MX-5 OC Forum

Hi All, Im looking for some information regarding the engine reliabilty of turbo charging my mk1 1.6

Please go easy as i am new to forced induction on the 5 lol, Basically i am buying a turbo kit wich is good for 250bhp, and would like to know if the cars reliabilty will suffer at all

what i am buying:

Turbo kit With front mount intercooler

Megasquirt Plug n Play Ecu

Uprated fuel pump

Uprated clutch

bigger injectors

Other than that the engine is not being uprated, just bolt on and go lol

any info would be gratfully apreciated

G'day Dai

Not really en expert on big bhp in a '5, mine only has 175 bhp on a supercharger. I do know of a number of cars that go to 250 without breaking up, but I would want to be pretty sure of the state of the engine before I went that far. The 1.6 '5 engine is based on the old turbo 323, so it's a pretty strong unit. Try posting your question on the mx5nutz forum, there is a lot more FI activity over there. Interested in why the 250bhp figure?

 Basically thats what the website claims the turbo is good for with proper setup: so just going by that lol

I've run a £500 second hand turbo set up reliably despite some very abusive driving (high revs and poor cooling airflow). 3 years and 10,000 miles trouble free apart from the fire.

I'm only running 6psi of boost though. And no control over spark or fueling apart from some retard and an AFPR (I know it's a bodge, but it works)

If you want to avoid a fire make sure you use good quality hose for your oil drain - mine became soft from the heat and oil, then split and dumped hot oil on the exhaust. If your kit is new you shouldn't have to worry.

 lol, fair enough mate, i think you prbably know the legend thats doing the conversion for me lol, mike stealth performance. He was the one that sr20d jamie kenyons mx5,

Dai1uk:

 Basically thats what the website claims the turbo is good for with proper setup: so just going by that lol

What website is it?

 http://www.cxracing.com/mm5/merchant.mvc?Screen=PROD&Store_Code=CXR&Product_Code=TRB-KIT-MIATA-16-IC&Category_Code=TRBMIA

Any Body used this kit before or know anything about them

Dai1uk:

 http://www.cxracing.com/mm5/merchant.mvc?Screen=PROD&Store_Code=CXR&Product_Code=TRB-KIT-MIATA-16-IC&Category_Code=TRBMIA

Any Body used this kit before or know anything about them

I've personally no experience of  this company. But I noticed a couple of things looking at that site. It says it is a 'bolt on kit' which would make me think everything should be included in the kit to fit and go. But there is no method included for adjusting fuelling or timing. I'd at least expect to see an AFPR for fuelling and something to retard timing if not an aftermarket ecu to do both. It has a stainless steel manifold which may be more prone to cracking than a well designed cast manifold. The site mentions bigger injectors but doesn't picture them or say what they are.

The generally used kits tend to be greddy (no longer made, often needs lots of its components replacing when upping power), hks (no longer made and oil return is through the dipstick tube!), BEGI (good kits on the whole, interesting customer service) and FM (good kits and good customer service - but that's just what I've heard).

I'd always go for something that has a cast manifold as these are much more durable (but the greddys needed relief cuts putting in them), FM and BEGI do reliable units.

For 250bhp with the standard compression ratio, it's going to have to run pretty rich at high boost to avoid detonation, and you'll need super unleaded.  Fuel costs will be high!

rogerzilla:

For 250bhp with the standard compression ratio, it's going to have to run pretty rich at high boost to avoid detonation, and you'll need super unleaded.  Fuel costs will be high!

Plus, in the end, it will be a 19 year old engine, with a 19 year old gearbox, differential etc. Putting a turbo on an older car is going to have different reliability issues from when these were 5-10 years old. One has to maintain a little bit of realism.

Mazda's own effort also uprated other items besides the clutch, such as the radiator, oil cooler, rods/pistons, head, gearbox, propshaft, driveshafts, suspension & further chassis stiffening; but then they also had a warranty to stand by.

I'd do the suspension and brakes first if they are stock at the moment. 

Edit: FM definitely the best.

There are people putting turbos on older cars and getting high power figures without too many relaibility issues, but obviously the older the car the more you have to be happy that the car has been well maintained and be prepared to uprate a few parts here and there.

If it's a 1.6 with 250bhp you will quite probably have to uprate the diff to deal with that power level, a 1.8 unit would probably do it but if going to that hassle you might as well put a torsen in, for this you will need not just the diff but the prop and halfshafts too. You will need an uprated clutch to deal with that level of torque as well.You will probably want to upgrade the brakes to 1.8 units as the 1.6s are on the small side for that power level, uprated pads and braided hoses lines will make sense too.

You won't necessarily have to run super unleaded but it will give an extra degree of safety.

I've been running a 1990 1.6 with 212bhp at the rear wheels (as tested on a dyno) for nearly 10 years now and have covered around 50K miles with it. It's also had a lot of track action - I do around 5-6 track days a year.

The rule of thumb for Mk 1 1.6 is that you can go to around 12-15psi maximum boost without having to strengthen the bottome end or go for different pistons, lower compression etc. Flyin' Miata have been offering 12 psi kits for years and some of their customers have over 100K miles on a turbo engine.

You do need a programmable ECU (I have the Link but Megasquirt is well known) and bigger injectors but if the programming is correct you don't need a bigger fuel pump - I'm still using the original one! Yes you do need a reasonable size intercooler and I would echo the comments about the manifold - cast iron ones seem to be more durable. you don't say what type of turbo is been used and whether it is water and/or oil cooled, I think that you need both for longevity since it gets pretty hot! I'd also strongly recommend spending money getting the ECU properly set up - it's all too easy to get detonation (does the kit have a knock sensor?) and wreck your engine.

What's been my experience? First I needed a new clutch since the original couldn't handle the power and I fitted a stronger diff with a Torsen LSD as a precaution. The biggest issue has been heat - especially on track when water and oil temperatures can soar. You might get away with a standard radiator but you'll need to make sure that as much air as possible gets through especially since you're likely to have an intercooler radiator mounted in front! I have a double capacity radiator, oil cooler, coolant re-route and two extra powerful cooling fans in a shroud that have solved all my cooling problems. Possibly OTT but I'd rather be safe than sorry. Finally another worthwhile mod is to use a dual feed fuel rail ( the standard fuel rail is fine for NA cars but there is a view that with the higher fuel demands of forced induction the farthest cylinder can be starved of fuel unless you add a lot to compensate). I found that when I fitted this I could reduce the fuelling significantly at high boost suggesting that there is a potential issue there.

It's been great fun and transforms the car - of course if you're going faster you might need to uprate brakes and suspension too !

 I should have looked at the website! I see they're suggesting 180-200 rwhp which seems reasonable for 7 psi - you would probably be needing closer to the 12psi to get around 250bhp at the crank. The picture also shows what looks suspiciously like a larger capacity radiator to cope with the extra heat. It's interesting that they describe this as "bolt on" since if the turbo is oil cooled you'll probably have to drill into the oil pan being careful to avoid damaging the oil pick up!