redraif

So the results are in...

The exhasut on my car was replaced from the collectors on the headers back! Nothing smaller then 2.5 was installed.

What did the custom 2.5 inch (primaries) mandrel bent y-pipe to a single 3inch pipe with 3in cut out to 3in Magnaflow convertor to Flowmaster's American Thunder mandrel bent exhaust system do for RAIF's performance (3.4l)????

Well some said it would kill the torque...
>>>WRONG!

Others said the exhaust system is too long from the start and a 3in would cause too much backpressure loss causing reversion & a lack of the proper scavaging effect...
(hence my old 2.25 crimp bent system initially gaining HP and torque when the cut out was opened. See an ideal system would see no difference with the cut out removed because it is flowing optimally!)
>>>WRONG AGAIN!

And others said is would sound like crap...
>>>WRONG! WRONG! WRONG!
(The car's sound impressed a VIPER guy with a 1000HP VIPER. Heck, the whole dyno shop thought I swapped in an V-8!)

Check out the gains yourself....




The graph is comparing my best pull with the cut out closed with the old crimp bent 2.25in system with the cut out closed!

Max Power = 141.3 @ rear wheels (+20%) = 169.56hp @ the fly wheel
Max Torque = 221.3 @ rear wheels (+20%) = 265.56ft-lbs @ the fly wheel

This puts me at 9hp over stock 3.4 numbers...
(Granted the 2.8 plenum probably is more restrictive then the 3.4's & my heads are 160,000 miles w/o a valve job!)
My torque is 65.56 over stock 3.4 numbers!

My gains with the 3inch exhaust over the 2.25...

Horsepower gains...15.4HP
Torque gains...18.2ft/lbs

And when the car was uncapped...I had instead 140hp and 222TQ...so esentially the same...meaning the system is very efficient!

BulliTooth

1989GTATransAm

iTrader: (3)

Excellent report. I love these kind of comparisons where it is cut and dry. Hope to see similiar gains with my 3.50" Mufflex system. Allen

dimented24x7

iTrader: (2)

A larger then stock exhaust is a must for making power, especially on a high winding motor like a V6. My 0-60 times dropped from 6 secs to 5.5 secs with a larger 3" exhaust as opposed to the 2.25 one I had origionally. Wouldve been more, but I had to richen the mixture up ALOT to protect the new 3" cat from melting down at high loads. Should be around 275 HP or so with my vanilla flavored 350.

redraif

Well I also had a straight pipe made to replace the cat so I would not ruin it while getting the custom programing ironed out! I just bought this one and I passed emissions last week with flying colors, was not going to toast another one due to running rich!

********************

Oh and just so everyone knows...I'm not saying all 3.4s or v-6s (2.8s or 3.1s) can benefit from this, but there are some of us that are modified to a point of actually being able to use a 3in upgrade. And I was sick of hearing it was too much for my car, so I just did it and proved it was not! And of course when I say modified that does not mean just air intake or free mods are enough...cam, porting, headwork, ect... is needed to see a benefit!

redraif

Yeah ok so I jumped in on a thread where they were bashing the choice to go to a 3in on a 3.4 that did not have nitrous, a blower or and turbo...

Told them what I had here...

Someone asked... I went from a 2.25 crimp bent sys to a 3in mandrel how do I know what would have happened if I had gone with the 2.5 mandrel bend system?

Reply:
Well I have PF&E headers and their mandrel bent y-pipe was 2.5...it flowed then to a 2.5 inch cut out. There was little restriction in this area (crimp bends)....So it was effectively a 2.5 inch system to the open cut out. I opened the cut out on a run not listed on the above dyno sheet...it is what gave the indication that I was in need of a better exhuast system.

I pulled on that run...


134HP and 207 TQ At the wheels... so if I had only gone to a 2.5 inch system and it was as effective as the cut out, I would have flowed just that on a 2.5 inch system!

So my dyno diffrence from a 2.25 crimp bent sys to a 2.5 decent system...
9hp gained
4ft/lbs tq gained!

So my dyno differences from a 2.5 inch system to a 3in
7hp gained
14ft/lbs TQ gained!

As I said before... with the 3in sys I can run open with the cut out and there is essentially no difference. See a near perfect exhaust system will actually have little to no difference with a open cut out!!

GOY

I think the more telling point of this is......

... it becomes obvious that the 3 inch systems are not up to the task in a v8 application. If a v6 made these kind of gains - which I consider HUGE given that fact that 15+ more HP is a much greater % gain of stock, than 15+ on a v8 with a higher factory output. (150->165 = 10% greater, 300->315 = 5% greater)

4+ inch for single system and 2.5+inch for dual systems seems like a logical minimum if money is going to be spent in the first place on a v8 exhuast. But please, that is just

unknown_host

iTrader: (1)

Exactly.

redraif

Agreed!

The point for me is that there are alot of things that people have taken for fact over the years. Only because this is what they have been told. No one has proved it, just said you can't because of this and that. So they hear this and think, ok you can't or its too much and they just take it and say I won't...

Well sometimes you have to challenge some of the assumptions and supposed facts and see for yourself. Esp in an application like mine (v-6) where people have not invested the time and energy because they deem it not worthy of the effort. What if it really is and people don't know because they have never really tried?

I had so many saying the car would not be able to make use of the exhaust and why bother... we did not know till we tried! And just as you are saying...what if 4in could be the key to SOME v-8s? Maybe and say it has not been tried enough because "Oh 3in is plenty..." Granted with v-8s more people have at least put in the effort to try more options, but people are quick to give you the "winning combo" and say this is the best, blah, blah and not really give it serious thought!

Just a thought following the above statements train of thought!

GOY

Well, I have always suspected that 3 inches was just not enough for a 305, and not even close for a 350 or larger. Having seen this, my 3 inch edelbrock system will probably be up for sale to a welcoming v6 owner later this summer - I'd rather see a v6 guy spend GOOD money on a GOOD mod, than a v8 owner spend money on a mod that isn't nearly what they are looking for or need - even if they don't know it.

Thanks for taking the dyno time to do that - it helps v6 and v8 guys alike.

Conv389drv

I saw a good t-shirt that's appropriate for this story. It said:

"One test is worth a thousand expert opinions"




This just goes to show that sometimes you just have to go and DO it rather than talk about it. After all, if no one ever went against the convention, a lot of technical advances would've never happened.

unknown_host

iTrader: (1)

I think the line of thinking is more like "this is what I have, so it must be the best".

There arent really any inexpensive 3.5" or 4" exhaust systems for our cars, so people would like to think what they have is best because they can't afford or fabricate anything else.

People will argue all day long that "this car with a 383 ran XX.XX ET's with single 3", well congratulations. That doesn't mean it was optimal, and the fact that people are against trying something out of the norm because "this is what everyone else is doing" is not the true racing mentality.

Nate86

I don't know much about the 3.4s, so go easy on me.

What's the deal with the torque and horsepower numbers? Is it normal for these V6s to have such a large gap between the two, or is there something holding the engine back?

redraif

I have really high TQ compared to most 2.8, 3.1, and 3.4 v-6s...but my HP is about average...lower then some of the other modded v-6s! I have been meaning to search up everyone elses numbers just to compare!

In the case of my car...yes there is definately something holding it back in the hp range! Stock numbers at the fly wheel were 160hp and 200TQ... So 40hp difference. Granted GM designed it this way so the tq could get the car up and moving better. In fact most of the 3rd gen cars are designed to be TQ engines! The longer runners help them out! When you talk about LT1 and Ls1 cars, they are less TQ, but more HP compared to the tuneports.

When I upgraded to the 3.4 I retained the stock 2.8 top end...granted it was ported, but this is still not enough! I have the long runners, so I have good tq. But due to the intake being too restictive, I'm lacking in HP. I looked into extrude honing, but they would not port it enough. Said I would kill Tq and gain HP, but the car would be unstreetable! I'm not convinced...with porting I had planned a runner increase to compensate. The cam was supposed to be a HP cam, but instead it turned out to be a TQ cam once it was installed in the 3.4! So to help out with this dilema...I have a custom intake being made, with a 65mm TB and longer runners. This will get more Air volume in and should help HP significantly, hopefully the longer runners will compensate and keep the tq numbers high!

Nate86

Sounds good. Keep up the good work.

redraif

The v-6s don't wind up too high...5500-6000 RPM is mines HP peak before it drops off...

Detail your system for me...

do you simply have a 3in cat back?

Is the whole system madrel bent?

Whose headers?

Y-pipe...what size primaries to what size pipe?

What cat back?

Just trying to get details on what people ahve and how it has benifited! This is a good thread to throw more info into!

dimented24x7

iTrader: (2)

Relatively speaking 5500-6000 pretty high.

I have hooker 2055's, catco 3" cat, and the force II catback.

engine is a vortec 350 with a small performer plus cam 204/214 .420/.442. Stock rebuilt trans and 2.77 gears.

Nate86

What I'd really like to see is someone with a V8 do a similar test. Not only do these results reveal obvious restrictions with the catback size, it is also making me wonder if perhaps even 1 5/8" headers are holding back some power compared to 1 3/4" headers like SLP's.

Another test with similar results on a V8 would also be great for some verification purposes. I don't doubt that you picked up that additional power from the larger exhaust, but (although highly unlikely) your car could just be one of those weird ones that seem to make really good power with simple mods.

In any case, the results are still good to know.

ShiftyCapone

iTrader: (7)

I don’t think anyone would have said you would have a power loss with a 3” system if they knew your projected power gains. Your motor is well above most V6’s and is making roughly the same power as a well running LO3. 99% of people will say that you will lose power with a 3” because on a stock motor it may. Your gains are typical of a car making that kind of power. Saying a 3” exhaust is too small for a V8 is a blanket statement without much merit. You need to look at power levels when choosing an exhaust size. Displacement and the number of cylinders don’t mean much. Any V8 making the same power as his 3.4 would need the same size exhaust. A 170hp V8 won’t need a different exhaust than a 170hp V6. They will expel roughly the same amount of spent gasses. That 3” system should be able to take him near 300hp at the wheels (assuming he has future mods that could warrant an exhaust size change).

Too many people are jumping on the bigger is better band wagon. Raif chose an exhaust size perfect for the amount of power his/her 3.4 is making. It means nothing that his V6 made X amount of power with a 3” so a V8 making the same power would need larger than that. Any engine making the same power will need the same size. There are countless dyno runs out there combined with track times that show how far you can take a 3” system before it becomes a hindrance. As for sound; that is only quantified by the discretion of the owner. Raif, you have a great running car and your results should be encouraging to any V6 modder.

Remember people, bigger isn’t better. Raif had to go step up his exhaust size to support his power level.

GOY

Displacement.......

5 liters displaces more mass than 3.4 liters..... I don't care what set of heads, cam, and intake surround it... it will by virtue of physics displace more mass (air+gas). LG4, or LB9.... they will move more air, and require a larger exhaust, yet have completely different forms of induction. Does not matter, in a pump, space = volume = vacuum = mass.

Big cams, and nascar heads will increase the requirement of air, but the volume of displacement is the primary factor... Agree with me or not, physics doesn't change just because a someone wants to feel good about their exhaust and will defend it until the end.

ShiftyCapone

iTrader: (7)

Your physics and understanding of the intake stroke is flawed.

The power level of the motor tells you how much air that motor is moving. Just because it has a larger cylinder doen't mean it is taking in a certian amount of air. You wouldn't need an intake or throttle body if you wanted the cylinder to take in the exact amount of ambient air it can hold per unit volume. You would also lack any vacuum at all if this were the case. Sure, a larger motor has the ability to displace more mass, but you do that by increasing the power of the motor. How do you increase the power without getting more air into and out of the motor? More air goes into the cylinders of a 500hp 350 than a 100hp 350, yet they have the same displacment. Why is that? Where else would the power come from besides the amount of air you can get into that cylinder? Power is made from air and fuel and nothing else. An engine whose displacement demands more air will pull vacuum at WOT and will have a drop off in power. Increasing the VE of the engine will fix this and increase its air flow. This why a 350hp LS1 can net 28mpg on the highway. The engine is basically running as a vacuum with only traces of air and fuel entering in the cylinder. It is hardly displacing any mass at all.

People add heads and cams to make better use of the displacement they have. GM basically gave us cars with wasted displacement. The engine is capable of moving more mass than it comes in stock form. Adding new parts gets more air into the motor and in turn makes more power.

I am not changing physics you are just not understanding it correctly when applied to an IC engine.

GOY

Shifty..... dear Shifty.

Given that the materials are the same, the larger rotating assembly will sacrifice more measurable power just in operation alone. Everything your just typed up there takes NONE of that into account. The "Operational Energy" of a 3.4l isn't close to that required of an LG4, or LB9, or LO3, or basically any other v8 in GM's product line. Even the LS1 (which I've been trying to avoid) requires more power to operate, yet it's made with extremely lightweight factory parts, which should reduce the amount of power consumed.

If you are going to go down the road of "X amount of air = Y amount of power" and are dead set on it, keep in mind you are considering a 3.4 l v6 and a minimum of a 5 liter v8. Even if they made the exact same power numbers, at the exact same rpm - a 5l v8 would consume maybe 30-40% more air, BARE MINIMUM! 36% just in space + operational power loses greater than the v6, caused by crank length, pumping loses, extra radial weight, etc. Maybe if they were both 3.4's made from the same material, this might be reasonable. (Chew on this - if that space in the 5 l isn't mostly filled, do you think that suction takes place to move the piston face up? If so, why would the piston travel down so easily?)

There are several reasons light weight components are used in modern engines, and many race applications. One of the major ones are lowered pumping loses... resulting in more measureable power. Then engine consumes the same amount of air, but more power is put to rotation, not to heat, friction, and... can I say it enough or what... pumping loses.

A v8 consuming a v6 air would equal starvation. Imagine you alone have 100 units of air. This is just a generalization for example. The v6 get's to have 16.666 units of air per piston, the v8 only gets 12.5 units of air pure piston. Since, in your own words, air = power, which will make more power... the 16.5 units of air or 12.5 units of air? There is no way a v8 could make the same power as a smaller v6 consuming the same amount of air... not possible. In a situation where airflow is limited, the v6 will operate more efficiently every time assuming all things are equal - and once again, that's not taking into account all of the above mentioned loses that come with have 2 extra pistons to sling around.

Then next logical question is why even have a v8 then? Because you have greater opertunities to DISPLACE more MASS because you have more SPACE. Is requires more effort to operate an engine with that greater mass at the SAME power level, but you can also increase the large engines efficient to produce more power due to that increased size.

Shifty, you've been against big exhausts in basically every post I read... I just wish I understood why when you have everyone around you upgrading to 4 inch units and gaining power, and v6 guys using the "V8 intended" 3 inchers and gaining power. Fact is fluid dynamics don't apply to exhaust, and the idea that the exhaust will cool off too much and "Stall" in the pipe is simply INSANE. After the header or Y pipe, exhaust velocity does not matter because no scavaging takes place in your cat or muffler... It happens up front, so whats to fear but power from giving those gases someplace to go intsead of back up to the headers. (That's not going to help scavaging any....)

I'm gunna get out of this thread too, there's no point in beating this to death any further than this already long-winded post

ShiftyCapone

iTrader: (7)

You are 100% correct on rotational masses and friction being a component for power loss. I won’t argue that. However the two aren’t that drastically different. Two differently sized engines consuming 100 units of air will only express slight power differences associated with friction losses.

I also agree that the larger engine has the potential to move more mass. That has always been my point all along. I really don’t want to beat this to death either. I have taken a tremendous amount of IC engine courses and vehicle performance courses throughout my ME undergrad. I have plenty of books to read to confirm/re-check my stance on air flow and engine design. I am not against large exhausts but merely poorly selected ones. There are plenty of people are have become disappointed by going too large on their 150hp cars. I guess we will have to agree to disagree respectfully at this point.

GOY

It's always with what I hope is mutual respect



..
..


Now if you were some from Pa it might be different

ShiftyCapone

iTrader: (7)

Or worse, Michigan!

I will go easy on the cat-back debate until I see more dyno sheets. I am really curious now and I want to see before and after sheets from various motors with different power outputs. We can't focus on a few dyno runs quite yet. Much more data needs to be collected before a real trend can be observed.


In a nutshell though,

It would be safe to say that header and collector size should be one of the most important factors. We have all read the header comparison charts that the magazines conduct and it is clear that proper selection in respect to a given motor is key.

redraif

Believe me my car was the one that seemed to never respond to mods as well as others peoples cars...until the exhaust that is! I think it was part of teh problem all along. I think even increasing the y-pipe primary size was alsopart of the equation. So yes in some cases the header tube diameter could be important to your projected powerband.

For the 82...383 Lt1 we are planning a true dual 3in system to exit out the sides! Though it will be a 500+ hp vehicle

redraif

I'm female...

I agree...its all in the amount of power you are running...
more power, more flow and more gas expelled. Though I feel sometimes you have to test the commonly believed rules of thumb! There is alot of this should be fine ststements that have been floating around for a while. Its just like the new intake with larger TB we are getting...people think they know what is larger enough...but no one really knows...

What I was hearing is that a 3.4 does not need anything bigger then 2.5....blah, blah...blanket statement. No turbo, no 3in...
Well turned out we made a good choice and even if we did go a bit large...the turbo planned will more then make up for it!

Seems people don't think a v-6 could step into any v-8 territory, so it could never need a v-8 exhaust system. Well the truth is I'm not far behind the 305 cars... as you mentioned. This is what people need to look at...not get hung up on the fact it is a v-6!

The car sounds a feels awesome with this combo. I probably got more comments at the Gathering about the way the car sounded then anything else

redraif

This was a theory I was hit with from people when I was discussing this upgrade. Well I added the cut out to the system...if this "cooling" was occuring and hurting then I would have significant gains with the cutout open... there were none!