Typical Boost Response/Stock Turbo?
Typical Boost Response/Stock Turbo?
I would like someone to describe for me how a fairly stock Evo 8 with a hallman mbc, AMS LICP, open dump STM 02 housing, and cat delete pipe should spool. Car is running stock catback and was tuned at STM.
Right now I have literally NOTHING until 3 grand. You can roll on the throttle in second gear and mat it as soon as you hit 3 grand and the car still hesitates for a full second before I get any kind of pull. It doesn't sound right, and it certainly doesn't feel right. Are these cars supposed to feel like the boost is an on off switch? When I first bought this car and it was bone stock I remember it being very peppy and rev happy, now it feels like I am driving around with a parachute behind the car.
Once the car starts spooling around maybe 3200rpm it makes good power all the way through the RPM band, but it just feels very boggy. STM has done boost leak tests and a compression test on the car, and are fairly insistent that there is nothing wrong with the car. I feel like a related issue is very noticeable in the morning when I first start the car, regardless of temperature every initial start after a significant amount of time it will stumble and hesitate for the first few minutes, then clean out.
I guess I would feel better if someone could tell me they feel the same and it is normal, but I expect that the mbc, o2 housing, and cat pipe combined with a tune and stock turbo should be a pretty snappy little car?
Right now I have literally NOTHING until 3 grand. You can roll on the throttle in second gear and mat it as soon as you hit 3 grand and the car still hesitates for a full second before I get any kind of pull. It doesn't sound right, and it certainly doesn't feel right. Are these cars supposed to feel like the boost is an on off switch? When I first bought this car and it was bone stock I remember it being very peppy and rev happy, now it feels like I am driving around with a parachute behind the car.
Once the car starts spooling around maybe 3200rpm it makes good power all the way through the RPM band, but it just feels very boggy. STM has done boost leak tests and a compression test on the car, and are fairly insistent that there is nothing wrong with the car. I feel like a related issue is very noticeable in the morning when I first start the car, regardless of temperature every initial start after a significant amount of time it will stumble and hesitate for the first few minutes, then clean out.
I guess I would feel better if someone could tell me they feel the same and it is normal, but I expect that the mbc, o2 housing, and cat pipe combined with a tune and stock turbo should be a pretty snappy little car?
Going to a MBC and cranking up the boost should make the car MORE responsive, not less. I am just struggling to agree that it is "ok" for the car to be flat as a pancake from a 3000 rpm roll in second gear. I really thought boost was almost instantaneous at that point....someone correct me if I'm wrong. I will take some videos and post them for a little better description.
Evolving Member
Joined: Feb 2011
Posts: 181
Likes: 1
From: Woodbridge, VA
I just want to know, if you roll the car to 3 grand on dead flat ground and then mat it, how long does it take to hit peak boost? I am waiting almost a full second to feel any kind of pull from this RPM, and I just think it seems quite odd. If its normal so be it but I have a hard time grasping the fact that the car has zero power from a roll at 3000 rpm.
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Evolved Member
Joined: Jun 2006
Posts: 6,902
Likes: 151
From: Grand Island, NE
With engine alone (no boost) you are not making much power. Add hot weather with the A/C turned to blast and you lose some of that. I've heard the A/C takes 25 hp.
On the other hand, I spend the morning driving my stock WRX. The engine in it makes more torque down low, then you wait for the turbo to kick in which seems to never happen. Back in the summer Evo it seemed like a beast.
On the other hand, I spend the morning driving my stock WRX. The engine in it makes more torque down low, then you wait for the turbo to kick in which seems to never happen. Back in the summer Evo it seemed like a beast.
The car is spooling slower than stock even modded.
Am I correct in assuming that in stock trim the 8 should see about 19psi by 3200rpm?
I know an exhaust would help, but I'm not going to slap an exhaust on the car and band aid the fact that there is something wrong.
Am I correct in assuming that in stock trim the 8 should see about 19psi by 3200rpm?
I know an exhaust would help, but I'm not going to slap an exhaust on the car and band aid the fact that there is something wrong.
Mine in 3rd runs this with a 3port:
2750 start - 22psi 3250, 25psi 3500
3000 start - 22psi 3500, 25psi 3750
This was eyeballing the guage, not datalogging. The stock cat is holding you back.
2750 start - 22psi 3250, 25psi 3500
3000 start - 22psi 3500, 25psi 3750
This was eyeballing the guage, not datalogging. The stock cat is holding you back.
Last edited by ReaperX; Jul 22, 2013 at 07:31 PM.
If he has an 05, he's got the 10.5 hotside. If boost leak and compression come back clean, then double check the parameters of the tune. A decent cat-back is not that much coin either. Free up the entire system. It's not a band-aid, it aids flow and helps the car breathe. Doesn't make sense to have a bottle neck in the system.