newbenz2

Is there anyone who has a c32 here with all the cats deleted? Some of us live in states with no emissions and can get away with this. What is needed to do this? I have seen with other cars people take sparkplug non-faulers and drill them out so the filliment of the O2 sensor can fit threw it. They screw that in the secondary O2 bung and then the O2 sensor into that. I guess this gets the secondary O2 out of the exhaust stream enough so it dosnt throw a code. Anybody try this? Any ideas?
Kevin

Gramma_Benz

I dunno, but I'm in LOVE with your Cosworth...

newbenz2

Thanks I got a 86 and a 87.. 86 is under the knife.. turbo.. shooting for around 600hp.

newbenz2

bump?

newbenz2

bump again anyone?

Lenin

Are you looking for something like this?
It's for an SRT6. I'm in the process of building a new exhaust out of these bits and a few other parts.

loudandheard

I think someone has done it before, but if I remember correctly the car loss power and it was too loud. I've read that if the tubing for the exhaust is the same size from the headers to the end there shouldn't be any loss, but hopefully gain. Toque could suffer, but I know nothing about designing a good exhaust system. I think a majority that has done their exhaust delete secondary cats, but leave primaries in place.

You can buy the o2 bungs for your o2 sensors at needswings, they're fairly cheap. I would definitely like to see what you come up with.

ohlord

secondaries. Leave the primaries you only gain a few hp deleting them anyway
Avoid the expense of trying to fool the ecu.
You need a bit of bp to provide proper scavenging.
H-pipe


as a side note what trans is going to stand up to 600 hp on the 190?
Have a good friend that just did a 36AMG and 5 speed conversion to his 87 and he can barely keep it glued to the ground

newbenz2

Here is my dilemma, My primary took a ****, So I have to either buy new cats or delete them with the long tubes I'm building. As for the bungs I can make my own with scrap stainless laying around the shop. Also i'm going to do a x-pipe...

newbenz2

I think the stocker will hold fine because there wont be any load on it.... due to uncontrollable wheels spin... ha

ohlord

primaries and splice them in or high flow stainless primaries and splice.
H=pipe will give better balance and torque on the M112.

The stock 16v trans will puke its guts out on 600hp wheel spin and all

newbenz2

my buddie Jacob Rogers turbo 16v holds just fine (around 600hp)... Blows rear diffs though..

reflex92

I'm gonna get the res deleted but not the cats..

Lenin

Obviously Rob from Needswings figured out how to fool the ECU with minimal expense with the little j-pipes.
The x-pipe will give you more (hp) higher up in the rpm range. It should have a little bit higher pitched exhaust tone than the h-pipe.
An h-pipe will give you more power (mainly torque) low in the rpm range. It will also have a deeper exhaust tone.
Most of the configurations from well known exhaust builders like Supersprint use the x-pipe but that is an old debate and will not be resolved in this thread. All that is theory until tested on the dyno on a specific car.
I'm going with an 2.5" X-pipe. With my 60' time being 1.8 seconds already, I need more top end to get past 112 MPH at the end of the 1/4 mile run. I should be done within a month, so we will see what the end result is.

doom239

This is what I am doing at the moment.

I ordered 2 of these http://cgi.ebay.com/ebaymotors/ws/eB...T#ht_908wt_927
Installing them as my Primary's

I am also going to Delete my secondary's
I am in California so smog is a problem but if I could I would just do a complete Stainless Setup Straight back.
It should still pass smog no problem.

It all depends on your mods I would only go this route if your doing a pulley swap in the future, I have the 185mm kit and Shortys on my car so the cats are the last thing to go.

ohlord

Change your gearing or tire diameter.
Going through the traps at more than 112 is not going to be done on top end HP at least not when you won't even be in that power band with stock gearing.
V6 H-pipe debates aside it is the physics of gas flow and the design of the engine and firing order that make it the best option.
I don't think the OP wants to be driving around in a constant Rich a/f ratio so that Rob of needwings can be validated for fooling the ecu with a j pipe
But hey I could be wrong
I predict with straight pipes X over and j pipe o2 delete and no BP you move further away from your goal. But keep us posted.

ohlord

Don't you have enhanced smog test in SD?
You surely won't pass visuals.
You won't like it if they label you a gross polluter.

doom239

Haha Yea I have a buddy here who lets me off the visuals part. As far as passing the test easy... our cars are pretty good at keeping it clean.

Lenin

Changing the gearing is not in the plans. Too much involved. Tire diameter is a maybe. I ran 18" last time. My target is to get to 115 MPH.
Leaving the needswings j-pipes aside, as long as the AFRs are constant, a proper tune will bring the AFRs into the appropriate range (I hope).
Care to share some of the physics you are referring to? Like any calculations related to the h-pipe vs. x-pipe, pipe size, back pressure and the scavenging effect?
After I'm done, I'm hoping my back pressure will not drop by more than 0.5psi. What is your opinion on the use of the cutouts for the track?
It may sound like I'm challenging you but I'm really just looking to learn. If you have some specific knowledge on building and tuning exhausts for the M112K, then share it vs. just making general "mom and apple pie" statements.

ohlord

from the m112 just needs to be moderated for sound purposes (H-pipe rids some of the motor boat sound.
Exhaust scavenging and speed of flow provided by a x over is overkill and robs power on the m112
Cut outs sound great but also kill torque on the small displacement M112
Tire diameter mentioned is not in rim size but in profile. You will need to match front and rear rolling circumference but a taller tire will drop effective rear gear ratio and smaller with raise final gearing.You need to record what rpm and accurate mph you are reacing at the top end of the track and adjust the final gear ratio to maxamise the rpm needed to best attain your goal.
A 17in tire with the right profile will hook you up better and allow you to gain that trap speed.
I hope that was beyond apple pieish

Lenin

I guess I will see if the x-pipe will be an overkill and will have a negative effect on the exhaust scavenging. I'm prepared to experiment. I happen to have an 2.5" Supersprint x-pipe from an SLK55 so, I'm not spending too much $$ on this. My main theory hangs on the fact that Rob from Needswings gained 0.2 seconds ET on a 1/4 mile run with his SRT6 (M112K based) with the cutouts. This tells me that at least at higher RPMs the negative effect on the exhaust scavenging is greatly diminished (as the pulsed flow becomes more and more like constant flow).
I agree with the your tire points. My comment regarding the 18" rims was related to the limited choice of the tire sizes I was left with. Even still, I managed to brake one of my axles. So, traction is not a problem. But rims, tires and tire pressure is something I will continue to play with. I record a lot of data with my setup and wouldn't start a performance related project without it. It also makes it more fun.
And thanks for your comments.