www.RX7fb.com

Lucky wrote:Are the turbos so small due to the problems of cooling the charge? Obviously you can't have a carburetted application blowing through an intercooler cos then that makes basically a bomb out of the 'cooler. Maybe the turbo is kept small to avoid shoving too much air in too hot?

All turbos have a sweet spot, measured in % that represents the adiabatic effiency of the turbo - a small turbo with high boost will thrash the air and heat it up far more than a larger turbo that will shift more air at a lower boost pressure - trade off if a higher moment of intertia to reach the same air volume. Read that as 'lag'. Much generalisation in there but you get the point.

The aim of the game isnt how much boost or air mass enters the engine, its the oxygen content of the air - cooler air is more dense (more O2 %) so a lower boost, cooler charge makes more power that a hotter higher pressure charge. Intercoolers reclaim some lost efficiency, but as they are also a restriction to flow they will reduce pressure before and after the turbo - at least 1psi, but could be 3-4psi. Lucky - where do you take your boost reference from? The inlet manifold is a more accurate source of pressure for both a boost guage and the ECU, but the turbo outlet will exhibit a higher pressure ratio than this.

If you have the spare time, connect you boost guage to your turbo outlet and check the boost - compare to what you expect and see how many PSIs are being lost through your cooler. In the case of an intercooler upgrade, trhe benefit can be 2 fold, cooler air becuase it has more cooling capacity, and lower turbo pressure for any given manifold pressure which further reduces the temp and increases density.

Rogier wrote:

ruby wrote:does anyone know what it means if you have a tag on the glove box that says ´´black rotary nr18´´

Having asked a bunch of people i thought i´d ask here :p

thx anyway

I believe it was a limited edition, black exterior, lether interior and I believe special rims etc. Pretty rare I think. Take good care of your car, it's a keeper!

wow nice to know and it would explain the different rims and why i have a washer bottle for the headlights Altough i haven´t got any nozzles on the bumper

Lucky wrote:Are the turbos so small due to the problems of cooling the charge? Obviously you can't have a carburetted application blowing through an intercooler cos then that makes basically a bomb out of the 'cooler. Maybe the turbo is kept small to avoid shoving too much air in too hot?

i thought about using water injection to cool the air but since i´m not familiar with it i really don´t wanna try it because i don´t know the engines either but i´m planning to buy a second engine ( rebuild or new ) with the ports midly tuned and then use a stand alone management with an intercooler setup maybe even a different turbo but i don´t really know how much boost pressure these engines can handle but i read somewhere it has a 9:1 compression ratio so i don´t think i´m gonna give it a lot more then this turbo can deliver

on second thought ( after reading ramonz posts carefully maybe do fit a larger turbo haven´t really thought about it that way
so thanks for the advice

codge wrote:Just noticed, besides the leather, the dash is not UK standard. Is is from an FC?

dash isn´t from an FC but i´ve been told that it would be a US spec dash altough i wouldn´t know the difference with a european one :p

it is the facelifted fb dash...... only ever available in the left hand drive cars though so it was never offered in the UK.

Ramo wrote:stuff

I take what you're saying, dude, but the Elford setup is so asthmatic I don't think it's really troubling the laws of thermodynamics unduly. It's at what, five or seven psi? it's hardly a big-power Cosworth trying to wedge three BAR of boost out via a CD-sized Garret.

I don't want to spam up Ruby's thread but since you asked (presumably about my FD?) the boost readings are taken one from the UIM and one from the coldside intake pipework. FWIW I noticed almost no discernable consistent difference in intake temperatures swapping from twin stock turbos (a legendarily hot setup) to a much bigger T04S with the same intercooler with a maximum boost of 10psi on both setups. It only changed when I put in a bigger front-mount intercooler. Now I run a much bigger turbo at 1.2 BAR max but I've no scooby what the intake temps are because a) the new ECU doesn't come with a Gameboy like the old Apexi did and b) I stopped caring about anything like water temp, oil pressure or intake temps because I realised no matter how paranoid and obsessive and careful you are with a rotary, when it's gonna blow it's gonna blow no matter which gauge you're watching at the time Now I just kick the doors in every time I drive it and live in blissful ignorance

Lucky wrote:

Ramo wrote:stuff

I take what you're saying, dude, but the Elford setup is so asthmatic I don't think it's really troubling the laws of thermodynamics unduly. It's at what, five or seven psi? it's hardly a big-power Cosworth trying to wedge three BAR of boost out via a CD-sized Garret.

Regardless - I checked the turbo compressor map and she is outa breath at 200bhp, and tearing the air to pieces from 15psi.

A small boost increase and free up of the exhaust and I estimate you'll net 180-190bhp and that's your lot until new turbo time.

Oh, and if you compared the heat output of both your turbo combos at 1.2 bar there would be a very big diff in intake temp

thanks ramonz

i´ll definetly take all this info with me if i start the second engine build