mid pipe or hi flow cat?
#2
depends if staying smog legal is important to you. Hi flow gives alittle more torque as well, but Mid pipe gives alot more top end and is better overall. Both are better then stock
#6
Original Gangster/Rotary!
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Re: mid pipe or hi flow cat?
Originally posted by azndisgrace
which is better?
which is better?
Do you have a boost controller?
What ECU do you have?
Are you still running stock twins?
Is your motor ported?
What fuel mods do you have?
Without knowing all of this I would say definitely go with a high flow and stay far, far away from the midpipe.
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#8
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removing cat converters on standard cars could hinder performace, because this may adversely effect mixtures, boost levels etc etc. However if other mods such as aftermarket ecu, fuel pump and injectors have been fitted no problems should be experienced. Just be prepared for that stench of rich rotary exhaust fumes!!!!!
#9
Original Gangster/Rotary!
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Originally posted by rotator
removing cat converters on standard cars could hinder performace, because this may adversely effect mixtures, boost levels etc etc. However if other mods such as aftermarket ecu, fuel pump and injectors have been fitted no problems should be experienced. Just be prepared for that stench of rich rotary exhaust fumes!!!!!
removing cat converters on standard cars could hinder performace, because this may adversely effect mixtures, boost levels etc etc. However if other mods such as aftermarket ecu, fuel pump and injectors have been fitted no problems should be experienced. Just be prepared for that stench of rich rotary exhaust fumes!!!!!
Even with ecu, fuel pump, inj's (all of which I have) I was still creeping to 13psi hot day/15psi cold day *with a ported wastegate!* Imagine what would/could happen with a stock wastegate...
#11
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Originally posted by rotator
hey goodfella...would adding a good quality external gate fix the boost/lean out problem?
hey goodfella...would adding a good quality external gate fix the boost/lean out problem?
So, to answer your question--yes, kind of. If you keep the stock twins then you're stuck with the stock WG.
And of course, you can still lean out, although it won't be b/c of excessive boost creep.
lemme know if you have any more questions....
Rich
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I was planning on getting a midpipe but my mind has now been changed after reading these posts. To hell with a blown engine. I'm paying $3K for a tranny swap so I definitely don't have the funds for a new motor.
#13
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Originally posted by FD3S LIGHTNING
I was planning on getting a midpipe but my mind has now been changed after reading these posts. To hell with a blown engine. I'm paying $3K for a tranny swap so I definitely don't have the funds for a new motor.
I was planning on getting a midpipe but my mind has now been changed after reading these posts. To hell with a blown engine. I'm paying $3K for a tranny swap so I definitely don't have the funds for a new motor.
3 grand for a tranny shop? KD charged me about a third of that for my rebuild....are you going from auto to manual?
Rich
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Some hi-flo cats flow pretty close to midpipes as stated above but I think most of the pros are with the hi-flo cat.
Hi-Flo cat you definitely get more low and mid-range but overall less peak hp, much quieter, easier to tune and can help solve boost creep and spikes - the only bad thing is if used without the airpump they might go bad in a few years
Midpipe sucks with low-end power but really pulls above 6K rpms, uncontrollable boost, can lean out (especially on cold days) and is hard to tune perfectly, smells like a truck stop in your car, mind-boggling noise
Most drag racers will stay with a midpipe but for street cars, I think the midpipe is overall the better choice.
Hi-Flo cat you definitely get more low and mid-range but overall less peak hp, much quieter, easier to tune and can help solve boost creep and spikes - the only bad thing is if used without the airpump they might go bad in a few years
Midpipe sucks with low-end power but really pulls above 6K rpms, uncontrollable boost, can lean out (especially on cold days) and is hard to tune perfectly, smells like a truck stop in your car, mind-boggling noise
Most drag racers will stay with a midpipe but for street cars, I think the midpipe is overall the better choice.
#19
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So which HF cat seems to the one of choice? I mean the one that is similar in flow to the midpipe, gives some low-end, is smog legal and controls boost creep better? Am I asking too much? lol
#21
I really dont know much about exhaust systems or dp or mp's. would it be better to just but on a high-flow cat, or a dp, and which one is more cost effective? what are the results of putting a 3 in dp on there?
#22
I run full sequential with a full open exhaust (DP/MP/Cat-back) and have been doing so for about 25K miles with the proper tuning. Do I have boost creep? Yes. When? 5th gear lugging it at 2K rpm and flooring it. How often do most people do that? Never. Sure, you'll have boost creep in 5th running down the back straight at Sebring International, but day to day, if your car is tuned right and you have a competent boost controller, it works just fine. A midpipe will be less expensive than a high flow cat. Your car will be louder however and not meet federal or state emissions. I saw a 40hp gain going from the stock main cat to a midpipe. I've posted dyno graphs on the forum so just do a search :-) If you're looking for a resonated stainless steel midpipe, I just happen to have a Pettit one for sale. Swapping out the twins for a modified T78.
Oh, going non-sequential will not solve boost creep problems. Even if you port the wastegate, you'll get a bit of it under certain circumstances. A way to safeguard the motor in those instances is to simply enrich the fuel maps considerably above a pre-determined boost level. Typically I run .95kg/cm2 on the twins daily in S. Florida (hot). Above that level on my PFC fuel maps, I've maxed out the fuel correction cells to 149's across the board (a percentage increase of the base map injector duty cycles). If I do overboost, it happens quickly and the extra fuel protects the motor.
So...if your car is properly modified then go with a midpipe for the power. I had MANY people, who really had no experience with midpipes, tuning, etc...say that I'd blow my motor within a week.
Michel
Oh, going non-sequential will not solve boost creep problems. Even if you port the wastegate, you'll get a bit of it under certain circumstances. A way to safeguard the motor in those instances is to simply enrich the fuel maps considerably above a pre-determined boost level. Typically I run .95kg/cm2 on the twins daily in S. Florida (hot). Above that level on my PFC fuel maps, I've maxed out the fuel correction cells to 149's across the board (a percentage increase of the base map injector duty cycles). If I do overboost, it happens quickly and the extra fuel protects the motor.
So...if your car is properly modified then go with a midpipe for the power. I had MANY people, who really had no experience with midpipes, tuning, etc...say that I'd blow my motor within a week.
Michel
#24
Original Gangster/Rotary!
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Originally posted by Don-94BB R2(NJ)
So which HF cat seems to the one of choice? I mean the one that is similar in flow to the midpipe, gives some low-end, is smog legal and controls boost creep better? Am I asking too much? lol
So which HF cat seems to the one of choice? I mean the one that is similar in flow to the midpipe, gives some low-end, is smog legal and controls boost creep better? Am I asking too much? lol
This high flow has stainless steel piping and has a bung for the airpump already welded on. It bolts right up. Can't beat the price, too....it's less than half the price of the one I have on right now. I think it's time for a change .