be a slightly smaller turbo, torque is way too low though. I think going for a later 1.8 and doing a conversion would be a better option. Which later year of the mk1 would be the best to turbo?