redraif

So the results are in...

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!

Edit: making the custom exhaust changes more clear (what Dean pointed out below)

LT1guy

iTrader: (1)

Needless to say, we're pretty happy with the numbers for now, esp considering the custom chip isn't in yet and we're still waiting on the new intake! After that, we'll be doing a valve job and a few other tricks to the heads, 1.6 rockers, installing the MSD Digital 6 ignition and new fuel pump, and maybe a few other surprises.
For those of you that have heard Redraif's car before, you'll probably agree that it sounded pretty good for a V6...but it sounds SO MUCH BETTER NOW! None of the gurgling, popping, etc you often find on a car with a too-large exhaust. I had hoped that we weren't going too far, and I'm really glad we went through with it, esp the larger y-pipe.

Project: 85 2.8 bird

Doward

LOL, yes, but aren't you running a modified 3.4L motor?

A stock 2.8L will hurt from a 3"

Dale

iTrader: (12)

nice.

LT1guy

iTrader: (1)

Most here thought it would hurt a modified 3.4 too...I even had my doubts, but as soon as I heard it I knew we had done the right thing!

AM91Camaro_RS

very nice!

redraif

Of course, but that still did not stop everyone, including you, from saying it would be too much for my car and hurt the performance... so see you are not the only one who can benifit from a 3in sys...lol...

AM91 and I are doing just fine with ours!

So when are you going to jump in the 3in club Doward? My results should totally prove you could use it!

redraif

I remember we got in a good debate one night over what to do first...I kept saying exhaust...Joe said the tune was the real problem...it turn out fate got the exhaust done before the chip arrived! And the exhaust alone was a huge gain. I'm glad it worked out this way. It was going to bug me till no end to know what a real system would do on the car, despite the other weak areas! Now I know...

now to go torture the exhaust forum!

KED85

That is very impressive.
Very Impressive.

AM91Camaro_RS

I think Doward is running 3".

Doward

I've been running a 3" mandrel exhaust for over 2 years now

All in preperation for the turbo... and yes, it DID reduce performance vs running stock. (17.224 vs 17.071)

I'm glad you were able to make better use of it, vs stock... You were running all stock, right? I think the fact that your increase in power increased with rpms, should show you that as you pushed more air through it, the system came more 'in line' in regards to exhaust velocity.

I do think a properly set up 2.75" exhaust will do you better than the 3". Although, unless you were to bring your car to me, and let me build you a system, we won't exactly ever know :P

All in all, that's a nice healthy increase, on a very healthy motor. I only ask that we not turn this into a 'every motor must have a 3" exhaust!' debate.

143/221, hmm? That's damn respectable! Plenty of torque in that motor!

redraif

Doward...I don't know how I missed that you were running the 3in system... It must have been the way I read you post before...oh well...Sorry! So now I'm the 3rd in the club I guess! You change over before or after the turbo? Cause I know you have been turbo tinkering for a while...

I might have gone 2.75, but when have you heard of a flowmaster 2.75 in system? Plus with us going turbo eventually its best to only do the exhaust once if you can manage it! Esp when you tally up the cost of a custom mandrel bent sys! Yikes! I would not want to do it twice!

NO, I WOULD NOT ADVOCATE A 3in FOR EVERYONE, JUST THE HIGHLY MODIFIED 3.4s and those with larger motors! 3.1s and 2.8s have to be so, so far modified for it to be benificial (AM91...& Doward's turbo) People need to understand the reason we did this is that the car is very modified, but something was holding it back... Air flow was the key in MY CASE! Thanks to an enlightening dyno run with the old system and a well placed cut out! Air both in and out are MY car's weak points! I can't wait to see what the new intake brings!

Dale

iTrader: (12)

I know my engine doesnt like the cut-out I put in it. It has more top end, but down low it is more sluggish.

I am not pleased with my choice of installing a dump.
I am pleased with the 2.5"?? dynomax.

redraif

You dynoed it Dale, to see what it really does in comparison?
I was floored when the cut out changed nothing on my dyno pull this time. Just made it louder!

I noticed I got reved at by alot of imports when I capped my 2.25 system for the week I was getting emissions done. Un capped though they try to hide! Esp with the 3in system open!

LT1guy

iTrader: (1)

My intention wasn't to make it sound like every 60 degree out there needs a 3" exhaust...far from it, just that on this particular vehicle with its combo it works, and may work as well on a similarly modified car.
The main thing I have learned over 20 years of messing with cars is that the conventional wisdom on ANY modification isn't always correct in every case. Take in what others say as far as their experience goes, but what worked on theirs won't necessarily work on yours. When I first installed the cam in Redraif's engine, most said it would kill torque...the same cam is in it today, and it did not. i didn't think a cutout would help her old setup; it helped tremendously, and gave us an idea just how bad her exhaust system really was.
The real mistakes come with the hard and fast "rules" some spout as gospel, though, esp concerning exhaust sizing and fuel delivery. There are exceptions to every rule. Back in 96, when I was starting to mod my 95Z, I was told by several "experts" that my lightly modded car (4.10 geared 9" and a few bolt ons) didn't need a larger fuel pump...the stock one would support way over the HP I was making. Well, I put in a larger one anyway and picked up 3 tenths and 5 mph!!! Unusual? Yes. But without testing, trying new ideas, and dynoing your results you really don't know, esp if you are working on something off the beaten path, like a V6 Firebird! When I first started coming here, there was very little aftermarket support for these engines, and few that had ventured very far from stock, so a lot of what we and others have done (AM, Ked, Doward, Dale, Dean, etc) has been done with very little guidance. Things are a lot easier now...there is plenty of good info here...but there is still a lot to learn. IF you have an idea, try it...if it doesn't work, take a step back, and figure out why, and come up with something else.

AM91Camaro_RS

I guess now I'm not the only one who says that my car runs no different whether its full exhaust or open headers! thank you!

Dale

iTrader: (12)

Shannon, no I havent dynoed the car, the shop around here wants 150 to dyno at 3 pulls F-THAT!!! but that is full ecm scan, pipe sniffer, and the works. I love my car and building it, but I have much better things to spend 150 at this time.

I was refuring to my butt-dyno The car goes like hell around 45 and up with the dump open, but below that, its slugish.

Close the dump, I seem to have more on bottom end, and little less up top. The car is mainly driven in town from light to light, I need the torque/low end and less noise.


Joe, I didnt think I "figured" much out on these engines other then the rockers. I try what others try and post my results.

Right now I'd just be happy to figure my starter problem out

redraif

Hey Joe don't forget TomP with his helpful insights, esp on the rearend swap! Could not have done it w/o him!

Joe and I were just talking last night about how nice it is to be able to come here and post our acomplishments... help people out... share what works and does not! I know alot of my car's issues would have taken longer to solve w/o this board! Plus you all are the fuel for my fire to keep going on the 6 and not let the v-8 guys push me to the other side! I'll have one in the 82, but RAIF needs to stay v-6. Keep him different!

AM...I never knew you have the cut out and had no gains with it. If I had known that I might not have waited so long to do this!

AM91Camaro_RS

i don't have a cutout but i have pulled my y-pipe out of the car at the dragstrip. i do want to put a cutout on it though (maybe 2 of them) just cause it's fun to make all the noise with it! It sounds incredible idling with open headers!!!!

redraif

I have to agree...its such a satisfiying sound. I had a crowd yesterday when I was pulling out of Joe's neighborhood...they heard the car idling with the open cut out in the drive as I dashed in for the cutout's cap for the dyno test... they came out to look and were trying to get me to light up the tires! I gae them a quick spin and took off!

Too bad you are not coming up to GA for the F-body Gathering...be nice to hear the car!

Dizturbed One

I'm about to put a 3" catback on my otherwise stock 3.1

lol

redraif

Expect somegurling and possible back fire if the back pressure is not enough... What are you doing about the exhaust manidfolds, y-pipe, and cat? If they stay stock you have effectively done nothing. The car can only flow as much as its smallest bend or pipe!

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 atits exit (2in primaries into 2.5in)...it flowed to a 2.5 inch pipe then to a 2.5 inch cut out. 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 difference 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 mandrel bent sys with custom 2.5 inch primaries to a 3in (y-pipe)
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!!

RTFC

Redraif and Lt1, I am not surprised at all that you showed gain over the 2.25" factory exhaust with the 3" exhaust.

I am also not sirprised that you showed no difference under maximun rpm and HP readings under the 3" compared to the cutout. What I am surprised and would like to see the dyno results is the low down rpms and tourqe ratings on the motor with the 3" exhaust. What I am saying is that the HP output of the car at max HP readings is enough flow of a V8 5.0L motor at idle/cruising speeds so of course the max HP reading will flow the 3" fine. I am (respectfully of course) skeptical of the low down power output being max potential through the entire powerband leading up to the higher rpm flow and output.

I still dare to say that the that the lkower rpm #'s would look better and the high rpm #'s would not change with a 2.5" exhaust. It is my opinion, I have no proof- just speculation on my part based on what I know about HP ratings and tube size.

duranged

red, i love you, will you marry me?? PLEASE?? i will treat you good, and i got 2 firebirds? we can let our cars mate and grow our own little firebird farm??

redraif

What range RPM would you need me to try and get...going to go back soon! Testing the new chips...see if I can get a chart showing low rpms as well! Hopefully my old pulls on file will have the lower RPM for the 2.25 & 2.5 exhaust pulls!

redraif

Well thats my first on line proposal!

duranged

hey hun, a hot girl with a nice v6 bird, your the girl of my dreams, come to connecticut, we'll get a house with a 5 car garage, let our birds mate and live happily ever after in our own little bird sanctuary,lol

TomP

(laughs)

Congrats on the mod and the gains! How did the 3" fit over the rear axle? Did they at least crimp the pipe so the suspension doesn't crunch it? Was it an aftermarket cat-back or a custom-bent one?

LT1guy

iTrader: (1)

Leghumpers!

Tom, it started out as a Flowmaster cat-back, but it was modified a little at the front (the cat is now flanged on both ends, so it can be removed and replaced with a "test pipe", and there is a 3" cutout) and at the back (to accomodate 4 tips, which didn't turn out like she wanted so its being re-done, as soon as the tubular a-arm issue is resolved). All the mods were done with mandrel bends. The y-pipe was custom built from 2 1/2 mandrel bends.

redraif

Tom...I plan to get some pics when I get the tips redone! I will document what he did and post it up for you guys!

redraif

Though now that I think about it the car is not going to really be able to show anything till the stall point of the convertor anyway, right?!

AM91Camaro_RS

yup....pretty much.

redraif

Figured...oh well the point was to have a system that was matched to my car, with my mods...that it is!

Sucks I could not get a dyno run in with the new chip...they were closed on Sunday when we got there. Then on the way back my A-arm broke...tubular unit... car and I both fine. Broke just before i entered the expressway...in turn lane before ramp. One leg of the A snapped... passenger side... rear leg! Car is still drivable to manuver only... would not trust it for anything but a crawl!

So no new dyno results yet with the new chip!

AM91Camaro_RS

a. you're running tubular a-arms?? nice, i want some, too!

b. how did it break? did you (or have you) hit a pot hole or something?

redraif

Check this out...

no pot holes or anything. Just driving along straight and actually only at about 15mph in turn lane! Or if it happened in the gas station...2-5mph!

Mcdamit

redraif this is a purely honest question, what did that do to the torque curve and did you keep the stock manifolds, or headers that would fit that 3.8?

87blueracr

i have been thinking about making tubular truck arms for mine, but haven't gotten ahold of some square tubing to play, but it really doesn't look that hard to do. perhaps you could post some pics.

RTFC

Redraif, I am trying to understand the details of your exhaust before and after.
Wahat I am curiuos to know is-
1a)What Y-pipe did you use for the first dyno run using the PF&E headers and the cutout? Was it one from Greg, or was it something you had made? 1b) Where exactly was the cutout (pics?) and did the y-pipe flow into the 2 1/4" system at all then to the 2 1/2" cutout?

2) Sound like if I am understanding correctly that you made a completely new Y-pipe coming of the PF&E headers into 2.5" y-pipe primaries, then y-merging into a single 3" flange? The PF&E Y-pipe has 2" primaries and then Y-merging into a 2 1/2" flange. IS this info correct? Pictures if possible?

If I am understanding this info correctly, you are saying that there was restriction in the PF&E y-pipe even with the cutout and that the y-pipe needs to be larger?
Dean

RTFC

Here's a pic of the PF&E y-pipe in question. Was your y-pipe on the first dyno test with the cutout identical to this? and was there any 2 1/4" crimp bend pipe exhaust section in between this y-pipe and the cutout you ran?

LT1guy

iTrader: (1)

Its a 3.4, not 3.8. The dyno tests shown are with PF & E headers, though some of the earlier tests were with stock manifolds. No improvement was seen initially from the headers and y-pipe (also PF&E), but this could be due to the fact the car was never tuned for the new engine and had a terrible crimp-bent exhaust system behind it. The torque has always been good (well, since it has been a 3.4), but it is FAR better than before as shown by the graph.

LT1guy

iTrader: (1)

I'm sure Redraif will pipe in at some point, but I'll try to answer your questions.
1) the y-pipe used in the first dyno test was made by Greg, and was the original prototype used on his personal car. The cutout was behind the y-pipe, and frankly all the exhaust work done by the muffler shop to connect it all together was a complete abortion. Notice the bend behind the y-pipe, which severely restricted flow.
2) Yes, a new y-pipe was built out of 2.5 inch mandrel bends, and goes to a 3 inch collector. The PF&E y-pipe had 2 inch primaries going into a 2.5, but 2.5 collectors. Not sure if there are any pics of that yet, I'll check.

I know part of the restriction was the bend just past the y-pipe, but based on the torque readings I would say that a similarly modded 3.4 needs a 2.5 inch y-pipe. The cutout could not fully overcome the restriction inherent in the whole system; now, the new cutout gives near identical results when open.

LT1guy

iTrader: (1)

The old system. As you can see those two bends were a major restriction.

RTFC

Well I'll be damned. Now I understand why the 3" catback was beneficial.

I first thought you simply plugged a 3" catback setup onto the exit of the PF&E 2.5" y-pipe exit and where claiming better #'s than a 2.5" catback on that same setup. I now see that you completely built a new y-pipe off the header primaries that do NOT funnel down to 2.5"at the exit of the y-pipe.

Now I truely see where the 7hp and 14# torque came from in the larger y-pipe with cutout (regardless of yet getting to the catback system) Very impressive work and laying down money in experimenting. It could have been a costly mistake and you gambled and won- to the benefit of myself also. Thank you very much for the info, time for me to re-evaluate my y-pipe choice and overall catback setup when I install the 3.5. I am expecting it to yeild about 250hp+ and some major rpms. Just like everything else I have done to this car already, I think we I know I mean business (just have to get some other projects out of the way first and then finish this damn motor build)

The PF&E setup is going to go onto the car then ASAP with the 2"y-pipe onto the current 2.8 motor with the existing 2.5" cat and mild steel 2.5"catback with the rear Flowmaster. I will put the rest of the custom SS exhaust on hold until the 3.5 install and will worry about rebuilding the entire exhaust with an I-pipe muffler then. Good thing, I was just about to order mt 2.5" SS mandrel bends, tubing, v-clamps, cat, and muffler to rebuild my entire system custom getting ready for the 3.5. I will now just order some steel mandrels just to connect the PF&E setup to the current steel 2.5"exhaust for now.

redraif

The above dyno chart is the best way to compare what it did to my curve...basically the curves trend was the same...the difference in the numbers increased a bit more the higher the rpms...as did the hp... So basically to summarize the Car gained even more TQ and HP the higher the RPM then before. Though the peak reading were in about the same place RPM wise!

The stock "3.4" manifolds are still at my house.

redraif

The link I posted above are the pics I have of the a-arms...check it out...see if those pics help. If not we are removing them tonight/tomorrow night and will be taking plenty of pics!

LT1guy

iTrader: (1)

Yes, it was a pretty big risk...all those mandrel bends plus a catback, new cutout, and lots of fab time at the muffler shop...lots of $$$, with the risk that it might not have worked. Needless to say I am very pleased with the results. Sometimes you just have to go with an idea and see what happens.