Turbo exhaust brake on gasoline motor?
 

I'm actually thinking of doing this, not just wondering for the sake of wondering.

Diesel motors use either a jake brake or an exhaust brake to basically turn the motor into an air compressor when engine braking. Gasoline motors use a throttle plate to block air when the accelerator is let off, causing the motor to expend energy in the opposite way.

I'm wondering if adding an exhaust brake to a turbo on a gasoline motor would help with engine braking, or if it wouldn't make a difference since the throttle plate is already restricting air under engine braking conditions.

Another thought is that the exhaust brake might help spool the turbo back up when going from the brake to the accelerator pedal, since those compressed exhaust gases would pass through the turbine as soon as the exhaust brake was opened. If I were going for this effect it might be better to create an exhaust manifold with more volume.

Re: Turbo exhaust brake on gasoline motor?
 

good thought and all but why not just brake boost if your tryn to build boost better ?

Re: Turbo exhaust brake on gasoline motor?
 

I want engine braking more than I want to build boost. That was just a secondary benefit.

Re: Turbo exhaust brake on gasoline motor?
 

I've '07 yamaha R6's have exhaust brakes.

@least thats what the look like in the exhaust system

Re: Turbo exhaust brake on gasoline motor?
 

Thought this topic would have provoked a little more discussion than this here.

Re: Turbo exhaust brake on gasoline motor?
 

Why the ---- would you want to "increase engine braking"???

On a gasoline engine powered street car whose 'wheel' brakes are adequate, what need do you have for this? Not to mention the fact that most gas-powered engines dont have the rotational mass of a diesel.

Honestly, do you drive down alot of hills all the time with your ass end loaded up with lead bricks???

BTW engine braking is not exactly a good thing for your engine. Disk brakes and pads are cheaper than motors.

Re: Turbo exhaust brake on gasoline motor?
 

I don't think you guys have any idea how complex it would be to add an engine braking system.

You are talking about adding some sort of actuating system usually driven by oil pressure to open the exhaust valves. This is usually placed between the head and the valve cover.

Engine braking is where on the compression stroke, the exhaust valve is opened, thus preventing the rebounding effect on the compression stroke and making the engine do more work.



Engine braking is not harmful to an engine.

Re: Turbo exhaust brake on gasoline motor?
 

Nor anywhere NEAR the compression.... :S

Re: Turbo exhaust brake on gasoline motor?
 

I'm pretty sure he didn't want a jake brake, more like an exhaust brake. A flapper of some sort that increases backpressure by a ton put in the exhaust.

Re: Turbo exhaust brake on gasoline motor?
 

You are a moron. I have plenty of good reasons to want more engine braking. And please go tell a trucker that engine braking is bad for a motor. See how he responds. :3

You have nothing to add to this discussion, besides misinformation.

Re: Turbo exhaust brake on gasoline motor?
 

It would actually be quite simple and easy. Buy a $800 turbo exhaust brake (widely available at diesel shops) and bolt it up to your turbo, then wire the rest up.

I think you're thinking of a Jake brake, which really has nothing to do with a turbo.

Re: Turbo exhaust brake on gasoline motor?
 

No that's the secondary exhaust runners for higher rpm/ different load on the engine.
It's like VTEC y0!
well more like the Ford Z-tec

Re: Turbo exhaust brake on gasoline motor?
 

Ok since im a retard and opened my mouth about this without any proof of what I said other than what ive been told I decided to do some research. Your right. I cant find anything that would suggest engine braking would be harmful to your engine other than normal compression wear. My bad.

I would have some concerns about exhaust gaskets leaking and things like that due to increased exhaust back pressure. What kind of engine/transmission and what car are you planning to perform this too?

I also had an idea. Since the throttle plate would be a problem, you could rig a solenoid of sorts or something similar to open the throttle automatically when the exhaust brake is engaged. That would help because you would no longer have a vacuum in the intake, and would allow more airflow available to the cylinder.

Surely though you can make something work without having to spend $800 on it. Could you use an exhaust cutout inline with your exhaust system, Or maybe a large throttle body like ls1 or something and simply shut it for engine braking, open throttle-on???

Re: Turbo exhaust brake on gasoline motor?
 

Sorry for my response to your first post. I was short-tempered.

Good exhaust brakes actually go for less if you buy them used. I would personally rather spend $400-500 on a good used brake that's properly designed than to attempt to fab one up. I know this is HMT, so ghetto=good, but something like this needs to be designed and built properly in order to function and last. I'm all for square tube log manifolds and nasty flux core welds, but not for something like this.

I am still not sure that it would really add much. When the throttle is closed there is good vacuum in the IM, so there should not be much air flowing through the exhaust for the brake to block. I think it might be fun to try to enhance spool up with a brake though. Especially if it was rigged into an electronic boost control system. Have the plate close pretty tight if the TPS senses quick decel, then open it on acceleration. I'd think it might help on a road course rig. I guess you would need a manifold with quite a bit of volume though in order to have enough gas built up to spool the turbo well. Either that or a brake that's able to hold a lot of pressure.

Some (if not all?) diesels use an exhaust brake in lieu of a throttle valve, I wonder what a gasoline motor would do with the same setup. Or if there are good reasons why you don't see it often.

Re: Turbo exhaust brake on gasoline motor?
 

I would think that cylinder filling would be an issue with the throttle shut under decel, since your braking on compression, and vacuum in the intake wouldnt be what you would want, since the exhaust valve is shut, to maximize the effect of the compression load on the cylinders you would need as much volume of air crammed into the cylinder as you can get? Or maybe im totally off base in my thinking.

I believe noise polution would be a big concern to the ruling bodies. That and they would find some way to say that an exhaust brake increases pollution or some bullshit.

Re: Turbo exhaust brake on gasoline motor?
 

Regardless... You are a moron

Re: Turbo exhaust brake on gasoline motor?
 

using an exhaust brake is hard on the engine, but a jake brake isnt that bad at all. I think this is much more trouble than its worth. BTW, gas engines have much more engine braking ability than a diesel engine does without a jake brake etc

Re: Turbo exhaust brake on gasoline motor?
 

Exactly, you already have decent compression breaking with your gas engine.

Re: Turbo exhaust brake on gasoline motor?
 

it's because you have a ------- ability to close the intake tract from straight air.