Linear torque curve

metris · Postby **metris** » Mon May 04, 2015 8:24 pm

Hey all, I'm in a roadster again finally after a long stint with e30's! (Still got the dirty e30 too).

I'll be using it mainly for hillclimbs, road rally sprints and track days to begin with, and road rally and time attack one day soon... when I can afford them haha

I bought a 92 off mr bender with the following:

*b6 (1.6L) rebuild motor (forged pistons and upgraded rod bolts)
*rebuilt Trust TD05 18G turbo, Tial 38mm external wastegate
*Steam pipe manifold
*big intercooler
*plumb back BOV
*2,5in exhaust
*haltech sprint 500
*large fuel pump
*kelford 256 cams
*850cc injectors
*52mm radiator
*ATI Super Damper
*cam gears
*ls1 coils
*polyurethane motor bushings mounts
*runs on E85
*twin plate clutch

I knew from research that the TD05H-18g was going to be far too laggy and far too top end for the tight windies, but the engine work is a great foundation and the interchangability of the TD05's gives me a few options...

So, I was hoping to get some advice or personal experiences before I embark on this journey.

I figure I'd have to jump straight to the smallest TD05, so my questions are directed that way, but please feel free to offer other suggestions!

-Is it possible to get a relatively linear torque curve with a TD05-14b?

-Does the 14b run out of breath up high even on a little 1.6?

-How much really can you adjust the torque curve with tuning?

-Does a short intake tract (inline water-air IC) really reduce spool time noticeably?

-What do you guys think is the max power you can put thru an mx5 before your concentration on throttle control starts taking away from your concentration on max cornering speed? Ie. What should I be aiming for?
(With 15x9's 225/45/15 Hankook RS3's for example)

Any help is greatly appreciated and I hope to return the favor once I refresh my mx5 knowledge!!

Postby **NitroDann** » Mon May 04, 2015 8:29 pm

metris wrote:Hey all, I'm in a roadster again finally after a long stint with e30's! (Still got the dirty e30 too).

I'll be using it mainly for hillclimbs, road rally sprints and track days to begin with, and road rally and time attack one day soon... when I can afford them haha

I bought a 92 off mr bender with the following:

*b6 (1.6L) rebuild motor (forged pistons and upgraded rod bolts)
Good
*rebuilt Trust TD05 18G turbo, Tial 38mm external wastegate
[bGood[/b]
*Steam pipe manifold
[bGood[/b]
*big intercooler
[bGood[/b]
*plumb back BOV
[bGood[/b]
*2,5in exhaust
[b}Not a 3" straight through but good[/b]
*haltech sprint 500
Basic but good
*large fuel pump
Unecessary but good
*kelford 256 cams
Good
*850cc injectors
Good
*52mm radiator
I hope it has all of its ducting in place, good
*ATI Super Damper
Good
*cam gears
Probably useless but wont hurt
*ls1 coils
Good
*polyurethane motor bushings mounts
Good
*runs on E85
Good
*twin plate clutch
Good

I knew from research that the TD05H-18g was going to be far too laggy and far too top end for the tight windies, but the engine work is a great foundation and the interchangability of the TD05's gives me a few options...

So, I was hoping to get some advice or personal experiences before I embark on this journey.

I figure I'd have to jump straight to the smallest TD05, so my questions are directed that way, but please feel free to offer other suggestions!

-Is it possible to get a relatively linear torque curve with a TD05-14b?
Absoilutely but how much power that is I cant say without a flow map, do you have one for this turbo?
-Does the 14b run out of breath up high even on a little 1.6?
Not if you tune it not to
-How much really can you adjust the torque curve with tuning?
Almost completely.
-Does a short intake tract (inline water-air IC) really reduce spool time noticeably?
No
-What do you guys think is the max power you can put thru an mx5 before your concentration on throttle control starts taking away from your concentration on max cornering speed? Ie. What should I be aiming for?
(With 15x9's 225/45/15 Hankook RS3's for example)

Its max torque not max power. 250 ft lb is starting to get difficult for most people in lower gears.

Any help is greatly appreciated and I hope to return the favor once I refresh my mx5 knowledge!!

Any time.

Nevyn72 · Postby **Nevyn72** » Mon May 04, 2015 9:00 pm

NitroDann wrote:
metris wrote:Any help is greatly appreciated and I hope to return the favor once I refresh my mx5 knowledge!!

Any time.

Listen to this man, he knows what he's talking about...... :wink:

metris · Postby **metris** » Tue May 05, 2015 9:33 am

That's great news, thanks!

I found this flow map, it's a little hard to read but the only one I could find:
http://www.stealth316.com/images/td05-14b-raw.gif

I'll check the rad ducting is still in place, if not I'll make something out of an old real estate sign and some cable ties!

I'll replace the exhaust with a 3" straight thru eventually.
Until then hopefully with the 2.5 it will still spool nice n early. This 2.5 sounds soooo sweet too!! It'll be a shame to replace it.

Can you fit a 3" dump? It currently has a 2" > 2.5 dump.
The exhaust looks like it follows the original route but with a straight thru muffler.. can't remember if it's mandrel bent or not... Will have to check.

Postby **NitroDann** » Tue May 05, 2015 9:43 am

According to that map, that turbo is tiny. 150rwhp tiny.

You will get a flat curve out of that easily.

Dann

metris · Postby **metris** » Tue May 05, 2015 11:49 am

NitroDann wrote:According to that map, that turbo is tiny. 150rwhp tiny.

You will get a flat curve out of that easily.

Dann

Ah I may have jumped to the extreme with that one... too small for me...

The other options are the TD05-14g but they seem really rare, and the TD05-16g but I've read a few miata owners found it too laggy... Could it be their tune?

Here is the map for the 16g:
http://www.stealth316.com/images/td05-16gsmall-raw.gif

metris · Postby **metris** » Tue May 05, 2015 6:45 pm

NitroDann wrote:According to that map, that turbo is tiny. 150rwhp tiny.

You will get a flat curve out of that easily.

Dann

Hey Dann do you think the reason this guy is getting bigger numbers is because he is out of the turbos efficiency range?

http://www.miataturbo.net/dynos-timeshe ... psi-50724/

Or is it that if the focus is on creating a linear torque curve, it usually results in lower than potential peak power?
That tune certainly want focused on linear torque...

Postby **NitroDann** » Tue May 05, 2015 7:00 pm

I wonder about the accuracy of the graph you gave, and the accuracy of the tools I used to calculate HP.

Why dont you just run a GT2554r?

Flat torque is achievable through tuning, Here is an example that I did recently on a high hp(ish) car. This needed quite a combination of methods to limit torque in the low end and we couldnt get it dead flat with the time we had, but if gives you a good idea. It wanted to make a LOT more midrange, where the waves are.

Dann

metris · Postby **metris** » Wed May 06, 2015 9:29 am

NitroDann wrote:Why dont you just run a GT2554r?

The only reason is the manifold and dump. If I can achieve what I want without having to replace them or chop flanges, I'd much prefer it. If I can find something in the TD05 range that suits, it'll be a straight replace and off for tuning woohoooooo! (Hopefully)

I just wanna start racing again asap... I was racing my old mx5, then switched to e30's for out-of-the-box power and apparently good handling (nope!), but never raced cause it took me so long to get it to corner as good as an mx5 (which I eventually managed with custom designed coilovers haha), and don't even mention the steering rack!
....7 years later.