legacycentral bbs

Ok I have built boost,fuel, and timing control into the Torquechip and have set boost at 15lbs. I did this as we ran into fuel delivery problems with The EJ22t with a stock fuel pump and injectors at 17lbs boost and had a lean out. We did have a 13.3 second car but were worried as it did lean out at the top end. Question I can set the boost wherever I want and use the stock boost control but where is the real safe limit considering the size of the injectors, fuel pump, and all else?? I also had a lean condition show up with a n/a engine in my car at the strip when over 8500 rpm this tells me that while there is room for improvment there is a safe limit but just what is it?

mile hi! We've missed you!

I don't have a good answer to your question, but I'd love to hear more about the updated Torquechip you're working on.

This is the info we have; maybe you can figure out your answers based on it:

Stock fuel pump flows 150lph at 43.4psi with a 12-volt power supply.
Stock injectors flow somewhere between 360 and 390 cc/min (I believe this is measured at 36.something psi, which is the fuel system's static pressure).
There's a compressor map at the end of this document which is allegedly for the Legacy turbo compressor:
1992_Subaru_Service_Manual-Engine & Wiring.pdf

But the safe limit of boost is probably lower than the fuel system's llimits, no?

I have been real busy. If you do the math the limit should be 17lbs I have run 20lbs for very short bursts with no real problems that I know of although I did have to replace my motor for a #2 rod bearing that shouldn't be boost related but boost probably didn't help. If anyone has the same problem the new 2.5 STI shortblock is almost a bolt-in and it runs very well with8.7:1 compression with the right head gasket. I was just trying to find a safe boost level taking into consideration that our fuel systems and injectors are not new anymore and I don't want to be buying an engine for anyone. We had enough of that with our last venture buying 3 new engines didn't help the bottom line one bit. I finally did find out why it is almost always #4 piston that goes first and that is that it runs hotter the only solution is to drill and tap the rear of the head and pull some water from it.
Al
al@iwtu.net

oh... you wanted to know about the new Torquechip. It is microprocessor based and adds fuel all the way through plus it leaves the original boost controller alone except for raising the limit and I left that fixed. It also flattens out the timing curve a bit and tricks the ECU into not retarding the timing as much.

well i ran 18psi for 400thousands Ks, in the winter i would get crazy and run 21psi. but 17psi should be good for a while. you siad #4 piston blows all the time well #2 blows all the time in my car #4 is perfect in my car.

Is that 21psi why you know that #2 blows allthe time?

21 psi boost on my factory turbo. we have change #2 piston 3 times it all ways blows up.

I would suspect a injector problem they can stick and cause a lean condition.
Alan
al@iwtu.net

i heard its a problem with legacy turbos all ways #2 piston gos.

i thought the #3 cyl was the lean one since its at the end of the fuel rail?

ahhaah who nows may be every car has its on piston problem thats funny.

then again it could be we're numbering pistons differently.

when you look at the engine from the front of the car subaru uses the system
3 4
1 2

maybe you're thinking something different? not that it's really all that important

Well a common complaint is #4 and I got curious and measured the temperature on the head and #4 is hotter and should be more likely to detonate I just didn't know why it was hotter. At the time we were doing some work on a real stock car and the owner sent an automotive engineer down to see (check on) us and I asked him what he thought. After looking at the engine and the manual he showed us why the cooling system design would cause a higher temperature in #4 and he agreed that that would be the most likely cyl. to give problems under high boost. He also gave us the fix of drawing water out of the head behind #4,. The next cyl to give us problems was #1. Now you can take it or leave it I just happen to think the man knew what he was talking about.
Al
al@iwtu.net

If its a head coolant passage issue, that would make sense as the heads are interchangeable left to right. Meaning if #4 had some kind of restriction to flow, #1 would also. I always thought #3 was the worst due to the fuel rail and turbo sitting next to it. Where exactly would you drill the head? Is it an easy operation?

Steve

Not really, the way he looked at it was #4 was the only cyl where the water didn't have a flow around the cyl. and an exit and had to "turn around " and come back to the crossover was slowed down and enough volume wouldn't pass to pick up the heat. The coolant volume and speed are critical as far as cooling goes. #1 and #2 were closest to the feed so a drain behind #4 should equal things out. And it did seem to do so as I checked the temps and they were very close after the mod. I will have to check and see just where we drilled the head for the drain. I have an extra set of Turbo heads and will try to take a look tommorow. The factory did a pretty good job probably because of the EA 82 mess. The
temperature on the turbo side of that engine was well over 300 degrees after a hard run and cracked heads and melt downs were commonplace. The USMB had a record setting thread on this problem that I started I wonder if it is still there??
Alan al@iwtu,net

your right maybe it is #4piston. two #2pistons that we changed, they both broke in the same spot. where they broke, was closest to #4 pistons wall side. maybe there is some thing really wrong in that area for cooling. how about if I get my dad, to port the cooling holes in the head. is that even possible. or a crazy idea

I think they are two different issues from different problems.

Guys who have piston #2 go are suffering from a lean run condition and fuel starvation. Nico, I know you have told us previously your set up gives enough fuel for how much boost (too much, IMHO) you are running, but if you keep blowing #2, it is because your engine needs more fuel.

As for the #4, as Mile Hi has mentioned, my understanding is that it is an issue with coolant temps. Historically, the traditional fix is a bigger radiator to get the coolant temps down across the board. I don't know about this tapping the head fix, but seem to remember seeing something posted about it elsewhere a while back. I'll see what I can maybe dig up and post back...

i only changed it twice in 6 years, thats not bad for my type of driving and boost. but there has bin other pepole with nothing done to there motors have problems with #2piston, we fixed to diffrent legacy with this problem