Getting a better exhaust note from a twin turbo...

[StainlessBullet]

This isn't really on the top of my priorities at the moment, but I figured I'd ask for future reference anyway.

I have an Island twin turbo car and was wondering what options I have to improve the exhaust note. If you've ever heard a turbo car in person, you'll know the car is a lot quieter than even a stock D'. I'm not looking to make it obnoxious loud, raspy or ricerish. Just deeper and a little louder.

Recommendations? Any known aftermarket muffler options? The car still has the two tiny original mufflers that came with the Island kits.

[Brian_SS_TT]

Good question! I have the Island setup with twin cats that leak around the welds, looking to replace them with mufflers. Something with alittle deeper tone without the drone sound.

[Delorean Industries]

Get rid of the internal waste gates, reverse the turbos and orientate properly facing aft. Our turbo cars can be heard spooling at upwards of a half mile under partial load. The key is get it out the back as quickly as possible with no consideration for anything else. In short the turbo is the muffler. In conventional applications sound is controlled through the length of the car with a longer exhaust system. You can get the same results of course by restricting sound but keep in mind the island kits don't make much power to begin with. Adding much of anything to the system will take that away. At that point you might as well just have a stock engine with an exhaust.

[StainlessBullet]

Get rid of the internal waste gates, reverse the turbos and orientate properly facing aft. Our turbo cars can be heard spooling at upwards of a half mile under partial load. The key is get it out the back as quickly as possible with no consideration for anything else. In short the turbo is the muffler. In conventional applications sound is controlled through the length of the car with a longer exhaust system. You can get the same results of course by restricting sound but keep in mind the island kits don't make much power to begin with. Adding much of anything to the system will take that away. At that point you might as well just have a stock engine with an exhaust.

In that case, would cutting the mufflers off and running no mufflers at all make the car obnoxious loud? I know on a non-turbo car it would be loud, but since the turbos seem to muffle the exhaust down maybe it would give me the tone that I'm looking for?

Not to get off topic, but what do the Island kits normally put down? Ever have one on your dyno? To me the car seems a lot faster than any stock D' I've drove, but that's not saying much. :biggrin:

[Delorean Industries]

In that case, would cutting the mufflers off and running no mufflers at all make the car obnoxious loud? I know on a non-turbo car it would be loud, but since the turbos seem to muffle the exhaust down maybe it would give me the tone that I'm looking for?

Not to get off topic, but what do the Island kits normally put down? Ever have one on your dyno? To me the car seems a lot faster than any stock D' I've drove, but that's not saying much. :biggrin:

I have run a number of these cars across the dyno and have never seen favorable results. The fueling via K jet doesn't do anything other than soak the cylinders as much as possible. This doesn't make power and just keeps you in a safe zone.

I think you will be surprised by the quality of sound provided by the turbo's spooling.

[David T]

I have run a number of these cars across the dyno and have never seen favorable results. The fueling via K jet doesn't do anything other than soak the cylinders as much as possible. This doesn't make power and just keeps you in a safe zone.

I think you will be surprised by the quality of sound provided by the turbo's spooling.

The exhaust manifolds on the Island kit were not optimized, instead they basically the stock ones modified to mount the turbo on one end. The early kits just had a muffler on each side. The later kits did away with the muffler and had cats instead. Legally you need something but you will get more noise if you don't have mufflers or cats. Because the boost is limited and there is no intercooling, you can't get the full effect from the turbos with "just" the Island kit. It does pep the car up but once you have a little you always want more! Make sure both wastegates are set for 5# and move freely. You should have the switches and wiring set up to force the Lambda into full rich. The timing and advance must also be changed from stock.

[Delorean Industries]

By far one of the worst things to happen to the car in the last 30 years. No where near optimized even to the simple standards it was developed around. I have never seen on that doesn't push oil everywhere. Crank case isn't ventilated properly even for 5 psi. Throwing k jet full rich is anything but optimal. The distributor is modified with two set screws and I would argue that the mod was completed without pulling the dizzy down. Distributor is limited to 22degrees advance total.

[David T]

By far one of the worst things to happen to the car in the last 30 years. No where near optimized even to the simple standards it was developed around. I have never seen on that doesn't push oil everywhere. Crank case isn't ventilated properly even for 5 psi. Throwing k jet full rich is anything but optimal. The distributor is modified with two set screws and I would argue that the mod was completed without pulling the dizzy down. Distributor is limited to 22degrees advance total.

The DMA had, as a guest speaker, John Conway, the "tuner" who worked with the guy who created Island Turbo (his name escapes me at the moment). John explained how they developed the Island kit from the knowledge gained from Legend Turbos who the founder of IT had worked for. He explained how he basically locked the mechanical advance and left the vacuum working for some advance. He would remove the distributor (or have it shipped to him) and he has a test set-up in his garage to set and measure the advance. I had him do a distributor for me when I put an Island kit on 7138. The boost must be limited to 5 # for a couple of reasons:
The stock pistons are cast and the lands between the rings will break
The input shaft for the transmission will break
The crankcase ventilation system is pretty poor and can't handle all of the leakage and when you are running positive pressure the intake manifold can't maintain vacuum to prevent any backpressure from shooting oil. The kit was OK for what it was but it was never really the best solution but it was all there was "back in the day". The other way to go was the BAE kit. A little cheaper since it was only 1 turbo but because it was so big it has noticeable lag. There was a demand to increase the performance of the Delorean and some venders came up with some bolt-on solutions. Right now the Stage II is probably the best way to go since you can no longer get the Island Turbo kit or the BAE kit unless you can get the parts used.

[StainlessBullet]

Josh, what setup are you running in this video?


https://www.youtube.com/watch?v=PQo_7BOwFtA

This is the exhaust note that I'm looking for. Would it even be possible to get close to that sound with my setup?

I'm going to be flat out honest, I don't know jack about turbos. Other than my diesel pickup, this is the first turbo car I've ever owned. Everything seems foreign to me, so forgive any stupid questions here. :biggrin:

I pulled the manifold off to install a new gasket a couple of weeks ago. I kept everything attached to the manifold and pulled it off in one whole piece. I didn't want to break anything a part because I wasn't sure what gaskets / flanges would have to be replaced in the process. Are there any parts available for these things if I did start taking it apart? I know eventually I will have to rebuild one of the turbos, as it's starting to leak a little oil.

Here is what my setup looks like, (I know it's not pretty and needs some cleaning and paint etc.)
http://dmctalk.org/attachment.php?attachmentid=33027&d=1424050224


Get rid of the internal waste gates, reverse the turbos and orientate properly facing aft.

So, I'd be safe running just external waste gates? Any good tech notes / how-to on the subject?


Make sure both wastegates are set for 5# and move freely.

Ok, how do I know if they are set for 5psi or not?

Thanks for the help guys!

[PJ Grady Inc.]

Both kits are flawed and unreliable.

The BAE kit burns oil like crazy and even most rebiulders have a tough time fixing them. One owner figured out the cause after multiple teardowns and traced it to a machined groove in the turbo hsg overlapping into the seal area or something like that.

In the Island turbo kit various components tend to rust out after as little as a year or two.

Both kits run rich and dirty and suffer from a lack of proper engineering and development.
At least they are faster than stock but if you have one getting replacement parts is very difficult as both entities are long out of business.
Rob



The DMA had, as a guest speaker, John Conway, the "tuner" who worked with the guy who created Island Turbo (his name escapes me at the moment). John explained how they developed the Island kit from the knowledge gained from Legend Turbos who the founder of IT had worked for. He explained how he basically locked the mechanical advance and left the vacuum working for some advance. He would remove the distributor (or have it shipped to him) and he has a test set-up in his garage to set and measure the advance. I had him do a distributor for me when I put an Island kit on 7138. The boost must be limited to 5 # for a couple of reasons:
The stock pistons are cast and the lands between the rings will break
The input shaft for the transmission will break
The crankcase ventilation system is pretty poor and can't handle all of the leakage and when you are running positive pressure the intake manifold can't maintain vacuum to prevent any backpressure from shooting oil. The kit was OK for what it was but it was never really the best solution but it was all there was "back in the day". The other way to go was the BAE kit. A little cheaper since it was only 1 turbo but because it was so big it has noticeable lag. There was a demand to increase the performance of the Delorean and some venders came up with some bolt-on solutions. Right now the Stage II is probably the best way to go since you can no longer get the Island Turbo kit or the BAE kit unless you can get the parts used.

[David T]

Josh, what setup are you running in this video?


https://www.youtube.com/watch?v=PQo_7BOwFtA

This is the exhaust note that I'm looking for. Would it even be possible to get close to that sound with my setup?

I'm going to be flat out honest, I don't know jack about turbos. Other than my diesel pickup, this is the first turbo car I've ever owned. Everything seems foreign to me, so forgive any stupid questions here. :biggrin:

I pulled the manifold off to install a new gasket a couple of weeks ago. I kept everything attached to the manifold and pulled it off in one whole piece. I didn't want to break anything a part because I wasn't sure what gaskets / flanges would have to be replaced in the process. Are there any parts available for these things if I did start taking it apart? I know eventually I will have to rebuild one of the turbos, as it's starting to leak a little oil.

Here is what my setup looks like, (I know it's not pretty and needs some cleaning and paint etc.)
http://dmctalk.org/attachment.php?attachmentid=33027&d=1424050224



So, I'd be safe running just external waste gates? Any good tech notes / how-to on the subject?



Ok, how do I know if they are set for 5psi or not?

Thanks for the help guys!

You get a regulator set to 5 psi and apply the air pressure to each wastegate actuator. Adjust to where it opens the wastegate at 5 psi. Try to get both wastegates as close to each other as possible too. As to longevity, no one said this stuff will last forever. In fact, when you have a turbo you really should be using synthetic oil and changing it every year or 5,000 miles. By 50,000 miles figure the turbos have to be rebuilt (if they lasted that long!). The Island Turbos do run rich, much safer than running lean. Do NOT expect to pass emissions testing but that's not why you have them! You have a turbo to go FAST! As for engineering, it was the best they could do for a tiny company with no resources to do a lot of testing. They probably went with the "Looks Good To Me" kind of design engineering. They also had to make a kit that was affordable. Legend spent millions on designs and testing, one reason why they went broke when DMC went broke. How much do you think Island Turbo spent on design? If you have an IT kit take good care of it, as Rob says, parts are hard to come by. There are places you can still get the turbos rebuilt. And if you need any little bits they can generally be fabricated if necessary. The main thing is to make sure it is properly installed and set up and working as it should. Many kits were not. Not too many guys can even do this stuff anymore either.

[StainlessBullet]

You get a regulator set to 5 psi and apply the air pressure to each wastegate actuator. Adjust to where it opens the wastegate at 5 psi. Try to get both wastegates as close to each other as possible too.

We were hit with more ice / snow (what's up with the south lately?), so I don't have the car out in front of me at the moment. When it warms up I'll take a look and try to get a better grasp on all this.



As to longevity, no one said this stuff will last forever. In fact, when you have a turbo you really should be using synthetic oil and changing it every year or 5,000 miles.

I run full synthetic oil in most of everything I own. The PO of this car ran normal oil. Since everything is so old now, I've been afraid if I switched it over to full synthetic oil, I may cause oil consumption issues or it might start cleaning and clog all my oil channels. Should I take a chance?



Do NOT expect to pass emissions testing but that's not why you have them! You have a turbo to go FAST!

That is one benefit to living where I live, no emissions testing.

One more thing, what octane should I run in the car? I've read elsewhere since it's a turbo it needs premium fuel only. Is that true?

(I'm getting off subject now :rolleyes1:)

[David T]

We were hit with more ice / snow (what's up with the south lately?), so I don't have the car out in front of me at the moment. When it warms up I'll take a look and try to get a better grasp on all this.




I run full synthetic oil in most of everything I own. The PO of this car ran normal oil. Since everything is so old now, I've been afraid if I switched it over to full synthetic oil, I may cause oil consumption issues or it might start cleaning and clog all my oil channels. Should I take a chance?




That is one benefit to living where I live, no emissions testing.

One more thing, what octane should I run in the car? I've read elsewhere since it's a turbo it needs premium fuel only. Is that true?

(I'm getting off subject now :rolleyes1:)

You can try regular and if you get knocking or the plugs get burnt you can either try higher octane fuel or retard the timing. The safest thing is to just run the highest octane you can. Changing to syn depends on how many miles on the car, how dirty the engine is, how bad it leaks, how much oil it consumes, etc. If the oil is clean and you don't have a lot of miles on it and you aren't leaking or burning I would switch to synthetic. If you find syn is a bad choice you can switch back. On the news I saw how bad you have it lately with all of the snow. Not any better here in the NYC area. I am hoping the weather breaks, I have a St Pat's parade scheduled for Sunday. As for your set-up. Get it painted and wrapped with some high temp wrap. When handling the parts you should plug ALL of the openings so you don't get anything in that could cause damage. The oil line too. Use Never-Seize on all of the hot section hardware. Make sure you have NO leaks on all of the air hoses, replace any (and any clamps) that are questionable. Examine the air output side for any oil contamination. Feel the impeller for any looseness or play.

[Delorean3610]

33244 33245
My turbos seem to be in good condition for being 30 years old. Only 25k miles on them.

[Patrick C]

33244 33245
My turbos seem to be in good condition for being 30 years old. Only 25k miles on them.

Nice, but upgrade that POS Fram oil filter!

[Farrar]

For my (non-turbo) exhaust build, I did a lot of research on what would reduce drone or rasp while allowing as much flow as possible. I found a chart somewhere (can't remember where right now, sorry) showing that the Borla Pro XS were the best for sound-to-power ratio. These are a perforated-core straight-through muffler. I believe what I saw on the chart was 93% flow rate. However, even at 93%, as Josh said if you're running 5 PSI boost you would miss that 7%. If your mufflers are clamped on, you could experiment. If they're welded on, then ... well, never mind. :) But I look forward to seeing what your solution is. :)

[David T]

For my (non-turbo) exhaust build, I did a lot of research on what would reduce drone or rasp while allowing as much flow as possible. I found a chart somewhere (can't remember where right now, sorry) showing that the Borla Pro XS were the best for sound-to-power ratio. These are a perforated-core straight-through muffler. I believe what I saw on the chart was 93% flow rate. However, even at 93%, as Josh said if you're running 5 PSI boost you would miss that 7%. If your mufflers are clamped on, you could experiment. If they're welded on, then ... well, never mind. :) But I look forward to seeing what your solution is. :)

Because of the odd-fire arrangement the noise the motor makes is never going to be what most people are looking for and you can't change it much by changing the kind of muffler. Driving a loud, noisy car can become VERY tiring, especially if you drive it for any length of time. You can't talk to your passenger, you can't listen to the radio, and when you get out of the car you can't hear anything for a while. Make sure the rear window is firmly secured to the fiberglass all the way around especially on the bottom. If it comes loose it can get VERY noisy in the passenger compartment. The turbo, all by itself, reduces the noise a LOT. A 7% loss of efficiency in the exhaust system does not translate directly into a 7% loss of HP.

[StainlessBullet]

Took the car to an exhaust shop yesterday. I had them cut the mufflers off, then put a straight pipe in there place. I also had some new tips installed that fit better with the fascia cut-outs. Looks a lot better in my opinion.

But it now has the weirdest exhaust tone I've ever heard from a car. At idle it sounds sorta like a V8. The only thing I know to compare it to while under throttle is something like a stock Dodge Viper. Can't really say that I like it. I also can't say that I don't like it. I guess it will take a little time for me to figure out. :dunno: The guys at the exhaust shop loved the sound. They said it sounded very "exotic" (whatever that means). You can hear the turbos spool a little better, but still nothing like my truck.

On the plus side, the car does feel noticeably faster.

[David T]

Took the car to an exhaust shop yesterday. I had them cut the mufflers off, then put a straight pipe in there place. I also had some new tips installed that fit better with the fascia cut-outs. Looks a lot better in my opinion.

But it now has the weirdest exhaust tone I've ever heard from a car. At idle it sounds sorta like a V8. The only thing I know to compare it to while under throttle is something like a stock Dodge Viper. Can't really say that I like it. I also can't say that I don't like it. I guess it will take a little time for me to figure out. :dunno: The guys at the exhaust shop loved the sound. They said it sounded very "exotic" (whatever that means). You can hear the turbos spool a little better, but still nothing like my truck.

On the plus side, the car does feel noticeably faster.

It will get VERY tiring driving the car without either a muffler or a catalytic converter, the car will be LOUD! Never mind passing inspection, you might get pulled over because the car will be so noisy. Although the turbos muffle the exhaust a little it is nowhere near enough.

[StainlessBullet]

It will get VERY tiring driving the car without either a muffler or a catalytic converter, the car will be LOUD! Never mind passing inspection, you might get pulled over because the car will be so noisy. Although the turbos muffle the exhaust a little it is nowhere near enough.

Believe it or not the car is not that loud. Noticeably louder over stock? Yes. Obnoxious loud? No. All I can say is the turbos must really muffle the sound on this car.

I don't know if my car has dynamat or some other sound deadener installed, but the car is not too bad on the inside either. I can easily have a conversation and the car has no annoying drone.

I had a Mustang GT that I installed an off-road x-pipe and SLP resonators on. That was obnoxious loud. :hihi2: It had a very bad drone too. That was a tiring noise, the D' not so much. Just wish I could get a better tone out of it.

[Brian_SS_TT]

Can you post some pics?

How is the "drone" sound inside the car?

[StainlessBullet]

Can you post some pics?

How is the "drone" sound inside the car?

Yeah, I'll post some pics and a few videos. It'll be this weekend before I get a chance though.

If you're thinking about doing it to your car, I don't think I could recommend it. I'm leaning more towards not liking the exhaust note.
It's not really what I was I looking for, but it is different. I'm indecisive to say the least. :smashfreak: I guess I need to drive the car more to come to a conclusion.

I'll post a video and let you guys decide.

[StainlessBullet]

Yeah, I'll post some pics and a few videos. It'll be this weekend before I get a chance though.

Had to work so I didn't get a chance this past weekend to get a video. If it's not raining, I'll try to get a video this weekend.

[Brian_SS_TT]

Much appreciated! looking forward to it.

[StainlessBullet]

Much appreciated! looking forward to it.

Here ya go!


https://www.youtube.com/watch?v=m6fVFGafCls

NOTE: The car idles high (1100rpm) at the moment due to a sticky linkage, so the car will sound better once that is fixed.

[StainlessBullet]

AND another...


https://www.youtube.com/watch?v=4boyytnbpFU

Around 1:20 you can hear the turbo spool. I only revved to around 3500rpm in the video.

[Domi]

Nice sound :thumbup:

[Brian_SS_TT]

Sounds good,
It just a straight pipe no muffler of any kind correct?

thanks for posting.

[StainlessBullet]

Nice sound :thumbup:

Thanks! It's not the sound I was going for, but it does sound better than it did before. It also sounds MUCH better in person than what the videos sound like. It sounds a lot like my friend's Dodge Viper when he was running stock exhaust.


Sounds good,
It just a straight pipe no muffler of any kind correct?

thanks for posting.

That's correct. I'll take some pictures of the set up and post them when I can.

I've got a cabin noise video uploading at the moment. I'll post it once it finishes.

[StainlessBullet]

Exhaust from inside the cabin


https://www.youtube.com/watch?v=FOSqc-uBdtU