Thanks for sharing the info, as usual, Dave. Much appreciated.

 

DB .....you say small tube and big tube, but have you considered long tube vs short tube ? I would think that a short tube header would also help gain low end (up to a certain HP level).

 

What will be really interesting is autocrossing an 8 second car!

 

it is a bit absurd. i like his style!

 

I've done long tube vs. short tube testing already. That was a few years ago when I went from my long tube header that had the turbo down by the passenger side frame rail. Not as much difference in that testing but the shorter the runners the quicker the turbo hits.

One thing I've come to accept is equal length plays either absolutely no effect in the peformance of a header or so little my dyno won't pick it up.

Also, since I'm in that kind of mood, to the haters-> My testing is flawed, this testing is as useless as all I've done in the past and hopefully an honest shop will do this testing some day too and post the same results as I just posted.

 

Found a little bit more power with the turbo swap. Not posting the graphs from that test. Power is up about 10 whp over 6400 rpm. Power is down in the low/mid range.

Tomorrow, if the guys have time, we'll put the new cams in. Glad this is moving along so nicely.

BTW, the small runner header, absolutely with complete certainty pissed the car off. I had one run all day the car didn't feel right and that was the only run at high boost with the small runner header. Not a good choice for this power level. Swapped the large runner header back on, car is smiling again.

 

Anytime David.

 

Thanks Cris, I truly appreciate the help. The idle about had me throwing in the towel. It's weird cause my settings were very close to yours but something wasn't quite right cause as soon as I changed them to yours, BAM, rock steady idle. Thank you! I owe you dinner and a few beers.

 

that is unreal! congrats david.. i think you just made my decision on what motor of yours ill be going with

 

nice work as always, can't wait to see this at the shootout in the summer!

 

I'm sitting at home working on the Haltech. Trying to learn more about the logging and go over more of the programming. You can never learn enough. While doing this I found one of the greatest features ever for testing. This feature now allows me to compare multiple runs, boost, rpm etc. and be sure what I am comparing is equal. This make gathering data so much faster and makes it easier for my brain to grasp it. If you look at the logs of the boost, they dyno graphs look the same way. Check out this RPM vs MAP log of three of the highest WHP runs of the day with three different combinations.

 

Hey Dave, just after reading through the entire thread and seeing the differences between the small and large runners, have you guys thought of taking a look at the idea of having different internal runner area? Basically if you've ever looked at a two stroke quad or bike, about how the exhaust diameter is small when it first comes out, then expands then contracts. With this theory, you would get the stronger bottom end benefits your looking for with the smaller runner, and the top end performance with the expanded internal area.

Could be just some stupid thought, or just what you need.

 

It would be a PITA to build. I am sticking with what we've built so far. For a smaller HP guy the small tube makes sense.

 

dave awesome tests. i enjoyed reading that actually. but i have a question if you dont mind.

the small runner clearly is smaller then the ports on the head. was the flange that is bolted to the head port matched to the same size of the head or was it left alone?

 

also dave being TS do you think the effects you saw would be the same/better/worse with small vs large runner being its TS and not single??