1989GTATransAm

Hehehe. Rest assured the tune will be next. However I will have to try the 18.5" collector deal and see how much horsepower might be there. If like you say if it is only 5 or 10 horsepower then I will leave it alone. However there might be more horsepower lurking there. I gots to find out. If there is I have in place a plan of attack on how to get it.

Orr89RocZ

indeed, i hope you get those results soon so i can decide if its necessary for me to pursue this further. I dont think its gonna be 5-10 hp tho, i'm thinkin more like 20

1989GTATransAm

Vincent, one more thing. The next time you are over at Dyno Dons look at his dyno program and the difference in horsepower between a mufflered exhaust system and and open exhaust system. That is what I'm looking into. Remember nothing ventured nothing gained.

VincentZ28

The only problem is that I'm not trying to run open exhaust or the cutouts. You, Don an I did the best thing already and that is modifing the header collectors from 2 1/2 to 2 3/4 and the 2 3/4 pipes through the 3in cats to 3in catback(for you 3 1/2 catback). Not much gain any other way. My gain was 20hp. How much more do you think you're gonna get?

Orr89RocZ

If you gained 20hp with those mods, i'd be curious to see what open headers with proper collector length would gain over that. Hopefully Allen gets to discover this and feed us the information to help our builds

VincentZ28

Allen wouldn't know! He made lots of changes all at once. So he doesn't really know how much of a change it will be. He change the exhaust at the same time while making an engine swap.

Orr89RocZ

well i think he plans to dyno the current setup with no cats and the current exhaust system with better tuning. Then run straight headers with collectors at 18 inchs or so to see if it does anything different. should be a interesting comparison

skinny z

[quote=VincentZ28;3718329]Is all of this really needed just to make 5-10 more hp in an everyday driven street car? $500 to $800 and the labor may be alot of time wasted. I was told along time ago to work with the stuff already on the car and get the most out of it. It's a lot cheaper!

I see your point however the terminator box set up we've been discussing may be more along the lines of 40 hp. That's only 10% (or less) on the vehicles we're talking about. There may be a higher percentage available. We'll see when Allen gets his dyno results with collector extentions installed.
40 hp is worth a lot of fabricating if it can be accomplished.

skinny z

Even a measly 10% is 40 hp!
I understand there's more. Mind you , you have to start with a poorly performing exhaust in the first place.
Like Vincent says, the've already done quite a bit of modifying in this area.

skinny z

[quote=VincentZ28;3718514]The only problem is that I'm not trying to run open exhaust or the cutouts.

I don't think they are either . The plan is to determine proper collector length first and then build the resonators from there.
Or am I missing the point boys? Allen? Orr?

Orr89RocZ

thats the point indeed. to simulate a open header exhaust with a full mufflered system. Its called a zero loss mufflered exhaust system. Find the proper open header length for best hp, and then build the rest of the exhaust to make the motor act like its still in open header mode

skinny z

And that's worth more than 10hp!

always tinkerin

You guys were talking about lots of time and money for only a 10-15 horse gain. You're absolutely right..."most" people won't spend the time or effort to even try.

Skinny z and others who already have an existing exhaust to optimize, by all means...DO SO! And to you I really hope the wave term. boxes can work because it really is an excellent idea and I envy your enthusiasm.

To those starting with a clean sheet of paper and are planning a complete new exhaust, I urge you to at least try the recommended lengths/diameters...it will not be a wasted effort. I will say nothing more here on the subject.

EXCEPT:

They say knowledge is power...if it's only 10 horses, then it's 10 horses more than "most"... but you're forgetting about torque! (which is what really matters).

Some folks have seen over 60 ft/lbs. of additional torque occuring before peak power (with all areas optimised). If you're upshifting slightly above max power, your rpm's should fall right into the max torque "niche" and the car will recover from the shift better and accellerate quicker with that extra torque!

Good luck to all!
-Jesse

skinny z

And that my friend is what it's all about!

1989GTATransAm

Yep I could not have said it better myself. The above seven replies are entirely correct. It is quite posible that only ten peak horsepower would be obtained but as stated the increased torque output in the lower rpms and under the curve might be considerable and that alone would make it well worthwhile. We will not know unless we try and that is the whole point of this exercise.

Orr89RocZ

well i'll take torque if i can get it too i got a 383 so i should have plenty of torque reguardless... the stock L98 with bolt ons was enough torque for me.

But yes, i'm doing a from scratch build so i cant wait to see how it turns out.

I want to get it done asap so i can go to Pittspeed Dyno day again end of may. I probly will have it on a dyno before that tho

skinny z

I'll be passing by Pittsburgh (on the turnpike) 24th of May and staying in Virginia for a week. Going golfing and possibly purchasing a 84 Camaro coupe rolling shell I found on Craigslist.
It'd be cool to see your machine on the dyno.

Orr89RocZ

haha the 24th is the dyno day!!

skinny z

That's wild.
I'm supposed to take my car as part of group. If I can pull it off logistically, (because of our scheduled arrival time in Virginia) it'd be a blast to watch the session. Provided you don't mind.

Orr89RocZ

free to anyone who wants to stop by and watch goes on most of the day from 10am-4pm

If mycar isnt ready i'm gonna go watch

1989GTATransAm

I would love to be at your dyno session but to much distance.

Anyways picked up the 2 3/4" L bends for my temporary collector mod today. Dyno Don will order the clamps for me and make them up to the 18.5" length.

I don't expect to get on the dyno for that test until some time in June. I will be on the dyno for my current combination in May. Got to get ready for the Los Angeles F-Body invasion drag race on May 26. There will be mostly 4th gens but I think our club will hold its own and surprise some of them. Maybe even embarass a few. The lowly TPI strikes again.

Orr89RocZ

Go get 'em man! Love to see some thirdgens holding their own against some lsx cars. I got my hands full this year with MANY 4th gens, from mild cammed only cars to full blown 408's with heads/cam. This 383 better get it done

still waiting on my headers to come in and few other little motor parts so i can start to assemble it. gonna wire up the ignition box this weekend and if my parts come in by friday, i should have most of the engine done by sunday

Then i can start looking at the headers and how they will dump below the car. That will help me design the exhaust system

skinny z

[quote=1989GTATransAm;3721029]

Anyways picked up the 2 3/4" L bends for my temporary collector mod today. Dyno Don will order the clamps for me and make them up to the 18.5" length.

QUOTE]

Do you think you will have an opportunity to experiment with various lengths? Maybe open headers with no collector extension vs the 18.5" piece.

1989GTATransAm

"Do you think you will have an opportunity to experiment with various lengths? Maybe open headers with no collector extension vs the 18.5" piece."

The chasis dyno's in my area are fixed in the floor. If there was one of the elevated type then maybe. The logistics are going to be bad enough because I don't want to drive over to the dyno shop with open exhaust. We are looking into putting the car on a trailer and taking it over to the dyno. The dyno shop does have lifts but that gets more involved and time is money.

Regarding the 4th gens. I have had good luck with them out at California Raceway. I have raced four over the years and won them all. Even beat a SC Mustang Cobra. The Cobra guy was so confident he had his girl friend ride with him. Probably cost him the race.

However I think at this meet my winning streak will come to a close. I know there are some pretty nasty 4th gens out there and I'm sure I'll line up against a few.

5678TA

i dont wanna say why.. you know why..

1989GTATransAm

Yep. Hehehehe. Anyways I raced another SC Cobra and he beat me. He ran something in the very low 12's.

Oops, I think the thread is getting off subject and my fault.

What needs to be discussed is what is the best exhaust system for our cars.

1. What is the best system for long tube headers using mufflers?
2. What is the best shorty/mid length system for our cars using mufflers?

1989GTATransAm