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primary length is a touchy subject. In theory yes you would think shorter will keep more heat in the pipes and more heat will spool better. BUT you also have to remember the engine is still breathing thru those pipes and you don't wanna choke the motor down..
I admit i have not tested back to back on a rotary engine but i've done alot of testing on piston motors... Yes it's not a rotary but the same concepts apply here. All of them make more power with longer primarys compared to short primarys. Spark plugs would also come out looking alot better. The engines were small high revving engines and the charge seemed to be going back into the intake when using shorter primarys.. I have been using anywhere from 10 to 15 inch primarys and seem to have good results.. If you look back at Turbo F1 days alot of those guys also used somewhat longer runners as well.. Most of those engines were revving upto 12k rpms.. |
Eye Candy,
http://i287.photobucket.com/albums/l...IMG_1748-1.jpg[/QUOTE] There you go again Barry, making me get all excited!!!! |
Originally Posted by BLUE TII
(Post 10036408)
Are you saying that short individual tubes would be at a disadvantage in driving a divided housing turbo?
It is all compromises. At low rpm (say 1,000-3,000rpm) where exhaust flow is small and there is no intake charge being forced into the exhaust to enhance the external combustion there is a definite advantage in spool to standard short tubes with high velocity and less heat loss. At higher rpm (say 3,000-6,000) where exhaust flow is large and intake/fuel charge is being forced into the exhaust enhancing the external combustion a long runner manifold will allow more time/space for the exhaust to combust/expand before it hits the exhaust turbine. Even some of the guys going for high RPM, high power use short as practical tubes. The eyecandy is pretty, but those tubes look like the typical length of a shorty tuned header. Also, what is the overlap on those turbo cams compared to a rotary- usually much lower on a turbo piston engine. Apples and oranges. Consider that these engines don't have the advantage of running a single tube straight to the turbine impeller undisturbed by the phasing of another cylinder/rotor. Two more examples of F1 engines. More Candy for Chuck! Barry http://i287.photobucket.com/albums/l...s/IMG_1743.jpg http://i287.photobucket.com/albums/l...s/IMG_1740.jpg |
the 13brew has a huge (+) peripherally located (++) exhaust that has monster duration (++) that can be tweaked (++). by the time the port closes it is game over as there is little left to vent.
i digitally log exhaust backpressure. the data is spike and flatline cycles. i am anti bends and pro heat. more bends choke off energy by adding resistance. long runner manifolds have at least 2 more bends and more pipe to heat. further, if you graph an explosion in relation to distance from the epicenter it falls off rapidly. this is not to say a longer runner manifold if done properly can't work very well. maybe manifolds are just something to hang a turbo on... that's why i am doing the test... inquiring minds want to know. i do have my suspicions. howard |
stop it w those pics, i am getting a thrill up my leg
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chuck that pic you posted is a reversed engine setup on a v6 not commonly seen. nice pics being posted i love the turbo f1 age. the bmw 4 cyl turbo setup made close to 1400hp i believe. i forget what the cc was though.
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found it it was a 1500cc bmw setup with 1300 bhp at 5.5 bar.... lol holy sh**. whats that 75-80 psi of boost.
heres a link with PICS.http://www.gurneyflap.com/bmwturbof1engine.html |
Yes, please test the things you think will work well and things you do not think will work as well. There are so many variables with the turbo rotary that it become a bit like aerodynamics in the wind tunnel- where you will not find the best solution if you only what seems intuitive.
As Jim Downing has said "black is white, white is black in that business[windtunnel testing], what you think it's going to do it doesn't, it does that, it just fools you every time, you got to go try it." |
One saying I'm fond of is "If you aren't testing, you're guessing".
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1 Attachment(s)
apples!
http://www.racingbeat.com/Mazda-Perf...tNumber=Engine hard to see in the pics, but the exhaust manifold on that thing is maybe 1.5" O.D. and its maybe 8" long.... |
I've seen that engine. It was originally built for an airplane. Spool really isn't an issue.
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i'd really like to bolt the turbos on the engine:)
actually my twin setup that i ran for 4 years has a 3 inch primary runner on the rear turbo. interestingly the EGTs were 40 degrees colder in the rear. so a 3 inch runner works. the back pressure was the same front and rear and my plugs looked the same. the other runner was 6 inches long. i know i know, equal runners. but mine worked just fine. hc |
Originally Posted by Barry Bordes
(Post 10036879)
I agree that we work with compromises, but could the headers shown have made them any shorter?
They could have easily saved a few inches by running the exhaust to the turbo on the same side of the motor.. instead they ran it across the motor to the opposite side. Looks neat but I imagine it was to stretch the primaries. Also, is it me or did they stretch the wastegate dump tube overtop of the flange and weld it directly to the body? |
add to the opinions,, the latest GM Ecotecs 4CYL. 2L, have been makin 1200-1400hp for last 5yrs, with some relativly long runners.
but about 2003, a guy came down from Canada,4cyl. mopar FWD car went very well,drag racin, he had the longest runners i ever seen, from the exhust port to the turbine inlet was around 4 feet, i asked about it, he said the key was to bundle them into a long straight run of piping, before the small collector into the trub.hsing. car did good and made good torque in the mid track. I will probably get some ops, i daily drive a remote turbo.T28, on my 1.8L , turbs located back near rear axle , pipes are 6-7 feet long, turb runs super cool. BUT any kind of positive pressure in the intake mani. is better than a vacuum. and thinkin about HC it aint a quarter mile, you really need the HP in the last 1000-1500ft, its 5280 ft. and all in all, HC good LUCK with your project,and you best use your own common sense. |
and i know this totally off topic;
WW2, P47 airplane had the turbocharger mounted vetically in the tail of the plane, pipes were 12-14ft away from engine, and to make things more interesting , pipes were rectangular and about 6" in size. talk about unusual, but they made power. |
some of those Buicks had the WG bolted on top of the turbine hse. with a direct flow to the WG, seems Garrett cast them for a short while, havent seen one in over 10yrs tho.
just so many ideas!! |
Originally Posted by Howard Coleman CPR
(Post 9998446)
you may recall that i designed, built and ran a two TO4E 46 trim setup. i fired it up in 2004 and put about 20,000 miles on it. i went thru 5 iterations of turbo wheels, housings etc and really enjoyed it. it made 507 SAE at 20 psi and is capable of another 50-75 hp at 26 psi. in order to properly tune it i was forced to push the envelope as to instrumentation. i digitally logged backpressure as well as front and rear EGTs etc.
when i made the decision to go single i found i was actually looking forward to designing my own manifold. |
three of the four turbos have arrived and i thought you might be interested in seeing them before we turn the turbine housings cherry red.
BorgWarner S300 63 compressor very close to same average area of a TO4z or PT67 BUT w a significantly smaller Trim so it should spool better. has a bigger turbine area 6.3 sq inches V the other 67s which are 5.8. GT4094r i picked it as i need 600 rw for my 200 mph Texas Mile attempt. a bit small on the turbine but i didn't want the huge bulk w the GT42. GT3574 GT35r compressor w a larger P trim turbine. journal bearing. it will be very interesting to compare spool etc to the other turbo to be tested which is not in the pics... a ball bearing GT3582r. i did have to jump thru a hoop or two to get the uprated Garrett compressor housing on this turbo but Sean got it done. http://img811.imageshack.us/img811/6798/023r.jpg http://img812.imageshack.us/img812/488/029i.jpg GT4094r 1.06 A/R. S300 1.00 A/R http://img227.imageshack.us/img227/5739/027ws.jpg GT3574 .84 A/R http://img227.imageshack.us/img227/8383/028xm.jpg BW S300 63 http://img683.imageshack.us/img683/8071/030ux.jpg GT4094r http://img811.imageshack.us/img811/9163/031b.jpg GT3574 http://img97.imageshack.us/img97/4194/032jl.jpg here's what they look like ready. almost to do business: GT4094r http://img811.imageshack.us/img811/3166/001f.jpg GT3574 http://img263.imageshack.us/img263/1568/006hcz.jpg BW S300 63 http://img149.imageshack.us/img149/1425/010fj.jpg |
looking good Howard, also looking forward to the results..
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Hoora!!! I'll help you out as best I can with this stuff sir I may have a idea or two for you myself I'll shoot you a email later about it. :)
~S~ |
Howard, wouldn't it be great to have an engine dyno for these tests. You could change each turbo so much more easily. That way others could send in their favorite pick for comparison.
How about someone sending a billet compressor wheel turbo? You should really consider keeping this as an ongoing test. OK I guess I'm going a little crazy now! Anyway, keep up the good work and thanks for sharing. Barry |
Looking good Howard! Damn you with your fast domestic shipping! I cannot believe how long it takes to ship to Canada.
It will be very interesting to see what happens. =Benjamin |
commmeeee ooonnnnn GT3574
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Howard,
Cool project! Can't wait to see what the results are! Regarding exhaust manifolds (and the quote below) I believe you'll find the longer runner manifolds make more high rpm horsepower, shorter have better spool. All else equal, of course. Back in the early 2000 timeframe I had Carlos Gonzalez (G&S Racing) make a manifold for my FD. He was one of the leading NHRA rotary drag racers at the time, and I gave him complete discretion to build what he thought would work best for horsepower. What I wound up with was manifold about as long as the RB manifold - runners at least 8 inches long. Air filter fitment problems up the wazoo. Anyhow, the point is that Carlos had built dozens of manifolds for his tube frame drag car. No space limitations and no concern for spool since he was only concerned about 6k to 10k. Through trial and error he found that the longer manifold resulted in faster times at the drag strip. By the way, he explained to me at one point that he determined the length by seeing how far up the runner the pipe would burn to. This was an indication of how long (in terms of space on the exhaust runner) the combustion process would take to fully burn the fuel. He'd cut the pipe there and weld the turbo flange at that spot. Have fun, Howard! Best, John PS I'm pretty sure I have a picture of the manifold back at the home computer, if anyone is interested in seeing the monstrosity.
Originally Posted by j9fd3s
(Post 10038157)
apples!
http://www.racingbeat.com/Mazda-Perf...tNumber=Engine hard to see in the pics, but the exhaust manifold on that thing is maybe 1.5" O.D. and its maybe 8" long.... |
update:
things are taking shape in the intercooler department. it is clear from the following pics that intercooler configuration w my CPR manifold will be different depending on the turbo... if you want to do it right. i don't like bends anywhere. so we are looking for straight shots into the IC. along those lines the standard new design Pettit IC will work fine w the BW. http://img97.imageshack.us/img97/500/005jz.jpg with the Garretts a Low-Port design is needed. Pettit is flipping the new design cast end tank and fixturing a down to the rear 5 degrees intake to match up. further Pettit is fabbing a neat short aluminum intermediate tube. we worked over the weekend on this so as to juice the schedule. http://img227.imageshack.us/img227/1723/014do.jpg |
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