I've seen your car on the internet I really love it. I hope you could enlighten me here,

My fd has a large street ported motor atm and an Adaptronic Select ECU.
So, if I get a twin scroll internally gated EFR 8374 with Turblown's shorty manifold and custom vmount how early would my car hit boost? My goal is 3k. is that achievable?

 

3,000rpm goal.
OK, how much boost are you trying to have by 3,000rpm?

 

Thanks for replying man.

As much as European 100 octane fuel can provide safely. I'm guessing around 16-17 psi?

If you consider the following how early would a 7670 and an 8374 hit full boost at 16 psi?

• Large street port
• Adaptronic select ECU
• Turblown Shorty manifold
• IWG
• Custom vmount
• 3 inch decat exhaust

I don't want to sacrifice drivability as I enjoy my car on the road. How much power would you think each would make with these specs?
Just to see if the extra time to spool up is worth it.

 

Both the EFR 7670 and 8374 will hit 16psi around 3,000-3,400rpm on a 2 rotor depending on mechanical set-up, boost control/tuning, elevation, weight of car, gear, etc.

The 7670 will have slightly faster response, but the 8374 is no slouch.

Here is a boost by rpm chart of my 7670 on a dyno dynamics. Boost came on a tad faster on Dynojet (26psi peak boost 3,800rpm on Dynojet instead of 4,000rpm on DD) and the street from more load I guess.

 

So you made 360whp with the 7670 at 26 psi?
We don't get e85 over here so 100 octane pump has is what i'll have to go with. i'd love if the 8374 reached 16 psi by 3400. I hear the 7670 is kind of weaker in terms of top end compared to the 8374. How does it feel on the road?

 

 

On low boost my EFR 7670 felt great on the street as it was very responsive and power kept going to redline.

On high boost where I maxed the compressor flow out the EFR 7670 "lacking in high rpm power" on the street since like a piston engine car torque drops so fast after 5,000rpm. The EFR 8374 would provide more top end power with plenty of response and low end power when downshifting is always an option. My EFR 7670 build was for "racing" in a parking lot in 2nd gear.

Remember terms like "lacking in power" are relative as when I tried high boost 4th gear freeway roll on on my 225/50-16 Hankook RS3 street tires it blew the tires of ~4,500rpm. On 255 DOT-R tires warmed up it held traction well in 3rd and up and on 255/55-16 MT Street drag radials warmed up and 12psi pressure it held traction in 2nd gear and up with gentle shifts.

I think EFR 8374 is the right turbo for 90% of 2 rotors.

 

wow that's a bid difference. I still haven't understood which one I should go with lol

 

The 8374 will give you a linear powerband that compliments your engines natural powerband at those boost levels. Your whp should be getting towards mid 400's

 

mid 400whp at 16 psi or higher? I'm looking for usable power at 3000rpm

 

^ get the 7670 or a v8 then. Also it depends on your definition of usable - the 8374 will get you around town at 3000 pretty bloody smartly. But if you want the same power and torque at 3000 as at 5000 forget about it. But if you are driving it in anger you wont be at 3000 rpm very often.
I was torn between the two turbos too - i didnt really neeeed 450hp, and wanted plenty of torque down low, but the 8374 just fit the engines breathing characteristics better and i like the idea of the compressor and the exhaust flowing better and more efficiently.
Some times i think id like to try the 7670. The 8374 is pretty good though. Sorry to be of no help lol.

 

I know this is a super tough choice for a 2 rotor- EFR 7670 or EFR 8374.

Both turbos can make ~300ftlbs torque at 3,000rpm and 16psi boost on the 2 rotor so you have to decide if making a bit more peak power (8374) or having that 300ftlbs available some thousandths of a second sooner after pressing the gas (7670) is more of a priority.

If making more than ~300ftlbs torque at 3,000rpm is the priority you might want to look at even smaller turbos like EFR 7163 or a bigger engine.

 

Vs. the 7670 I agree with that statement

My (completely non-EFR, lol) PT6466 is very responsive, surprisingly so (although the system was set up to optimize response)...... I need to take some logs of the boost response

 

You can definitely make 400rwhp at 16psi on the 7670 kit.

Generally if you have a medium to a large streetport the 8374 will fit the engine characteristics better.

Stock/small streetport 7670 does really well 3-400rwhp.

 

Sounds like you're driving the car wrong.

Why are you in such a high gear? What are you doing? You do realize fuel economy is better at higher RPM, low load, and transmission lifespan is better there too. If you keep lugging a motor around, expect issues...

 

My car is a large street port, it even sort of braps lol.

Think I'm leaning towards the 8374 now.. The thing is though, what other mods can you do besides those i've already mentioned to minimize lag on this turbo?

Do you guys have a dyno of an 8374 streetported fd at 16psi?

 

I'm not driving the car wrong lol I know rotaries like high revs I just want usable power in the streets and a broad curve, it's not a racecar or a drag car. It's a street car. In street car situations a car that makes 350hp for most of its rpm range is "faster" and more enjoyable than a car that makes 500hp at 6000rpms. You get my point.

 

A car with 500hp probably makes 350hp for more of its rev range than a 350hp engine,, just sayin....

 

Well excuse my english (not my native language) I couldn't explain it any better. I'll try this. I prefer power that is distributed broadly in the rpms rather than no power until 5000 and then boom. And from what i've seen in street situations unless you're drag racing the first example feels faster.

 

You're English is perfect dude. The 8374 is definitely not nothing,nothing,boom. Its linear and progressive, possibly moreso than other turbos the same size. There will be boost at 2000rpm.

 

Then 8374 it is.. Should i hope for 400whp at 16psi?

 

I think it is more about the transient response than the boost thresh-hold - ie, how long after you press your right foot until boost comes on.

 

Easily. ..assuming everything is in order.

 

Yes but that is dependent of where in the RPMs do you mash the throttle? I mean if it's 1500 or 3500 there should be a huge difference I guess.

 

A bigger exhaust like the 3.5" option will reduce lag, but that comes at the cost of boost control. Generally one sees 17-19 psi with a full 3.5" exhaust on the 8374+ turbochargers.