Aftermarket turbos vs. Stock turbos
 

Hey guys new to this forum and am looking into maybe getting a begi-s or jrsc mp45. (I know go with begi-s)

Anyway I have heard a lot of criticism towards the MSM NB and honda s2000 having too much lag or feeling stockish before over 5000 rpm. I was just wondering why the aftermarket turbos don't get this same complaint. Especially the higher horsepower kits that Begi and FM provide. I am assuming boost comes earlier. Do automanufacturers have boost come later for better fuel economy? Anyway I am a FI newbe and I learned a lot about turbos within a couple days just from this forum and am just throwing this out there.

By the way I have a Black NB with intake, headers, exhaust and a couple of suspension mods.

first off.... the S2K is Not a turbo car....

2nd, the response from a factory turbo is limited by both restrictive intake and exhaust systems, as well as ecu mapping.

A simple exhaust and intake upgrade on an MSM frees things up quite a bit IHMO

People tend not to complain about response time on their aftermarket kits because they know what to expect from them. OTOH you will find quite a few threads on other sites complaining about the response from some of the aftermarket turbo options out there.

There is a tradeoff between response and outright HP capability. I for instance have sacrificed some response in my quest for horsepower. Aftermarket "kit" options from FM and BEGI have very nicely researched and sized turbo options that should appeal to the vast majority of enthusiasts.

People love to whine and cry about "lag" which is actually "positive pressure threshold." No blower is going to make 200lb/ft at 2000rpm...period. If you're worried about "spool" then buy 3" exhaust and a gt28r which will make 8psi at roughly 3000rpm according to most people here. Where the turbo makes lets say 75% of max torque, the blower is only going to make 50% or less because of the mechanics behind it. However the blower will make noise and you'll think your going faster than you are outside turbo boost threshold.

If you're expecting to make peak torque below 4k rpm, you should kill yourself because you've failed at life.

my 1.6L T3 with 3" exhaust vs a stock 1.8L MSM turbo with 3" exhaust:

http://www.boostedmiata.com/dynos/scott_vs_evan.jpg

where is all that power from the msm coming...the exhuast?

My sister bought 2.5" exhaust on TDR's recommendation which I said was stupid considering another $150 would get her a 3" enthuza. Her car makes 152whp...lol.

we were both running 12-13psi, and ultra low restriction turbo-back exhausts. but i gotz the low end :)

Before I went with my turbo setup, I did a couple of charts where I overlayed dyno figures from, say, a JRSC vs an FM-I on the same plot. I was specifically looking for the point at which the torque output of the turbo crossover over the torque output of the supercharger, "knowing" that turbocharged engines do not make torque at the bottom end.

What I found blew me away. Typically, the turbo setups that I looked at surpassed the supercharger systems by at most 3,000 RPM, some of them closer to 2,500 RPM.

Here's the only one of the charts I made that I can find. This shows a '99 with an FM Voodoo-1 vs a '99 with an Ubercharger stage 1. Since they are both FM products, tested on the same dyno, and set to the same level of boost with the same engine management, I felt this was probably a fairly accurate comparison:

http://img511.imageshack.us/img511/8...perubervd3.gif

Really opened my eyes...

god look how flat that SCer torque curve is!

but made like 35# less torque! :eek:

It was really a startling revelation when I saw the two curves printed together on the same piece of paper.

Yeah, the S/C torque curve is damn near flat. And yeah, the S/C makes more torque at the bottom end (about 9 ft/lbs, at the highest point). But by 3,000 RPM the two are dead-even, and after that the turbo just keeps climbing.

Now I grant you- If you're just tooling along the highway at 3,000 RPM light cruise and suddenly decide to floor the pedal, the S/C will have a slightly faster response time. But is that really worth the huge trade-off in power at 4,000 and above?

here's a good one for you joe.

mine vs a 99 MP62:

http://www.boostedmiata.com/dynos/scott_vs_99mp621.jpg

it would only take a quick burn of the MS (1psi on the EBC) to surpass it from 3500RPM up.

The stock cams in the miata suck balls till 4500 rpm anyway..

I know this is an old post; stumbled onto it just now. My car during that test had the puny stock IC and stock computer. Since then I upgraded to a large IC, Megasquirt, larger injectors, and ported turbo set at 14psi. Wanna rematch? :laugh:

yes. will it have working cops?