My next mod

[BlacknBoostn]

Just picked up a Borla/Mopar catback for the ride.. going on soon I hope! Picked this up for a STEAL. Stay tuned...

exhaust is 2.5" piping all the way through, 4" tips... exhaust is painted black and I haven't decided officially if I will touch up the black with High Temp paint or strip the tips and polish back to their original sheen... should be a nice little power adder for my stock turbo and make a huge sound difference... next meet i'll have her hood popped! Maybe even a new BOV...

I'll post up some pictures of the installation, really interesting design, all slip jointed, no bolts or flanges anywhere. slip it on and clamp it down! Should be a breeze. exhaust is light, less than 25-30 lbs.

[SeanPlunk]

Just picked up a Borla/Mopar catback for the ride.. going on soon I hope! Picked this up for a STEAL. Stay tuned...

exhaust is 2.5" piping all the way through, 4" tips... exhaust is painted black and I haven't decided officially if I will touch up the black with High Temp paint or strip the tips and polish back to their original sheen... should be a nice little power adder for my stock turbo and make a huge sound difference... next meet i'll have her hood popped! Maybe even a new BOV...

I'll post up some pictures of the installation, really interesting design, all slip jointed, no bolts or flanges anywhere. slip it on and clamp it down! Should be a breeze. exhaust is light, less than 25-30 lbs.

Tyler, I know the SRT doesn't have mufflers (resonators), so how much difference power wise does it actually make?

[BlacknBoostn]

Tyler, I know the SRT doesn't have mufflers (resonators), so how much difference power wise does it actually make?

It should be good for about 8-12whp, the Borla/Mopar design offers increased exhaust flow, eliminates some of the bends along with larger diameter piping. 2.25 up to 2.5 (almost bought a 3in exhaust from the turbo back but this was such a steal I couldn't turn it down).

The SRT does have two resonators, just no mufflers... the Borla/Mopar eliminates one of the resonators.

http://www.modernperformance.com/product_info.php?cPath=174_187&products_id=1251

Link to back it up.. you can see the dyno sheet along with the stock and mopar exhaust, very easy to see that the Borla/Mopar one has a better design...

That 3in turbo back is still in the sights but this will be a good start for my stock turbo!

youtube video..

YouTube - SRT4 Mopar Catback

[94cobra69ss396]

You'll probably make more HP with the 2.5 as your car sits right now anyways. I think the 3 inch will be too big until you get some more mods.

[BlacknBoostn]

You'll probably make more HP with the 2.5 as your car sits right now anyways. I think the 3 inch will be too big until you get some more mods.

Exactly what I was thinking myself... i'm on stock boost, stock turbo, stock stock stock. When i go with a ported turbo or s3 turbo i'll upgrade to 3in :) only way it'd help now is for mileage haha...

[Vettezuki]

Exactly what I was thinking myself... i'm on stock boost, stock turbo, stock stock stock. When i go with a ported turbo or s3 turbo i'll upgrade to 3in :) only way it'd help now is for mileage haha...

I sure as heck don't understand all the combustion theory and engine dynamics, but it does seem one of the most commonly overdone mods for I4s is an overly large exhaust. As I understand it, the problem is excessively reducing cylinder back pressure, thus torque and finally power.

[big2bird]

I sure as heck don't understand all the combustion theory and engine dynamics, but it does seem one of the most commonly overdone mods for I4s is an overly large exhaust. As I understand it, the problem is excessively reducing cylinder back pressure, thus torque and finally power.

Urban myth BS.;)

[BlacknBoostn]

I sure as heck don't understand all the combustion theory and engine dynamics, but it does seem one of the most commonly overdone mods for I4s is an overly large exhaust. As I understand it, the problem is excessively reducing cylinder back pressure, thus torque and finally power.

Too true...

3in piping should only be for boosted cars! If I was running a BIG turbo like a GT35R or bigger... THEN a 3-4in piping might be beneficial.

Till then, this will do the job nicely :) one thing is for sure, SRTs have lots of power to free up!

[BRUTAL64]

Urban myth BS.;)

Yep, I was going to say that. You DO NOT want back pressure on any kind. :bigthumbsup:

[BRUTAL64]

I sure as heck don't understand all the combustion theory and engine dynamics, but it does seem one of the most commonly overdone mods for I4s is an overly large exhaust. As I understand it, the problem is excessively reducing cylinder back pressure, thus torque and finally power.


Ok, why would want any back pressure? That ONLY causes the the in coming charge to be reduced. Thus less power. :motorsmile:

[94cobra69ss396]

Ok, why would want any back pressure? The ONLY causes the the in coming charge to be reduced. Thus less power. :motorsmile:

So what you're saying is that if I put a 5 inch exhaust on my 160hp Explorer it will make more power than if I put a 2.5 inch one on? Does that also mean that I will make more power if I go to a bigger exhaust than the 2.5 that I have on my 500hp Cobra?

[BRUTAL64]

So what you're saying is that if I put a 5 inch exhaust on my 160hp Explorer it will make more power than if I put a 2.5 inch one on? Does that also mean that I will make more power if I go to a bigger exhaust than the 2.5 that I have on my 500hp Cobra?


Well, anything is possible. I'm saying that from what all I have learned over the years is; back pressure kills horse power. Now if someone wants to show me that this is wrong I'm all ears.:D

[Vettezuki]

Well, anything is possible. I'm saying that from what all I have learned over the years is; back pressure kills horse power. Now if someone wants to show me that this is wrong I'm all ears.:D


I'll see if I can look it up from someone who actually knows. The way it was explained to me, it had to do with cylinder pressure affected by the back pressure in the exhaust line. Cylinder pressure relates to torque. Certainly it's not a matter of maximizing back pressure either, its just that reducing it as much as possible (like taking your manifolds off) isn't the right thing to do either. There's a balance point depending on the rest of your motor setup. Spooling up a turbo adds another complex parameter.

I think Top Fuel Dragsters and funny cars run stepped headers. That is smaller diameter off the block going to larger diameter down line, specifically for maximizing this effect. Or at least that's what I thought. They have the room to run larger straight pipes right off the block. So why don't they? :huh:

I'm looking for headers and they typically come in 1 3/4 vs. 1 7/8. They explicitly say don't go to the larger size, until you're making very considerable horsepower, like beyond 500whp to the wheels in a SBC/V8 like setup. The costs are the same. Why would manufacturers make and distributors stock different size headers for the exact same car. Is it just marketing BS?

There's got to be some good docs, maybe with dyno comparisons according different exhaust setups on the same basic setup.

[94cobra69ss396]

If that were the case then everyone would be running the largest header they could fit on their car. Back when I had the 396 in the Chevelle and it was making about 350hp I switched from 1 3/4 primary tube Hedman headers with 2.5 inch exhaust to 2 1/8 primary tube Hooker headers and 3 inch and I lost power. I went from turning 104mph to 102mph. Back then the car was very consistant. It's my opinion (not a fact just an opinion) that because of the larger size I lost some of the scavenging effect and thus power.

[Vettezuki]

If that were the case then everyone would be running the largest header they could fit on their car. Back when I had the 396 in the Chevelle and it was making about 350hp I switched from 1 3/4 primary tube Hedman headers with 2.5 inch exhaust to 2 1/8 primary tube Hooker headers and 3 inch and I lost power. I went from turning 104mph to 102mph. Back then the car was very consistant. It's my opinion (not a fact just an opinion) that because of the larger size I lost some of the scavenging effect and thus power.

Similarly I've seen guys at the track who say they consistently ran slower after using cutouts, or my personal favorite, the Hondas that actually hack their exhaust off right by the manifold. This is anecdotal, but tends to support the same hypothesis.

[Vettezuki]

I've made a new thread for this subject.

http://www.motorgen.com/forum/showthread.php?t=1008

[BlacknBoostn]

I've made a new thread for this subject.

http://www.motorgen.com/forum/showthread.php?t=1008

Good plan good sir... I was beginning to feel hijacked... LOL

[94cobra69ss396]

Good plan good sir... I was beginning to feel hijacked... LOL

Sorry about that. Did you get it installed today?

[BlacknBoostn]

Sorry about that. Did you get it installed today?

Haha no worries my fellow enthusiast! I enjoy learning additional information! I'm glad there is a second thread about exhaust theory...

Not yet, I'm waiting to receive some exhaust clamps the seller forgot to bring... should have them on friday or saturday. will be going on sunday hopefully

[94cobra69ss396]

Haha no worries my fellow enthusiast! I enjoy learning additional information! I'm glad there is a second thread about exhaust theory...

Not yet, I'm waiting to receive some exhaust clamps the seller forgot to bring... should have them on friday or saturday. will be going on sunday hopefully

You should take some video of the sound of the stock exhaust and then the new exhaust as well as pictures to post up on here when your done.

[BlacknBoostn]

You should take some video of the sound of the stock exhaust and then the new exhaust as well as pictures to post up on here when your done.

Good Idea!!!

[BlacknBoostn]

what should have taken an hour didn't get done today... mopar exhaust is 2.5 and has a section that necks down to 2.25 to meet up with the stock downpipe. that part isn't on my section haha. so needless to say the project has been postponed until the near future. anyone know someone who can help cut and weld a reducer onto this bish?

didn't really do much else today other than simple green the engine, I was hoping to have a whole bunch of stuff done today for saturday but looks like it'll have to wait till febuary.

almost makes me wish i'd bought a 3in turbo back side exit exhaust system with cat no resonator for 375... still thinkin about it

[enkeivette]

2 1/4 :lame: I need to see a 3" pipe on that thing. :judge:

[SeanPlunk]

2 1/4 :lame: I need to see a 3" pipe on that thing. :judge:

After you're done being a jackass (which I condone by the way), any possibility you can help him with that welding? I think you do that kind of stuff :)

Tyler, if not, let me know. I might know someone else who can do it for you.

[94cobra69ss396]

After you're done being a jackass (which I condone by the way), any possibility you can help him with that welding? I think you do that kind of stuff :)

Tyler, if not, let me know. I might know someone else who can do it for you.


If you don't find anyone out there I'll be more than happy to help you but you'll have to come out here to Fontana. I'm about 5 miles North of California Speedway.

[BlacknBoostn]

Adam... you're funny. I'm already peeping a 3in turbo back side exit catted system as mentioned above... when I upgrade my turbo she will be well equiped.. till then 2.5 borla will do just fine for my stock turbo... Hell, adam if you couldn't mind... i love for you to teach me how to do it!

Sean thanks for your feedback! see you on saturday... and for outting adam about the welding.. ;)

94Cobra (don't know ur name yet) If i can't find anyone closer i'll definitely get in touch with you... my friends friend works at a muffler shop in anaheim so I may try there first.

[94cobra69ss396]

Adam... you're funny. I'm already peeping a 3in turbo back side exit catted system as mentioned above... when I upgrade my turbo she will be well equiped.. till then 2.5 borla will do just fine for my stock turbo... Hell, adam if you couldn't mind... i love for you to teach me how to do it!

Sean thanks for your feedback! see you on saturday... and for outting adam about the welding.. ;)

94Cobra (don't know ur name yet) If i can't find anyone closer i'll definitely get in touch with you... my friends friend works at a muffler shop in anaheim so I may try there first.

It' Ron.

[SeanPlunk]

It' Ron.

LOL, I don't think Tyler has met you yet. Ron, when can we go off road again? Next time we go I want to go all the way through with you guys.

[94cobra69ss396]

LOL, I don't think Tyler has met you yet. Ron, when can we go off road again? Next time we go I want to go all the way through with you guys.

Anytime. You guys want to do the same run again but go all the way through to Dish Pan/Deep Creek or do you want to try another trail?

By the way do you want to move this into it's own thread so we don't hijack Tylers again?

[Leedom]

LOL, I don't think Tyler has met you yet. Ron, when can we go off road again? Next time we go I want to go all the way through with you guys.

Hi, my name is Sean and I am a total tread high jacker. :rolling:

[SeanPlunk]

LOL, fine, here is a new thread (http://www.motorgen.com/forum/showthread.php?p=12896#post12896):sm_laughing:

[BlacknBoostn]

Hi, my name is Sean and I am a total tread high jacker. :rolling:

HAHAHAHA and you're the MODERATOR!!!

[BlacknBoostn]

It' Ron.

Thanks Ron :bigthumbsup: can't wait to meet ya... you be at the meet on saturday???

[94cobra69ss396]

Thanks Ron :bigthumbsup: can't wait to meet ya... you be at the meet on saturday???

I don't think so. My brother (Throttle Crazy) and I are building a 383 for his '78 Jimmy this week and we're planning on doing the swap on Saturday.

[BlacknBoostn]

sounds like loads of fun!!! I wish I had the $$ and time to build myself a motor...

[94cobra69ss396]

sounds like loads of fun!!! I wish I had the $$ and time to build myself a motor...

It only cost him $40 so far for bearings. By the time it's complete he will only have about $300 into it.

[BlacknBoostn]

It only cost him $40 so far for bearings. By the time it's complete he will only have about $300 into it.

??? I don't get it... you just have parts lyin around or what? find a salvaged motor??? can we move this to a new thread haha I'm curious!!!

[94cobra69ss396]

??? I don't get it... you just have parts lyin around or what? find a salvaged motor??? can we move this to a new thread haha I'm curious!!!

Yes, he has a complete ZZ383 that we are assembling that he got for free.

[BlacknBoostn]

Yes, he has a complete ZZ383 that we are assembling that he got for free.

Wow that sounds like so much fun! How do you stumble accross these blocks? I want to start keeping my eye out for a good fun project!

[94cobra69ss396]

You already have one. Now get that downpipe done. Did you get some video of the before sound yet?

[BlacknBoostn]

You already have one. Now get that downpipe done. Did you get some video of the before sound yet?

not yet... everything is on hold right now until I have time to make it over to someone who can weld..

I'll take b4 video, during video (open downpipe) and after :thumbs_up:

[94cobra69ss396]

Did you get someone to weld this up for you?

[BlacknBoostn]

Did you get someone to weld this up for you?

not quite yet... still waiting.. on it's way though for sure