13+ psi on c30 kraftwerks kit? Should I be worried?

[captain awesome]

Originally Posted by Irace86.2.0

I think the 90mm gives around 12 psi. What should it do?

If anything those mods would lower boost. Temperature can do it too, but I doubt that is a problem, and we won’t know IATs. I don’t know if running as lean as you are would cause that boost peak.

I'm honestly at a loss as to what could be causing this. Exhaust restriction has been mentioned by others as well, so certainly worth looking into. The 95/128 pulley combo is correct for my application at the 9 psi range, it's just weird this is happening.



I imagine my BOV or diverter valve couldn't be responsible for the overboost?

[Irace86.2.0]

Originally Posted by captain awesome

I'm honestly at a loss as to what could be causing this. Exhaust restriction has been mentioned by others as well, so certainly worth looking into. The 95/128 pulley combo is correct for my application at the 9 psi range, it's just weird this is happening.



I imagine my BOV or diverter valve couldn't be responsible for the overboost?

I reread what you wrote. I missed it that you are running the 30mm belt/pulleys now, so that meant you now have a 95mm pulley because I thought you just said you were running the 90mm.

It is odd. You have zero reason for restriction with your exhaust mods. Scratch that off the list.

This isn’t a turbo, so there is no boost creep issues, wastegate spring issues, vacuum line issues, etc. The supercharger can’t accidentally overboost.

The BOV vents boost when the throttle body is closed. If there was no BOV or it didn’t open then the boost would build pressure against the throttle body, and it would work itself back to the turbine and cause damage. If the BOV stayed open the boost would constantly leak from the compressed side to the lower pressure intake side, so boost would drop.

This has to be an issue with the supercharger or pulleys.

[steve99]

Quick look at the logs, its making boost fine.


You have a fuel supply problem.


Generally you dont want to run di injection time over 6 maybe 7 ms, and port injection over about 15 ms.


The port is getting to about 18ms but past about 15 ms the fuel delivery appears to drop off quickly.
You might have low fuel pressure sgould be 60psi or i partially blocked fuel filter.


You are pushing the limits if the stock fuel system


The di pressure seems stable and its only runnng to 5ms or so so that looks ok


My guess would be fuel pressure issue, bad fuel pump blocked filter or some kind of fuel restriction.
Or your just maxing out ghe stock port injectors and pump


If you run a different pully to lower boost to say 9psi you will likey be ok, if its still a problem at 9psi , ie leaning out at top end then you got fuel delivery problem

[Irace86.2.0]

@steve99

This is about what I said earlier, but we are still trying to figure out the boost. He says he is on a 9psi pulley, but he is making 13psi. Any ideas? I’m convinced something with the pulleys is off.

[captain awesome]

It's a head scratcher for sure. I imagine there isn't anything in the Rotrex unit that could have been done to increase boost.

[Irace86.2.0]

Originally Posted by captain awesome

It's a head scratcher for sure. I imagine there isn't anything in the Rotrex unit that could have been done to increase boost.

Are you on the stock map sensor?

[captain awesome]

Originally Posted by Irace86.2.0

Are you on the stock map sensor?

3 bar Omni

[Irace86.2.0]

Originally Posted by captain awesome

3 bar Omni

OK, I verified that on Datazap. Hmm, I thought maybe you were on the stock MAP sensor and was getting bad data because of its limitations.

I wish you had another sensor to verify the reading. If the 20mm belt has a 90mm pulley then have you run your car with that pulley? If so, do you have a datalog? If not, would it be worth trying? If you can then you could verify things.

Hmmm man, I am at my wit's end.

[BRZSer]

Hi,

Purchased an frs that came with the Kraftwerks carb legal c30 kit. I believe previous owner bought the upgraded pulley kit if that matters.

It was tuned with all of e85 supporting mods and was seeing around 11.5~12psi. Since I live in california i needed to put it back to stockish and planned on smogging it with carb legal tune.

Did just that put the stock header with cats on and calmed down boost to around 9~9.5 psi in a cold day. It might or might not matter but also put the recirculating BOV back into the intake (it originally was venting into atmosphere).

[Irace86.2.0]

Originally Posted by BRZSer

Hi,

Purchased an frs that came with the Kraftwerks carb legal c30 kit. I believe previous owner bought the upgraded pulley kit if that matters.

It was tuned with all of e85 supporting mods and was seeing around 11.5~12psi. Since I live in california i needed to put it back to stockish and planned on smogging it with carb legal tune.

Did just that put the stock header with cats on and calmed down boost to around 9~9.5 psi in a cold day. It might or might not matter but also put the recirculating BOV back into the intake (it originally was venting into atmosphere).

So you are saying the kit made 12psi and now it makes 9 psi after putting the stock exhaust on? This might happen on a turbo, but not on a supercharger. Something is odd.

[tomm.brz]

Also to me it looks ok the boost
the IAT is not so high and when ambient temperature goes lower, it s easy to reach a lot higher boost
Also 30/30 of cam timing at high rpm will provoke this, i keep them lower

Anyway just keep lower limiter, it s kind of irresponsable to reach more than 7500rpm on 91oct with high boost
And fix the lean afr doing what steve said and asking your tuner to stop maxing out the PI

[BRZSer]

Originally Posted by Irace86.2.0

So you are saying the kit made 12psi and now it makes 9 psi after putting the stock exhaust on? This might happen on a turbo, but not on a supercharger. Something is odd.

Yup, here is my log : https://datazap.me/u/brzser/log-1574...g=0&data=14-26


It was with Tomei uel header. At 7200 rpm I'm seeing a manifold pressure of 27.49 which is around 12.79 psi. It was also leaning out just like OP mention (later figured O2 sensor was possibly busted which caused the very high AFR)



With stock header on: https://datazap.me/u/brzser/log-1574...data=4-5-14-26


Manifold pressure shows 24.5 psi which is around 9.8 psi at 7200 RPM.


Also this FRS is running the Kraftwerk c30 supercharger with stock pulley, and I'm sure of that lol.


My brz has a turbo and pretty sure I can tell the difference, haha.

[tomm.brz]

you can t even remotely compare turbo with sc, totally different managing of the boost, you have a wastegate working for it, sc boost depends entirely on pulley, restrictions and iat temperature

[BRZSer]

Originally Posted by tomm.brz

you can t even remotely compare turbo with sc, totally different managing of the boost, you have a wastegate working for it, sc boost depends entirely on pulley, restrictions and iat temperature

Both of those logs I posted are from the Supercharged FRS.


One with First one was with Tomei UEL, second one with stock header with cat......


I own both cars Supercharged FRS, and a Turbo BRZ.
I'm focusing on the supercharged FRS which those two logs are from.