decoupe
(deceased)
I undertook a conversion from 38/38 downdraft to EFI (using stand alone engine management) a few years ago detailed in the links below.
http://www.e9coupe.com/forum/showthread.php?t=5841
http://www.e9coupe.com/forum/showthread.php?t=6865
I mentioned that I had a set of e21 (320i) intake runners that, because of their longer length, are supposed to increase the low to mid range performance. The test was as intake to intake on the same dyno, roughly at the same temp and elevation and with no changes to the programming. Calgary is 3500' or roughly a 10% loss in power due to air density. There was an average gain on both torque and horsepower of roughly 3%. At no point is there any loss. Not to bad a return on a $40 purchase price for all 6 runners. The dyno below shows the dotted log versus the solid plot for the log plus 320i runners.
Last winter, I removed everything and installed the b35intake, throttle body and fuel rail from a 1989 735i. The dyno plot indicates a slight increase in both torque and rwhp up to approximately 4000 rpm for the B35 intake and then a steady increase in both for the b35 of about 7% before redline - a gain of 10 rwhp and 4 ftlb of torque.
To put into perspective what the current state of tune translates into and feels like I had the b35 (dotted lines) plotted against the performance of a 1998 M3 (very clean, 100,000km owned by the dyno operator). The engine with the current intake is very close to the M3 up to 4500 rpm, reasonably close to 5500 rpm and then finishes down 21 rwhp (but less than 3 ftlb max of torque) at 6400 rpm. Respectable numbers in both versions of the L Jet to the M3 as well. With a more aggressive CR and more appropriate cam plus some flow work and I think my goal of e28 M5 performance is with in grasp for not much more $$$$$.
Some comments and observations. In all cases there were no changes to the engine spec, no porting of manifolds, same dyno machine and very knowledgeable operator, same engine management program (http://sdsefi.com/). The only variable is the hardware of the intake systems.
I had the 38/38 carb setup dyno'd after I bought the car in 2004 to tweak the jetting for altitude (3500') but it was done on a different machine so wasn't apples to apples but again the only thing changed in that case as well was the intake not the engine. I'll see if I still have the print out.
The engine itself has flat top forged pistons of 9:1 CR, a 282 "shrick pattern" reground cam (no details) and is in very good overall condition with compression between 170 - 180psi across all six cylinders. No flow work to the head and stock 3.0 exhaust manifold with resonator and stock muffler.
The best sounding setup was the weber downdrafts - music to your ears. Best power is also the best gas mileage - the b35. Best looking was the L Jet - either one - that looked like a pipe organ stuffed into a small space. Easiest to work on is the b35 - fewer pieces and I can change injectors without taking the whole thing apart (changed any main fuel jets or chokes on the 38/38? or injectors on the L Jet?). Least original looking is the b35 - obviously but I felt compelled to say it.
Hope this is interesting to someone other than just me.
Doug
http://www.e9coupe.com/forum/showthread.php?t=5841
http://www.e9coupe.com/forum/showthread.php?t=6865
I mentioned that I had a set of e21 (320i) intake runners that, because of their longer length, are supposed to increase the low to mid range performance. The test was as intake to intake on the same dyno, roughly at the same temp and elevation and with no changes to the programming. Calgary is 3500' or roughly a 10% loss in power due to air density. There was an average gain on both torque and horsepower of roughly 3%. At no point is there any loss. Not to bad a return on a $40 purchase price for all 6 runners. The dyno below shows the dotted log versus the solid plot for the log plus 320i runners.
Last winter, I removed everything and installed the b35intake, throttle body and fuel rail from a 1989 735i. The dyno plot indicates a slight increase in both torque and rwhp up to approximately 4000 rpm for the B35 intake and then a steady increase in both for the b35 of about 7% before redline - a gain of 10 rwhp and 4 ftlb of torque.
To put into perspective what the current state of tune translates into and feels like I had the b35 (dotted lines) plotted against the performance of a 1998 M3 (very clean, 100,000km owned by the dyno operator). The engine with the current intake is very close to the M3 up to 4500 rpm, reasonably close to 5500 rpm and then finishes down 21 rwhp (but less than 3 ftlb max of torque) at 6400 rpm. Respectable numbers in both versions of the L Jet to the M3 as well. With a more aggressive CR and more appropriate cam plus some flow work and I think my goal of e28 M5 performance is with in grasp for not much more $$$$$.
Some comments and observations. In all cases there were no changes to the engine spec, no porting of manifolds, same dyno machine and very knowledgeable operator, same engine management program (http://sdsefi.com/). The only variable is the hardware of the intake systems.
I had the 38/38 carb setup dyno'd after I bought the car in 2004 to tweak the jetting for altitude (3500') but it was done on a different machine so wasn't apples to apples but again the only thing changed in that case as well was the intake not the engine. I'll see if I still have the print out.
The engine itself has flat top forged pistons of 9:1 CR, a 282 "shrick pattern" reground cam (no details) and is in very good overall condition with compression between 170 - 180psi across all six cylinders. No flow work to the head and stock 3.0 exhaust manifold with resonator and stock muffler.
The best sounding setup was the weber downdrafts - music to your ears. Best power is also the best gas mileage - the b35. Best looking was the L Jet - either one - that looked like a pipe organ stuffed into a small space. Easiest to work on is the b35 - fewer pieces and I can change injectors without taking the whole thing apart (changed any main fuel jets or chokes on the 38/38? or injectors on the L Jet?). Least original looking is the b35 - obviously but I felt compelled to say it.
Hope this is interesting to someone other than just me.
Doug
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