1JZ power levels

[Guest |489|]

Hi all, just wondering how many people have used the ViPEC's on 1JZ and what sort of power they are getting. I had my 1J tuned this week and got 250rwkW at 22PSI. After reading a lot of forums, similar setups to mine are getting more power. I am wondering whether my setup has a problem or whether some forum results are over exaggerated. During testing we tried 20psi and got 235rwkW which is not much lower than the final pressure with not much gain. Is this common to get a small increase? Below is what parts i have,

Stock 1JZ engine/head/inlet

GT3540 with custom steam pipe manifold and 46mm tial gate plumbed back into 3 inch exhaust pipe after a foot or so.

full 3 inch exhaust with hi flow cat and muffler. (car is still loud)

Vipec V44 running with wasted spark

Vipec CDI with standard 1J coils

Big bosch fuel pump, 650cc injectors and turbo smart reg set to 40psi

Evilbay 600*300*80 FMIC with 2 1/2 inch piping from turbo to FMIC and from FMIC to TB. The FMIC has a 3 inch inlet and outlet

Auto trans with 3 grand stally and tougher valve body (MV autos)

3.9 diff gears and mini spool

If i have left any details off that you may require don't hesitate to ask. Any thoughts or comments would be greatly appreciated, maybe some can confirm similar results or put a finger on a flaw.

Thanks

Pat

[Guest |129|]

What rear housing, ignition timing and AFR are you running?

Power doesn't seem too bad for an auto, who tuned it?

I'd take it to the drag strip and check your MPH, that will give you more of an indication of power compared to other 1J's in similar weight cars.

[rayhall]

Drill a hole in the exhaust manifold near the turbo flange and connect a boost gauge. Compare the exhaust pressure to the boost pressure. If your exhaust manifold and exhaust housing are correct, the exhaust pressure will be the same as the boost at the engines maximum torque. At maximum rpm the exhaust pressure should be 2 psi higher then boost.

If the exhaust pressure is twice the boost or more, then the engine will not make the power it should. I have seen a 100 hp gain at the rear wheels just by lowering the exhaust pressure by 60 kpa (9psi). This was archived by just moving the wastegate position on the exhaust manifold.

Ray.

[Guest |489|]

Thanks for the replies. The rear housing is a .82, 650HP I think. I will do what you have suggested Ray. I currently have a little test point on cooler piping either side of cooler and 1 on the dump pipe straight after the turbo, where O2 sensor usually sits.

How much power difference do we get up north compared with down south due to heat etc? Do dyno's vary slightly?

Thanks

Pat

[Guest |489|]

Sorry, forgot to add a detail that may make it hard for me to measure the weight Vs MPH and that is the 1JZ is in a VR commodore ute.

Also, i don't have a gear hold for the auto, so when running the car on dyno it would kick down and took a few goes get speed high enough as to not kick down. Next time i can fix this by removing the TPS signal i have running back to the old ECU that is being used for the auto.

Pat

[rayhall]

and 1 on the dump pipe straight after the turbo, where O2 sensor usually sits.

No.. you have to messure the pressure in the exhaust manifold, not the dump pipe.

Ray.

[Guest |489|]

Hey All, sorry for the delayed reply, i have been working out of town and so on. Drilled a hole just below turbo flange in exhaust manifold and attached some copper tube to my boost gauge. In second gear (3 speed +overdrive AUTO) , once on boost the pressure jumps up to 23 psi and stays there until around 6000 rpm where the pressure rises to 25/26 psi just before i hit the rev limiter. Using the same gauge i am measuring 22/23 psi inside the inlet manifold. So i am getting around 3 psi higher at full 7000rpm. I am not sure where max torque is.

Going off Ray's rule of thumb (2psi increase) my manifold is pretty close to passing.

I know you didn't ask for the pressure drops across the cooler etc but i did them any way. The turbo side is putting out around 27/28PSI, so i am losing 4/5 psi across piping and cooler. Probably not real flash.

I have made up a new 3 inch cooler to inlet pipe to replace the 2.5 inch one. Am going to see if this makes any difference, and then replace cooler with a non crappy one if no luck.

Pat

[Guest |489|]

OK, replaced pipe with 3inch and remeasured all pressures and there is basically no losses now.

I also remembered something i did a while ago. Before i installed my Vipec CDI i was having problems with spark blow out so i re-gapped my BKR6E's to 0.6 instead of the standard 0.8. I bought new plugs and left them at 0.8. I don't know whether it has a made a difference power wise as i haven't dynoed yet, but it feels different. Before it seemed to flatten out and now it seems to continue pulling. What plug is everyone else using?. Was told to run a hotter plug with smaller gap.eg 7E with 0.7 gap.

Thanks

Pat

[rayhall]

With the Vipec CDI or any other CDI you do not need small plug gaps. You can run values of 1.1 without problem. This will also help fire lean mixtures. Small gaps are needed with weak ignition systems.

Do not use Platinum or Iridium plugs with the CDI. Use "normal" projected nose plugs with the standard gap. Use a heat range of 7 or 8.

Ray.

[Guest |489|]

Cheers, will this make a difference power wise? Maybe not as a direct result of replacing the plugs but allow me to add some timing etc. I will find out figures once i get it re-tuned.

Thanks