Exhaust set up
- Thread starter dropteeth
- Start date
You can still find 3” stuff.
larperformance.com
As for the tail pipes need to know LX or GT. Pypes Performance Exhaust has 3” cat backs.
LAR Performance Mustang X Pipe 86-93
LAR Performance x-pipes are crafted with precision using an automated mandrel bending machine and meticulously assembled by skilled hands. Each x-pipe is immaculately crafted to complement your powerful Mustang. Direct bolt-on installation with no cutting or welding required. All O2 sensor bungs...
larperformance.com
As for the tail pipes need to know LX or GT. Pypes Performance Exhaust has 3” cat backs.
thanks for this- would you go this route? my car is a 1993 GT and installing a terminator ecu? my old set up is mac longtubes, mac mid and flowmasterYou can still find 3” stuff.
LAR Performance Mustang X Pipe 86-93
LAR Performance x-pipes are crafted with precision using an automated mandrel bending machine and meticulously assembled by skilled hands. Each x-pipe is immaculately crafted to complement your powerful Mustang. Direct bolt-on installation with no cutting or welding required. All O2 sensor bungs...
As for the tail pipes need to know LX or GT. Pypes Performance Exhaust has 3” cat backs.
I have an injected 331 making in the 460fwhp range (engine dyno’d with a carb before it was installed) and I am running a full 2.5” exhaust with shorties through a 5 speed and an 8.8. Made around 370 rwhp on a Mustang dyno. Would it make more with full length headers and a 3” system? In short absolutely.
So with that if I already had a 2.5” system would I move up to a 3”? Probably not unless I was racing.
My T-Bird has a custom made 3.5” / 3” system with a 351W that is 0.03” over.
I personally think that when you hit the 350ish cubic inch mark a 3” or larger system makes sense $$$ wise if you are wanting it to perform. And especially if it’s a striker. They will run on a 2.5” and smaller system all day long as the old big block cars of the 60’s, 70’s, and early 80’s proved albeit horribly.
So with that if I already had a 2.5” system would I move up to a 3”? Probably not unless I was racing.
My T-Bird has a custom made 3.5” / 3” system with a 351W that is 0.03” over.
I personally think that when you hit the 350ish cubic inch mark a 3” or larger system makes sense $$$ wise if you are wanting it to perform. And especially if it’s a striker. They will run on a 2.5” and smaller system all day long as the old big block cars of the 60’s, 70’s, and early 80’s proved albeit horribly.
I figured i had 1 3/4 bbk long tubes - and needed to complete the set up or should i just stay with my Mac longs 1 5/8 set up ? not sure if the bbk will fit the mac midpipe. I guess im looking for opinions with my 347 set up.
thanks for this... i have a complete set up with my mac long tubes 1 5/8 with mid pipe. and cat back... but purchased some bbk longtumes 1 3/4 and was pondering what i should do.
Can you detail your 347 build? Stock or CAI, throttle body, intakes, heads, cam, compression ratio, and what will your shift point be?
I limit myself to about 6200 on shifts but can spin it pretty tight with the hydraulic lifters and stock block (6600 to 6800) but on the dyno it all starts falling off around 6400. If I do anything else it will be a solid roller cam and aftermarket block so I can move the shift point up. Stock blocks don’t particularly like high rpm shifts while north of 500 fwhp. Will I ever do it? Probably not unless Blue Print starts selling the four bolt main block and it’s half of a Dart block. Anyhow, all of that and I’ll still keep the 2.5” exhaust.
I limit myself to about 6200 on shifts but can spin it pretty tight with the hydraulic lifters and stock block (6600 to 6800) but on the dyno it all starts falling off around 6400. If I do anything else it will be a solid roller cam and aftermarket block so I can move the shift point up. Stock blocks don’t particularly like high rpm shifts while north of 500 fwhp. Will I ever do it? Probably not unless Blue Print starts selling the four bolt main block and it’s half of a Dart block. Anyhow, all of that and I’ll still keep the 2.5” exhaust.
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I bought this engine with the info you see in the below pictures. I purchased Holley Systemac intake and terminator ecu with 24 lbs injectors 65mm throttle body with anderson power pipe... my current set up has the mac long tubes 1 5/8 that i can reuse or figure out a new set up with my BBK 1 3/4 ....
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In general -
350-450 HP is the tipping point where you should start thinking about 3" exhaust then stepping down as it exits. This is the point where 2.5" [begins] being a restriction (meaning backpressure starts to rise) but scavenging is about perfect. 3 inch all the way to the tips at this point, would have an overall negative effect on an N/A car (unless you're turning 6000+ RPM).
At 450+ HP I would start at 3 inch from the collector through the H/X pipe and then back down to 2.5" for the cat-back.
This will give the best exhaust scavenging for a street/strip car.
If you're planning for boost in the mix, then exhaust scavenging isn't as big of a deal.
Don't forget that the exhaust charge becomes more dense and takes up less space as it cools.
350-450 HP is the tipping point where you should start thinking about 3" exhaust then stepping down as it exits. This is the point where 2.5" [begins] being a restriction (meaning backpressure starts to rise) but scavenging is about perfect. 3 inch all the way to the tips at this point, would have an overall negative effect on an N/A car (unless you're turning 6000+ RPM).
At 450+ HP I would start at 3 inch from the collector through the H/X pipe and then back down to 2.5" for the cat-back.
This will give the best exhaust scavenging for a street/strip car.
If you're planning for boost in the mix, then exhaust scavenging isn't as big of a deal.
Don't forget that the exhaust charge becomes more dense and takes up less space as it cools.
Looks like a pretty solid build, though the 15k estimate is probably off.
You can goto fordstrokers and build a 347 with a Dart block and come up a couple grand under.
Not sure what you plan to do with the car, mostly street? Mostly drag racing? Road course?
Be realistic, i used to think street track, except i never went to the track, lol.
I don't see many Pros in the 3 inch.
Probably be crazy loud without cats.
Probably be crazy expensive with the cats.
Could have rattling issues going over the axle. You certainly aren't using road race style parts and an off the shelf catback.
Gains at this HP level will probably be minimal since you already have 1 5/8 headers (lmr states 20hp over STOCK headers)
Let's say they do gain 10hp over what you have now which is likely 400-425rwhp, is 10 more hp really going make it much better?
BTW, a quick search (could be wrong, not foxbody specific), suggests the collector on BBK 1 3/4 long tubes is 2.5 anyway.
I'd run what you have now and if you want to mix and match exhaust parts later, go ahead.
What i wouldn't do is run 24's or a 65mm Throttle body, your setup most likely exceeds both.
You can goto fordstrokers and build a 347 with a Dart block and come up a couple grand under.
Not sure what you plan to do with the car, mostly street? Mostly drag racing? Road course?
Be realistic, i used to think street track, except i never went to the track, lol.
I don't see many Pros in the 3 inch.
Probably be crazy loud without cats.
Probably be crazy expensive with the cats.
Could have rattling issues going over the axle. You certainly aren't using road race style parts and an off the shelf catback.
Gains at this HP level will probably be minimal since you already have 1 5/8 headers (lmr states 20hp over STOCK headers)
Let's say they do gain 10hp over what you have now which is likely 400-425rwhp, is 10 more hp really going make it much better?
BTW, a quick search (could be wrong, not foxbody specific), suggests the collector on BBK 1 3/4 long tubes is 2.5 anyway.
I'd run what you have now and if you want to mix and match exhaust parts later, go ahead.
What i wouldn't do is run 24's or a 65mm Throttle body, your setup most likely exceeds both.
Thanks for this response- price of 15k was canadian as i live in Canada- will likely just be a street car... i think ill stick with what i have and sell the BBK headers....what size throttle body do you recommend for the holley intake? i was told the 24 pnd injectors for this set up was plenty.....but i can still change this..
If the systemax will accept a 75mm (and i think it's one of the few that will, again check), i would run a 75mm accufab, i'll agree they are just the best, period.
If you were going to run the stock computer i would for sure says 30's, but since it sound like you are going to run a terminator setup, you have the ability to adjust for the injector size, so you could go bigger.
If you were going to run the stock computer i would for sure says 30's, but since it sound like you are going to run a terminator setup, you have the ability to adjust for the injector size, so you could go bigger.
gkomo
now i can hopefully expect to receive the shaft
Only thing i don't like about the Accufabs is i believe they only come in chrome? I could be wrong but thats what i've noticed. Id like a satin finish Accufab for when i upgrade at some point.
i just realized my throttle body is a 70mm BBK ( i still may upgrade to a 75mm accufab) but you have me shopping for injectors now.,.. with the terminator what injectors and brand do you recommend I get?
I'm not totally sure 5 mm is worth the effort to change the throttle body at this point. I kinda felt like 10mm was...
I probably would, but that's because i'm a big accufab fan, not sure what the gains would be though.
If you are using an entire terminator X setup (not sure if they make just a plug and play ECU), first thing you need to do is see if the injectors are EV1 (old style) or EV6 (newer). I've always used ford racing injectors which were probably bosch, but go a little more on what the other guys suggest, i've been out of the injector brand game for a long time.
I probably would, but that's because i'm a big accufab fan, not sure what the gains would be though.
If you are using an entire terminator X setup (not sure if they make just a plug and play ECU), first thing you need to do is see if the injectors are EV1 (old style) or EV6 (newer). I've always used ford racing injectors which were probably bosch, but go a little more on what the other guys suggest, i've been out of the injector brand game for a long time.
So just for reference the 65mm Accufab will almost flow what the BBK 70mm unit will.
BBK 70mm - 726 cfm
Accufab flow numbers:
Ford Mustang 5.0L, 1986-1993
Stock – 495cfm
65mm – 664cfm
70mm – 787cfm
70mm (Race) – 896cfm
75mm – 924cfm
75mm (Race) – 1045cfm
80mm – 1142cfm
85mm – 1322cfm
90mm – 1369cfm
105mm – 1550cfm
I really don’t think you will need anything larger than the one you have for the 347. There are all kinds of cfm calculators out there and I have used a few of them and they pretty much all came up with the same cfm for a given motor size. So for a 347 at 6500 rpm and a VE of 0.85 you get 680 cfm. So with the 70mm BBK flowing 726 cfm so you should be good to go. Just make sure the upper intake throttle body opening is 70mm or larger.
Was looking at the dyno numbers and imade a little more hp and torque than my 331. Two things come to mind which are I’d bet money the pistons are flat tops so you are in that 10:1 to 11:1 compression ratio area so yes super unleaded fuel and the cam is pretty mild based on the dyno. You can figure the lift by using a dial indicator on the rocker.
BBK 70mm - 726 cfm
Accufab flow numbers:
Ford Mustang 5.0L, 1986-1993
Stock – 495cfm
65mm – 664cfm
70mm – 787cfm
70mm (Race) – 896cfm
75mm – 924cfm
75mm (Race) – 1045cfm
80mm – 1142cfm
85mm – 1322cfm
90mm – 1369cfm
105mm – 1550cfm
I really don’t think you will need anything larger than the one you have for the 347. There are all kinds of cfm calculators out there and I have used a few of them and they pretty much all came up with the same cfm for a given motor size. So for a 347 at 6500 rpm and a VE of 0.85 you get 680 cfm. So with the 70mm BBK flowing 726 cfm so you should be good to go. Just make sure the upper intake throttle body opening is 70mm or larger.
Was looking at the dyno numbers and imade a little more hp and torque than my 331. Two things come to mind which are I’d bet money the pistons are flat tops so you are in that 10:1 to 11:1 compression ratio area so yes super unleaded fuel and the cam is pretty mild based on the dyno. You can figure the lift by using a dial indicator on the rocker.
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Did some digging and found this jewel of a thread on throttle body sizing.
Much debate is brought about over throttle body sizing and the effects of each.
I decided to bring out a little fact and a little common practice, so pardon some of it being unorganized, but I put this together quickly and wanted some feedback and thought. If there is anything you see that you feel is inaccurate or bias please post up and we will go from there
I notice that there are a few stangers out there with the notion that a bigger throttle body has no effect on engine performance or drivability and is needed to get the correct amount of air in the engine. I attend to show...
I decided to bring out a little fact and a little common practice, so pardon some of it being unorganized, but I put this together quickly and wanted some feedback and thought. If there is anything you see that you feel is inaccurate or bias please post up and we will go from there
I notice that there are a few stangers out there with the notion that a bigger throttle body has no effect on engine performance or drivability and is needed to get the correct amount of air in the engine. I attend to show...
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