Choosing and Building an 1.8 Turbo engine for NA 1.6r
 

I currently have an NA with 1.6, stock internals, with GT2560R ball bearing turbo, MAF less tune, Intercooler, 550cc injectors, bigger fuel pump, Wolf 3D V4 Computer, running up to 14psi boost. Engine always has and still is going fine as I run the tune a bit rich top end to look after it and always run 98RON fuel. I have upgraded everything else in the car in readiness for eventually going for more power. I have a 1.8 torsen, mazdaspeed 6 spd box, mazdaspeed brakes, Tein super streets, full superpro bushes, front/rear subframe braces, frame rail braces, butterfly brace, frog arms, custom roll bar, sparco sprint V seats, as well as cosmetic stuff like new carpets, full respray in original colour, all new trims, new mohair softop etc etc but am undecided on how to proceed with the engine upgrade so would like some constructive advice. Currently around 220HP but would like to step up to 300-320HP, and still have it as a road car for occassional track days . My feeling was to get a low klm 1999 1.8 high port without VVT and build with eagle rods, weisco pistons, acl race bearings, arp head and rod bolts, put an ATI harmonic damper on it and so on but leaving the head as is (apart from adjustable cam gears) but basically going for what I can without making the car unreliable at up to 20psi of boost, which should give me the power I am looking for with useful gains in torque also once properly tuned. Not sure till I get to tune how efficient this turbo will be at that boost but it is responsive so would rather keep it in preference to a larger turbo. Other options would be all of the head work, valves, springs/retainers, billet caps and also porting and such but I would like to know if the gains of doing this would be marginal for the level of power I am looking at as the cost starts to really get away from you and at some point it looks better to do a V8 swap and I would really like to keep with the basic Mazda gear. I guess I'm resolved to do it but I'm looking for some Brainstorming feedback.

put on your flame suit, this has been discussed many times!!

220whp on that turbo at 14psi is WAYYYYY low. I made 200whp on a 1.6 with a GT2554R and a stock exhaust at 15psi.

and a return key.

Geez guys, hammer a guy that has done more to his car than 70% of the posters here. He's obviously from outside the country which had to cost him double to do what he has done so far. Save it for the "which china kit should I buyz" crowd.

That said, yes, I believe you are on the right track with your motor selection. The 99 head will pay dividends. Forged rods and pistons-which compression ratio is always a topic of discussion here. Unless you are planning on raising the revs to 7500+ the stock valve train will do what you want. Oher than casting cleanup, you don't have to get carried away with porting. The stock head is good for 300. You don't have to get carried away.

Stick with the 2560 for now but it may run out of steam around 280. If it won't get you to where you want to go, you can get into a T28 variant which will fit the same mounting footprint as the T25's. GT2871 has been used here with success.

What are you going to use for a mani/DP? Plan on 3" exhaust all the way through.

Oh, and welcome to the forum.

Thanks Stein. You're right, I'm from Oz. I have done a bit of searching but they mainly relate to other peoples circumstances. Thanks for the advice, if I do what I'm planning and want more power a turbo swap could be something worth doing later but other than that I might invest in my own driving ability also as with 300hp it should be formidable around the track and on the road. Thanks again.

Yeah, you are already going to be investing a pretty penny getting the 99 1.8, getting it up to snuff, plus manifold and downpipe. It will get you to 280 easy and you won't have to touch 20 psi to do it. Probably 16 but just guessing.

I was going to get the cast manifold from Flyin Miata with their cast downpipe. I got my turbo from AVO and the downpipe may not be perfect. Maybe the FM one is better. My current exhaust is 2.5" but you are right, with more air flowing a 3" might be the go also. I was looking also at the kit from Belfab with the rods and pistons. They also look good due to the lower expansion pistons. I'd be interested in any comparison with the Weisco/Eagle scenario as the cost is similar.

That is definitely something you can search under "Belfab" and "Weisco". Lots of threads.

FM and Begi both have good cast manis.

200some odd whp at 14 psi? Dude that shit is way low, throw some WI on there and regain some of your timming along with a bigger turbo and viola 300 is atainable stock. The belfab rods are pretty damn good, and affordable fwiw.