Ideal turbo specs?

[wiggy]

Hi all

Just wondered if someone could point me in the right direction when it comes to the IDEAL turbo specs for the FD...

I am currently shopping around and the choices are endless when it comes to turbos. I could be boring and buy a complete kit for the FD, but wheres the fun in that

I need to know A/R\'s etc and if someone has it, a turbo map would be useful

The car will be used with a mix of RWYB days, track days and some daily drives. I would ideally like something that spools quick and can maintain boost at high revs.

Being new to the whole rotary thing I am still on the learning curve to know whats best suited to the lump. All advice welcome chaps.....

Cheers

[Fish]

Save yourself a load of time and effort. Get yourself a GT35/40 kit.

Fish

[wiggy]

Hi Fish

Cheers for that, whats the spec on that bit of kit? know where I can get any flow maps for it fitted to an FD? Who sells the kit? How much?

Any detail you have I\'d appreciate so I can make an educated choice when the time comes.....

Ta

[bill shurvinton]

No such thing as Ideal. But some idea of what you want from your FD might help.

[wiggy]

As I put in the original post its going to have a mixed bag of uses really.
Track days (low down power for getting out of those bends)
drag strip (high end power for the red line)
Daily drive from time to time (bit of both of the above)

I can have different setups stored though for different situations so driveability shoudn\'t be a prob. And a quick re-map on the back roads is fun anyway

Things I don\'t want:

waiting half a year for the turbo to actually do anything. I am told though, the rotary breaths more/better due to lack of gubbins on a traditional motor such as valves etc.  For this reason its more the size I need to know thats useable on the rex.

So I guess what I\'m asking is whats a good all round sized single turbo? This is why I wanted to see some flow maps of various turbos on the rex so I can decide whats going to offer me what I want.

Its ok someone saying the T67 is a great turbo but I\'d like to see why its so good in terms of flow and when that flow happens.

Surely there must be info out there on turbo specs etc??

[bill shurvinton]

Try google. The maps for most turbos are out there just a click away.Then you can have a look at them and work which match your requirements.

[Grizzly]

You are going to struggle, You want a Fast spooling big HP turbo.

I think Fish is proberly right GT3540,T04S,60-1, somthing like that.is the best of both worlds, you want to be looking at what Hot side AR you want.

Also what HP you going for? i am presuming you\'re looking for the 400\'s

Chris

[wiggy]

Hi Chris

I never like to say what power I want (I have to get it then) 400 would be nice and I think plenty for my needs.

Obviously there are a lot of turbos on the market and deciding which to buy or use is a challenge to say the least. I do have a Monster stone Super T70 BB turbo which I got for the GT4 and never used as I thought it was a bit big for that application and went for the TD06-20G. I am concidering trying the T70 out on the rex though to see how it goes?

The specs are almost the same as the Garrett T61 I\'m told. It has a turbine housing A/R of 0.84 and compressor housing A/R of 0.70

further input and assistance appreciated

Cheers all

[Grizzly]

Well i had a Turbonetics T66 with a 1.15 on a half bridge at one stage and that was a bit slow on the spool up. If you are going to be looking for 400\'s and using it on the road dont get too big a Turbo.

If your only going for the 400rwhp mark get your self a GT3540 you will have a smile from ear to ear. (Just make sure you get a biggish AR Exhaust housing (1.15 ish)

The cheaper option is a t4 60-1 they happily make 400bhp but are a bit slower on the spool than the GT but you can get a good Divided duel length manifold that can help with this.

O yeh you have not even got into the Manifold lenths yet.

Chris

[wiggy]

Thanx for the input...

Out of interest, wheres a good place to buy a GT3540, what flange do they have (manifold side)

Whats all this about manifold length then? I know the pipes need to be equil length but does having them longer or shorter make any odds??

Cheers

[Grizzly]

Basicly the shorter the manifold the better it spools, the longer the better the power.

It also changes the power delivery.

I have just had a 13" Devided manifold done but i\'m sorting out my T04R on a Bridge.

If you go for the GT3540 there is plenty of kits you can buy, they have a T3 Footprint and are a fairly small\'ish looking Turbo (dont take up too much space) which is also a factor on an FD, but the main Plus is it\'s a much more up to date Turbo, there for has a Full RB Core and Aerofoil blades (more efficant).

Chris

[bill shurvinton]

Originally posted by Grizzly
Basicly the shorter the manifold the better it spools, the longer the better the power.

It also changes the power delivery.



Chris

Well there\'s another couple of laws of thermodynamics thrown out the window for you.

You are badly wrong on this.

[Grizzly]

Ok, Sounds like you can explan better, this is the layman terms it was origanaly explained to me. I have a few manifolds and it seems to work to me? but if i\'m wrong put me right, i can only live and learn.

Chris

[bill shurvinton]

It\'s a complex interaction of the following:

1. Heat. The turbine extracts heat from the exhaust gas, so the hotter it is, the faster you will spool. Conversely too much heat at the top end and you melt things (inconel turbine blades are an option on some  turbines). And this is why you retard the spark to help spool. Retarded spark means hotter exhaust

2. Velocity. You want to be near supersonic flow into the turbine. Fast flow is fast spool, but you can choke at higher flow rates. Divided turbines aid velocity.

3. scavenging between rotors. If you get a tuned length on the exhaust, then you get enhanced low end VE, which helps. Part of the reason why the OEM inlet systems are so sh!te as they are designed to maximise torque at 4500RPM. Generally the longer the primaries the better, but there are books written on the different operating modes of exhausts and how to optimise them. In the end few can afford days on the dyno testing theories so just go with what fits easily.

4. Balancing the operating phases of the turbine between pulse mode and constant flow. You have a very high energy pulse at the beginning of the exhaust cycle that can be used to not only give the turbo a big kick, but also help in 3.

5. Dealing with the packaging issues, which usually mess up all attempts to actuallly optimise things.

Remember the first 2 laws of thermodynamics, which in laymans terms are

1. Heat is work and work is heat
2. You lose. (and yes that is the crux of it. You cannot win, and you cannot even break even as far as mother nature is concerned).

And I do not have the definitive answer on this as I still have much to learn on the subject. Gimmie 20 years.

Bill

[wiggy]

Keep this up fellas, the spare part of my noggin I set a side for learning about rotaries is lovin it

Can\'t beat a good technical debate, its THEE best way to learn stuff

Respect