Value 1.8 NB Turbo Build, Input Needed
I've already got a cat, so I'm planning to boost my car.
(Kinda) useless details about it : 2003 NB SE, called MX-5 Twins Sport Brakes/Braces 5spd 4.1 Torsen T2 LSD D2 Coilovers Kinda more useful info about it : 1.8 VVT EUDM engine, it's got the squaretop intake manifold afaik It originally was a 1.6 car, and during the swap we already tapped into the oil pan for oil drain. MS3 Mini w/ Innovate wideband 52mm alu ebay radiator with silicone hoses I'm putting a 6spd before boosting Parts I've already got : ACT 6puck sprung disc Used FMIC setup, 2.5" coldside, 2" hotside, intercooler the size of the miata's mouth, routed straight front and down the radiator. Will require cutting the finish panel Audi S3 mk1 bov Maxpeedingrods GT2871 turbo Used genuine rx-8 yellows Parts I've planned on getting : custom shop-built 70mm turboback with two big resonators ebay cast iron t2 manifold custom strengthened oem pressure plate mac ebc valve (probably genuine, but are ebay ones worth it?) ebay replica boost, water temp, oil temp, exhaust temp gauges to get a vague reading Kemso/Walbro uprated fuel pump Goal : Taking the stock motor to its limits, reasonably. It'll be a street cruiser, with the occasional drag race, occasional skid. No track time, or heavy abuse. No money wasted, but I don't want to end up with something totally unreliable either. I want it to be a value for money build. I don't mind some extra turbo lag or 20-30 less hp compared to a far more expensive setup. Would you change something and why? Thanks |
While it's apart, and easy to do, I'd go with a better pressure plate, as in a matched set of disc and PP, and ditch the injectors for a matched set from Nigel, and get real, quality gauges for temp and oil pre. just not worth wondering if the numbers you are seeing are accurate or not.
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Originally Posted by tomrev
(Post 1553719)
While it's apart, and easy to do, I'd go with a better pressure plate, as in a matched set of disc and PP, and ditch the injectors for a matched set from Nigel, and get real, quality gauges for temp and oil pre. just not worth wondering if the numbers you are seeing are accurate or not.
Quality gauges would be great, but they can get stupid expensive to the point a single one can cost more than my turbo. I mean I won't be hitting the track with it, and all I want is to know then the car is up to operating temp, and when it gets into danger zones, eh, accuracy aint all that much of a priority Hm, what about the injectors? Am I going to run into fueling problems? Won't 425cc be enough for couple horsepower under 300? I am gonna send them to get cleaned and flow tested |
Just found this while googling :
A quick trip to the injector calculator shows that at 250 crank hp you are needing about 430 cc @90%. so you are probably maxed out. Oh well. I need to research some more on injectors or decide to stay at 250hp. |
Originally Posted by carhub_miata
(Post 1553738)
Just found this while googling :
A quick trip to the injector calculator shows that at 250 crank hp you are needing about 430 cc @90%. so you are probably maxed out. Oh well. I need to research some more on injectors or decide to stay at 250hp. |
Originally Posted by tomrev
(Post 1553740)
Nigel, at Flowforceinjectors, will set you up with modern, EV 14 style (off the top of my head) injectors that will have a better spray pattern, and all 4 will be closely matched for flow. I'd recommend the 640 cc set for you power plans, and added bonus is the improved idle they will bring. I have used AutoMeter gauges on a lot of project cars, and find them to be accurate, and reasonable in cost. Cheap Ebay gauges will probably not be any more accurate than the stock dash, so no benefit in my mind. The important ones are, of course, oil pre., but specific to a Miata, the coolant temp., as it's easy to cook a head while a shitty gauge is getting around to telling you about temps.
Good points indeed. I may opt for used genuine gauges. |
430cc injectors won't get you to your power goals.
I strongly recommend flow force 640cc. They're awesome, and on my setup got me to 309whp |
Originally Posted by borka
(Post 1553748)
430cc injectors won't get you to your power goals.
I strongly recommend flow force 640cc. They're awesome, and on my setup got me to 309whp |
My initial plan was to retain my current custom 60mm exhaust (two big mufflers on it) and create a custom 70mm (2.75in) downpipe that will connect with a reducer to the current exhaust's middle muffler.
What if I do that, with the exception of a vacuum actuated cutout right before the middle muffler? Won't that allow for more top end hp and less noise during cruising compared to a 70mm turbo-back with just a muffler on the end of it? Also, people say rods are good for X tq. If you gain tq up top due to a freeer flowing exhaust, will the rods still endure more abuse, or are you just getting free torque that would otherwise be lost due to exhaust backpressure? |
Cylinder pressure kills rods. Those numbers are averaged guestimates from years of engine failures. Nothing scientific is involved in arriving at them.
Cut outs require tuning for them. If it always opens at WOT you can maybe tune for it, if you are lucky. If it is a sometimes thing it will make the tune rich or lean in boost and can cause it to detonate and destroy the engine. |
https://loudvalves.com/collections/b...nt=32909551436
That's the ideal cutout solution IMO. It should eliminate the potential tuning issue. |
Originally Posted by sixshooter
(Post 1554321)
Cylinder pressure kills rods. Those numbers are averaged guestimates from years of engine failures. Nothing scientific is involved in arriving at them.
Cut outs require tuning for them. If it always opens at WOT you can maybe tune for it, if you are lucky. If it is a sometimes thing it will make the tune rich or lean in boost and can cause it to detonate and destroy the engine. That makes an absolute lot of sense. It'll be just like the one Spartan linked, it will be vacuum actuated, it'll have a wastegate on it, so as long as the vacuum hose remains intact and it's tuned correctly, it should be fairly fine. In fact, why not put my oem exhaust back on, and buy a cutout that opens up with positive manifold pressure? Off boost it should sound even more quiet than stock, it'll have a cat on so it won't be smelly and it should offer reasonable backpressure to allow for some more fuel eco. And when map exceeds -3psi for instance, boom it'll open up and go fast. |
Just get a 2.75-3" free flowing exhaust with the huge magna flow muffler that me and everyone here runs.
It's a fairly quiet and great deep sounding exhaust, quiet while cruising and deep but not loud at WOT. With the cutout it will be crazy loud and attract every cop in a 1 mile radius every time you press the happy pedal. |
Originally Posted by borka
(Post 1554346)
Just get a 2.75-3" free flowing exhaust with the huge magna flow muffler that me and everyone here runs.
It's a fairly quiet and great deep sounding exhaust, quiet while cruising and deep but not loud at WOT. With the cutout it will be crazy loud and attract every cop in a 1 mile radius every time you press the happy pedal. I put my foglights back on, oem chrome badge, traded my front blacked out headlights for stock ones and I'm putting oem 15" enkeis back on. It'll look cutesy and stock so I ain't very scared lol. I mostly need to figure out the technicalities |
You want a full 3" exhaust.
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Originally Posted by shuiend
(Post 1554359)
You want a full 3" exhaust.
Now in theory : 1) I'll get an exhaust valve with a -3psi actuator, or something that opens up during positive manifold pressure. 2) Said valve will work properly 3) Car will be tuned correctly and will not be tuned to the "limit" 4) I won't get into trouble with the law 5) The ecu will have AFR limit fail-safes tuned correctly so that even in case something goes wrong, power will be cut, my motor will be given a second chance. Now I'm a newbie, these are all just my theories, I ain't buying exhaust parts yet and not willing to until I fully understand what I actually should do, can you explain why said plan is a bad idea and I need a full 3" system? |
Because anything smaller then 3" leaves mid range spool and torque on the table for exactly zero difference in cost. This is something we learned over a decade ago by doing back to back testing.
I am not saying you can't have a cut out or anything like that. Just that you want to up to 3" as soon as possible in the exhaust. |
Originally Posted by shuiend
(Post 1554368)
Because anything smaller then 3" leaves mid range spool and torque on the table for exactly zero difference in cost. This is something we learned over a decade ago by doing back to back testing.
I am not saying you can't have a cut out or anything like that. Just that you want to up to 3" as soon as possible in the exhaust. What if after the donwpipe, there's a Y pipe, where on one end there's a 3" cutout that opens up past -3psi of boost pressure, and on the other there's my stock exhaust or my current 2.4" system with two straight through mufflers? |
Why do you want a cutout so bad? I mean, a turbo miata is already a cop magnet.
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Originally Posted by ryansmoneypit
(Post 1554392)
Why do you want a cutout so bad? I mean, a turbo miata is already a cop magnet.
It's going to be really loud and exciting when I want and can thrash it It'll essentially be a 3" straight through system with minimal backpressure when I need the flow It'll be damn cheap, im saving up a considerable chunk of money if I do it this way, compared to a full 3" system with a big magnaflow and a resonator. Now, what I'm wondering is, except for the noise, what downsides can such a system have assuming everything works out the way I intend it to? Could it for instance significantly hurt my fuel economy due to excessive cruise backpressure for instance? Boost buildup shouldn't be a problem as the exhaust will open up as soon as I go wot, where it should be even better than a proper full 3" system |
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