I'm taking off my cat. I decided. It's plugged, restrictive and just a pain in my ass right now. What is the diameter of the downpipe and the pipe to the y-pipe? Anyone done this? (Im sure someone here has...) and what are all the materials needed. Thanks in advance any help would be appreciated.
ME + PLUGGED CAT + TGP = :evil: :evil: :evil: :x :x :x
measure the length of the cat. cut it out and clamp it in place of the cat. the stock pipe is 2.25" diameter. it may leak if it is clamped but not bad. you may have someone weld it in. it is not legal to remove the cat so most likely most muffler shops will not do it for you.
or another option is to take it to a muffler shop and have them add a flange on the back side of the cat. then go home and remove the cat/downpipe and bang the guts out of the cat. that way it still looks like there is a cat in there. big fines if you get cought without a cat in most states.
RedZ
well cut out the cat... runs 100000000 times better! now i take OFF! I'm gonna gut the cat later tonight and clamp it back on... but now I'm setting a code 31... whaaaaaat?
Quote from: jheivwell cut out the cat... runs 100000000 times better! now i take OFF! I'm gonna gut the cat later tonight and clamp it back on... but now I'm setting a code 31... whaaaaaat?
Well, there is some good news, and I am glad to hear it as well since the more cats we find bad, and the more complaining about lame quarter mile times the better the chances this will help them too, but hopefully not like you getting a code 31/over-boost condition :lol: Since you're car has been buggin you running poorly in the past, you did not by chance mess with the boost control system?
Jeff M
i don't know about a TGP, but on Turbo Dodges, a free flowing exhaust + small turbo = boost creep. i would "assume" the same is true for the TGP or any other turbo car with small turbo + free flowing exhaust.
even my brother's Omni GLH-Turbo with Garrett T03 (a fairly large turbo for a 2.5L 4-banger) and NO boost control (full manifold pressure to wastegate) will pull up to 10psi under heavy load on the highway. his GLH has full 3" exhaust - from turbine to tailpipe with no cat and an Dynomax 3" Ultra-Flo muffler. this is not enough boost to cause an overboost condition on his GLH, but it did cause an overboost condition when he used a 3" JRB system on his '89 Shadow ES 2.5 Turbo with the small Mitsu turbo (Turbo Dodges basically come with two turbos - a Garrett T03 or a very small Mitsu TDO5H). fwiw, the TDO5H and TGP T-25 look about the same size-wize)
my point is, and this is just an observation! - a large free-flowing exhaust WILL cause the boost to creep up when used with a small turbo, even to the point of causing an over-boost condition.
Quote from: malibuoldsi don't know about a TGP, but on Turbo Dodges, a free flowing exhaust + small turbo = boost creep. i would "assume" the same is true for the TGP or any other turbo car with small turbo + free flowing exhaust.
even my brother's Omni GLH-Turbo with Garrett T03 (a fairly large turbo for a 2.5L 4-banger) and NO boost control (full manifold pressure to wastegate) will pull up to 10psi under heavy load on the highway. his GLH has full 3" exhaust - from turbine to tailpipe with no cat and an Dynomax 3" Ultra-Flo muffler. this is not enough boost to cause an overboost condition on his GLH, but it did cause an overboost condition when he used a 3" JRB system on his '89 Shadow ES 2.5 Turbo with the small Mitsu turbo (Turbo Dodges basically come with two turbos - a Garrett T03 or a very small Mitsu TDO5H). fwiw, the TDO5H and TGP T-25 look about the same size-wize)
my point is, and this is just an observation! - a large free-flowing exhaust WILL cause the boost to creep up, even to the point of causing an over-boost condition.
Good point 8) , I have not seen it for the TGP setup yet, and have run some larger turbos and exhaust upgrades, even unplug the wastegate and only see a spike of 16 psi that drops down to 11 to 12 psi as the rpms climb (until your tighten the wastegate rod, no-no :nono: ) but you are right, there are some problems like this with some of the Diamond Star guys and especially the SyTy guys who remove the cat, turbo keeps creeping UNTIL they replace with a better turbine housing or open up the wastegate hole in the stock one!! Hahn Racecraft even went so far to cure this for their bigger turbos by getting a new designed turbine housing made up that would not creep. There are a few guys here in town that run straight pipe no nothing, even the Pike Peak racer had a straight pipe until it went up for sale, but only has a cat and a very straight exhaust system ;-). So, you are right on all counts, there are a lot of guys getting this, just don?t think yet it?s a TGP problem, but we will wait to hear what the owner has to say here.
Jeff M
right now my Lebaron GTS has the very same Mitsu-turbo'd 2.5 Turbo engine that was in my brother's '89 Shadow :) while i don't have a 3" exhaust, i did just install a full 2.5" JRB exhaust last week :) i'm hoping i don't have the same boost creep issues! that 2.5 engine in his Shadow was enough to beat out a new Saleen S-281:) i'm really hoping my GTS is in the mid-high 14's right now. if i do have boost creep issues, well i guess my T03 2.2 Turbo engine will be back in within a couple/few months and hopefully that will take care of any boost creep and maybe even get the car into solid mid-14's.
wow i'm going off-topic...
jheiv - would love to hear what's causing that overboost!
Quote from: malibuoldsright now my Lebaron GTS has the very same Mitsu-turbo'd 2.5 Turbo engine that was in my brother's '89 Shadow :) while i don't have a 3" exhaust, i did just install a full 2.5" JRB exhaust last week :) i'm hoping i don't have the same boost creep issues! that 2.5 engine in his Shadow was enough to beat out a new Saleen S-281:) i'm really hoping my GTS is in the mid-high 14's right now. if i do have boost creep issues, well i guess my T03 2.2 Turbo engine will be back in within a couple/few months and hopefully that will take care of any boost creep and maybe even get the car into solid mid-14's.
wow i'm going off-topic...
jheiv - would love to hear what's causing that overboost!
Now you did it :evil: :lol: , I was getting ready to crash early for me and all you said got me thinking, if this TGP has an ignition problem, that would let the air fuel mixture go rich which CAN cause it to over-boost, even bog rich! Also you forgot to read the PART about enlarging the wastegate hole trick to fix boost creep :lol: , give it a try, works for others! Now quit thinking, gotta crash.
Jeff M
Quote from: Jeff MI was getting ready to crash early for me and all you said got me thinking
lol glad to help :)
Quote from: malibuoldsi don't know about a TGP, but on Turbo Dodges, a free flowing exhaust + small turbo = boost creep. i would "assume" the same is true for the TGP or any other turbo car with small turbo + free flowing exhaust.
even my brother's Omni GLH-Turbo with Garrett T03 (a fairly large turbo for a 2.5L 4-banger) and NO boost control (full manifold pressure to wastegate) will pull up to 10psi under heavy load on the highway. his GLH has full 3" exhaust - from turbine to tailpipe with no cat and an Dynomax 3" Ultra-Flo muffler. this is not enough boost to cause an overboost condition on his GLH, but it did cause an overboost condition when he used a 3" JRB system on his '89 Shadow ES 2.5 Turbo with the small Mitsu turbo (Turbo Dodges basically come with two turbos - a Garrett T03 or a very small Mitsu TDO5H). fwiw, the TDO5H and TGP T-25 look about the same size-wize)
my point is, and this is just an observation! - a large free-flowing exhaust WILL cause the boost to creep up when used with a small turbo, even to the point of causing an over-boost condition.
The biggest reason for this problem is lack of significant boost control. Most of the TD guys are looking for the cheap answer to everything, and while effective, it does have drawbacks. Turbo's LOVE open exhaust. The snail creates enough backpressure for the engine, and the open exhaust allows it to expel the exhaust faster and spool better. Unfortunately, without adequate control, the turbo releves vacuum on the engine and causes boost spike and boost creep. With a good quality boost controller, it is gone.
Hope there's an answer to this soon. I am going to replace the entire exhaust system here very, very shortly. I have also decided much of my running issues are due to clogged cat. I was hoping to go 3", but if that's going to be a problem, I'd like to know now before I pour the money into a 3" exhaust all the way through. :shock:
Thanks for everyones replies... no i didn't mess with anything in the boost control area. When I put my engine back together I replaced the wastegate solenoid cracked brittle vacuum lines with softer rubber ones and plugged back in the sensor. I don't know if thats the problem or not. I'll check them later.
Along with the Code 31, I'm getting something that feels like fuel cutoff (which sounded to be normal when you get a 31) and then sometimes it will straight drop the RPMs off the tach and stall.
This car is loves its new legs-- I'm getting tire squeal again! The only real mods I've done are cone filter on turbo... I've replaced TONS of random parts and sensors but with OEM or OEM equivalent stuff.
I bought the two band clamps today and am gonna finish gutting it today. Still curious about this boost creep -- Are you saying that when I put back on my gutted cat and dual exhaust I'll have some backpressure that will limit overboost? Right now its just runnin on open headers. What do you think about waiting until I bolt up the gutted cat and see if I still throw a 31? Thanks again, this is great.
This boost creep that you are talking about. Could you describe it exactly for me?
In my STE if I go WOT most of the time it will only get ~6psi boost until about 5000rpms then it climbs to ~8.5 by the time it shifts, and in the next gear it goes back to 6psi and does the same thing. Is that what you're talking about?
The only exhaust work I have done is removed the cat and magnaflow mufflers, so it doesn't seem like it would've effected it much.
Shawn
Gutted the cat-- putting in on today-- Whaaaaaaat is boost creep?
I've driven my first TGP around with only the downpipe on and nothing else. My cat was broken apart and I could hear it rattling so I dropped the exhaust and figured I would beat it around and see if it made a difference. The "butt-dyno" didn't feel a difference, but it was really hot that day so she was kinda doggy anyways. :twisted:
My friends '91 sentra has T-25 on it with very close A/Rs to ours and he runs full 3" exhaust with no cat and it exits before the rear tire on the passenger side. Right now, he just runs 7.5 psi as his injectors are getting close to maxing out. We just have a vacuum line with no boost controller so the 7.5 psi is what the wastegate actuator is set to. He hits full boost by 3500, and it holds perfectly all the way to redline(~7500 rpms). :twisted: 8)
oh by the way... now I'm getting no boost and a coolant leak... haha the coolant leak is near the water pump... ill have to look into that more... and the weak boost i think is from a broken hose... we'll have to see