Do you have the dyno sheet for your run? Would love to see it. Also what AR housing?

 

i keep seeing people post this concern.. about cruising in positive boost on a fast spooling turbo. have you really experienced this? I dont see how that would happen unless you have really shitty tune, really poor compression, or towing a boat. even the 13B-REW running only on the primary turbo does not see constant positive boost in steady state cruise

 

gxl90rx7

i keep seeing people post this concern.. about cruising in positive boost on a fast spooling turbo. have you really experienced this? I dont see how that would happen unless you have really shitty tune, really poor compression, or towing a boat. even the 13B-REW running only on the primary turbo does not see constant positive boost in steady state cruise

I have only had this problem of positive boost while "cruising" way above the speed limit where the load is high enough that even neutral throttle to maintain the speed is enough to keep you in boost.

On my EFR 7670 FC the response was definitely hair trigger at 3,000-4,000rpm freeway cruise (more so than the primary turbo on my FD). It wasn't a problem except that my gas mileage was abysmal compared to my lazier turbo.

You can definitely work around it. You can run closed loop under higher throttle position and boost like an OEM, but my experience of doing this is you lose much of the awesome torque response of the responsive turbo.

Lean and boost was a lot less hp than rich and boost on my set-up as we could see playing around on the Dyno Dynamics (it can tell you hp output at constant rpm and varying loads).

This is part of what the OEMs do with their switchable engine modes ("economy, sport, race"). It actually changes the mapping of the ECU.

 

if it doesnt happen on the STOCK twins , why on earth would it happen on a small single .

after all the advice here .. unfortuantely I went a different route . it wasnt a money issue I just wanted to try soemthing a bit crazy .
going with a much smaller exhaust housing than would be prudent . I will lose out on top end I'm sure . But Im a bit crazy. Should still flow better than the stock twins right? LOL

before I go ahead with my crazyness . I have a question for everyone here

what would spool faster a .81 normal back housing on a P trim

or a .84 twin scroll ?? anyone have any idea on this.

I've been reading up and down some people claim a 1000 RPM difference in spool , others a 250 rpm difference lol

 

A Syncronic BOV would almost certainly solve that issue as it would not allow boost to accumulate pre throttle under those conditions.

 

Tem120


if it doesnt happen on the STOCK twins , why on earth would it happen on a small single .

On my FD even with exhaust and intake the stock primary is slow responding to throttle input compared to the much larger EFR.

I think it is the drag of the journal bearing turbo and thrust bearing compared to the dual row angular ball bearings of the EFR with no thrust surface.

Also could be stock leaky BOV..

Also, it is harder to pack a 3-4" downpipe onto the stock twins and 6" velocity stack to 12" filter.

It could also be that the stock FD ECU maintains very lean mixture in closed loop and my aftermarket ECU I just run open loop with it pretty rich as it comes into some load (even climbing a moderate hill).

If you had the Revolution Twins with the ball bearing primary turbo upgrade and all the mods the stock FD twins might be as hair trigger.

The first time I had boost while high speed "cruising" was actually on stock HT-18 turbo with just open exhaust and intake. It lead to some overheating pretty quickly!

 

first the Dyno sheet some one asked for and was tuned by Steven Kan. i had a bad exhaust manifold at the time and oil drain and now have better stuff on that he told me i should get for it.

The reason why highway travel is not fun is when I was doing 75 on highway and when going up a hill the car tends to slow down a bit and you step on the gas just a little to maintain speed and it is like WOOOO LETS HIT FULL BOOST AND GO 100 MPH!! that is why I was saying traveling on highway is not much fun. All rolling hills here in North Dakota and small towns so we don't have solid highway to travel on at a nice speed. in flat areas it would not be so bad to roll around in.

 

^ sounds like injector staging, perhaps? Nice graph though.

 

maybe the primary injectors. with the PFC he was unable to play with the primaries i have. If I ran a different ECU he could have done something a little different. I have the 1000ID primaries and 2000ID secondaries.

 

ah ok yes i know what you are talking about, yes that is annoying. like rolling into the throttle to climb a hill, and as you get near 0psi, AFRs drop out of closed loop down to 12's and power starts taking off, next thing you know youre at 5+psi and hauling ***