Turbo Project questions

[HANKSXXX]

Damn turbo made 250+HP/150+ ft lbs tq and on a stock wheelbase BB, it was way more than I needed...

If it's too fast you're too old.

Well yeah, that too...

Hi. Do you know what is the thickness stock head gasket ? cometic head gasket + shipping to Poland costs $ 350. little expensive.

I Need to find a man in Poland who will do custom head gasket.

I think the standard head gasket is .030" thick

[XXitanium]

How much would it cost to ship 10 or twelve?

[nonam3k]

How much would it cost to ship 10 or twelve?

I think the price will be the same for 10 pieces.

Inlet manifold,

[superhawk996]

That manifold is pretty, but I wonder what's gonna happen with air rushing in across the stacks. Looks like there could be a lot of turbulence equating to flow restriction and imbalance between the cylinders.

[superhawk996]

I see many goofy intakes built for forced induction engines and many people's theory is that it doesn't matter because now the engine isn't having to suck air in, air is being blown in. My position is: whether force induction or not, all engines breath on the basic principle of pressure differential. Naturally aspirated they operate on 14.7 psi intake pressure and with boost they get more pressure. I see similar with turbo exhausts where suddenly people ignore the basics we know about exhaust tuning. I've only had a chance to drive one vehicle with a turbo that had long tube headers and a standard style intake, a VW powered sandrail. The thing ran like it had a V-8 instead of a small turbo engine. There was none of the common turbo lag/jump, just a linear increase in power with very quick boost. No idea if it was because of the intake and exhaust or maybe just the lightness of the vehicle, or maybe the engine combination just happened to work better than average. The turbo system had no special engineering, just a 2 barrel carb feeding into a standard T4 turbo.

[HANKSXXX]

Think pressure, not flow.

[superhawk996]

Think pressure, not flow.

There has to be flow into the manifold to create pressure until the point that the pressure is stabilized with no outgoing flow. Since the engine is running there's never an end to the flow needed to maintain the pressure. The outgoing flow is pulsed further complicating flow.

All intakes are pressurized compared to the cylinder's negative pressure created during the intake stroke. A turbo just increases the existing pressure creating more flow as well. As the air is flowing into that manifold, whether boosted or not, it will blow across the intake stacks possibly creating turbulence and uneven cylinder filling. The first stack looks to be kinda shrouded and will likely see less pressure available for it reducing its flow, the others have the air blowing across the stacks.

It would be interesting to put pressure gauges on each cylinder and see how much difference there is between them. I'll vote 1 psi at peak power.

Edit: This isn't really an intake manifold, more of an air manifold or airbox really, but it doesn't change what I've said about it.

Edited March 3, 2016 by superhawk996

[Redbird]

Edit: This isn't really an intake manifold, more of an air manifold or airbox really, but it doesn't change what I've said about it.

Plenum.

And when Hank talks turbos, people listen.

[superhawk996]

Edit: This isn't really an intake manifold, more of an air manifold or airbox really, but it doesn't change what I've said about it.

Plenum.

And when Hank talks turbos, people listen.

Yea, that's the word.

I get that he has plenty of experience. Maybe we're just not connecting thoughts/words, but the thought of pressure without flow in a flowing plenum doesn't jive with me.

[HANKSXXX]

Take a quick look at this manifold. It's manufactured by Terry Kizer's company, Mr Turbo.
He is a many time record holder and builder of turbo bikes.
I had one of his kits and this manifold in particular on a Suzuki Bandit.

It is far from a good design but is necessitated by the space confines of a motorcycle.

The intake or pressure side is the single hole.

The boots to the intake ports match up to the 4 spigots on the reverse side.

Number 2 and 3 cylinder spigots are partially in line with the single pressure (intake) port while

number 1 and 4 are at the opposite end's of the manifold, requiring a ninety degree turn to get going down the manifold and another 90 degree turn to enter the spigot/port.

How would flow in the traditional sense function with all these obvious roadblocks?

Would the center cylinders not burn way differently than the ends?

In use, all plugs burn the same because there is a reservoir of pressurized air looking for a place to escape.

Hence my (hopefully) thought provoking statement: think pressure, not flow.

Edited March 3, 2016 by HANKSXXX

[jon haney]

I think I understand what Hank is saying. Any differences in flow through the plenum don't hardly matter, because the bottle-neck is really at the intake valves. Correct?

[superhawk996]

I found a computer model as well as some actual flow testing of a plenum that looked just like the one in the poster's project. The three far cylinders do a little better than I'd expected, turbulence, but fairly even flow. The first one is in a vacuum and had much less pressure/flow as I suspected. I can see the center inlet ones working better. I assume if there was space for a better design in the bike they'd take advantage of that.

[HANKSXXX]

I found a computer model as well as some actual flow testing of a plenum that looked just like the one in the poster's project.

Man, I'd like to see that. Got a link?

Just bumped into this, a Kosman Funny Bike from the early 90's...note the plenum/intake manifold:

Bike went 4.62 1/8 mile 169mph 7.08 189mph in 1992 on old carb set up

Edited March 6, 2016 by HANKSXXX

[superhawk996]

http://forum.e46fanatics.com/showthread.php?t=735897

I googled plenum design flow.

This is one of them, don't recall how I got to the others. Google comes up with a crapload to sift through quickly.

The center inlet one you showed in your post probably only works as well as it does because part of the incoming air hits a wall instead of just the intakes. Still very hard to believe it flows evenly to all 4. I suspect that if the poster's inlet were pointed towards the back wall and/or diffused it would do better.

The problem with "think pressure and not flow" is that it's not a static build of pressure but a very high speed flow of air. Again, whether boosted or not plenum designs will respond similarly so if you build a plenum based on the theory of it being a pressure container you'll be far from an efficient design. A boosted one will generally pose more issues to achieving an ideal design, but many people just compensate for flow inefficiency through more boost and a richer mixture. If you can adjust each cylinder's mixture individually then you'll be less likely to have a huge issue. I've seen two engines smoked because of flow issues; one of them was turbo, the other was nitrous.

I've seen similar flow issues in compressed air systems where manifolds can make huge differences in machine performance. The only system I've ever had a chance to work on was running at 100psi (over 5x average pressure of a turbo) and 20-30 CFM per machine (about 1/4 or less the CFM requirements of a bike cylinder) which should make it fairly easy to achieve a balance. There were varying intermittent imbalances and surges between machines that couldn't be figured out, I cured it by building a different manifold. I had nearly unlimited space to work and fairly low individual CFM requirements so it was much easier than building something for a motorcycle, but these machines had to be certified with no more than 5% imbalance between them under any possible operating conditions.

[HANKSXXX]

Thanks for the research and the very informative link. My statement was meant to be more basic.

I meant traditional tuning that works with a NA engine doesn't necessarily work with a boosted engine and to consider pressure in the plenum rather than flow through the intake tract generated by the piston. We all know port design on most street engines can be improved up to a point. One of the limitations is the size of the (intake) valve through which air is pulled by the piston. With a boosted engine, air under pressure is pushed through the valve,The more pressure, the more air, the more horsepower. Of interest is that rods are less stressed in a turbo motor because of the cushioning effect of the pressurized charge. It's not unheard of for stock rods to remain intact at almost twice the horsepower output with a turbo as opposed to NA. Valve spring pressure has to be increased when using a lot of boost because of the pressure on the port side of the valve when seated. Rule of thumb is add a lb of spring pressure per lb of boost. This isn't necessary with low boost but becomes more so as boost pressure rises.

Per plenum design, I have no problem trying to fix a problem shown by irregular plug readings etc. but in practice, I haven't seen a problem.

[superhawk996]

All engines ingest air based on pressure differential, looking at a boosted engine in a totally different light than a NA engine is flawed. As far as there being less stress on the connecting rods of a boosted engine, no. There's is no 'cushion of air' protecting them. Adding boost to an engine and doubling it's HP can not remove stress from the rods. All engines operating properly have an 'air cushion' above the piston, a boosted engine has a hotter denser charge of air and therefore more stress to components than the same engine without boost.

If we were to compare two identical size and design engines making the same HP, one using boost and the other NA, the stresses on their rods would be different since the NA engine would probably have to spin faster and be more aggressively tuned. No way a double HP engine has less stress on it's rods assuming both engines are properly tuned.

[HANKSXXX]

So I've been thinking about how to tactfully reply to your post and frankly, I can't. You really seem like a guy huddled around a book with little real world experience (in building high performance NA and boosted motorcycle motors), not to mention riding high horsepower turbo bikes. How did you feel when you got off your first 250HP, 155 lb tq, stock wheelbase turbocharged motorcycle? How about after riding your first 300HP motorcycle? How about you post your qualifications and achievements in building high performance NA and turbocharged motorcycle motors and I'll then be happy to do the same.  There is flawed thinking here, but it isn't mine. Mine is first hand experience which I'm happy to share.

A quick question and something for you to think about: Why do turbocharged motors with mild camshafts, turning less rpm's than a HP NA motor, require heavy duty intake valve springs, larger exhaust valves and porting on the exhaust side?

 

 

[superhawk996]

I won't engage in the dick swinging competition.

 

Stiffer intake springs to counter the additional inlet pressure trying to keep the valve from seating.  Exhaust valve and port because exhaust flow is un-proportionally increased with an increase in power.  Not always beneficial, but those are some reasons to do it.

 

Edit: I've never owned or read any books on turbo charging or any other power enhancing procedures so I can't be huddled around one.

Edited March 13, 2016 by superhawk996

[HANKSXXX]

Answer to my question:

Normally aspirated engine tuning and building techniques do not apply with a turbocharged motor largely because of pressure induced by the turbo..:)

See what I did there?

Peace!

 

[superhawk996]

Yup.  You were challenging me while attempting to show that turbo motors may be built differently than NA motors.  Still doesn't change anything about my plenum statements which centered around fluid dynamics.

[HANKSXXX]

No challenge at all...I was qualifying the source of knowledge of your statements; be it first hand  or reading.
You have answered that you haven't built any turbocharged motorcycles, ridden any or read any books on the subject.

Nothing else needs to be said.

 

[Firedragon]

Since it may be important, I have never built a turbo bike and I love reading books. Allowing for the fact that both HanksXXX and Superhawk996 are keeping the terminology simple I believe they are both right.

Fluid dynamics shows that work has to done to move a fluid(air) through a port whether by sucking it or blowing it. Any extra work brought about by not flowing the manifold has to be generated by the system. Since however the thing has to be fitted on a bike these niceties are way down the list. If a bit of extra work(in the physics sense) is needed that is just too bad as long as the plenum chamber pressure has the ability to supply the extra work.

As far as conrods go the BMEP with turbo would not range as widely but would be higher but that extra loading is in the direction that the rod usually has plenty of spare capacity and less in the direction the rod is weakest assuming revs are the same. Even a small increase in revs induce large extra stresses for the rod, turbo or N/A.

[superhawk996]

13 hours ago, HANKSXXX said:

You have answered that you haven't built any turbocharged motorcycles, ridden any or

Really, where?  If I did it was a mistake and is incorrect.  Having ridden turbo bikes doesn't give any credibility to one's knowledge about how they work, that's plain dumb.  Having built them only proves someone could bolt parts together so it still doesn't make one the authority on the intricacies at work.

[superhawk996]

11 hours ago, Firedragon said:

Since it may be important, I have never built a turbo bike and I love reading books. Allowing for the fact that both HanksXXX and Superhawk996 are keeping the terminology simple I believe they are both right.

Fluid dynamics shows that work has to done to move a fluid(air) through a port whether by sucking it or blowing it. Any extra work brought about by not flowing the manifold has to be generated by the system. Since however the thing has to be fitted on a bike these niceties are way down the list. If a bit of extra work(in the physics sense) is needed that is just too bad as long as the plenum chamber pressure has the ability to supply the extra work.

As far as conrods go the BMEP with turbo would not range as widely but would be higher but that extra loading is in the direction that the rod usually has plenty of spare capacity and less in the direction the rod is weakest assuming revs are the same. Even a small increase in revs induce large extra stresses for the rod, turbo or N/A.

The base problem here is looking at a NA motor as sucking air because it's not.  Air is pushed in by atmospheric pressure or by additional pressure if there's boost.  Intake flow is often deemed less important in a boosted motor because inefficiencies can be compensated for with more boost.  When limited by space or other issues preventing a better system I understand having to forgo a more efficient system, but to state that one should ignore flow because there's pressure present is absolutely flawed.  Cylinder balance/flow is where this debate all started and with an unbalanced plenum the effects become greater as flow is increased which is what boost does.  Plenum inlet air with a  turbo is often turbulent which can add to the ill effects; air exiting the turbo is spinning instead of a straight flow of air.  If it goes through an after cooler, or a lot of piping, the air can be a straight flow like in a NA intake.

 

Adding revs will stress rods so trying to make the same HP without a turbo to compete with a turbo motor could lead to higher rod stress, but that wasn't what was posed.  The stated "cushion" that boost provides for the rods makes no sense at all, I don't know where in the cycle the cushioning effect happens and am interested to hear about it as maybe there's something I'm not thinking of.

[Firedragon]

Well you can't say I didn't try. "Work" is done to get air into a cylinder. We can all agree on that I hope. Anything done to reduce that is beneficial as is anything done to stabilise the air flow. A 60 cubic foot plenum would be better that a 6 cubic inch and somewhere between the two, while we are deciding the the exact perfect theoretical size, HankXXX is riding past on his turbocharged Bird!