Catless midpipe increased boost pressure.

[yudkib]

i believe so, but dont quote me on it. can someone whos been around longer back me up...?

 

[Wagonbacker9]

I can't remember which ones came with a distributer... but if you just need the bottom end you'll be fine.

 

[codex]

I'm thinking of doing megasquirt, since I've wanted to try it for a while. Is megasquirt more cost effective than the ssafc?

 

[Wagonbacker9]

depends on your goals. if you want over probably 250, SSAFC won't get you there.

 

[yudkib]

megasquirt doesnt have a ton of support for these cars yet, but people have made it happen, and i know im personally hoping to run it eventually. if you want to control timing, its the only thing that can advance it aside from a $1000 standalone. you have to be dedicated and knowledgable about soldering, hardware, software, the sensors/fuel system/ignition system on these cars, tuning... and good at finding your own solutions.

someone correct me if theres a good MS thread out there, but ive never seen one that had a ton of info.

 

[Stormtrooper77]

HP gain?

Just curious as to what kind of hp gain should be expected with an SLS Catless midpipe on a completely stock exhaust, if any?

 

[Wagonbacker9]

something at least, 5-10 maybe. the cats are the main restriction in the exhaust.

 

[Sport23]

Codex. If you use any 626 motor make sure you swap the protege cam gears over. The 626 and protege have a different number of pickups on the cam gears. I don't know for sure if you have have to swap the CAS. Check these two threads for more FS-DE info:

http://www.mazdas247.com/forum/showthread.php?t=123739954

http://www.mazdas247.com/forum/showthread.php?t=123713157

 

[codex]

So I've noticed that at WOT it is more like 9.5psi. But, when I first give it throttle, it spikes to about 11-12psi before settling to 9psi, I'm assuming this is a delay in the wastegate opening. Is this what blows the motor up? Or is it boosting to 10 at low rpm? I've noticed that by 2.5k rpm it will boost to 10psi. Does changing the vacuum line to the WG eliminate the boost spike?

 

[Sport23]

I believe a dedicated vacuum line for the WG will help with the spike but it's been a while since I've looked into it.

 

[yudkib]

probably not, the ATP has a tendency for small spikes. [edit: no shame in trying. generally the mantra is to use a dedicated line to the WGA anyways]

blowing up engines in these cars cant be boiled down to one thing, its more like "when the stars align". its the bad tune, weak rods, bad tranny, etc, etc etc.

if you have a boost spike too low in the RPM youre out a tranny. the torque added after spooling is just too much for our third (and sometimes fourth) gear. the best way to avoid the issue is to avoid boosting past a couple psi when youre in third or fourth and are below 3500 on the tach. personally, i dont boost in third, fourth, or fifth at all unless im over 4000.

the other issue is the engine... basically, if the spike is at that 400-500 RPM window where the lean spot in the WOT open loop is, it leans out and detonates until you spin a bearing or throw a rod. nothing you can do to avoid that except get a tune and hope you have a freak engine... some have survived 12psi with no tune or FMIC, some have blown totally stock.

 

[Stormtrooper77]

Since adding the midpipe my car spikes at 10ish but settles at between 6 and 7 (all stock).

But in general, like yudkip said, just be smart about it and not boost in 3 - 5 in the lower rpm ranges.

 

[codex]

I'm still debating whether running colder plugs, ssafc and a wideband is necessary. Seems like people get away without these things without any problems.

 

[yudkib]

just because they get away with it doesnt mean its right. some people do get away with it, but as mentioned, some people dont get away with being almost stock. thepope540 blew his engine at ~5psi just because he was unlucky.

http://www.msprotege.com/forum/showpost.php?p=5033688&postcount=33

 

[Wagonbacker9]

if I wasn't running 5-6 psi, I'd step to colder plugs... believe it or not plug temp can significantly change your AFR.

 

[codex]

if I wasn't running 5-6 psi, I'd step to colder plugs... believe it or not plug temp can significantly change your AFR.

This would mean that having the correct heat range plug is very important. So, how do we know that running 1 range colder is correct for 9psi? Do we have actual proof of this? AFR-RPM charts?

 

[Wagonbacker9]

This would mean that having the correct heat range plug is very important. So, how do we know that running 1 range colder is correct for 9psi? Do we have actual proof of this? AFR-RPM charts?

if you're in the 9 range, you want to go a step colder. yes, its been documented on widebands. (no, not by me)

 

[codex]

Could someone help locate the difference in AFRs between stock plugs and 1 range colder at 9 psi? Was it on this forum?