Houstonderk

iTrader: (3)

So i now about people taking the exhaust sleeves out of the n/a housings and porting it to match the Tii sleeves to swap into it. Know Has anyone just ported it and left the sleeves out completely along with an intake port to increase exhaust volume? I know about the 5/6th ports with the backpressure but this is a n/a turbo with no 5/6th ports and a 3in downpipe probably with no cats.

Houstonderk

iTrader: (3)

So am i going to have to get some Tii sleeves then? Also what kind of engine management would be needed for a streetported n/a turbo?

ddub

Removing the exhaust sleeves entirely and porting it and leaving it open is not usually suggested for street cars. It creates a HUGE exhaust port, and any stock header/turbo manifold will no longer match up with the opening (they'll be too small) so you'll need something custom or you'll have to port the flange to match. Also, coolant temperatures will increase if you go this route, since the sleeves help dissipate heat a little and protect the coolant passages above/below from heat. It'd also be suggested to ceramic coat the inside of the exhaust port if you leave the sleeves out.

Plus, with a port that huge you'll need a VERY free flowing exhaust and it will be unberably loud most likely. It's a much better idea to merely swap the n/a sleeves for TII ones and port the exhaust.

Engine management needed or suggested? People have run turbo'd n/a's off an s-afc and slightly retarded timing before, but it's not the best route. Best route would be some kind of standalone, megasquirt would be the cheapest but harder to setup and tune most likely since you have to build and tune it yourself.

Here's an example of a port I did recently, n/a housings with removed n/a sleeves for TII ones and then ported. This exhaust port is quite large also, more for a turbo car usually.

Houstonderk

iTrader: (3)

Ah so a megasquirt should be alright. I'll start saving for one i guess.

ddub

Yep megasquirt should be fine. Get the megasquirt and spark, seems to be an awesome setup (which I'm installing myself).

Also, 88IntegraLS is going to use Megasquirt n' Spark on his huge streetported/supercharged n/a, it's just all about tuning.

Houstonderk

iTrader: (3)

Is that housing scratched?

ddub

No?

Houstonderk

iTrader: (3)

I am just trying to get as much done on the inside so by the time its broken in i will have all the exterior performance items. There are alot of people now adays that are all out.

ddub

Where did it look like it was scratched? I'm curious now.

Houstonderk

iTrader: (3)

right down the middle

scathcart

Opened that a little early, no? Might cost you some power...

Houstonderk

iTrader: (3)

Will it? I am trying to find a really good port for both intake and exhaust. I got the 6 port one from mazdatrix.com.

scathcart

Generally not meant for a street car... huge ports tend to have higher flow, but much reduced gas veolcity. Tends to shift the powerband up... way up.

Low gas velocity on a turbo engine tends to hurt spool, but, high-end power *can* be improved.

Exhaust ports that large mean any exhaust manifold bolted to the engine will have to be custom-built.


I'm porting a set of housings right now and leaving the sleeves out. I'm also going to have to fab a header for it using 2.37" ID pipe. This engine is designed to be driven to 10,500 rpm, and will not be very drivable on the street. 4-port N/A bridgeport with 9.6:1 comp rotors.
I'll take pictures so you guys can ****. I'll post a couple tomorrow.

ddub

Oh no that's not a scratch, that's just how housings wear. They go from the milky coating to shiney, starts on the outside and in the middle from what I've seen.

And as for the port, I was going very large because I'm trying to push to 9-10k rpms as my redline and needed something large to support this and my port, at least in my opinion.

Houstonderk

iTrader: (3)

So the higher you go on the exhaust the higher the rpms? What about getting some lower end? My car seems to be really slow till the turbo starts to spool.

scathcart

Opening the exhaust port too early tends to cut into the powerstroke, which costs power. That's why we don't port downwards too much.

Racing beat ports open way too early and close way too early. These ports open even earlier than RB's.

If you give me a measurement from the exhaust port, I will tell you the exact port timing of that port.

scathcart

I'm not saying your port was too large, I am saying I think it opens too early.

Houstonderk

iTrader: (3)

If you give me a measurement from the exhaust port, I will tell you the exact port timing of that port.[/QUOTE]
Whatchu talkin bout? Also is it better to go wider than up and down then?

ddub

Well, I guess the person that designed this exhaust port for me just disagrees with you then, but that's fine we're all entitled to our own opinions.

The RB one is also an awful shape in his opinion. I trusted him, he seems to know enough, it's Kahren by the way. Using the stage 1 version of this exhaust port and his own designed streetport, s-afc, and TII manifolds on an s5 n/a block he hit 195rwhp before redline (leaning out too much) so it seems to work good enough. This is the stage 2 version of the exhaust port, though, but oh well. We'll see what happens when I hit the dyno after break-in.

scathcart

Whatchu talkin bout? Also is it better to go wider than up and down then?[/QUOTE]

Wider helps flow, but puts more stress on the apex seals.

Up increases overlap.

Its all about compromise...

Houstonderk

iTrader: (3)

So how much of the apex seal should be in contact to last around 100k at least? Its not a daily driver its just a fun weekend woop all *** car.

scathcart

I can think of quite a few top-end builders that use a similar shape to the RB port style (rounded opening, squared off closing) for street engines. Doesn't do too badly on the flowbench, either.

Generally, porting down too far costs power. Mazda knew this... they actually made thier race housings open even later than stock housings.

What IS the opening timing on your port? If you give me a measurement, in millimeters, (compared to stock) of your opening compared to where the stock oening is, I'll whip out to the degree wheel and let you know.

Houstonderk

iTrader: (3)

Its still all stock. I haven't got the templates yet. I just got done painting the engine at work since it was all apart. I was wanting to see if anyone has tried making the intake ports into one were the six ports are if they don't have them anymore. And then enough exhaust porting to handle it along with good power.

scathcart

I aim for 2.30" wide on the exhaust port, never less.

ddub

According to the template he gave me, the top edge lined up at 123mm from what I recall, the template is in the garage and I don't feel like getting it to make sure, but 123 sounds right.

I realize that doesn't help you for the bottom, but oh well the engine is built now so I can't measure the actual housing, I can measure the template later, though.