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replace stock muffler or?

5K views 30 replies 13 participants last post by  terrylewisac 
#1 ·
Hello all,
After a few good rev's today before a ride we came back to notice black marks on the concrete
my son and I found a hole in the muffler today on the bottom.
I was going to temp patch it and order a new one later
However my son wants to cut out the muffler and install a thrush glasspac
Has anyone done this if so how did it sound?
Or have you used something else as a replacement?
 
#2 · (Edited)
It will sound like crap with a Thrush glasspack.

I suggest getting a new regular muffler from OGTS. Keep it simple at this point in your build.

If you want to get fancy, then the ass-kickin' great sound way I went was to have a stainless Flowmaster muffler installed, a split Y pipe over the axle(I think Hondas use them), and then have the shop make 2 exhaust pipes to fit the Y. You then buy high quality tips to put on them. Have everything be stainless so that you pretty much don't have to replace anything for a long time.

Pipe Auto part Exhaust system
Gun Trigger Auto part Exhaust system Firearm
Auto part Fuel line Pipe Automotive fuel system Engine
Auto part Pipe Automotive exterior Exhaust system
Auto part Fuel line Automotive exhaust Automotive fuel system Pipe
Auto part Fuel line Engine Pipe Automotive engine part


I think the resonators are useless junk. They're not a muffler, they're just a hollow can made to try to add some balls to the sound of our engines. They fail miserably at it. The modern way to go is to shape the sound of your exhaust with your exhaust tips. Stainless steel also adds a nice low note.
 
#8 ·
It will sound like crap with a Thrush glasspack.

I suggest getting a new regular muffler from OGTS. Keep it simple at this point in your build.

If you want to get fancy, then the ass-kickin' great sound way I went was to have a stainless Flowmaster muffler installed, a split Y pipe over the axle(I think Hondas use them), and then have the shop make 2 exhaust pipes to fit the Y. You then buy high quality tips to put on them. Have everything be stainless so that you pretty much don't have to replace anything for a long time.

View attachment 391571 View attachment 391573 View attachment 391575 View attachment 391577 View attachment 391579 View attachment 391581

I think the resonators are useless junk. They're not a muffler, they're just a hollow can made to try to add some balls to the sound of our engines. They fail miserably at it. The modern way to go is to shape the sound of your exhaust with your exhaust tips. Stainless steel also adds a nice low note.

Always a fan of the K.I.S.S. procedures.
Keeps me in line and out if trouble
Thank you Gordo
 
#6 ·
Interesting guys Thank you,
I put a glass pac on my v6 dakota and adjusted the carb to sound more like a v8.
Seemed to work well in that application
But a 4 cyl stock 1.9 opel :ugh:
First thing I told my son was no obnoxious rice burners in my garage :no:
If were to do something that's not stock it will need to be appropriate and ad to the harmonics
Not just make it loud and ridicules
If there's one thing I can't stand it's something loud and sounds like there may be something under the hood just to see it pull away so slow it can't get out of it's own way
 
#9 ·
Looking at my pictures I see that I don't have a Honda or whatever style of split Y over the axle. I have the disconnect or coupling over the axle, but then just a single pipe bent to go to the driver's side exhaust arch and then another pipe grafted in on the bend of the first pipe to go to the passenger side exhaust arch. I don't know, I just tell the muffler shop what to do and they do it. You definitely don't want the first pipe to go to the passenger side in a straight line from the axle area and then try to splice in the second one to go towards the left side........all the flow will go to the passenger side. Don't do the resonator delete mod that way, do it the way you see in my pics.
 
#11 ·
Looks to me like they did a pretty sweet job Gordo,
They are keepers for sure nice work

Thank you Okieopel if I were 20, 25 years younger glass pack for sure but my chick no diggy
I can't even watch a good movie with the surround sound up with out it getting turned back down
And the stereo in the Dakota, forget about it she wont even turn it on.
7500 watts is way to much for her listening pleasure :haha:
 
#13 ·
Thank you Okieopel if I were 20, 25 years younger glass pack for sure but my chick no diggy
I can't even watch a good movie with the surround sound up with out it getting turned back down
And the stereo in the Dakota, forget about it she wont even turn it on.
7500 watts is way to much for her listening pleasure :haha:
Got "Sennheiser RS120 On-Ear Wireless RF Headphones" for my Dad so he can watch TV.
https://www.amazon.com/Sennheiser-RS120-Wireless-Headphones-Charging/dp/B0001FTVEK/
 
#12 ·
Nice set up Gordo, I like it :yup: One of the first things I changed when I bought my Opel GT was replace the original muffler and exhaust pipes. Terry I went with the stock from OGTS and yes I kept the resonator. I would agree with you Gordo its useless, but doesn't sound bad. Next time I replace and probably not waiting for it to rust out, is to go with stainless and no resonator, but still keep it stock from OGTS.
 
#15 · (Edited)
Thanks to Mike aka opellane, I acquired an almost NOS stock'ish exhaust system for my Opel GT restoration last year. I installed it this past week, with a few improvements.

My engine is fairly stock, with stock forged rods, 40 thou over forged flat top pistons, stock valves, an OGTS Combo 0.420 Hyd cam and modified cam gear w/ the Comp Cams offset bushing (set at 4 degrees advanced). I'm running a 38 DGAS on a quite modified stock intake (tented floor, welded and radiused ports and matched openings). Exhaust manifold is a Sprint, so less issues of heat transfer to the intake. I also wrapped the Spring and down-comer to reduce engine compartment temps. That might reduce the life of the down-comer, but I can accept that. The flywheel is lightened (19.4 lbs down from 23.4 lbs) with a stock clutch, and the entire rotating assembly was dynamically balanced to a tenth of a gram. I expect ~100 Hp and perhaps 110 ft-lb at the wheels. I have a Getrag 5-speed to keep the rpm at a decent limit on the highway.

The stock 1 5/8" pipe is quite restrictive, perhaps more so than the Walker muffler and Bosal resonator that came from Mike. And especially as it leaves the two-to-one down-comer collector, with multiple bends that crush the pipe a LOT. I also wanted to incorporate a wide-band AFR system to assist in carb tuning. My goal was "drive-ability", not peak performance. While I enjoy a throaty exhaust sound, the novelty wears off after a couple of hours on the highway. Driving fun places in Canada usually entails big distances and LOTS of hours....

A Calgary friend, Sterling Rempel, has an Opel GT with a similar drive-train. He bought it with an OGTS header feeding a 2" pipe, no muffler and a very nice 4-outlet ANSA resonator. It sounded great, but talking while driving was problematic. His solution, that I assisted with, was to cut in a 6" long flex joint just behind the header and stock muffler, but leave the rest as-is. It still sounds great, has loads of power, but doesn't make you want to wear noise-cancelling headphones on the highway

So unless/until I upgrade to a stroker 2.4 (and MegaSquirt etc etc). I elected a similar route, except my resonator is stock, and had all the 1 5/8" pipe replaced with 2" bent at a local shop. Cost $58. Canadian, so like 10 bucks.... Fired up the MIG welder, added a couple of meaty flanges to assist installation, and replaced the weak exhaust hangers with decent ones to keep the system close to the body.

I am a month or two from first firing of the engine, but I am confident that this exhaust system will work, and sound, terrific.

Here's some photos:
 

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#17 ·
Hmmmm.....a flex pipe section to act as a sound deadener.......interesting idea!
:yup:
Not so much a "sound deadener", but I believe that the flex pipe reduces the physical engine vibrations and such otherwise imparted to the exhaust system and then to the body. Less "NVH" (Noise-Vibration-Harmonic)
 
#21 ·
Can look it up here. OPGTS is out of stock right now at $899.00:
https://opelgtsource.com/search/3284/details
https://splendidparts.de/kaufhaus_2/index.php

Gee, OPGTS located approx. 500 miles from San Diego.
Would have to arrange an appointment with them to pickup if shipping is too high.
Maybe schedule a camping trip up North in warmer weather?

Think that Opels Unlimited might have them, also.
Perris, CA is only 80 miles away with an easy Saturday drive.
 
#24 ·
Start at Page 3:
https://www.opelgt.com/forums/general-discussions/33289-splendid-parts.html
In 2014, ordered 3-row radiator. Shipping at that time was $90.00 to San Diego, CA.
Used PayPal with my Checking / No Charge Cards Accepted.

My Splendid parts ordered arrived Wednesday (2014) in San Diego.
Excellent packaging with no crushed box and no damage to any parts.
I had a question on the order and emailed Splendid/ Udo.
Udo responded within two days to answer my question.

(2014) Order required one week to process (after their vacation shutdown),
and less than four weeks to arrive in California.
 
#26 ·
It and splendid parts are about the same in price. Stainless Steel is a good selling point too. I've got 285,000 miles on My Saab SPG and never had a problem with the exhaust. It too was/is stainless. Just ran out of other parts for it. Darn shame, that little 4cyl would run, esp with the turbo on it. Now she's parked.:sigh::ugh: Jarrell
 
#28 · (Edited)
I just got my new stock muffler in Thank you Bob
woo hoo still doing it original.
I think I'm gonna add the flex pipe and the clamp at the rear
sure will make much easier for me to attach instead of welding it
I really liked that idea you guys did
 
#29 ·
exhaust back pressure Myth or is there some truth here

Good Morning all,
I 'm allowing my son to play with the exhaust while were working the rear end.
He saw Kyler's video with the straight pipe set up as well as some of the posts here where exhausts were modified and begged me to let him play with it.
So for now let the young man play Right? why not we have plenty of time and he is a part of the fun :yup:
I was talking with a neighbor whom is wiser than I about engines & yada yada.
I mentioned what my son is wanting to do and he went into this long rant/conversation about exhaust back pressure?
I couldn't make heads or tales to what the heck he was going on about but I politely let him go on
So I made a phone call after words to a friend whom's an engineer for Mitsubishi to get his thoughts
He chuckled and said there is no relevance to or for any back pressure specially in your case on the exhaust side and simply said let breathe and exhale with the least of resistance
And the idea of needing back pressure to the exhaust side was a hoax.
Is there some relevance or reason that one might think that there is or isn't a need for back pressure?
Again I'm not the smartest by no means about this stuff but I couldn't wrap my head around the idea of any of this
Thank you in advance for your thoughts
 
#30 ·
Good Morning all,
I 'm allowing my son to play with the exhaust while were working the rear end.
He saw Kyler's video with the straight pipe set up as well as some of the posts here where exhausts were modified and begged me to let him play with it.
So for now let the young man play Right? why not we have plenty of time and he is a part of the fun <img src="http://www.opelgt.com/forums/images/smilies/yup.gif" border="0" alt="" title="Yup" class="inlineimg" />
I was talking with a neighbor whom is wiser than I about engines & yada yada.
I mentioned what my son is wanting to do and he went into this long rant/conversation about exhaust back pressure?
I couldn't make heads or tales to what the heck he was going on about but I politely let him go on
So I made a phone call after words to a friend whom's an engineer for Mitsubishi to get his thoughts
He chuckled and said there is no relevance to or for any back pressure specially in your case on the exhaust side and simply said let breathe and exhale with the least of resistance
And the idea of needing back pressure to the exhaust side was a hoax.
Is there some relevance or reason that one might think that there is or isn't a need for back pressure?
Again I'm not the smartest by no means about this stuff but I couldn't wrap my head around the idea of any of this
Thank you in advance for your thoughts
You want zero backpressure, regardless of the engine’s state of tune.

However, what is often lost in this translation is the fact that you don’t want to lose exhaust gas velocity.

A 100 hp engine of a given displacement/design has lower exhaust velocity (and volume) compared to say, a 200 hp engine of the same displacement and design. So they will have different needs in terms of exhaust design and diameters.

You need to balance the ’no backpressure’ versus ’maintaining velocity’ aspects.

So while a 2.5” exhaust (for example) might be ideal for 200 hp, the flow advantages would not come into play until very high rpm’s on a 100 hp engine. This lack of velocity at lower rpm’s on the 100 hp engine would hurt performance during 95% of real-world driving.

A good rule of thumb I’ve observed on most street driven CIH engines is to keep the exhaust at 2” unless you are making over 135-140 hp. Even a stock engine seems to run well with this diameter.
 
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