Car bogs when it hits 15psi

[Luderacer14]

Ok, I was just wondering why it bogged when it got from 13-15 psi before it blew. Could it be my MAF maxing out?? My wideband reads perfect, I'm running a 12.7 all across. It's a T28. Anyways, I already have my metal headgasket on order and I still gotta save up for the stupid boostdesigns clutch and flywheel. My engine still starts and runs, i feel the air push out from the headgasket everytime it turns. NO water at all. I'll post once I get it all fixed and running again, it sucks that I'm carless and it especially sucks that I can't race it!!!! Ohwell, my timing was'int retarted too, any of u guys think retarding from the distributer by itself is good enough. It's .5 degrees for evey psi right? Anyways, I'm probably not gonna have the head resurfaced because of $$$ issues. It did'int overheat so I'm good right?? The T28 is a fun turbo and had no lag compared to my stock gst, I don't know about u guys, but I don't even think I have lag, but eventually, I'm gonna go for a t3/t4 for bigger power numbers.

[nissanfanatic]

12.7 sounds a little lean for a 15psi setup. Esp for street running. You shouldn't require anything leaner than 12.5 for max power. And even so, a 11.5 would be the best for street running.

It prolly bogged because of loss of cylinder pressure. Your car almost always bogs before something breaks. If I even feel the slightest bog, I let off immediatly.lol

[turtl631]

12.7 is kinda lean; 15 psi from a t28 on a ka24 is gonna be past that turbo's efficiency range, so the charge will be hotter than it shoudl be. Thats a bad combination

[klattr1]

if you are utilizing the .5 deg retard for every lb of boost, that would put you at 12 deg. base timing. that just kills driveability. get a preprogrammed ecu, standalone or at least a MSD BTM and call it a day.
Modified by klattr1 at 11:40 AM 4/29/2005

[Structure240sx]

i think we should take in account that 15psi out of the t28 would be a bit less out of a t3/t4. so maybe jsut a base retard of 4-5 degrees would be enough, not saying go by this, jsut saying. with no retard and lean afr's you're lucky it was only a headgasket

[paemt6220]

I've heard several people on here say, .5 degrees retard per Psi OVER 8 psi. That would be about 4 degrees at 15psi, like Structure said.

[AmoebAssassin]

As mentioned, you seem like you're pulling a lot of timing for a turbo that doesnt flow very much (comparatively). Also, 12 is on the lean side of stoichiometric. An ideal a/f is on the order of 14. If memory serves me correctly, 14.7 is a perfect a/f.

[WDRacing]

We also need to remember that at 15 psi the tiny T28 is nothong but a heat pump. So your turbo is spent, your pumping hot air on a bad tune.

Your ideal AF's for a daily should look read 11/1 to 11.5/1 until you pass peak torque, so somthing around 4500. After that you can run it to 12.5 at the leanest without running alcohol or water.

Also, retarding that much base timing is horrible. When you retard timing your EGT's go up rather then down, mix that with a inefficient turbo and you've got a recipe for a blown headgasket.

Save up 100 bucks and build a water injection kit. Real easy and real cheap.

WD

[wild_maxx]

hey WD i am interested in a water injection kit. do you build them yourself and sell them?

[WDRacing]

I could build you one, but they are so easy I could just tell you how and list all the parts you'll ever need. Email me..

[email protected]

[hysteria]

water injection huh... might be looking into that when i turn my boost up a bit... just one more thing to add to this neverending to do list...

i have a friend that lives in tucson and goes to U of A

[blubottlemax]

You were running 15psi without your timing retarded at all? Damn, you really just hate your car don't you? Now, after all that abuse, you want to go the cheap way and not even get the head resurfaced? Not having money is more of a reason to it. Do it right the first time, so you don't have to spend money a second time when it goes wrong. Not that it matters, with the way your treating your car, that engine won't last long at all. Keep running 15psi on that T28 with stock timing and a metal headgasket. You will be posting more problems soon. I tried to point you in the right direction, but your obviously not interested.

Ok, I was just wondering why it bogged when it got from 13-15 psi before it blew. Could it be my MAF maxing out?? My wideband reads perfect, I'm running a 12.7 all across. It's a T28. Anyways, I already have my metal headgasket on order and I still gotta save up for the stupid boostdesigns clutch and flywheel. My engine still starts and runs, i feel the air push out from the headgasket everytime it turns. NO water at all. I'll post once I get it all fixed and running again, it sucks that I'm carless and it especially sucks that I can't race it!!!! Ohwell, my timing was'int retarted too, any of u guys think retarding from the distributer by itself is good enough. It's .5 degrees for evey psi right? Anyways, I'm probably not gonna have the head resurfaced because of $$$ issues. It did'int overheat so I'm good right?? The T28 is a fun turbo and had no lag compared to my stock gst, I don't know about u guys, but I don't even think I have lag, but eventually, I'm gonna go for a t3/t4 for bigger power numbers.

[Luderacer14]

That sucks, 15 psi is pushing the limit on a t28. I guess your right, I'm probably gonna pay the extra $100 to get my head resurfaced. So 12 psi would be good right?? I'm trying to get an idea so I can do it right the next time. At 12psi, my stock maf is still good right? I think it maxes out at 250horsepowers. Is there anyways my t28 can make 300 horses to the wheels. I'm guessing a t3/t4 don't bolt up to a t28 mani. It looks like my turbo sucks!! Should of bought the boostdesigns kit!! I really want 300 Horses bad!! Is a safc and 370cc, 300zx fuel filter and walboro pump good enough?

[Jookmasta]

its really tough to say if the fuel setup is good enough. the t28 does become a heat pump after that 15 psi threshold. It really depends on the turbo and what ur afrs are. If you can still get 11 afrs and ur running 12 psi on a t3/t4 with the same injectors, then ur good to go. Of course u have to watch the duty cycle on ur injectors but u get what im saying.

As bluebottle said, dont spend money twice if u can just do it once...........