Jump to content
SAU Community

Recommended Posts

I don't know for sure, but I'd be pretty suss of pushing a little GT2871R to around 20psi on a 2.5litre - I'd have thought that would be well and truly maxing the turbo out and doing some nasty things to exhaust pressure/temps?

I don't know for sure, but I'd be pretty suss of pushing a little GT2871R to around 20psi on a 2.5litre - I'd have thought that would be well and truly maxing the turbo out and doing some nasty things to exhaust pressure/temps?

+1

The science is with you on this one.

Not sure about ANY boost level being acceptable, as there are a few design limitations you need to consider. Like valve spring pressure, rod strength, chamber design, etc. Depends on what you call safe and reliable. I personally would think 1.1bar, but if you have a fat tune, no pinging and aren't pushing the turbo too hard I'm sure 1.4 bar could be considered safe - if given a large enough margin to cope with varying fuel, temperature, filter blockages.

But...a 2871 at over 1.1bar on a 2.5L would be running into choke (unless you taper the boost down as the revs rise ala Evo-style)

Edited by simpletool

I don't know for sure, but I'd be pretty suss of pushing a little GT2871R to around 20psi on a 2.5litre - I'd have thought that would be well and truly maxing the turbo out and doing some nasty things to exhaust pressure/temps?

Maybe not to redline, but in the midrange it will do 20psi, probably drop to around 15-16 by redline.

my highflow is built to similar specs and would peak to around ~19 at 3-4k then slowly drop down to 15 by 7500rpm.

Edited by Rolls

I pushed mine to 263rwkw on 20psi dropping off to around 17-18psi by redline (tuner didn't really do anyting with the boost controller so perhaps may have been able to hold 20 if setup right). Only reason I could't try to run a little bit more was that the old Microtech had a 20psi MAP sensor.

But yeah 18psi is about the sweet spot of the GTRS. Above that the only gains are in the midrange (because if setup nicely it will be on 20psi before 4000rpm), but not peak.

If you max out a turbo throughout the entire rev range it will always be able to flow more in the midrange (more psi) as more revs = more airflow needed.

So really if you want to get the most out of your engine and outright torque won't break it (build motor) then you should always be able to run x% more boost in the midrange than the top end.

i owuld be happy with 15 i just want it so i can drive it how i like and dont have to think about it giveing up !

If tuned poorly you could very easily destroy it on just 15, might as well spend the extra getting it tuned properly and run 18+ and reap the rewards.

If tuned poorly you could very easily destroy it on just 15, might as well spend the extra getting it tuned properly and run 18+ and reap the rewards.

true true !! the plan was wen the ecu gets done run 17 on high and 12 low on a switch as the ipec has its on boost controller ? ..anyways as i said i would be happy on 15 ..

Run low boost on hot days

Or just tune it with a coolant temp trim table, even a plain old nistune lets you do that. If it is going to ping on hot days then something is wrong.

Obviously within limits eg a 40c day, but you shouldn't be revving it out more than once in that weather no matter what the boost settings is imo.

Edited by Rolls

Or just tune it with a coolant temp trim table, even a plain old nistune lets you do that. If it is going to ping on hot days then something is wrong.

Obviously within limits eg a 40c day, but you shouldn't be revving it out more than once in that weather no matter what the boost settings is imo.

im in tas soo its always cold our best day may be 20c :) at night its around 7 to 12 :thumbsup:

Need more than coolant temp dude. Air Temp is a MAJOR factor. An once the cooler is heat soaked than ur up shit creek.

You could adjust the MAP sensor temp calibration table above 70°c intake or whatever was deemed abnormally high. I have no practical experience with this, but I don't see why it wouldn't work.

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now


  • Similar Content

  • Latest Posts

    • 2 does "sort of" applies, maybe......but looking at what parts would be needed for the swap to get engineered, registered, and insured, and basically that's everything under the car, the modifications the make it legal would be problematic and horrendously expensive, all for a street car that just cruises around and hits a few twisty roads on the weekends Also, from looking at the NSW rules and Regs, with all modifications that is required just to make the car safe and not twist itself to pieces, and then actually get registered for street use, may still be impossible nowadays As for 1, when you add in a fresh engine, fresh transmission, rear cradle and diff, tailshaft, suspension, brakes, cooling, and all the other fabrication required, your probably looking at up to $100k to do it right, all for a 20 year old MX5 that is over engineered and you would never be able to actually use the power it has on the street, much like your beastie, which I love, but you actually track that thing and can use all of its powers in anger, in a safe environment  Hell, the old Bogan Cruise Ship had more power than I could use on the street, and in hindsight, I went a bit silly on that thing, it didn't really need the 500hp it had for what I actually used the car for, it was fun, but basically unusable on the street if you value your licence  As for cams, yeah, I'll probably book it in for them to get installed and tuned soonish, like next month after MX5 Mania are back at work....... and yes, I've already sent a email to bin the turbo quote and quote instead to install cams and a new Fluidampr balancer that will suit the 2.5 better than the OEM 2.0 balancer that is swapped over for the 2.5 install, as the balancer needs to get pulled to time the cams it's a while your in there sort of thing I did think a bit about flex fuel for a laugh, but being na, and no where really around locally anymore to get E85, I've binned that idea, so no sweet sweet corn smells are set for the car I wish E85 was more of a standard fuel, it's better for the environment, better for tuning, plus that sweet sweet smell we all love As for fitting in the family, that's not needed, as everyone in the family already owns a car that can seat 5 humans comfortably enough, the MX5 is "my toy" As for buying a car that is already built, nah, I would rather pick and choose my parts, I enjoy the process, and in the big picture, the additional cost is well worth the enjoyment, and the occasional frustration, I get out of doing it, albeit with other people spinning the spanners, and me, just paying the invoice 🤣
    • Excuse me, but 2) does apply 1) Would also apply if you consider how much is spent in the alternatives. Also there's the option of 3), buy one pre-built that you can put your family in (it's me, it's my car)   That said, I went on a ~500km drive the other day. I didn't use anything more adventurous than 3rd/4th gear at about ~3000RPM and 50% throttle and I was going as fast as anyone has any sense doing on a public road, with enough grip to the point where I didn't want to go any faster. I was obviously under the limit of the current car etc etc. MX5 with 2.5 N/A to achieve the same speed would be more fun for any road scenario. Maybe consider cams. I wouldn't boost it. The use case is just not there and it won't actually make the car more enjoyable unless you really do plan on wringing gears from 1st to 3rd (at least) at 100% WOT on a public road to 150+kmh.
    • Great if: 1. You had all of the money for everything else that is required  2. Lived in a country where you could actually do this and drive it legally on the road Sadly, neither applies to me As for the turbo, I am having second thoughts, mainly for engineering/registration legality reasons and insurance  Not saying I've finished doing stupid things that I probably should do to the MX5, but boost, and V8 engine swaps isn't on the cards Strange, but true 
    • I like this page, better than that silly turbo kit   https://v8roadsters.com/product-category/engine-conversions/engine-conversion-lsx/engine-conversion-lsx-nc/  
    • That would be my Shoei helmet
×
×
  • Create New...