Hey people.

I've been through some jspec's, and I was just wondering how much hell everyone is putting there un-rebuilt jspec through.

I got mine at 14 pounds on a basically stock turbo, with 11.3-11.5 air/fuel the whole way..


hah stock intercooler too..
nothing like 58 degrees celsius air temps

 

Mines is around there too but 15psi sometimes a little more. 3 inch RB cat back and down pipe with FCD and using a jspec ecu with a knight sport chipped cause Im using a USDM Harness. Even though its not so good Im happy.

 

are you over boosting to 15 or is it steady through out the whole RPM range? what size injectors do you have?

 

I think I just have stock injectors (I ordered my engine from tigerjapanese). I know its working at probably max but I try not to beat on it to much. Im not sure what you mean (sorry) but it reaches 15 at full boost.

 

what makes your jspec so special? they are identical motors except for the emissions system.

 

On stock injectors & fuel pump, 10+ psi will blow the motor. And taking the stock turbo over 12 psi will ruin it in no time. Not to mention, anything over 12 psi will net no hp gains since the air temps rise too much.

 

when i first bought my car & after the swap, i was overboosting to 12+ psi. Then after I'd say...6k RPMs itll drop back to 7 or 8 PSI. This was on stock intercooler, stock turbo, stock injectors (very sketchy) with a walboro 255 and a retarded timing.


Now that i have a AFC NEO and 720cc secondary injectors...and the stock wastegate actuator is in the trash with a new Tial 38mm is mounted in its place, im boosting 13psi but it still goes right back down to 7 or 8psi. How are you holding 15psi fcdin?

 

I have no idea. But I'll double check and see if it drops down when I get in the high rpms.

 

All you people running 15 PSI on your stock turbos are just wasting the turbo. The stocker is dead much after 12 PSI anyway and just begins pumping heat.

 

Ya, fcdin, if your running 15 pounds with stock injectors, your motor doesn't have many miles left on it.. Possibly small spikes to 15 wouldn't be devastation, either way, anything over 10 or 11 psi gets you pretty lean...

 

yeah I know. Thats why I dont drive to hard on it. I just take it out for regular cruises not racing really.

 

All it takes is one high load pull to redline to get the motor to knock and damage a seal. It will happen eventually so the choice is between spending $300 on a pair of 720cc injectors & a fuel pump or spending a few grand rebuilding in a month or two.

 

Well I already have a Walbaro Fuel Pump but about the injectors. I was thinking about getting some 720 secondaries but would I have to tune then or will it be just running rich?

 

If you're actually running 15psi, it won't be nearly as rich as you think...

 

So I can just get them and install with out too much worries? Yeah 15 at full boost. I cant control the boost unless I port the wastegate I believe. So I have to try my best to avoid redlining.

 

Boost is usually a little easyier to hold if your boosting higher.. Well, hold from overboosting anyways. Makes me feel pretty good if your doing 15 every now and then on stock injectors..

I was running around 16 pounds overboosting on all stock config, and my motor lasted 223 miles...

 

14psi with a 60-1 and un-opened block straight off the boat = 340 rwhp

 

Well im trying to get some more boost out of my stock turbo, it spikes 12 and bleeds back to 8psi at 6500, time to upgrade

 

Only 223 miles? Wow that makes me really scared now. So now I'll keep the psi low. No more boosting for me until I get injectors and what not.

 

223 miles...on his second motor. I drove most of those miles with out boosting it, and he boosted it probably like 10 or 12 times. His first motor pooped at 1000 miles.

Scary

 

58 degrees Celsius is pretty hot for air intake temps. Mine runs at ~35 degrees during the day....

And regarding Jspecs, they're pretty much the same as USDM engines, short of the EGR and such. Except for my old Jspec. It had slightly different spark plug placements on both front and rear housings...and it was an S4....Just a bizzaro engine I guess. I still have the old housings and compared them to a USDM housing and there was a noticeable difference between the two. They were S4 housings alright. Karack can verify this. It was relatively mind-boggling...like there was another S4 TII engine that Mazda released or something...lol.

 

Well does it help that I have a KOYO RAD? I think it does but not much Im guessing.

 

I shoved 20 PSI down my JSPEC for a while. It was the 30PSI spike that killed it.

 

I don't know whats going through your mind running 15 or even 12 psi on stocker injectors! thats murderous and last time i checked it ain't the funnest thing dropping $3000 on a new motor. its so easy to just upgrade the injectors rather than choke your rotary

 

If I dont really get any power after 12 psi. Does that mean that I can still beat my little brothers Type R EG Hatch only on 12 psi, maybe 11? I only got him a little over a car.