Ketchmi

Gee, funny story.....

I was dynoing our x-over last week and even Dr. Gas has to give props to Louie now. They thought it would be easy to get an additional 10hp out of his design, well, their first try was about 13hp shy of Louie's mark. They pulled two guys off of a NASCAR job to redo it while I was on the dyno. One hour later (the first x-over took a couple of months.....) we re-dyno'd. They are up 2 hp now and are working on "Phase #3". It should be tested later this week and all of ours will be available with or without cats. Prices to be determined........

BTW, 29 hp gain from factory cats to our latest X-over (catless). Back to back to back dyno runs, same car, same dyno, same day. 257rwhp uncorrected for altitude (4400') on my tired old 86.5', 290ish rwhp at sea level?

Mongo

someone PLEASE PLEASE post a picture of a factory 87 928 S4 catalytic converter system that shows the air inlet tube.

Ketchmi

Will these do? Fresh off of an 87'.....

Mongo

Thank you Dave!!!!

Now why do we need the air inlets again? (sorry for the stupid question)

rob rossitto

ah the x cronicles - a classic thread for sure, but not as bad as my friday posts...

fwiw, for my "85SS", devek is building mine w/random cats, and an x based on louis' stuff... w/dual 3" pipes, and a borla free flow muff, L2 headers w/jethot it ran about $3400... headers were about $800 of it, so you can kinda derive the other costs if the cats are $500, etc... seemed about what richard paid for his custom setup w/msds headers, so I figured it was an ok deal...

not cheap, but not bad considering all the engineering/development/ideas (from whereever) that went into the overall design... otherwise, parts is parts and sometimes they just don't work together as well as something that's been tested and tweaked to death... (never thought I'd say that! - ha!)

hope this helps...

heinrich

Rob not bad, especially compared to my 350 dollar Ott X

blau928

Hi MS,

It is coming along, back on track this week. I finally got some time to go over to my machinist tomorrow afternoon for a bit of development work... I hope to make some decent progress in the coming month or two, as work is still a bit dicey, and that comes first. It will be done before summer though, even if I have to take a vacation to finish it..!

As far as expectations, I do not have high expectations, I will only have expectations after it gets running and tuned properly... We shall see.

Rob,

I have DEVEK Level II headers... Thinking about Level III after the SC is up and running... 1.625 vs 1.75 ID tubes I believe....

Yes, that's what about what it costs....

bcdavis

The air inlets lead back to the air pump/smog pump...

For people who have to pass smog tests, this connection
is part of the visual inspection. The added air also helps
to burn off any unburned fuel that gets past the exhaust
valve. It's kind of like blowing air on embers,
and watching it burn a little more. That's the
concept behind injecting fresh air into the exhaust...

Jim bailey - 928 International

Dave your results are very close to the 29.5 HP that Ron here saw on his 89 GT when he X piped it and lost the cat used high flow mufflers dual 2 1/2 ....... subsequently he then used MSDS headers into the X to get about 20 HP more hitting 318 HP 317 torque with increased fuel pressure. Nice improvements for the price.

Ketchmi

That's with the stock rear pipes and an RMB, our 2.5" cat back is still in development. We're hoping for another 10 hp out of it.

Garth S

As we're into performance numbers, what are the anticipated gains on a stock S4 auto with a CAT going to
1) a gutted cat 'H' pipe
2) a X-pipe
The rest of the exhaust consists of GT resonators and GT muffler.
Without mods like RR fuel regs, etc., is there measurable gain to support going to a x- pipe? It is clear that is the case with 2.5" pipes, headers, etc - but many cars are close to stock.

Ketchmi

I just happen to have a gutted H-pipe sitting around, I may have to check. I do not have a set of GT resonators or muffler sitting around and I'm not taking the ones off of our 89' GT just for testing so that may have to wait.

Other than the RRFPR, my setup is mainly stock with a good tune. (at the moment)

heinrich

I had a gutted H and it ran mpre strongly than other S4's, as measured by road drives locally. Yes well not empirical, but it's generally accepted that my S4 was an ***-kicker. So, I fitted Ott X and I got as high as 299 at the rear wheels. The H was better, the X was even better. See Louie Ott's site, I think he has done dyno runs on all of these configs.

Thaddeus

I got the very last authentic Ott X-pipe. Neener neener!

heinrich

Lucky bostage