Tanabe Catback Fitment Issue

[Old Radar]

A couple of weeks ago I installed a 3” Tanabe Medallion Touring catback on the otherwise stock exhaust of my ’89 7M-GTE. It’s a straight-forward bolt-on installation, so I’m pretty sure I didn’t screw it up, but I’ve got a problem with the fitment.

The big 90-degree bend between the resonator and the muffler is pressed hard up against the pivot housing for the #2 Lower Suspension Arm. To get around this obstruction the pipe is pushed down, out of its channel, causing the entire catback assembly to be rotated slightly clockwise when viewed from the rear. This causes the outboard doughnut hanger at the rear of the muffler to be stretched tight while the inboard hanger hangs slack. It also causes me to lose about ¾” of ground clearance which I cannot endure.

I thought a possible fix would be to install a high flow catalytic converter that was ½” to 1” longer than the original cat. This should push the 90 degree bend backward enough to clear the obstruction, but now I’m wondering if the resonator would have enough room to move that far.





The questions I have are:
1. Has anyone experienced this issue with a Tanabe catback and what did you do about it?

2. I’m pretty certain I want a high-flow cat that is bolt on—not welded, since I may yet replace the downpipe, but haven’t found a bolt on that is longer than the original. Any suggestions?

3. Any point in contacting Tanabe for help?

 

[Piratetip]

Hard to tell from the photo but is there enough room for the resonator to move back about 1"?
Is it going to run into the diff or the subframe?
It looks like if that 90° Bend was pushed back about an inch it would clear the arm mount / subframe mount.
Then you could align everything better and push the pipe up into the stock location.

Your idea to use a slightly longer cat to push everything back is probably the easiest option.
If there is enough room to do this.

If I remember right the stock cat is ~11 or 12 inches long.

Best bet is to buy a magnaflow universal style 3" (They are about 13" long) then cut it to the exact length you need and weld the new flanges on it.
If you are pushing the catback "back" ~ 1 inch then the longer converter should still work with an aftermarket downpipe.

If you do some digging you might be able to find a "direct fit" 13" magnaflow cat that will just bolt up.
Trick is to find what vehicle uses that length OEM.

I am welding up my own custom 3" stainless exhaust, and also welded my own flanges to the 3" magnaflow cat.
Its really not that hard.

 

[Old Radar]

Pirate--

The stock cat is 11 1/4" long from outside flange to outside flange. I figure a 12" cat would do it, but I haven't gotten back under the car to see if the resonator has enough room for that kind of shift. As for the universal cats, I want to stay with a direct fit cat because I may decide to replace my downpipe and would rather unbolt than have to cut and re-weld.

 

[Piratetip]

I figure a 12" cat would do it, but I haven't gotten back under the car to see if the resonator has enough room for that kind of shift.

I would start with the measurements to see if that idea would even work or not.

Another simple option is to cut the pipe in half between the resonator and hanger.
Right at the point where the nose of the differential bolts up.
Have a good welder add in a 1" piece there to shift everything back.
Plus it will also allow you to clock or rotate the whole assembly to the exact position you want it.

The sad part about that is you would be modifying a brand new part.

 

[suprarx7nut]

Old Radar: I just installed the exact same exhaust and had the exact same problem. I thought it was from my BIC downpipe being a little off, but now I think it's just the Tanabe exhaust. It must have been patterned just a little off or perhaps off an NA.

I purchased a non-turbo 3" high flow cat from Raptor Racing which is 1" longer than the OEM turbo cat. It moved the Tanabe back 1" and solved the issue perfectly. The Tanabe sits where it should and isn't clocked (at least not that I noticed). It was a 100% bolt in solution and couldn't have worked any better.

I keep my stock system for emissions testing so now I've got two complete systems.

George is also awesome so I try to promote his business where ever possible. Stand up guy and a pleasure to do business with. Buy from Raptor Racing if you can!

 

[Piratetip]

If you are pushing the catback "back" ~ 1 inch then the longer converter should still work with an aftermarket downpipe.

I purchased a non-turbo 3" high flow cat from Raptor Racing which is 1" longer than the OEM turbo cat. It moved the Tanabe back 1" and solved the issue perfectly. The Tanabe sits where it should and isn't clocked (at least not that I noticed). It was a 100% bolt in solution and couldn't have worked any better.

lol
Confirmation!

 

[Old Radar]

I purchased a non-turbo 3" high flow cat from Raptor Racing which is 1" longer than the OEM turbo cat. It moved the Tanabe back 1" and solved the issue perfectly. The Tanabe sits where it should and isn't clocked (at least not that I noticed). It was a 100% bolt in solution and couldn't have worked any better.

I love it when a theory is borne out by practical application! :drink1:

One question though. Raptor is showing 2.5" ceramic high flow cats and an unspecified diameter metallic spiral core cat. Is the metallic the one you used? If so, do you notice any unburned fuel fumes after a cold start? I understand metallic substrate cats are prone to that.

Thanks for sharing!

 

[suprarx7nut]

I love it when a theory is borne out by practical application! :drink1:

One question though. Raptor is showing 2.5" ceramic high flow cats and an unspecified diameter metallic spiral core cat. Is the metallic the one you used? If so, do you notice any unburned fuel fumes after a cold start? I understand metallic substrate cats are prone to that.

Thanks for sharing!

If you go into the metallic spiral option, you'll see diameter choices on the product page.

I've used the spiral metallic core on two cars so far. I'd go that route if emissions isn't your top concern. If you want as little emission, hassle as possible and don't mind some power loss, go ceramic.

With my 90 I had the metallic spiral core and passed emissions for a few years then failed and had to replace the cat with a ceramic universal Magnaflow. The ceramic cat was a noticeable restriction, even though it was the largest single cat the shop had on hand (3" I believe). The difference in emissions was gigantic on the annual air test conducted by the state. I could also feel and hear a difference. I had to completely change the settings in my boost controller to achieve the same ~12 psi and the turbo needed to run audibly faster to get there. I've never experienced such a detrimental performance component aside from removing a boost controller. I would not have believed the difference in power was that large had I not experienced it.

With the metallic cats, you can smell a little more "character" in your exhaust gases - even when they're working well enough to pass Colorado emissions.

Hopefully that helps.

 

[Piratetip]

You could probably ask them to do a mangaflow 3" ceramic core instead of the 2.5".

Work on their end would be the same, they would just need to order the larger universal cat, cut to the same length and weld on a larger flange.

Heck I could weld up one for you!
I did the exact same thing for my setup.

With my 90 I had the metallic spiral core and passed emissions for a few years then failed and had to replace the cat with a ceramic universal Magnaflow. The ceramic cat was a noticeable restriction, even though it was the largest single cat the shop had on hand (3" I believe). The difference in emissions was gigantic on the annual air test conducted by the state. I could also feel and hear a difference. I had to completely change the settings in my boost controller to achieve the same ~12 psi and the turbo needed to run audibly faster to get there. I've never experienced such a detrimental performance component aside from removing a boost controller. I would not have believed the difference in power was that large had I not experienced it.

Interesting note here on flow rates, I wouldn't expect a 3" ceramic to be a restriction. What power level are you at?
I am curious how my 3" ceramic flows....
Might buy a metallic core to swap in as a comparison & install a pressure sensor pre cat & log via MS3Pro to get some real data...

 

[suprarx7nut]

Interesting note here on flow rates, I wouldn't expect a 3" ceramic to be a restriction. What power level are you at?
I am curious how my 3" ceramic flows....
Might buy a metallic core to swap in as a comparison & install a pressure sensor pre cat & log via MS3Pro to get some real data...

That was with a 50 trim CT26 and no fuel mods. I expect the power level was around 300-325 whp, but never dyno'd it. After the install without changing settings on the Greddy Profec B Spec I went from a peak boost of 12-13 down to about 9-10 if memory serves. The turbo was working a lot harder to get back to 12-13 after the new ceramic cat went on.

I just looked up my records. It was a Magnaflow 51209. I'm not sure if that's a "Hi Flow" or "Regular".

I'd be really interested to see pressure data.

 

[Old Radar]

If you go into the metallic spiral option, you'll see diameter choices on the product page.

Thanks for directing me to my obvious oversight!

Speaking of Hi Flow vs Regular cats, I ran across this interesting tidbit the other day in my research. http://www.catalyticconverter.org/news/news_page.cfm?Key=catalytic_converter-&News=89 CatalyticConverter.org is “an industry sponsored site organized to provide automotive consumer education.” In this little article from 2012 they state emphatically that ”THERE IS NO SUCH THING AS A HIGH FLOW OR PERFORMANCE CATALYTIC CONVERTER!!”

They continue with:
“In theory, an aftermarket cat is higher flow than its O.E. counterpart, because the O.E. converter has a substrate made up of 700 cells per square inch, so the exhaust flow with an aftermarket converter (with around 400 cells/sq inch) is a little freer, but not dramatically!

They conclude with:
“There is no Magic "Super Free Flow" Catalytic Converter out there and any company that tries to sell you one is not quite telling you the truth. The sad thing is, there are some web sites claiming they have High Flow Performance Cats, and by the way at a huge inflated price, when in fact all you will be buying is the same converter you would buy anywhere else for half the price.”

They then invite you to give them a call if you’re still confused.

The part that confuses me is the link to ConverterWarehouse.com and DiscountConverter.com that each sell “High Flow” cats for $153 to $213!
They don’t appear to have any more news articles after 2013 and sadly, their “contact us” links don’t work or I would have—but the links to converter sales sites still do!

I'm thinking that the "industry sponsored site" is really a .org front for a greasy commercial .com enterprise.

I just bring it up in hopes that the knowledgeable (and more trustworthy) members of SM could shed some light on the issue--especially since I couldn't tell a quality metallic spiral core cat from a quality flux capacitor.

 

[suprarx7nut]

Thanks for directing me to my obvious oversight!

Speaking of Hi Flow vs Regular cats, I ran across this interesting tidbit the other day in my research. http://www.catalyticconverter.org/news/news_page.cfm?Key=catalytic_converter-&News=89 CatalyticConverter.org is “an industry sponsored site organized to provide automotive consumer education.” In this little article from 2012 they state emphatically that ”THERE IS NO SUCH THING AS A HIGH FLOW OR PERFORMANCE CATALYTIC CONVERTER!!”

They continue with:
“In theory, an aftermarket cat is higher flow than its O.E. counterpart, because the O.E. converter has a substrate made up of 700 cells per square inch, so the exhaust flow with an aftermarket converter (with around 400 cells/sq inch) is a little freer, but not dramatically!

They conclude with:
“There is no Magic "Super Free Flow" Catalytic Converter out there and any company that tries to sell you one is not quite telling you the truth. The sad thing is, there are some web sites claiming they have High Flow Performance Cats, and by the way at a huge inflated price, when in fact all you will be buying is the same converter you would buy anywhere else for half the price.”

They then invite you to give them a call if you’re still confused.

The part that confuses me is the link to ConverterWarehouse.com and DiscountConverter.com that each sell “High Flow” cats for $153 to $213!
They don’t appear to have any more news articles after 2013 and sadly, their “contact us” links don’t work or I would have—but the links to converter sales sites still do!

I'm thinking that the "industry sponsored site" is really a .org front for a greasy commercial .com enterprise.

I just bring it up in hopes that the knowledgeable (and more trustworthy) members of SM could shed some light on the issue--especially since I couldn't tell a quality metallic spiral core cat from a quality flux capacitor.

Yeah, I'm not sure what the hell they're talking about. There are absolutely more and less restrictive cats. Now, I think what they MAY be trying to get at is that the high-flow cats simply have less substrate. In that train of logic, the high flow cats aren't any more efficient than the standard ones. The "high flow" are very directly "high polluting". Perhaps that's the aim they were taking.

I wish I would have dyno'd my last car. It was an obvious bolt on difference. My boost controller settings alone seem to be an objective piece of evidence.

 

[JDMMA70]

Just checked mine, although it is the older Super Hyper Medallion it fits fine. You sure it isnt your hangers pulling to much to one side?

 

[Piratetip]

Yeah, I'm not sure what the hell they're talking about. There are absolutely more and less restrictive cats. Now, I think what they MAY be trying to get at is that the high-flow cats simply have less substrate. In that train of logic, the high flow cats aren't any more efficient than the standard ones. The "high flow" are very directly "high polluting". Perhaps that's the aim they were taking.

I wish I would have dyno'd my last car. It was an obvious bolt on difference. My boost controller settings alone seem to be an objective piece of evidence.

Some documentation on catalyst substrates.
https://www.dieselnet.com/tech/cat_substrate.php
https://www.dieselnet.com/tech/cat_subs_met.php
http://www.hypercat-acp.com/catalytic-converters.html

The metal wound have less substrate and larger orifices, sacrificing emissions as you pointed out suprarx7nut.
Similar to how K&N filters work (always fun to take a stab at K&N).

A "higher" flow would also be the result of installing an over-sized converter for our 3L engine.
There are plenty of OEM large displacement engines out there you could steal a part from.
Sacrificing a bit of weight you could maintain emission levels if that is needed to pass the state requirements.

 

[Old Radar]

Just checked mine, although it is the older Super Hyper Medallion it fits fine. You sure it isnt your hangers pulling to much to one side?

I'm pretty sure. Had to stretch the outside doughnut hangers to get them attached. I think it may be poor placement of the hangers welded to the catback. I'm having a second pair of eyes look at it tomorrow to see if some strategic hanger bending will help. If not, I'll order the Raptor Racing converter.

 

[Old Radar]

So I ordered the 12.5" Metallic Spiral Core Cat from Raptor Racing--as recommended by suprarx7nut. It arrived yesterday and I installed it today after cutting off the bolts holding the original cat to the original downpipe.



Instant improvement!!


Below, before the new cat. Notice the big asymmetric gap in the channel and the down angle of the pipe.




After the new cat VVV

The cat’s extra inch pushes the 90 degree bend back to clear the #2 Lower Suspension Arm which allows the catback to retract back up into the channel where it belongs, giving back that extra ¾” ground clearance. I can go thru my normal gate on the way to work again as I clear the speed table by a full ¼”!!





Bonus: All the hangers are now at a relatively equal tension.

 

[Piratetip]

Good work.

 

[suprarx7nut]

Woot! Glad it worked. Thanks for following up with the result!

 

[figgie]

Intersting!

Back in the day i ran a Tanabe exhaust with a Random Tech hi-flow cat. The fitment was spot on...

i wonder if it was because of the Random Tech cat???