Boosted on stock 2.5" exhaust

[Jasonb543]

Yes, again…
Vague conjecture

Post a dyno of your boosted car before and after replacing 2 1/4 inch neck down connectors.

That’s what I’m looking for… data.. metrics.
I love the thread engineer Mike did… but again… no real world HP numbers to back up the theories in that thread… it was 30 pages of blue balls.

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[cbrtrx]

Yes, again…
Vague conjecture

Post a dyno of your boosted car before and after replacing 2 1/4 inch neck down connectors.

That’s what I’m looking for… data.. metrics.
I love the thread engineer Mike did… but again… no real world HP numbers to back up the theories in that thread… it was 30 pages of blue balls.

Then go do it yourself instead of complaining, you want an answer then you need to find it. You sound like it's our job to satisfy you.

 

[Jasonb543]

You misread my original post, it was commentary on the lack of data/metrics for one of the most well doccumented and verified vehicles in modern history… pertaining to OPs post.

That’s all

I’ve asked this same kind of question and barely found answers…for how well documented and tested these cars are, I’m yet to find before after HP/TQ gains from eliminating 2.25 neck downs.

 

[illtal]

Then go do it yourself instead of complaining, you want an answer then you need to find it. You sound like it's our job to satisfy you.

This fucker needs to go experiment on his own car and get some "data" in the form of Dyno sheets to satisfy his hard on.

I guess he doesn't understand that you pretty much need to be maxing out of he airflow in the exhaust under these conditions for what he wants to know about to matter.

I mean guys said they got 900 wheel on a full stock exhaust should tell you something.

 

[robvas]

I mean guys said they got 900 wheel on a full stock exhaust should tell you something.

He just wants to know what does a full 3" get you from there. 910? 925? 945?

 

[Cashley]

I'm betting gains are neglible

 

[Timbuck]

Not exactly what you want but probably one of the best mustang video ‘s I’ve seen when it comes to exhaust flow and dyno numbers , and the reason why. Truckandroll , The owner is on here.

 

[sk47]

No dynos, no ET or trap comparisons

Zero verified metrics…. just vague conjecture.

it was commentary on the lack of data/metrics for one of the most well doccumented and verified vehicles in modern history… pertaining to OPs post.

Hello; decided to follow this thread. There is a body of information on the subject of boosted engines and exhaust. I have been recording and saving a program called ENGINE MASTERS for a few years now. I have 100 episodes saved.
I do not think they have specifically tested a newer Coyote so likely will not find exact information. From memory I have a vague impression the exhaust diameter is not critical when boosted. Pretty sure there are several episodes related to a boosted engine.
They use a good dyno room and try to keep the variables within reason so as to get decent results. I will look thru the episodes later.
Am i correct the OP's initial question is about keeping a stock 2 1/2 inch exhaust compared to something bigger???

 

[Cashley]

Hello; decided to follow this thread. There is a body of information on the subject of boosted engines and exhaust. I have been recording and saving a program called ENGINE MASTERS for a few years now. I have 100 episodes saved.
I do not think they have specifically tested a newer Coyote so likely will not find exact information. From memory I have a vague impression the exhaust diameter is not critical when boosted. Pretty sure there are several episodes related to a boosted engine.
They use a good dyno room and try to keep the variables within reason so as to get decent results. I will look thru the episodes later.
Am i correct the OP's initial question is about keeping a stock 2 1/2 inch exhaust compared to something bigger???

Yes, curious to see how much power can be made on stock 2.5 exhaust before it becomes a choke point on a boosted car

 

[cbrtrx]

Yes, curious to see how much power can be made on stock 2.5 exhaust before it becomes a choke point on a boosted car

You're asking a question with no definite answer. There are way too many variables and setups. A larger exhaust can increase the engines pumping efficiency but you could still be limited by other components. In it's most simplest terms the engine is an air pump. It's like when people say how much hp will bigger injectors give me? Injectors don't make any hp they just support it. So again you'll get probably 10 different answers but not the one you're looking for unless you do the experiment yourself on your application under very controlled conditions.

 

[sk47]

Yes, curious to see how much power can be made on stock 2.5 exhaust before it becomes a choke point on a boosted car

Hello; did a quick look thru the episode titles. Found three episodes that might be of interest. Season 6 episode 15 - Exhaust for turbos
I think they ran a bunch of 3 inch mufflers on a turbo-ed engine. Then switched to full 4 inch exhaust. I will watch again and report any thing of interest.

Season 6 episode 4 - mandrel v. crunch bent exhaust
This one fooled me. Need to rewatch but seem to recall not a big difference.

Season 5 episode 7 - single vs. dual exhaust.
This episode stuck in my mind as i have as V8 in my pickup with a factory single exhaust. The factory exhaust is 20 years old and i will not feel bad about replacing with another single.


Not sure which episode of the 100 but I seem to recall a comment from one of the Steves. Do not count on this but I think he said 2 1/2 inch ought to be good for under 600 HP. For over that HP some benefit of bigger pipes. But just a recall impression.

EDIT -may have said 2 1/2 OK under 500 HP. If I find it I will report.

 

[sk47]

You're asking a question with no definite answer. There are way too many variables and setups. A larger exhaust can increase the engines pumping efficiency but you could still be limited by other components. In it's most simplest terms the engine is an air pump. It's like when people say how much hp will bigger injectors give me? Injectors don't make any hp they just support it. So again you'll get probably 10 different answers but not the one you're looking for unless you do the experiment yourself on your application under very controlled conditions.

Hello; This is what the ENGINE MASTERS guys wind up saying much of the time. They spend hours on a dyno testing things and wind up saying something similar. What applies to a big block in terms of cam, headers, and other variables may not be similar on a small block.

 

[robvas]

I'm betting gains are neglible

What's "negligible"?

Here's 13hp on a 600hp NA engine

900hp engine is going to be more but then again, how much? 15? 55?

How much HP to spend $1200 on new mid pipe, tailpipes, mufflers. How much is the extra weight worth? Extra volume?

 

[sk47]

What's "negligible"?

Here's 13hp on a 600hp NA engine

900hp engine is going to be more but then again, how much? 15? 55?

How much HP to spend $1200 on new mid pipe, tailpipes, mufflers. How much is the extra weight worth? Extra volume?

Hello; Good points. Something for the OP and others to decide. An old saying is something like how much power do you want? Answer depends on how much you are willing to spend. Another is the last few MPH or HP cost a lot more than the early gains.

Rather than peak HP & torque the curve of each is what i would be interested in. Broad flat curves are another set of goals to chase.

 

[engineermike]

The title says boosted but the mechanism for gains is very different between pd, centrif, turbo, and even na. A pd supercharged won’t gain nearly as much as turbo for the same backpressure reduction, for instance.

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