choinga

I've been reading a ton of posts on WG, MBC, dialing in boost, which chips, etc...

My car is a pretty stock 87 951 - only significant mod is a SFR 3" exhaust with cat delete.

I had my car in the shop last week for a head gasket and new belts and while it was in there we tried installing a 38mm Tial - but with the stock chips (I think they are stock...but will get to that in a sec...) with and without the MBC we were hearing some detonation...and at or below the stockish 12PSI of boost.

With the stock WG, Lindsey MBC I can boost up in the 15-20PSI range. When tweaking the MBC I've felt a cutoff a couple times but it wasn't until well past the 12PSI range from the factory chips (I've installed the Lindsey gauge cluster w/ autometer boost gauge). It feels almost like a governer...and if you try to boost immediately after it cuts off...the car jerks a little bit and then after a few times through the gears, it will boost with no issue again. I'm assuming that's the chip handling that but not sure.

My shop did all the work but from what I can tell it looks like the CV is out of the picture and we're just using the vacuum connection from the top of the stock WG that comes up into the engine at the heat shield to the MBC and then another vacuum line coming from the MBC to the manifold. They completely redid all the vacuum lines when they were in there with Lindsey's kit - so that's tight.

I have a set of the 951MAX chips - but with my stock WG and MBC I get detonation with those and not even at high boost. If I switch back out with the 'stock' chips, no issue.

So, I'm thinking about:

1) getting one of the DME chips or board from Vitesse to see if that helps and allows me to get my Tial back in. I'd like to go to dual port so I can get the turbo to spool a little quicker.
2) Get the Tial back in - I've got one with a .8 bar spring but after putting it on the bench we noticed that it doesn't even start to open until .8 bar whereas the stock WG starts opening at .5 and is wide at .8.

Anyone have any recommendations? The detonation thing is just bizarre to me. I can't figure out why with the stock WG I can show boost up into the near 20PSI range and I get nothing...but if I drop the 951MAX chips in (which my assumption is they are supposed to caution on the too rich side...) I get detonation and at or below 10-12PSI.

I've got a narrowband AFG and it shows with both the stock chips and the 951MAX that at boost, I'm definitely rich. (yeah, I know...get a EBC...but honestly, I don't think that's my problem at this point...)

I like the performance right now - but with the overboost that I get in 4th I've had to tweak that back and because of that I don't really see any boost in 1st until very high RPM, maybe 10PSI in 2nd, around 12 in 3rd. Those numbers sound about right but the boost is pretty late - would love for it to kick in a little earlier instead of in the 4500RPM range...

xsboost90

first off w/ stock injectors and no real control of fuel but the chips i wouldnt be running 20psi. With the stock chips you will get a ignition/fuel cut at 14.5psi. My car did this until i went w/ the Russel chips and KLR chip that got rid of the boost cut .You will want to make sure your boost controler is routed properly w/ the waste gate- since your WG is now a dual port. You also have to make sure if you have a lindsey MBC that the **** is popped back down after you adjust it. Higher outside temps will also cause you to get into boost cut at lower pressures-pressure drop through the IC.

choinga

Thanks Dan.

I have a set of 951MAX chips from Lindsey and dropping those in makes the engine detonate and not even at high boost (like 10-12PSI) - with or without the MBC.

I double confirmed with Dave that they are OK for my configuration (stock except 3" pipe) but my mechanic and I can't figure out WTF is going on with that.

I get the same damn detonation problem with the Tial but if I go back to stock with the MBC I can boost up into the 14-18 range and not hear a bit of detonation - my A/F gauge shows rich at boost with either configuration.

Drop in the Tial or 951MAX chips in an otherwise good configuration and my engine starts to kill itself. I'm running the best gas I can find around here - Shell or Exxon 93 octane always. I even tried some octane booster to see if that would fix it...nada.

I'm confused. I want to get the Tial back in there...I was emailing with John @ Vitesse today and may try his AFM chip to see how that works. If I can get that going with no detonation problems, I'll try putting the Tial back in. The other option would be dropping the spring in the Tial from a .8 bar to a .4 or .5 bar to get it to match the stock WG a little better.

Just looking for other thoughts/suggestions...this one is driving me nuts.