Revisiting..What is the concensus on Long Tubes?

[Pokageek]

How about with the 351 strokers? What about these? and if I have a guy that can custom weld stuff will that help or is it a lost cause with too many hurdles? Any pics or links welcome.. and do they add ANY performance to a stroker like mine?

http://www.accufabracing.com/exhaust.htm

 

[blksn955.o]

I dont think its so much should you get LT's...but what is the best size LT's for your motor/combo.

I dont think other than some issues with ground clearance/sealing issues they are ever really not worth getting.

 

[5spd GT]

I had a 162k bottomend (1993). This was topped off with AFR 165, OTB Performer Intake, and a custom camshaft, rusted out Mac 1.625" headers (pinched).

I decided to make a few changes, after a couple circumstances. The local track (that I frequent most) is a 1000 ft. track. Best run, off the street was a 10.65 @ 97.98 MPH with the combination above.

Okay, the changes I made were, rebuilding the bottomend (306). I used Probe's 030-10682 pistons (9.6:1 now), with more swept volume that will increase compression. KC did the bottomend.

I also replaced the old rusted short headers, with new BBK Longtubes and a new Offroad H (no dents like my last pipe). I then had Tom Moss port the lower to match the AFR 165cc heads, and he matched them great. Looking down the port, it matched the flange nicely. I even trimmed the gaskets (not done before), cleaned everything as clean as possible as well.

So these three changes were made:

- 306 (slightly more compression)
- Longtubes with H-pipe
- Ported lower to match AFR 165
- RP synthetic tranny fluid

After several runs throughout the next year, the best run I could get was 10.56 @ 99.31 MPH.

I kept the same exact timing, fuel pressure, driver weight, tire pressure, etc. I noticed a little more pull about 5300+ RPM, which I attribute to the lower porting by Tom.

A total gain of 1.33 MPH and .09 seconds. So roughly 13.30 HP.

I feel if you are going to get headers from scratch, go for longtubes, but do not believe the hype on how much better they are.

Now my example is for a 302-306, but many stroker guys run 1.750"-1.875" headers, but with more cubic inchs.

 

[Pokageek]

5spt that was an EXCELLENT summary. Thanks. I have also wondered and Mike (with the 418) how much the lower porting gives or what it does. Makes sense.

 

[BlackVert]

i had kooks long tubes. i did not like them at all. they hung so low that they scraped on even the slightest bumps. and forget speed bumps. they also leaked at the collectors, which made sitting at a stop light a nightmare. not good for a 100% daily driver type of street car.

perhaps other long tubes would have not hung so low, but i did not feel like dealing with it.

that is why i ended up going with mid-lengths instead. i am very happy with them