just wondering what the limiting factors are for the s5 turbo engine, why mazda says it should only ever go to 7k rpms. What needs to be done for it to hit 8k like it's n/a counterpart?

 

Number one.. it just doesn't make any power up there. Why.. I don't know.

Doesn't the FD engine redline at 8K? Do they make power all the way to 8K?

I wonder if the S5 turbo uses the same lightened, but lower compression rotors...

-Jon

 

i think its just an issue of it not making any powere up there and the increased risk of running lean/overboosting. i mean all the internals are the same except for compression right? i mean the rotors are the same weight with the same s5 hardened gears so that the only think i can think of. bu i might have missed something.

 

I think the boost starts to die of that high.. well at least on stock turbo. So I think the redline is for more of the turbo itself, not the enegine. I think S5 turbo enegine can handle the rpms.. but the turbo just can't keep up.

 

so if I were to upgrade the turbo, and have enough fuel pumping through, it would be fine up to 8k rpms?

 

& the intake
& exhaust

 

Actually, its really not the intake and exhaust that are the limiting factors. Its the fact that a stock ported motor torque curve falls off at those RPM levels. There isnt any reason to be revving that high, your just making noise, not horsepower. IF your just itching to make HPs at that level, your gonna need some port work and a turbo that can support it.

 

Na redline is 7k stock.

 

If you would have read the FAQ... I wouldn't be proving you wrong (sorta)

He stated the Series 5 N/A has a 8K Redling. The Series 4 has a 7K redline.

Don't believe me? Take a look at my tach.

 

Even with my big turbo, I don't usually go above 7.5k RPM. Don't really need to. I have an S5 engine.

 

sorry, intelligent people only.
get out.

just kidding

I staid s5 n/a for that very reason, becuase the s5 n/a is the only 2nd gen that has an 8k redline, all the others have a 7k.




stock s5 n/a and turbo ports have the same total amount of surface area (although look completely different), and should be able to support higher rpm's like the n/a, right?

 

ok, I thought u meant the s4 was 8k. My mistake, I own a s4 vert. Btw, neone know how to stop that redline beepin

 

even with upgraded turbo and all the bells and whistles, no need to go above 7.2krpm cause your powerband falls around that level, regardless the amount of air you pump into the engine, i.e. turbo.
To answer the original question, it is because of the 2 aux, ports that open up which in a way act as like 2lbs of boost once oponed up at 3800k, the turbo only has 4, while the N/a has 6,
The reason the redline was increased on N/a's (s4-s5) was because of advancements in rotary technology all across the board, in a sense they could do more, and take "more punishment" in a sense to get basic terminology wise.
My friend is making 475hp to the rear wheels, with his new single turbo, (dyno and pics available) and he never goes past 7.2, and his dyno sheet will show/prove why not too.
Hope this helps

 

Point here is, the power band in EITHER car is ALREADY falling off at the redline. Why they have different redlines is probably a combination of several things that arent really pertinent to this thread. Point is, if you want to rev past the redline, go ahead. If your car isnt made for that extra revving, all your doing is making noise and hastening eventual demise of your motor. I am sure Kevin appreciates the buisness.

 

ok, point taken.

now how would I increase this powerband farther?

 

porting will increase it higher, and its not so much the area as it is the locataion and opening and closing of the ports that determines this. its just that the only way to extend the timing is to enlarge a stock port, as there is no way to simply move or shift around the stock ammount of port.

 

I understand what you are saying, but on the n/a irons, the port location is very similar to that of a turbo, and extending it past that wouldn't be any problem, so how can the port location really be the limitation?