emwporsche

I was going to buy both the boost enhancer and an mbc from lindsey racing but:

the lindsey guys clearly stated to me that you cannot use the boost enhancer and a manual boost controller.

it constricts the system too much and you will get overboost/boost spikes

someone with both should weigh in here but that's exactly what they told me.
I went with the mbc.

RKD in OKC

First Point.
LBE works with the stock cycling valve becaue the cyclic valve starts opening the wastegate before reaching max boost. The LBE holds back the boost pressure the cyclic valve can send to te wastegate until the boost pressure reaches the setpoint of the LBE. If you have a MBC it should not be opening to send boost pressure to open the wastegate until boost reaches the set pressure of the MBC. If you use the LBE with a MBC it is just a restriction in the boost line going to the MBC.

Second Point.
Varying boost levels and MAF mapping. As long as you have your MAF mapped correctly throughout the MAF's range at the maximum boost you are going to run it is safe to turn down the boost because the MAP is based on air flow. However, The DME bases it's timing decisions on load. This load, in part is determined by the voltage from the MAF. If you have the MAF mapped for higher boost levels, it will not reach enough voltage at lower boost levels for the DME to think the car is under load. This means the timing will not be advanced at the lower boost levels making the car very sluggish and laggy.

Real world example: I turned my boost down from the 21psi of my 395 rwhp run to 17. Doing some data log runs with my Mafterburner my time from 3000 rpm to 6700 rpm in third gear was 14 seconds with perfect A/F ratios. And yes, if felt sluggish and it wasn't just from turning down the boost. The maximum air flow at 17 psi was only sending 4.2 volts to the DME where at 21 psi it was sending the required 4.6 volts, ie more boost, more flow. I turned down my fuel pressure and remapped the MAF MAP to basically the same A/F ratios but with more voltage going to the DME so the max voltage was once again 4.6 volts. After the re-mapping the data log showed a decrease in time of the 3000 rpm to 6700 rpm run from 14 seconds to only 6 seconds. Quite an improvement timing makes yes it does!

azmi951

no wonder Vitesse chis feel sooooo good. John must have gotten the timing right.

eniac

I thought most of the timing was done in the KLR based on vac./boost pressure, then makes adjustments from input of other sensors, such as the knock sensor.....or does the KLR only retard timing on boost and does nothing else with timing at any other time?

Am I completely wrong in thinking this?

Mike1982

Hally, when I did the dyno run I had the afm in the car, not the MAF or vitesse chips. I had everything in my profile as well as Guru chips. I did NOT hold full boost until redline, it still dropped down to about 12 at about 6,200 or so. With the MAF installed it seems to hold longer but I only had the MAF on my car short period and got into an accident not even a week after installed, so it is still at the shop right now. I can say the with the MAF and John's chips the car DOES have more pull in the upper rpm's! The MAF and his chips really opened up the top end on the car, it just pulls hard compared to just so-so.

fast951

Back to basics! If the DME is programmed with the correct transfer function for the MAF used, it will know how to calculate the LOAD based on the voltage from the MAF. This is what you call "MAF chip". The DME always knows the correct LOAD, the correct air mass and will calculate the correct amount of fuel and timing needed.

If you are using a signal massager to modify the MAF signal to fake it so the DME handles it (as DME is setup for a AFM transfer function and AFM data). The DME is not calculating the correct LOAD. (the MAF voltage correlates to actual flow, but you change the voltage, so DME is getting modified values). More than likely, with this setup you will have to modify the signal with a deviation in boost. If the signal is greatly modified, you will be picking up the incorrect timing values. This appears in many forms, one of which is hesitation at part throttle.

ehall

SO....back to the topic. Which is better for this guy? Hijacks aside.

Skip Wolfe

Along the same line...I drove a buddies car with a mechanical boost control and a Tial 38mm wastegate. I found the boost control to be very binary - on/off, which may be great for a drag race but it suck when trying to modulate the throttle while going through a long sweeper at the track. Is this lack of partial throttle control - small throttle difference between full boost and no boost - a characteristic of a manual boost contoller? I am getting a Tial wastegate but am wondering what the best method of control is based on this experience.

eniac

I say EBC all the way. It's worth the extra money.

pcarphanatik

My biased opinion is that you should get a decent vac/boost gauge and also order an accuboost from boostsciences.

The accuboost was simple to install and has had "set-it, forget-it" accuracy and reliability for me.

Once your performance goals increase you may want to step up to a nice EBC, but in most cases it is more of a luxury than a necessity.

As always your mileage may vary and don't forget to sock away some change for the day you need a new clutch/trans/belt job

Crazy Eddie

Speaking of .... Accuboost
I have a brand new one in the bag it came in with the "ceramic upgrade ball" from the group buy last year. It's anyone's for the price I paid which was a very good deal.... It's supposed to be one of the better MBC'ss out there ...
If anyone is interested, Let me know
regards
Ed
ps I got an EBC because I have a 2 port WG and I was told it runs really good with my set up

GPF

Sorry to butt in, but MBC's don't work like that - they are pressure regulators.

Your description of the LBE is perfectly correct, but an MBC is permanently open - it simply restricts the maximum pressure that can flow past it.

To use an MBC you need a DP type wastegate, and the MBC has to be connected to the "spring" side of the diaphragm, whereas the LBE would be connected to the opposite side of the diaphragm ie the normal "signal" side.

Regards

Graham

'88 Turbo S

DanG

Here is the infamous level AND rate adjustable MBC...

page 1
page 2

I'm only going to keep those up for a few days, so save as "webpage complete" if you want to keep it.

Evan70

My car came with the Lindsey DP wastegate and MBC. Personally, I like the EBC that I upgraded to much better, mainly because I know exactly what it is doing and it's much more precise in it's adjustments. The MBC is very vague and you don't know what you're going to get until you spool up the turbo. Plus, there's no need to adjust the EBC for different weather conditions, it does it all on it's own and keeps the boost right where I want it all the time. It's also very nice to be able to see peak boost and a graph of the boost curve as well.

ninefiveone

Actually an MBC will work fine with a single port wastegate like the stock 951 gate. It does work better with a dual port just an EBC will work better with a dual port.

One shouldn't need to adjust an MBC for different weather conditions. Remember, a MBC is just a pressure regulator and it just so happens that boost is pressure. If you have the MBC set for 15psi in 100 degree weather, it will still give you 15psi in 30 degree weather. Now it is a mechanical device and in the 5 years I've had my car I've seen differences of +/- 1 psi in different temperatures but not once have I had to adjust based on weather.