|06-17-2002 12:34 PM|
|bullheimer||mustang maniac: true for most part making torque does cost horsepower, except in case of the tri Y header, which gives you both. Also, RPM air gap intake, with right engine, virtually no loss in low end torque (ex. very low r's), i think too, better carb, like a demon, and HRM says on last dyno losing stock steel blade fan and putting on a clutch driven fan-viscous drive-gained 15 ft lbs and gained 1 HP. i think i've seen where 1:6 rockers dont effect torque since it doesn't change duration, but adds HP because more lift. What have you heard. Usually, if you gain both torque and HP, however, you lose the torque at the low end, and catch back up in top end, which doesn't help a damn bit for me, i don't think.|
|06-17-2002 12:25 PM|
thanks everybody. i talked to a big giant brain at the local hot rod muffler shop over the weekend who told me that I can't beat tri Y headers. they are supposed to be even better than 4 equal tube headers for torque because the cylindar that's off will help scavange the others. He recommended i stay away from flow-tech's brand due to poor quality control, and only get the doug Thorleys, which is the same thing i've heard for what to get for my 326 pontiac. Until I get $350 for the Thorleys, I will stick with the 2" Rams Horns, because the shop said it would only be $60 to change over my coming new exhaust once i buy and install the headers. Besides, I have had my old motor (same mill /different cam) up to 6300 with my rams horns and my new cam stops at 5000. I need to get a new exhaust on both car and truck and was recommended to go 2 and a half inches to the muffler (flowmaster) and then 3 inches out the back of the car. cost $450-$500!! OUUUUCHHH! Can i have a reach around with that???
thanks again for everybodies input.
|06-15-2002 08:22 PM|
|blown69stang||The reason that the full length headers are the best is that they are typically designed to improve the scavenging effect of you exhaust system. The length of the primaries corresponding to which cylinder and firing order, if designed properly, will actually help suck air from the cylinders. This helps free horsepower and torque by putting less of a load on the engine. The less work the engine has to do just to run, the more efficient it will be, resulting in better performance. Smaller exhaust pipes to a limit will give you better torque because of the back pressure. However, smaller pipes can possibly not be big enough to flow efficiently at the higher rpms, causing horsepower to drop off on the top end. If possibly, get Long Tube headers; Hedman, Hooker or another reliable exhaust manufacturers; and 2.5" dual pipes with some free flowing mufflers. The design of the headers can also influence sound but this is not a big factor because you can't tell unless you try different brands.|
|06-14-2002 09:22 PM|
|4 Jaw Chuck||Full length headers will beat any shorty or stock (Rams Horn) manifold at every rpm, why? because tuned length pipes give you something for nothing. Willy knows what he's talking about.|
|06-14-2002 03:32 PM|
Well, it all depends on what RPM you want to make the torque. For a heavy hauler, I assume you will be operating below 3600rpm so the exhaust system should be designed for that. Stock exhaust manifolds, rams horn or whtever, are usually designed to fit the engine compartment, period. I seem to recall that rams horns are popular becaues they came out on Corvettes but they are not particularly designed for torque. For the relatively low speed application you need equal length 4 tube or tri-y tubes about 36" long and no larger than 1 1/2". Not sexy but that's what you need. The 24" x 2 1/4" headers you see advertised come on great above 5000rpm but I doubt you will be operation your hauler there much. A 180deg 4bbl manifold w/ 650cfm vacuum secondary carb is also great for below 3600 rpm torque as opposed to the more sexy Victor 360deg manifold w/1000cfm Dominator.
It's simply physics and you can't fool it. Engines are all compromise and for your application make it long and skinny!
[ June 14, 2002: Message edited by: email@example.com ]</p>
|06-14-2002 02:33 PM|
|mustang66maniac||I just looked at this engine performance book that i have which has numerous dyno test in it. It compared unequal length shorties to equal length shorties to long tube headers on a modified 302 ford. At only 2000 rpms the long tube headers outpaced the other ones by 4hp and out peaked the others by 12hp at 5400rpms. The lesser low end power maker of the bunch was the equal length shorties. Now thats looking at horsepower. From what i have read or looked at it seems to be that whenever there is low hp at low rpms there is usually higher torque at the same rpm as compared to higher hp at low rpms. Does that make since? Meaning you almost always have to trade off torque or hp. If you want big torque, you will loose big hp. If you want big hp you will loose big torque. So with this in mind since the equal length shorties made the least amount of low rpm hp, they probably made the greatest amount of low rpm torque. The book only shows hp numbers though. So maybe equal length shortie headers are the best way to go.|
|06-14-2002 02:22 PM|
|mustang66maniac||I would think that the ram horns would give the best low end torque. oh, 4-jaw, the ram horns are stock performance exaust manifolds used on small block chevys. They resemble the shape of rams horns because the ouside exaust ports go up and then curl back down and meet with the inner exaust ports. Maybe the shortie headers would be your next best bet, they would help build mid rpm torque and power over the ram horns. It seems to me that the horns would flow less than headers making more low rpm torque, but you would sacrifice more power found at 5000rpms as compared to the headers.|
|06-14-2002 10:44 AM|
|4 Jaw Chuck||Hey Bull, what the heck is a Rams Horn? I have never heard that term here in the great white north?|
|06-14-2002 09:20 AM|
|bullheimer||i want to add that i'm running 194 intakes, port matched to regular e'brock RPM intake, 1:6 roller rockers, hyd. lifters. i know that is not low torque stuff, which is why i'm thinking of opening up the exits alittle. 600 vac Holly, 3:50 gears/4speed truck tranny. cam has a 5000rpm red line.|
|06-14-2002 08:42 AM|
Best for Torque: Rams Horn or Headers??Help today! 6/14.
I have a sbc with a low reving torque cam in 5000 pound 4x4 56 truck. Presently have port matched 2 inch rams horns. Was planning on 2 1/2 inch pipes for a couple feet into 3 inch pipe out the back. Now i see new 2 1/2 inch rams horns for sale, as well as heddmans torque-step hedders. What is the best for low end torqued? And would it be that much better than my 2 inch rams horns to justify changing. Also, those shorty headers seem like they would have to flow better than rams horns.
I just don't want to spend high dollars on a new exhaust and find i could have done better, and maybe have to change it later!! Pleasse help me today! thanks,sfb