Turbocharger Pulse Tuning & Other Mysteries

[skywalker18]

Dynoroom is correct, this was regarding the 2014 engine.  There aren't too many details regarding the specifics of the manifold, but it is shown in the picture below on the left.  As stated, it definitely helped with packaging by keeping everything in tight.  Those engine bays are getting TIGHT!!



They did not have actual equations in the article.  It was more of a discussion regarding a University student's thesis.  I've got some papers filed away that may be of some help to you....let me see if I can find them.

This link has a copy of the article: http://www.f1technical.net/forum/viewtopic.php?p=550485&f=4&amp%3Bsid=afe787eec9868e630e09493443a90b97&utm_source=feedburner&utm_medium=feed&utm_campaign=Feed%3A+Formula1-Integrated-Feeds+%28Formula+1+Integrated+Feeds%29

Some more food for thought....

[Rex Schimmer]

Here is some more "food for thought" regarding log type manifolds for turbos. This is a pic of a 159 inch Offy at 56 inches of boost making about 760 hp at 9500. This is also the same exhaust manifold design that was used when they made 1200 hp with this engine at around 100 inches of boost. Not much got pass Leo Goossen. I asked Stu Van Dyne, who worked at Drake/Offy for a number of years and now own all of the rights to the Drake/Offy engine, if they had ever tried "tuned" headers on an Offy and he said that they had but did not find a reason to change.

Rex

[Stainless1]

At that RPM it all probably looks like continuous flow, not much turbo lag there 
 

[horsewidower]

I'm an old roadracing dog trying to learn new tricks. So I'm trying to adapt my previous thought process, attuned to multiple shifts up and down the rpm range, to the straight line reality of LSR.

It seems to me that the following apply (not in any particular order of importance):
 

• Maintain constant pressure upon the turbine once up to speed
• Maintain as much heat in the system as possible
• Deter reversion
• Provide for effective packaging.
• Provide for reliability

Are there other attributes we should add to the list?

[maj]

allow for heat expansion , only trouble i have ever had with log manifolds was expansion/ contraction
long term they get brittle from movement at critical points, last one i made back a few yrs now on a 6 cylinder i put 2 slip joints in
you will notice most truck manifolds have the same
4 into 1 usually has enough length for movement 

[Pickle]

I guess Ill throw my hat in the ring.

I have run turbos on engines as small as 1.2L and as big as 440 c.i. Pulse timing does have an effect but only on spool up regardless of engine size. Once max boost hits the waste gate opens. The entire system is then under some dynamic pressure and pulses back up and blend. In my experience pulse timing has a negligible effect outside of spool up, and during spool up a ball bearing (BB) turbo will do more for you. As far as log vs headers goes... I found under WOT logs work well, think drags, under throttle modulation, think road race, headers pull harder if your turbo is big and spools high in your power band. I have no experience using turbos for LS but from what I have seen I would assume either would work and BB turbos or pulse timing isn't needed IMHO.

One thing to keep in mind with logs... On one 2.0L I built one cylinder ran hotter than the others. When the WG opened and the exhaust system was pressurized the cylinder with the longest run to the turbo collector ran about 10% hotter. We put exhaust temp sensors just downstream from each port to see it. We built an equal length set to the collector and the hot cylinder dropped to match the others. We have been debating since then just why that happened. Food for thought.

James

[fordboy628]

One thing to keep in mind with logs... On one 2.0L I built one cylinder ran hotter than the others. When the WG opened and the exhaust system was pressurized the cylinder with the longest run to the turbo collector ran about 10% hotter. We put exhaust temp sensors just downstream from each port to see it. We built an equal length set to the collector and the hot cylinder dropped to match the others. We have been debating since then just why that happened. Food for thought.

James

If you could run individual ex pressure sensors in each port, or just at the beginning of the manifold/header, any pressure imbalance would be revealed.

Cylinder with the highest pressure is going to run the hottest, and is doing the most "extra work" during the exhaust pumping cycle.

Keeping the temps/pressures equal prevents melting  .  .  .  .  .  something.
 
Fordboy

[Pickle]

Cylinder with the highest pressure is going to run the hottest, and is doing the most "extra work" during the exhaust pumping cycle.

This is true, work being the product of pressure and change in volume, however we measured a 10% increase in combustion temp. I would agree with the "extra work" if it was 10% of ambient temp, but 10% of what 1600 Celsius? One possibility we discussed was the extra length in the log gave the intake charge somewhere to compress the spent gasses outside the combustion chamber allowing more usable air into that cylinder vs others effectively leaning out the cylinder running it hotter. Our ECU program didn't have the ability to adjust individual injector curves so we eventually set the curve to satisfy the hot cylinder and the other three ran rich. The next year we ran tubular equal length and all the problems disappeared.

James

[Paolo Castellano]

I guess Ill throw my hat in the ring.

I have run turbos on engines as small as 1.2L and as big as 440 c.i. Pulse timing does have an effect but only on spool up regardless of engine size. Once max boost hits the waste gate opens. The entire system is then under some dynamic pressure and pulses back up and blend. In my experience pulse timing has a negligible effect outside of spool up, and during spool up a ball bearing (BB) turbo will do more for you. As far as log vs headers goes... I found under WOT logs work well, think drags, under throttle modulation, think road race, headers pull harder if your turbo is big and spools high in your power band. I have no experience using turbos for LS but from what I have seen I would assume either would work and BB turbos or pulse timing isn't needed IMHO.

One thing to keep in mind with logs... On one 2.0L I built one cylinder ran hotter than the others. When the WG opened and the exhaust system was pressurized the cylinder with the longest run to the turbo collector ran about 10% hotter. We put exhaust temp sensors just downstream from each port to see it. We built an equal length set to the collector and the hot cylinder dropped to match the others. We have been debating since then just why that happened. Food for thought.

James

James did the log manifold you used increase in diameter as each primary dumped in the main log or was it constant ID? Also did you have any internal anti reversion steps?

When you swapped out to the equal length headers, did you change anything else like intake manifold, ECU/etc...?