What do you guys do for fastest spool?
 

I'm talking about engine porting or even forced ram air into the turbo maybe?

Are the 2 exhaust ports the most important or should you port the intake ports as well? I'm going to go with a twin setup in non seq or a small single and want to be able to spool fast. I wan't 450rwhp. Isn't it harder since we only have 2 exhaust ports than on a piston engine? Is there a way to measure how much exhaust gas our car can put out at WOT compared to other cars? And what would be the largest to port the exhaust ports to make sure the apex seals can't accidentally fall out. Pics of porting would be great or any other suggestions.

I feel like a newbie in this section but im ready to make some big hp now that I'm used to my car and learned a lot.

Thanks everyone
-Snook

You usually port the intake side plate ports only. That's what street and bridgeports are. (pics are in the 3rd Gen section)
Bridgeports(unlike streetport, you have to cut an "eye brow" port) may last 30-40K miles and it's powerband is way up there. (6K-10K range)

ok thanks thats pretty basic

I have a rx-7 myself and a pettit streetported motor with 3mm seals

I'm looking to find the port that will spool aftermarket non seq twins (most likely my next setup). I will have 1 exhaust port going to each turbo and I'm trying to figure out how to get them spooled as fast as possible.

thanks

Your will be hard pressed to get 450 out of twins.

GT3540 !!!!.

bnr stage three spools easily, can do ~400rwhp
in fourth gear at ~70mph they spooled as fast as the stock seq. twins in the car I was driving, and my car was in third :P

You need to port the rotor housings if you want to make power. There is more benefit from an exhaust port only than only porting the the side plates. A bridge port and no exhaust porting = slow and no experience.

http://www.nopistons.com/forums/inde...showtopic=6911


read that it will help you understand a little about what the ports are actually doing and what is excessive/unnecessary, and should help you understand what you should be doing to accomplish your goals.

now if it just had all the pics!:(

rotarypower are you fu**ing nuts!
Sadly, I read that already hahaha I got to around page 14 fully reading everything and then I got bored/confused.

I just want a simple answer...I also don't want to have any crazy porting just something simple to do while the engine is out. But I don't want to port something if I'm not going to need it for my setup.

Lets take the BNR stage 3s for example. What port would benifit those for faster spooling and overall more power?

No I won't.

Marcel: can't afford that

$150FC: I saw the video and I talk to stephen online
I wonder what kind of port he has and how much bigger those wheels are on the turbos than stock....

IGY: that makes total sense more exhaust flow should spool turbos faster....now when people port the intake ports they just do them on the inside side housings? they don't port intake tract that lines up with the LIM or the LIM?

thanks guys
I think I'll move this to the 3d gen section also

I thought you decided to sell the car? :)

If you're going to have an exhaust manifold made for the stock turbos, you don't want 1 exhaust port for each turbo. Even though the strength of each pulse is 1/2 with a collected exhaust manifold, you will have double the pulses. They are both important, but the increased frequency (not to mention the scavenging effect) in this case is more important than having a 'pure' pulse.

There is also an issue of the engine wearing more quickly on the rotor that is weaker. I don't understand the concept well enough to explain, unfortunately.

I think you're best served with the engine setup you currently have :)
Best,
John

You have non seq. twin turbos and want a faster spool??? Go sequential, that was easy!

thanks that was helpful

I'm talking about aftermarket twins where it's not possible to use the sequential system

I want very fast spool for traffic driving.

a bit of porting/overlap when porting the exhaust will give you the faster spool up and be able to spool some of the bigger turbos a bit faster.

I don't think that's entirely true.
Inducing overlap of exhaust gases into the intake charge forces you to be more conservative on a/f's and timing to prevent detonation. In the sense that you're retarding the timing and richening up the a/f - yes, you will make the turbo spool more quickly since you're keeping the turbo hot.

However, one can accomplish the same result and have more low and mid-range power by retarding the timing on a motor that has minimal overlap.

People normally overlap the ports trying to gain that extra top-end flow.
Cordially,
John

I think you meant advance the timing on a motor that has minimal overlap.?

No, I meant to say retard the timing. Retarding the timing helps to bring boost on sooner.

Retarding the timing will cause the mixture to burn more in the exhaust manifold/turbo. The additional heat/energy that is released in the exhaust manifold from the late ignition causes the turbo to spool more quickly.

Well retarding the timing and dumping a shit load of fuel in is called "anti-lag setup" and will make your turbos spool like crazy but its not something you can do in traffic. Its also creates SUPER high egt's that will screw things up (like turbine wheels).

If your a/f is in check having advanced timing will make your egt's go up and could help with spool.

STEPHEN

Hey Stephen,
"Anti-lag" is a term normally referring to retarding the timing and dumping fuel between shifts. Although similar to what I describe, anti-lag programming is much more radical than my suggestion. I'm talking about the general tune of the engine under load with the car accelerating.

You are right - if you allow the EGT's to climb too high, you can mess up turbine wheels and even cause problems with the exhaust manifold cracking.
~John
PS Thanks for the advice on my car, btw. I've been meaning to get with you on an update. Good news :)