3" full exhaust hurtin turbo spool?
05-18-2018, 01:56 PM
#41
I have a 3 inch fill exhaust on my vehicle with a cut out for when I want to be loud or go fast. The difference between opening the cut out and keeping it closed is a night and day difference. Turbo spools up way faster and I'm into full boost way sooner, plus it makes more boost with it open.
05-18-2018, 02:58 PM
#42
Boost is load dependent. As soon as those tires start to spin you unload the motor. If you could go WOT and keep the tires planted it will build boost more quickly. If you can’t get the tires planted... no need for quicker “spool”.
Also you are losing a TON of velocity with all the large piping pre turbo. The 76/65 is also a **** poor turbo design. The split between the 2 wheels is too large. You are asking a small exhaust wheel to drive a large compressor. Which will result in slower spool. If you want quick spool you want it the other way around or at least much less than an 11mm split between the two. That said the 76/65 is relatively small for that motor and you have the smaller housing. So I think you’ll be fine at your lowish boost levels.
Another option would be to place a 60mm or so wastegate or boost activated cutout on it. That way it automatically opens and closes.
I get the silent car appeal. I “T” my two 3” down pipes into a single 2” pipe all the way back to a stock 4 cyl muffler. Then have vacuum actuated 3” cutouts on each turbo.
Also you are losing a TON of velocity with all the large piping pre turbo. The 76/65 is also a **** poor turbo design. The split between the 2 wheels is too large. You are asking a small exhaust wheel to drive a large compressor. Which will result in slower spool. If you want quick spool you want it the other way around or at least much less than an 11mm split between the two. That said the 76/65 is relatively small for that motor and you have the smaller housing. So I think you’ll be fine at your lowish boost levels.
Another option would be to place a 60mm or so wastegate or boost activated cutout on it. That way it automatically opens and closes.
I get the silent car appeal. I “T” my two 3” down pipes into a single 2” pipe all the way back to a stock 4 cyl muffler. Then have vacuum actuated 3” cutouts on each turbo.
It does have a 60mm WG on it, seems to be able to bleed more than enough exhaust to get really low boost numbers... or did you mean put a boost activated cutout on a exhaust cutout? The thing with something opening automatically is that I wouldnt want to get on it if it gets loud every time. I like that I can get on it and it doesnt draw attention, even the WG dump isn't that loud for some reason.
That sounds like exactly what I want.. just all the time lol and less restrictive
05-18-2018, 03:00 PM
#43
I have a 3 inch fill exhaust on my vehicle with a cut out for when I want to be loud or go fast. The difference between opening the cut out and keeping it closed is a night and day difference. Turbo spools up way faster and I'm into full boost way sooner, plus it makes more boost with it open.
. I'm going see what stickier tires nets me, otherwise maybe I can delete the resonator with a straight pipe to gain a little more flow and not a ton of noise.
05-18-2018, 03:07 PM
#45
So guys what do you recommend for tire sizes?
MT Streets R2 compound (liked my 295/65r15s I had like 4 years ago).
18x9.5 rim
275/45r18 recommended 9" rim or 8.5 - 10.5 range $305 each
285/40r18 recommended 10" rim or 9.5 - 11" range $339 each
305/40r18 recommended 11" rim or 10 - 12" range $359 each
Clearly the 305/40 is large but might squeeze on. or I can run the 285 or 275 on my current rims. The 275 is the same width as my 275/40r18s now and i wish they were alittle wider, the 285 is just a smidge wider but only 4mm taller. Doesnt matter as I run a GPS speedo so tire/gear changes are not affecting the speedo.
MT Streets R2 compound (liked my 295/65r15s I had like 4 years ago).
18x9.5 rim
275/45r18 recommended 9" rim or 8.5 - 10.5 range $305 each
285/40r18 recommended 10" rim or 9.5 - 11" range $339 each
305/40r18 recommended 11" rim or 10 - 12" range $359 each
Clearly the 305/40 is large but might squeeze on. or I can run the 285 or 275 on my current rims. The 275 is the same width as my 275/40r18s now and i wish they were alittle wider, the 285 is just a smidge wider but only 4mm taller. Doesnt matter as I run a GPS speedo so tire/gear changes are not affecting the speedo.
05-18-2018, 03:10 PM
#47
I meant to make one more pass with the exhaust closed this past Saturday, but i forgot. Want to make a hit on the gate with the cutout closed to see what the slowest the car will go is. Then another hit with the cutout open.... but still on gate pressure. You going to the track soon?
05-18-2018, 03:20 PM
#48
9 Second Club
05-18-2018, 03:23 PM
#49
No, that's kinda what happens when you free up the flow on a turbo cars exhaust. Who has a cutout on a turbo car, but sees no gain?
05-18-2018, 03:26 PM
#50
It was in the the 1/4
I'm not going back to the track until I get my th400 in there later this year
It's 4 inches off of turbo and then 3 inches into a magnaflow cat back. I think the issue is where it Ts off of the 4 inch into the rest of the exhaust going back to the magnaflow. It really isn't designed all that great so I just leave the cut out open all of the time.
I'm not going back to the track until I get my th400 in there later this year
It's 4 inches off of turbo and then 3 inches into a magnaflow cat back. I think the issue is where it Ts off of the 4 inch into the rest of the exhaust going back to the magnaflow. It really isn't designed all that great so I just leave the cut out open all of the time.
05-18-2018, 03:34 PM
#51
9 Second Club
Same as the air filter scenario....no restriction is no restriction.
I think there was a cracking one a few years ago here, guy went better with a cutout.....his exhaust literally had 90deg bends on it, and I dont mean smooth bends, I mean actual cut 90deg bends LOL
05-18-2018, 04:14 PM
#52
05-18-2018, 04:29 PM
#54
It was in the the 1/4
I'm not going back to the track until I get my th400 in there later this year
It's 4 inches off of turbo and then 3 inches into a magnaflow cat back. I think the issue is where it Ts off of the 4 inch into the rest of the exhaust going back to the magnaflow. It really isn't designed all that great so I just leave the cut out open all of the time.
I'm not going back to the track until I get my th400 in there later this year
It's 4 inches off of turbo and then 3 inches into a magnaflow cat back. I think the issue is where it Ts off of the 4 inch into the rest of the exhaust going back to the magnaflow. It really isn't designed all that great so I just leave the cut out open all of the time.
05-18-2018, 06:06 PM
#55
BTW, I'm assuming you're t56? What did it run at the track?
Customblkbrd, I've attached a log so you can review. It was on the older version of hptuners so it might be a little funky.
Last edited by CyberGrey Z28; 05-18-2018 at 08:49 PM.
05-18-2018, 06:44 PM
#56
I picked up 20rwhp on an L33 with an mpt70 at 13lbs of boost by opening the cutout. I had a full 3" exhaust out the back on a mustang with a magnaflow muffler. Car made 589rwhp with cutout open. Every combo is different and until you try it on your setup you will never know what your missing power or spool wise.
PS- I picked up almost 25rwhp by putting the air filter on. I would have never guessed that until I tried it.
PS- I picked up almost 25rwhp by putting the air filter on. I would have never guessed that until I tried it.
05-18-2018, 07:25 PM
#57
It was in the the 1/4
I'm not going back to the track until I get my th400 in there later this year
It's 4 inches off of turbo and then 3 inches into a magnaflow cat back. I think the issue is where it Ts off of the 4 inch into the rest of the exhaust going back to the magnaflow. It really isn't designed all that great so I just leave the cut out open all of the time.
I'm not going back to the track until I get my th400 in there later this year
It's 4 inches off of turbo and then 3 inches into a magnaflow cat back. I think the issue is where it Ts off of the 4 inch into the rest of the exhaust going back to the magnaflow. It really isn't designed all that great so I just leave the cut out open all of the time.
05-18-2018, 08:41 PM
#59
Haha... not gona do it! Literally wouldn’t ever open it. I like the “quiet” quick. I don’t think 20rwhp is worth the noise and on the street it’s clearly “enough” lol. I have a feeling some new DRs will help.
Another thing i forgot to mention is that I’m running a eBay mushroom filter on the turbo. The filter is pressed up against the front headlight frame and it’s super hard to get it on and off the turbo. I have no room for anything else except maybe a cobra bell mouth and a filter under the car. But I don’t really have room for much so I feel like it’s not worth it. I know the filters suck but it came with the kit and I have no room for anything else. Maybe that’s choking the turbo?
Another thing i forgot to mention is that I’m running a eBay mushroom filter on the turbo. The filter is pressed up against the front headlight frame and it’s super hard to get it on and off the turbo. I have no room for anything else except maybe a cobra bell mouth and a filter under the car. But I don’t really have room for much so I feel like it’s not worth it. I know the filters suck but it came with the kit and I have no room for anything else. Maybe that’s choking the turbo?
05-18-2018, 08:46 PM
#60
Haha... not gona do it! Literally wouldn’t ever open it. I like the “quiet” quick. I don’t think 20rwhp is worth the noise and on the street it’s clearly “enough” lol. I have a feeling some new DRs will help.
Another thing i forgot to mention is that I’m running a eBay mushroom filter on the turbo. The filter is pressed up against the front headlight frame and it’s super hard to get it on and off the turbo. I have no room for anything else except maybe a cobra bell mouth and a filter under the car. But I don’t really have room for much so I feel like it’s not worth it. I know the filters suck but it came with the kit and I have no room for anything else. Maybe that’s choking the turbo?
Another thing i forgot to mention is that I’m running a eBay mushroom filter on the turbo. The filter is pressed up against the front headlight frame and it’s super hard to get it on and off the turbo. I have no room for anything else except maybe a cobra bell mouth and a filter under the car. But I don’t really have room for much so I feel like it’s not worth it. I know the filters suck but it came with the kit and I have no room for anything else. Maybe that’s choking the turbo?