This is a good thread. I am swapping a 99 spec twins set soon into my 94 touring with reman engine with 65k. There has been one question that has been bothering me: If the boost level is the same for the 99 and stock twins, where does that extra hp come from? 280hp-255stock hp=25 extra hp. Is it from the fast spooling of the lower rpm range to transfer more air into the working chamber? ummm.....

+1 ... good to know for those wanting conservative tunes

we should have a special place under 3rd gen for those who just want to do 300whp on stock or Efini twins and make the engines last for over 100K miles..

My question is still not answer though......if we run 99 spec twins but keep the stock boost level 10-8-10, do we get the 99 spec twins 280 hp or that will just be limited to 255 hp by the stock boost level?

My understanding is the 99 spec twins spool fast so that will give the car some hp and torque but the throttle would be more responsive and revs faster, which results in earlier boost therefore faster 0-60?

any thoughts?

PSI does not create hp, CFM does.

In example, a turbo that flows 520CFM@2.0PR will create more hp than a turbo that flows 450CFM@2.0PR at the same PSI.

Old thread but the 99 spec twins on the 99-02 cars run higher boost and have a slightly more efficient exhaust system (like 10% less back pressure). The boost pattern on the 99 spec on the stock ECU is more like 11.5, 10-ish, 11.5. That's where your power mostly comes from.

I have a 94 FD and I made 373hp and 310lb-ft on my stock twins at 14psi. I also live at 5000 ft. elevation, which doesn't help.

Thats WHP?

I guess you can subtract 50hp that gets lost in the drivetrain making it around 320whp.. My impression is that european donynumbers are more conservative than the American ones. 320rwhp on stock twins @ 14psi are numbers that wouldnt add up on european dynos. A friend of mine pulled 320rwhp on stock twins @ 17psi. That sounds more realistic. However, His twins lasted for about 1 month before they crashed and had to be replaced. He didnt do that again...

99 Spec twins have larger turbines, so I assume more CFM at the same level of boost.

As an FYI the last FD I had was running 99 spec twins on a streetport block plus usual bolt-ons and pulled 332 rwhp

No, 99 spec has smaller exhaust wheels.
Though, the 1mm smaller 99 spec exhaust wheels were longer to improve their exhaust flow capabilities.

Still, when one gets a high flow-ed hybrid turbo in Japan they always use the old larger exhaust wheel turbos as a base (which I doubt they would do if the 99 exhaust wheels flowed more).

http://www.rx7.net.nz/turbodia.JPG
http://www.rx7.net.nz/turboseal.JPG

'99 FD3S