MBC how much PSI???

[mkiiisupra]

I run into the fuel cut problem on stock boost with my current set up. TAking care of other problems before i address the FC one. Would suggest fixing the problem as in lexus AFM mod + 550cc injectors and a good tune rather than putting a FCD on it and turning up the boost

[Spudboy]

Originally Posted by mkiiisupra

I run into the fuel cut problem on stock boost with my current set up. TAking care of other problems before i address the FC one. Would suggest fixing the problem as in lexus AFM mod + 550cc injectors and a good tune rather than putting a FCD on it and turning up the boost

mkiiisupra...what is this 'divorced wastegate' you list in your mods?

I have the lexus AFM, took off my JC 550cc's because the performance shop who installed my AEM EMS and dyno tuned couldn't get them to work correct. He claims that the stock injectors are more than enough. My problem that he can't figure out for sure is my boost wont hold above 8 PSI. (modified turbo to 47 trim good to about 22 psi if I want to blow up my engine) He suggests a 3" downpipe may do the trick (I have stock still, but a big HKS drager cat-back over 3.5 inch diameter) but I'm not convinced. My feeling is the stock wastegate actuator I am running may be the culprit.
(I'm sure the downpipe and a good intercooler with hardpipes will be a great help but I'm not sure that's the root of this boost cut.)

Dyno'd at 252 hp and 318 lbs torgue at 4000 rpm when the turbo boost drops off, dropping HP and torgue a little before rising up again and leveling off at about 252 HP and 252 torgue around 5k through 6k rpm before slowly declining.

Any ideas?

____________________________________________
Current Engine Mods as of July 08

1) Metal HG with ARP studs
2) Turbo rebuild/upgrade by Majestic Turbo, TX to 48 trim.
3) K&N intake/filter
4) Flex-a-lite electric engine cooling fan
5) Lexus MAF (with stock Supra sensor)
6) HKS Super Drager Catback exhaust (95 mm or 3.75 inch piping)
7) Blitz SBC i-D (boost controller)
8) AEM EMS (Dyno tuned)

[j3pz]

spudboy: replace your downpipe and turbo elbow with a downpipe with the elbow integrated into it. the stock elbow is quite restrictive and maybe what is hindering you.

a divorced wastegate is referring to the downpipe. basicly it splits the wg and exhaust flow to allow a smoother flow. in stock form the flow is quite turbulent. look here to see a divorced down pipe

also if you have a standalone, why even use a afm? that is limiting you're airflow. and you're tuner said the stockers are adequet? for what? what are your goals? try replacing your downpipe and see if that fixes your boost problem, it will also net you a few ponies and spool your turbo quicker

[Spudboy]

Originally Posted by j3pz

spudboy: replace your downpipe and turbo elbow with a downpipe with the elbow integrated into it. the stock elbow is quite restrictive and maybe what is hindering you.

a divorced wastegate is referring to the downpipe. basicly it splits the wg and exhaust flow to allow a smoother flow. in stock form the flow is quite turbulent. look here to see a divorced down pipe

also if you have a standalone, why even use a afm? that is limiting you're airflow. and you're tuner said the stockers are adequet? for what? what are your goals? try replacing your downpipe and see if that fixes your boost problem, it will also net you a few ponies and spool your turbo quicker

Thanks j3pz...my tuner said exactly the same things as you: downpipe and get rid of the afm. He said the stock injectors seem to be adequate. We had a seperate problem with the injectors and mutually decided to go back to the stock for now. Still need to figure out the problem with the injectors but one thing at a time.

Did you notice great boost and power improvements with this divorced wastegate downpipe? What boost levels are you running and do you have the stock actuator?

My goal is a good fast street/track road course machine that can compete with modern 350z's, STi's, EVO's, S2000's, et al. A big part of that goal is to also learn about my car and others while doing as much of the work myself as possible. A big part of the fun is showing up at the track with a clean 20 year old car and 50 year old driver (not so clean) and surprising the others.

I've had 5 track days in the last 2 years with the car and driver (me) improving each time but can still do much better I'm sure.

[j3pz]

i actually dont have one yet, maybe within the next few weeks though. 935motorsports sells a cheaper one. on a stock ct, most people dont push more than 12-14 psi. also have read that boost comes on at a lower rpm.

[Spudboy]

Originally Posted by j3pz

i actually dont have one yet, maybe within the next few weeks though. 935motorsports sells a cheaper one. on a stock ct, most people dont push more than 12-14 psi. also have read that boost comes on at a lower rpm.

Thanks j3pz. I have heard the same on the boost dangers and don't plan on pushing my luck past 12 psi. I may go with that divorced downpipe but may do a little more research first. I have asked one guy (Majestic Turbo out of Texas) if he has any knowledge or warnings about running those. I will let you know as I learn things.

[mkiiisupra]

Originally Posted by Spudboy

mkiiisupra...what is this 'divorced wastegate' you list in your mods?

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