I'm getting a new engine next week and am now actually considering keeping the stock ports as opposed to porting it. I know I would loose top end power, but I don't care if my car makes 375 max rwhp or 420 max hp. I'm very concerned about lower end power and anything about 350 - 385 max is great for what I use the car for. It seems to me that a good "small" single (GT35R/RX6) on stock ports might provide some good low end torque/hp and a fair max hp number. I was considering the new BNR's but heat, weight and complexity savings is making me consider going single.

Who out there has a single running on stock ports? What are your impressions? Do you have any dyno sheets?

Are these advantages/disadvantages accurate?

Advantages to stock ports and single:
1) Better low end torque (how much better?)
2) Better turbo spool up (how much better?)

Disadvantages:
1) Lower top end power
Any input is appreciated. Thanks.

Matt

 

i have a gt35r on a completely stock motor stock ports... car makes 403rwhp at 15psi... spool is super quick 10psi by 4k...

 

I also have a 35r on stock ports. I am just starting to tune though. If you'd like I can send you an excel spreadsheet with boost recorded along with its corresponding rpm. Just pm me with your email address if you want a file.

 

Thanks for the info. So the low end ( 2-3k) feels strong?


Excellent . Thanks.

matt.oehler@gmail.com

 

I have stock intake ports and a very mild exhaust port(about + 1/16" to the top and bottom). When running 15psi boost, I have 14PSI by 3600 rpm. WG spring pressure value affects this.

Runs better all around than my non-seq twins did.

 

Bottom Line, Porting = more exhaust flow = faster spool.
It's not just about top end power, an engine that breathes better spins the turbine faster.... I have a GT35/40 with a horrific tune, (Soon to be rectified) but it spools by about 9-10 Psi by 3500... or even sooner depending on where in the map I am and how shitty the Ignition advance is @ that point.

Either way Porting = Sucks for Economy, Motor Warranty, and Smog
Porting = Rules for Turbo Spool Time, Top HP #

 

I always assumed that the air would be moving faster out of a smaller port and thus help spool the turbo faster. I thought that the air veloctiy was the cause for the lesser low end power on a ported motor. What am I missing, is air not pushed though a smaller port at a higher velocity? Granted more airflow makes sense for spooling time, but would "faster" air help as well for lower rpms (<3k)?

 

I have also always been under the impression that with a ported motor you are sacrificing some low end power.

 

basically when the port is opened up( exhaust port) the air flows better but at a lower velocity because there is not as much restriction. but you wont be able to feel 1/16".

 

My dyno w/ stock ports. Street port is money well-spent.

 

Can you elaborate on this? What turbo are you using?

 

Can you elaborate on this? What turbo are you using?

 

I have one rx-7 complatly standar with a single To4e turbo , its run much much faster than with the singles secuentials , you can drive it every day with no problems at all. Its start pulling at 3500rpm , but it runs very hard when it reach the 5000 rpm to the 8200.

It have a Pattit racing ecu and the Single turbo , only that.

I have another Rx-7 that's is ported , and it is much unstreetable , than the non ported one , too much lag , and , poor fuel economy. But it run faster.

 

I'm on stock ports, and wishing I had ported it when the motor was opened up to replace my front plate housing when it cracked.

 

This was at 10, 12, and 16 psi. Turbonetics T66 P-trim, 0.84 turbine housing. I actually made 402 whp, but I don't have that graph. Check my garage - I've listed all my mods.

 

Depending on the shape/size of the porting, you should be able to get more top end without losing any significant amount at the low end. Mild streetport should be good for at least 20 rwhp without losing any low end. Someone correct me if I'm wrong.