Custom headers/Side pipes for BDR

[native1]

Looking for someone in Tampa area to make custom headers and modify my side pipes. Bolt pattern for winsor headers makes it very restrictive. Looking for conversion plates to change bolt pattern to clevland style header flanges. BDR comes with inch and three quarter tubes want to switch to 2 inch tubes. Also, the side pipe mufflers are not straight through, they go into two tubes. To make a long story short I believe there is a lot of horsepower left on the table. Roush says motor should make around 540 hp at crank mine made 450 rwhp. Would love to see 500 rwhp Has anyone done these mods to their BDR? How many ponies is it worth? What do custom headers cost (mild steel)? Any problems with using conversion plates? I have earmarked 2 grand +- for project including hot coating is that enough. Thoughts anyone?

[Rwillia4]

native1,

I agree there is some HP left in the headers but before you spend 2K on header improvements there is probably some other ways to get the extra HP. I don't think header improvements will get the transmission loss below 10% (or 15%). You might see 5% improvement at the crank, provided the original 540HP numbers you have are with the BDR headers. You would probably have better luck with a more progressive cam if a peak HP number is what you are looking for but then your torque will suffer. It is the never ending saga of needing more HP that we all endure!! Good luck

Rob

[native1]

Thanks for the input. The crankshaft dyno was done at roush with their headers. Dont want to do anything internal on the engine for fear of voiding my warranty. I think exhaust is a way to get "free" horse power. Have read posts were guys talk about 50-60hp gains. That would put me at my magic number 500rwhp.

[Mac VABCH]

Check these out. I am going to cut my mufflers out of the side pipes and use these when I get back to the states...Mac

http://www.classicchambered.com/index.html

[froggyman]

You might rethink making the headers 2".. You may encounter a big torque loss. Be careful.

[Roush #1]

Native,
What I understood when I bought my 427 SR TW engine (#444) was the 427 SR with the twisted wedge heads is rated at a nominal 525 HP.
That is with the 8 quart oil pan and a single plane intake manifold and is tested on the Roush dyno with 1 7/8" inch open headers.
Most of the 427 SR TW engines I have seen make a little less than the 525 (mine made 515) and are equipped - as mine is - with a dual plane intake manifold.
Maybe the newer engines make a bit more horsepower?
I recently installed stepped headers and could definitely tell a difference from my original 1 3/4" headers. My new headers are 1 7/8" about 6" then stepped up to 2". The total primary tubes are about 34" long and empty into a 4" collector that is 9 inches long.
I plan to go to a chassis dyno soon to make exhaust changes as well as carburetor changes and will post the results.
Jody

[Roush #1]

Native,
On the other subject about the restrictive Windsor exhaust bolt pattern.....
My Roush heads (AFR 205) came with a dual bolt pattern that will easily accomodate a 1 7/8" tube and I think a 2'' tube as well. When I changed headers, I installed stainless studs for my header bolts and have a nut on them that requires a 9/16" wrench.
I can now tighten all the header bolts from the top side with a 10 inch long box end wrench.
I had trouble previously - when the bolts were in the narrow position - reaching all the bolts with a short 7/16" open end wrench.
Check out the dual bolt patterns by looking at the Fel-Pro #1487 header gasket.
Hope this helps!
Jody

[Slick61]

Originally Posted by native1

Roush says motor should make around 540 hp at crank mine made 450 rwhp. Would love to see 500 rwhp Has anyone done these mods to their BDR? How many ponies is it worth?

... not worth as many as you think. You're getting really good numbers. My aluminum 427 Windsor (TKO-600, 3.73's) dyno'd at 612 hp/615 tq, but it made ~ 458 hp/tq at the wheels... and that IS with 2" custom headers. I think you'd be VERY VERY hard-pressed to squeeze 500 whp out of your setup... there are just too many factors. Yes, the headers & sidepipes are lossy... so is the transmission & the IRS rear end. A drivetrain loss of less than 10% is unheard of in these cars. 15-30% is more realistic.

Save your money... and enjoy your car. Just quote everyone the flywheel horsepower/torque figures and tell them it's a 427.

[native1]

Thanks guys for your thoughts. Maybe I am getting ahead of myself to think 500rwhp is achievable with this set up. I thought the new pipes/headers would bring back some of the low end torque I lost due to the 950cfm carb. I was talked into the carb by local race shop paid 1000 dollars. Performs much smoother than the 770 street avenger it came with however, not as snappy. Should have done 750 or 850 cfm carb instead. My thoughts were, if I could get the air out quicker I could let more air in. Roush says 427srtw should be 535hp and 535tq with vic jr. and 770 carb. Thank for the advice.

[Doug I]

Honestly I'd leave it alone. If you're getting 540 at the crank and 450 to the contact patch that's a loss of 17% which really isn't that bad. Getting the losses down to 7.5% will I think be mechanically extremely difficult and expensive.

I hope the speed shop wasn't more interested in your $1000 over the correct spud. If you went with a Demon, assumed you've got 85% volumetric efficiency and spun it 6500 then you'd need a 720-750. A 950 will be letting in just a little too much when you drop the hammer.

A little pricey but VCP http://www.verycoolparts.com/Stack.htm could be 1 way to recover a few ponies and give you a lightbulb throttle response.

[Slick61]

Originally Posted by native1

I thought the new pipes/headers would bring back some of the low end torque I lost due to the 950cfm carb. I was talked into the carb by local race shop paid 1000 dollars. Performs much smoother than the 770 street avenger it came with however, not as snappy. Should have done 750 or 850 cfm carb instead.

... funny you should mention that. My engine was originally running a DaVinci 950 cfm carb, but was then later switched to a 770 street avenger for better streetability. Tuning is a big factor, though... I dyno-tuned the car last fall & with the 770 carb on, the power/torque was nearly identical to running the 950 cfm carb, once it was re-jetted & properly dialed-in. Horsepower/torque losses were maybe 3-5 hp/tq MAX.

[native1]

Was the 770 a lot quicker in throttle response? Maybe I should leave the headers alone and redo the side pipes with 3 inch straight through mufflers. Would sound better and is not as pricey as custom headers.


Wow! I love these cars ...... Timeless

[Mark Brye]

There is lots of good information in the post on a sidepipe mod that I performed on my BDR.

New Mufflers for the BDR;)

[efrost]

Originally Posted by Mark Brye

There is lots of good information in the post on a sidepipe mod that I performed on my BDR.

New Mufflers for the BDR;)

Mark,

I followed your side pipe build however I don't believe I ever saw your dyno results.

Were you able to find a working dyno? I'm curious if the tune was effected with the increase in exhaust flow.

After a little burn in time are there any lessons learned like flow path diameter?

Regards,

Ed

[Dwight]

This is a great thread and I'm waiting on the dyno numbers.


I have check out the Classic web site and like what I read. I don't know if I want (need) the 2 1/2" with out packing or the 3" with packing. My motor makes about 450 flywheel hp now. Which one do you guys think I should buy?

[Mark Brye]

I had a feeling you guys would ask about the dyno numbers......No, I have not made it to the dyno yet, even though I think about it every day. I have been having to much fun driving the car!
As far as the mufflers go, I have about 1000 miles on them now and love them the same now as I did when I first put them on. I would not change a single thing about the sound at all. Its just perfect for a cobra.
Guess I need to make it a point to get to the dyno. I have next Friday off and it looks as though weather will be nice. I will call dyno tomorrow and see if I can get scheduled.

[mtpockets]

Mark:
How is the vacuum pump working? I have been scratching my head, looking at the side pipes knowing something could be done to get some more hp. Send my some pics of the car and under the hood. I just finished my most recent add on/upgrade and testing and tuning now in prep for Run-N-Gun. Good luck at the dyno, keep us posted.

[Mark Brye]

Actually I have not got the pump on yet. I am having issues with the location to put it. I upgraded my cooling fans on the car so I don't have the space for mounting in the same location as you. My buddy that welded up the side pipes is going to help me build a custom bracket for installing the pump. Thats another thing that is on my long list of things to accomplish.