Turbo Manifolds

[wracing 19]

42mm internal diameter. it will increase backpressure very very slightly but increase velocity, thus improving cylinder scavenging and spool. in theory.

 

i will post cfd results when i get time

 

also i forgot its equal length and volume manifold!!

 

james

Edited February 6, 2010 by wracing

[All Praise The GTI 3]

keep up the good work mate

[Mandic 0]

42mm internal diameter. it will increase backpressure very very slightly but increase velocity, thus improving cylinder scavenging and spool. in theory.

 

42mm is rather large! 32mm would be much better.

 

Cheers

 

Ziga

Edited February 6, 2010 by Mandic

[wracing 19]

im aiming for 440hp with my build but im looking to have the ability to run over 1000hp with this manifold. thus the large runner is nessesary. cfd shows that there is no detriment with the larger runner to a point.

 

thanks

 

james

[Cameron 16]

42mm is rather large! 32mm would be much better.

 

Cheers

 

Ziga

 

Sorry what have you based that on?

[Mandic 0]

Well didn't know he will run that much power, for such power levels 38mm ID runners would be ideal.

 

Runners don't need be larger than the exhaust port. In Mi16 case 2x27 => cca 38mm.

 

Gas velocity is critical in a turbo manifold. Runners themselves aren't the restriction, the turbine housing and turbine wheel are. Smaller runners contribute to higher gas speed and the faster and harder the air travels through the turbo, the less back pressure the same turbo will impart on the system back pressure, up to a point of course, even 10-20% smaller runner diameter than the port ID represent less than 5% of the total system back pressure. Turbo manifold runner diameters are cca 2/3 of those on NA, at the same powerlevels

 

The idea is to get the exhaust velocity up quickly, to spool the turbo as early as possible. The discharge is just the opposite. You want pressure differential to be as high as possible. Running large downpipes is a way to go, just make sure that diffuser's angle is not more than 6-10°, as if greater turbulence starts to occur. Well actually for the first couple of centimeters You want discharge speeds to be higher, to get the gasses as quickly away from the turbine wheel as possible, then open it up.

 

Same goes for wrapping, You want manifold to be wrapped, to retain the heat (material stress excluded) and DP needs to be as cool as possible to take away as much heat as possible, again after those first few centimeters. That's why some choose aluminum for DP.

 

Cheers

 

Ziga

Edited February 6, 2010 by Mandic

[wracing 19]

the reason for the large runner is to prevent flow reversion(this is caused by the vortices induced by the step change between port and manifold) induced by the back pressure caused by the turbo, the whole philosophy of the 4-2-1 manifold is the accelerate the gas stream at the conversion between 2 cylinder pairs yet still supplying pulse energy directly to the turbine, thus hopefully utilising both schools of thought on turbo manifold design.

 

 

 

james

Edited February 6, 2010 by wracing

[Mandic 0]

Yes, but Mi16 head has 2 exhaust ports per cylinder, so You can put slightly larger ID pipe right at the port exit to prevent reversion, and then merging them into 38mm ID runner.

 

Cheers

 

Ziga

Edited February 6, 2010 by Mandic

[opticaltrigger 52]

Excellent,a real pleasure to read posts like that from obviously learned and tallented people.

 

O.T.

[iamjackiechan 0]

really interested in this, will be looking forward to the outcome

[jonnyturbo 3]

still have my intrest if you develop an 8v turbo manifold

[Arahan 4]

Me too mate

[wracing 19]

8v manifolds will come in good time once i've swapped my engines over then ill start on the 8v

 

james

[Cameron 16]

Well didn't know he will run that much power, for such power levels 38mm ID runners would be ideal.

 

Runners don't need be larger than the exhaust port. In Mi16 case 2x27 => cca 38mm.

 

Gas velocity is critical in a turbo manifold. Runners themselves aren't the restriction, the turbine housing and turbine wheel are. Smaller runners contribute to higher gas speed and the faster and harder the air travels through the turbo, the less back pressure the same turbo will impart on the system back pressure, up to a point of course, even 10-20% smaller runner diameter than the port ID represent less than 5% of the total system back pressure. Turbo manifold runner diameters are cca 2/3 of those on NA, at the same powerlevels

 

The idea is to get the exhaust velocity up quickly, to spool the turbo as early as possible. The discharge is just the opposite. You want pressure differential to be as high as possible. Running large downpipes is a way to go, just make sure that diffuser's angle is not more than 6-10°, as if greater turbulence starts to occur. Well actually for the first couple of centimeters You want discharge speeds to be higher, to get the gasses as quickly away from the turbine wheel as possible, then open it up.

 

Same goes for wrapping, You want manifold to be wrapped, to retain the heat (material stress excluded) and DP needs to be as cool as possible to take away as much heat as possible, again after those first few centimeters. That's why some choose aluminum for DP.

 

Cheers

 

Ziga

 

Very interesting stuff!

[wracing 19]

not as much progress as i would have liked but im getting there.

 

 

 

 

 

not as tight as i would have liked but im making progress! its only a prototype!

[kutija 1 1 Cars]

For 550-600 hp 38 mm ID will be enough but if you are looking for 1000 hp then 42mm ID is a way to go...

 

Here's the difference in spool between 38 and 42mm ID....

It's almost 500 rpm which is a lot for manifold itself.

42mm should be used for drag racing only....

 

 

Also forgot to mention if you want the best for spool and driveability then twinscroll is the way to go....

But it's a lot more expensive setup as you will need two external wastegates to make it properly....or use mitsubishi or holset turbos with internal wg for twinscroll.

Edited February 8, 2010 by kutija

[wracing 19]

before telling me what's best you should really ask me what setup im going to be running, as said this is a prototype derived from a cad model ive spent time looking into the different runner sizes and found it to be optimum, if im wrong then ill make another.

 

for the record im running a t3/4 turbotechnics and a gt42r on top in a sequential setup, hence the runner size.

 

i dont want to sound like a arse but from want i know of fluid dynamics the graph you've posted is incorrect runner size wasn't the only variable.

 

anyhow this is all irrelevant if this manifold makes good power efficiently and cleanly then ill make it available for people to make there own conclusions

 

thanks james

[kutija 1 1 Cars]

will IMO it would be better to go with compound boost setup with compressor and turbo rather than sequential.

 

What t3/t4 excatly are you using as primary turbo?

Either way it's gonna be a slow spooler....

 

For 42r 42 mm ID is a way to go but for sub 600 hp cars it's unneccesary and will loose spool and response...

Belive it or not that's the test changing only ID of runners....

 

This is just what I know about this matter and you can except it or ignore it..........

[wracing 19]

linked with a "high" compression ratio to will come on to boos finet. im building one because i can as a challenge dont want to be branded a keyboard warrior!

 

james

[Mandic 0]

Kutija is right, 42 ID for 1000HP, but at first I didn't take that very seriously. Are You really aiming at 1000HP mark?? If so, what's the engine spec?

 

There is a big difference between 500 and 800hp, but huge leap from 800 to 1000hp.

 

Not to mention gearbox problems.

 

Cheers

 

Ziga

[wracing 19]

not actually aiming for 1000hp i just want something that i can expand on. ill post the spec in my other build thread once ive confirmed but the usual forged everything,

 

james

[Mandic 0]

Maybe You'd be better off with slightly smaller bore, high revving, high boost engine. But in such case I'd choose RS head.

[wracing 19]

i like to keep my valves where they should be and sodium filled valves are easy to get for the s16 head.

 

james

[Mandic 0]

OK, would be good to see how reliable are blocks and cranks at those power levels. They seem to be happy at 600hp, things are also much beefier than other brands', so might just work. But for reliability sake 86mm bore is probably max. But question is, just how much twisting is present and does it affects clearances too much.

 

Also, where did You find supplier for S16 sodium filled valves?

 

Cheers

 

Ziga

[kutija 1 1 Cars]

linked with a "high" compression ratio to will come on to boos finet. im building one because i can as a challenge dont want to be branded a keyboard warrior!

 

james

Higher compression won't give you earlier spool only better off boost performance and response.

 

On 2 or 2.1l you will need to rev 9000+ rpm and around 3 bar to reach 1000 hp....

On regular fuel you will never see 1000 hp......race fuel or even better E85 or E98 or whatever E is available but for E85 you will need biiiig fuel system for 1000 hp....

 

You are not the first that is trying sequential system and reaching big power on small displacement engine but alot of big name companies failed to make it work like it should.

 

I don't know if you are familiar with compound boost but it's much better and efficient solution.

I'm looking forward to see this build and hope you will make it as you imagined.

Good luck...

 

Also interested where to get sodium filled valve for s16? Those off t16 can't be bought anymore at peugeot...