Actually, this post and several others concerning the problems with available headers helped Jamie (69-in-1/2) to convince Doug Thorley Headers to allow him to develope the new shorties that they are offering. Jamie is head of product development at Doug Thorley. When developing headers, he routinely dyno tests the cars before and after with the new headers. If we could convince him to spill the beans, I think he could offer a lot of insight as to the real differences between stock, shorties and long tubes. I know there is a lot of "marketing hype" concerning the power differences between header designs. After reading car magazine test results for 30 years, reading advertisers hype and talking to several reputable dyno operators, I have learned one thing. At the power levels and state of tune that most of us are running, we would be unable to tell the difference in the performance between long and short tube headers. Most of the engine combinations we are running are dictated by the parts we have available and the price rather than how well they work as a total combination. As such, you will probably gain more power by honestly evaluating the total combination of parts in your engine. Cam selection, compression ratio, head flow, intake, carb, timing, exhaust pipe size, type and placement of the mufflers all have to be correct for the way you are using the car. If you have a radical cam, high compression but are running stock heads or a poor flowing intake, it won't really matter what headers you use. If you have a stock block and heads, there is no reason to go with 1 3/4" primaries and 3" exhaust. You would actually be hurting your performance in the rpm range where you drive the car most. The purpose of this message is to get people to do an honest evaluation of the parts they are using, how they will be used most and try to put together a combination that will give them the best performance that they can get without looking at any one piece as being a magical power adder. It is the total combination that makes power, not any one piece.
Some of us are running at those power levels though. We are the guys buying this stuff. Racers will spend big bucks for that last piece of the puzzle. While the average guy would just stick with manifolds.
No offense, but I notice you run a 7.997 in the 1/8 mile. I believe the significant difference would be seen on a 7.2 second 1/8th mile car trying to break into the 6's. my
Ratio's got it... Longer tube lengths bring the power band down to a lower R.P.M. range. Shorter tubes move the power band up into a higher R.P.M. range. Engines that Red Line higher would need shorter tube lengths . Engines that produce more torque and Red Line lower would need longer primaries. This is what the term "tuned length" means. there are many other "features" that determine engine performance like... scavenging. This is what you get when you pair cylinders up according to firing order. If you are dealing with a "tri-y" this is done by pairing up cylinders with secondary collectors then finally with a single collector. If you are dealing with a 4:1 header then you arrange the four tubes in accordance with firing order, after one cylinder fires, the corrosponding cylinder fires, causing a vacuum effect. Also know as rotational firing. Collector length. A longer collector length moves the power band down and vice versa. tube diameter. A larger tube will increase your top end but decrease your bottom end and vice versa. As Jay said, What you need truly does depend on YOUR specific combo and what your intensions are for the car Stock manifolds are designed for one reason. To get the exhaust out. They have none of the features above. Performance is almost never a concern with auto manufactures. Most of the dyno research that I do concerns new vehicles where I'm limited to shorties due to cats. These newer cars/trucks usually yeild power gains of around 10-12 h/p and 5-10 ft. lbs. I had other concerns about building shorties for our cars. Ground clearance seems like a big issue these days. I think that a fairly large tube diameter and a short tube design was exactly what the general public needed, along with heavy duty flanges and oem dome collectors.
I agree with that philosophy too . My Supercomps almost drag the ground w/ the 3" collectors. If I ever wanted to go street with it, I'd want something just like what your'e talking about.
I went with shorties on my 69 Mustang with a 393 for one main reason: Fit. I hate PS drop brackets, and I hate ground clearance issues. Sorry I missed you at SEMA, Jamie. I would love a set of coated shorties that would go into a column shift car with no mods.
ahh, but you see my brothers maverick will be/is much faster. I built it so it is my maverick too It should have 375 to 400rwhp and a 200 shot of NOS. I may end up buying the car from him this year to. :evilsmile I have started a set of 1.75 inch tube headers for his. Been there done that. I hate to take about 30 plus hours to make them if I do not have to. Besides the "War Machine" will be faster in the near future. Heads are coming off this winter for some port work, a much larger cam than the .499 lift 220 duration along with some light weight valve train(titanium keepers,beehive springs, etc...) and a 100 shot of NOS Rick ,I noticed you have not posted any Times yet:evilsmile
Has anything more been done on this. I am looking for a header LT preferably that will bolt on without issue. No PS and want to keep the column shifter. Can someone please recommend header for me. I have been at this for a while and really want to get engine insalled and fired...
doug thorley is making shorty headers for couple months now for our cars if you want long tube, and have a 302 go with hooker 6901s
Slk70 We have recently verified that our shorties work w/ auto on the column. Heres the link... http://mmb.maverick.to/showthread.php?t=24841 Any questions feel free to pm me or call me (951) 371-1744 ext. 257 Heck man, your close by. Give me a call anyway . Jamie
