MarkRobinson

The stock location on my car brought back a wee bit of lost torque, plus the pulse was gone. I expect at or over 300rwhp/tq on the dyno next weekend (Porsche Dyno day).

I agree with your theory Marc, as my cross-over was about 6" farther back than stock, but turned out horrible on my car. Vibrations, z-28 sound, loss of torque, etc. sounds like a 928 again.

Hope things are well Marc, long time no talk

whall

Richard / Tom,
Yes, looking inside mine appears exactly like an "X" - can see daylight from one corner to the other. I should have mentioned this when I asked the question but never thought of it. I beleive that this is going to be a very loud set up. I will know very shortly, possibly this weekend if I can finish the bit of fab work left.

So I guess the question is still how effective is this likely to be compared to the X-pipe. Maybe this can't be answered because it hasn't been tested??

Chris Lockhart

Warren, do you happen to have the part number available for the Magnaflow muffler???? I'm looking at doing some more exhaust mods to my GT which would require a 2.5" pipe size, 2 in 2 out muffler. Basically putting the muffler just aft of my current X pipe, then installing 2 side exit "boom tubes" that they use in NASCAR, exiting just ahead of the rear wheels. Should sound obnoxiously wicked!!!!!! Thanks,

whall

Chris, I will get the number for you - box is on my garage floor at home. I will also let you know how loud my setup is - I am guessing just slightly less loud than straight pipes....

Chris Lockhart

Cool. Thanks Warren. That'll help me out alot!!!!!!!!!!!!

whall

Chris,
Magnaflow part number is 14386 - I paid $140 Canadian - about $110 US. Also FYI, I just picked up a set of very nice Magnaflow tips w. 2-1/2 to 3" outlets w. 45 degree cut-off.

Richard S

Chris, I have one of the Magnaflow mufflers with internal X. Dual 2.5" in/out, stainless, I think it's the same part number Warren listed. Still in original shrink-wrap packaging. I went with a different set-up, so I never even opened it. I paid $117, you can have it for $75....I can get pics if you like.

Rich.

Chris Lockhart

Warren, thanks alot for getting the p/n for me.

Richard, I'll PM you about the muffler. Thanks.

Joe F

Tom, please forgive this small hijack of this thread, but I had to ask about Mark's expectation of 300+rwhp. Can you/Will you tell what's done to your car to generate that much power? Is your '86 a US model, or a 4.7, 16V Euro. That's a pretty big number for an '86. Always looking for ways to make more HP. Let us know how you do. Thanks. And now back to the program about master welder and exhaust guru Tom. Who by the way, made a system for my '83 Euro S with MSDS headers. The system fit perfectly and all the bends were modeled after bent pieces of coat hangers. Yup, we're high tech hp here in the piney woods. Did I say it fit perfectly? And sounds fantastic.

MarkRobinson

Ah, something to do this saturday night> My last 86.5 car was tuned to 302rwhp/296rwtq with my exhaust design (sold to Tom Cloutier back in 1999, then he took it quite a few steps further it appears), AA chips, and fuel tuning on the dyno.

Universal problem found: '85-86 car's LH Jetronic has a huge hole in the fuel curve (lean) once an acceptable exhaust solution has been installed with the AA chips installed: between 3-4500 (ish), the engines run too lean to make an ideal air/fuel to maximize your torque: you can easily feel the power come on strong as the tires are spinning, then fall off like you added 4 more passengers, then come on hard again about 5,000 or so as the tires begin to spin again.

On the dyno (forgive me, it was over 5 years ago as I retrieve this from memory), air/fuel sniffers were uncommon for Dynojets in Austin, so we relied on a simple air/fuel ratio gauge to get us in the ball park, then lowered fuel pressure from stock to get maximum HP: but by doing this, we lost our torque. Over the course of dynoing my '86.5 car (FAST car before FAST kit), we observed the following on the Dynojet 248e:
-stock: 248rwhp
-AA chips: 268rwhp
-first exhaust: true dual with H but with a mix at the end ala stock: 278rwhp, but loss of torque
-2nd exhaust: true dual all the way but with H: 2.25" piping: 282rwhp/278tq
-3rd exhaust: same but with 2.5" piping & mandrel bends: 282/278
-fuel tuning: from 30psi stock: reduced to 29psi: 288/286
-fuel tuning: from 29 to 28psi: 296/290
-fuel tuning: from 28 to 27psi: 302/296
-fuel tuning: from 27 to 26psi: 299/290 (time to go backwards 1.5 turns for safety)

Now, that's with a $20 fuel pressure gauge, so I'm sure there's inaccuracies with the gauge, but still, we had to reduce fuel from AA's program to get our extra 20hp on the dyno.

The interesting thing: as we tuned, our torque-curve fuel dip got worse & worse, as we got leaner to maximize Hp. Our AF reading on our gauge was all the way off the gauge it was so lean

My black car (last year) had the same issues: 282rwhp/tq stock ('85 with polished heads & exhaust, no headers, misplaced H crossover. Huge dip in fuel curve.

My current Grey car is a very strong running car, probably as much if not more so than the red car, but the H is properly placed (semi-lucky on the red car), AA chps are in, fresh injectors, plug wires, plugs, resealed the intake, re-ran all the vacuum, & sounds incredible (much better than red car), so with tuning and using an AFC to bridge the fuel gap to get my torque back, I do expect to surpass 300rwhp/tq.

Odd though, with the supercharger kits, the mass-air is more than capable of allowing over 650hp through these motors with the changed air signals...dunno why it repeatedly on different cars cannot make this simple adjustment. WOT is WOT, it should work fine. My only thought is that there's a delay involved if the signal is not too grand (I think it is, but obviously not) so it does not react to violently under medium changes from the MAS (for emissions). Anyone else have thoughts??

Mark (good night, late in Austin....)

Garth S

[QUOTE=MarkRobinson
..... current Grey car is a very strong running car, probably as much if not more so than the red car, but the H is properly placed ....... I do expect to surpass 300rwhp/tq.
...dunno why it repeatedly on different cars cannot make this simple adjustment. WOT is WOT, it should work fine. My only thought is that there's a delay involved if the signal is not too grand (I think it is, but obviously not) so it does not react to violently under medium changes from the MAS (for emissions). Anyone else have thoughts??
[/QUOTE]

A very random hip shot - and we all know what they can be worth , but where is the O2 sensor located? - in the standard center of 'H'?
Were this the case, it may be remotely possible that a resonance node exists there at a specific rpm range ( with a customized exh. system) leading to a dead zone/ false reading. The LH would correct in the reverse sense and ..... The current 'X's have the sensor bung welded into a single run ahead of the blend zone, as you know.

Tom Cloutier

Seth,

My preference is for the customer to install their own cats unless they are the Random Tech cats with which I am familiar.

I don't know why work done at muffler shops does not fall into the "custom" category. Non-stock mufflers, pipes, cats certainly are not factory parts.

What are you doing in CA? See you next weekend.

Tom Cloutier

Tom Cloutier

Justin,

I don't believe anyone has done a dyno comparison of an X with stock exhausts, an X with 2.5" in stock layout, and a Y with single 3.5" pipe.

Any Bay Area guinea pigs for an extensive dyno day? I'd use my S4, but it has headers and it will take an act of Congress to get me to remove them!

Tom Cloutier

Tom Cloutier

Brendan,

I've had similar thoughts and have spent quite a bit of time staring at the bottom of my car too! Doing anything with these cars is usually pretty tough.

Tom Cloutier

Tom Cloutier

Andy,

Do you have a digital camera and access to a lift? I'm thinking that perhaps you could take some pics and measurements, we might be able to come up with a solution. What do you think?

Tom Cloutier