Turbosmart MBC won't hold steady boost! Normal?? - Zilvia.net Forums | Nissan 240SX (Silvia) and Z (Fairlady) Car Forum

ShimiBoi · 06-30-2013, 01:17 AM

Been reading up on MBC and "boost taper". It still feels better with the Turbosmart MBC. I have it on the first click, which is ~9psi. When I get past 4k the boost starts to taper off to a steady 7psi. Is this normal? Did you guys that have tried this find any way around this? Thanks in advance!

Some background info:
Stock block ka-t
Bottom mount T25 @7-9psi
Sr SMIC w/ Sr piping
Sr 370cc injectors
Z32 maf
Greddy RS recirculating BOV

EsChassisLove · 06-30-2013, 01:26 AM

It's a T25.

They don't hold boost for shit past 5000.

ShimiBoi · 06-30-2013, 04:12 AM

Good to know, I thought it would hold 9 til redline but it will hold 7. Will the MBC shorten the life of the turbo by a lot?

Croustibat · 06-30-2013, 07:26 AM

They dont hold boost on a CA18DET. And the SMIC is horrible, on CA and SR.

What do you expect on an engine that has 600cc more displacement ?

EsChassisLove · 06-30-2013, 08:55 AM

No it won't shorten the life of your turbo. The way you drive will make that call.

ShimiBoi · 07-01-2013, 02:00 AM

For sure. It holds 7psi all the way no problem, just wondering about boost taper. Or if anyone else had experience with it.

06-30-2013, 01:17 AM	#1
ShimiBoi Zilvia Member Join Date: Feb 2009 Location: Hawthorne Posts: 216 Trader Rating: (9) Feedback Score: 9 reviews	Turbosmart MBC won't hold steady boost! Normal?? Been reading up on MBC and "boost taper". It still feels better with the Turbosmart MBC. I have it on the first click, which is ~9psi. When I get past 4k the boost starts to taper off to a steady 7psi. Is this normal? Did you guys that have tried this find any way around this? Thanks in advance! Some background info: Stock block ka-t Bottom mount T25 @7-9psi Sr SMIC w/ Sr piping Sr 370cc injectors Z32 maf Greddy RS recirculating BOV

06-30-2013, 01:26 AM	#2
EsChassisLove Nissanaholic! Join Date: Jan 2011 Location: San Diego Age: 34 Posts: 2,090 Trader Rating: (26) Feedback Score: 26 reviews	It's a T25. They don't hold boost for shit past 5000. __________________ IG/TikTok-ThatS14_Z06guy

06-30-2013, 08:55 AM	#5
EsChassisLove Nissanaholic! Join Date: Jan 2011 Location: San Diego Age: 34 Posts: 2,090 Trader Rating: (26) Feedback Score: 26 reviews	No it won't shorten the life of your turbo. The way you drive will make that call. __________________ IG/TikTok-ThatS14_Z06guy

06-30-2013, 04:12 AM	#3
ShimiBoi Zilvia Member Join Date: Feb 2009 Location: Hawthorne Posts: 216 Trader Rating: (9) Feedback Score: 9 reviews	Good to know, I thought it would hold 9 til redline but it will hold 7. Will the MBC shorten the life of the turbo by a lot?

06-30-2013, 07:26 AM	#4
Croustibat Nissanaholic! Join Date: Aug 2011 Location: France - Toulouse Age: 43 Posts: 1,851 Trader Rating: (0) Feedback Score: 0 reviews	They dont hold boost on a CA18DET. And the SMIC is horrible, on CA and SR. What do you expect on an engine that has 600cc more displacement ?

07-01-2013, 02:00 AM	#6
ShimiBoi Zilvia Member Join Date: Feb 2009 Location: Hawthorne Posts: 216 Trader Rating: (9) Feedback Score: 9 reviews	For sure. It holds 7psi all the way no problem, just wondering about boost taper. Or if anyone else had experience with it.