Don Terrill’s Speed-Talk

I'm wanting to do some collector testing to try to improve my 60' and just to see what will happen. Also it's relatively easy and cheap! I won't be testing merge collectors.

The easiest thing to test is longer collectors so I made some extensions. Weather conditions were not satisfactory to get good data at my last test session.

I also bought a set of Flowmaster tri-y extensions to test. I noticed some design differences with them. Most notably the D shaped connections and smaller collector size. Also, based on my research, I don't think I can pair up the tubes to make them work to their potential. I'll probably try them anyway at some point.

All this got me thinking about the design of 4 into one collectors. I have seen recommendations to "square off" the inside of the pipes on 4 into 1 collecters to improve scavenging. Also, I'm curious to try smaller collectors than my headers came with. Another thought is how does performance change based on the configuration of the 4 into 1 collector configuration versus the timing order? It seems like a double swap timing cam would be advantageous when using a tri-y header (SBC).

Currently I'm using 1 7/8" X 3 1/2" headers. They are not equal length.

I'm really curious to hear comments, suggestions, experience, etc. in this area. Has anyone found gains in fooling around with their collectors? Is it worth the time?

Probably should let everyone know your motor/car combo first. On my car 3400# 355 9-1 motor appx 400hp I have yet to find a better collector than the flowmaster this is 1 3/4" primary tubes and 3" collector opperating between 5000-7000 rpm and I have tried several.

Good point!

421 SBC. Pretty much the standard race set up. 14:1, 273/280 roller, Track 1 CNC. 5300 converter, roughly 3000 lbs '69 Camaro. 1.89 glide, 4.30 gears, 29X12 tires. Usually runs in the 6.3-6.4 range. 1.43 60'.

How are your tubes paired with the Flowmaster collectors? What difference did they make?

GM-DR wrote:Probably should let everyone know your motor/car combo first. On my car 3400# 355 9-1 motor appx 400hp I have yet to find a better collector than the flowmaster this is 1 3/4" primary tubes and 3" collector opperating between 5000-7000 rpm and I have tried several.

Tough to draw conclusions like this unless you are a suitably qualified carburetor tuner optimizing each of the combinations - otherwise you are really just testing which collector is better for the tune you happen to have - not to question or challenge your knowledge or ability.

I'd run a 3" collector most likely, but ya need to try it to see.

Troy Patterson TMPCarbs.net TMP Carbs

My collectors are installed correctly on one side only ,the other side cannot be installed like that--the tunnig on this combo is a little different than most it is a Qjet no major mods are allowed except jet and rod changes I have compared my carb yo some pretty big name carbs and it seems to be able to hold its own.

Brktracer wrote:Good point!

421 SBC. Pretty much the standard race set up. 14:1, 273/280 roller, Track 1 CNC. 5300 converter, roughly 3000 lbs '69 Camaro. 1.89 glide, 4.30 gears, 29X12 tires. Usually runs in the 6.3-6.4 range. 1.43 60'.

How are your tubes paired with the Flowmaster collectors? What difference did they make?

The experts say that increases in collector lenght can produce more power UNDER pk tq...

If your car launch (flash stall) above the engine peak tq you probably will not have any BIG gain, but worth a try.

Can you get lower gears? How about the rpm at finish line?

With my baby SBC 292 my 3500 lbs 71' Z28 gained .5 mph with 18" extensions (crap grip and air at that day )

On one bracket 406 SBC with "average" (13/4x 28 x3) headers an 18" extension picked up 96 lb/ft of TQ @ 4500 rpm. I didn't believe what I was seeing so I did back-back dyno pulls and confirmed the results. All the TQ numbers increased below peak TQ and gained about 1% of HP.

On a 438 FE Ford street engine the increase was 51 lb/ft at peak TQ...no HP increase/loss.

I finally started throwing a long extension on almost every engine I dynoed and saw the TQ increase every time.

I added an 8" extension on one engine and lost TQ. The long extension increased TQ.

Not very scientific but it certainly opened some eyes and got people to thinking about the energy in the exhaust system.

Ron

Ron Golden wrote:On one bracket 406 SBC with "average" (13/4x 28 x3) headers an 18" extension picked up 96 lb/ft of TQ @ 4500 rpm. I didn't believe what I was seeing so I did back-back dyno pulls and confirmed the results. All the TQ numbers increased below peak TQ and gained about 1% of HP.

On a 438 FE Ford street engine the increase was 51 lb/ft at peak TQ...no HP increase/loss.

I finally started throwing a long extension on almost every engine I dynoed and saw the TQ increase every time.

I added an 8" extension on one engine and lost TQ. The long extension increased TQ.

Not very scientific but it certainly opened some eyes and got people to thinking about the energy in the exhaust system.

Ron

Ron

That's impressive!

How about the carb tune with and w/o the extensions?

There is a lot on power in correct exhaust length tunning to suit, different rpm's/race car combo's.
Have seen simlar gains, recently added long collector to give 36" total and picked up soild 0.10 th in ET, car only had 4000 conveter so any gains at that rpm helped

With the combo mentioned in above post if you turned around put way more conveter and gear in it and ran it right near peak power all the time (not saying you should, just that if you did), the long collector would likey be of little benfit, its all about optimising the whole combo to suit how you are using it

Per PipeMax, there's more than one 'correct' (or nearly so) collector length, e.g. if 16.5" is ideal, 33.0" is also very good, but 25" is terrible.

Z28,

If my memory serves me correctly I didn't even retune most of the engines for the long collector, just stuck it on to see what it would do. I'm sure some additional gains could have been realized if I had played with the length and tuning.

Vizard did some dyno testing on headers and wasn't too concerned with primary length but concentrated on collector length. He said a primary variation of 9 inches was acceptable. I know David is a lot smarter than I am so I have to take him at his word. Great guy!

Ron

Ron Golden wrote:Z28,

If my memory serves me correctly I didn't even retune most of the engines for the long collector, just stuck it on to see what it would do. I'm sure some additional gains could have been realized if I had played with the length and tuning.

Vizard did some dyno testing on headers and wasn't too concerned with primary length but concentrated on collector length. He said a primary variation of 9 inches was acceptable. I know David is a lot smarter than I am so I have to take him at his word. Great guy!

Ron

Thanks Ron,

I readed the Vizard's article ,very good.

I ask you because I realize my Z28 can show good gains with extensions, maily because the flash stall is only 2,200 rpm and the engine have shorty 1 5/8" headers with 32" total colector lenght... the extensions have 16" and the car pickd up .5 mph with they, then probably it will like more pipe lenght!

For the OP sorry for hijack the post a bit

I make up extensions a bit longer than I reckon I'll need,
Then at the track, I put a length of tape down the side. Have a run, see where the tape burns to, then cut off the extensions 2" past that.
Last car I did it was about 3 years ago. It picked up all over. 60ft + ET & mph.
I can't remember exactly how much the difference was, but I remember I was pretty happy with the result, as it was 3600lb car with 383 and a tight nitrous convertor which only flared to 3300rpm on the launch, so when racing with no gas, it was lazy off the line.

On my FE EMC stuff I have tried a bunch of headers - especially when we were required to run a "production" header that fit a vehicle. In simplistic terms I found that the really wide RPM range largely negated the benefits of one header over another one to an extent - but that getting collecter length right was comparatively huge and always positive.

Barry_R wrote:On my FE EMC stuff I have tried a bunch of headers - especially when we were required to run a "production" header that fit a vehicle. In simplistic terms I found that the really wide RPM range largely negated the benefits of one header over another one to an extent - but that getting collecter length right was comparatively huge and always positive.

Mr Barry
Had you tried shorty or intermediate lenght headers at that time?

I 'm wondering if they have pros and cons or only cons in the engine powercurve