[quote name='flash' post='58884' date='Sep 3 2008, 02:35 PM']arrrrgh - this thread is totally hijacked - i tried to hint at that earlier - i have now renamed the thread - my apologies to the thread starter and to SFR for letting this go this far
saxman - i think you are missing my point - you are talking about perfect worlds and utopian absolutes - i could care less about differences in efficiency - i am talking about 70hp for a retail price of $5k with all new parts and a complete kit - pure and simple, you cannot get close to that with a turbo, and that is the single defining characteristic that makes this the logical choice - it is also an 8 hour weekend warrior bolt on application - i've done about 30 of these over the years, on different cars (all paxtons), and they work! (i meant to ask, how many have you done?)
yes, the high compression makes for a more complicated engine management issue, but with the electronics available, i do not see an issue - if i could get there with a turbo OF COURSE i would go that route
however, at low boost (below 6psi) there is NO reason for an intercooler on a centrifugal supercharger, and it will in fact COST you about 20% of your power increase, due to the restriction - you have to add at least 2-3lbs of boost to make that up - that means more fuel, more timing, yada yada - bad net idea when all you want is a 30% increase over stock, and that is exactly what we are talking about - we are not talking about anything more
if an intercooler becomes a necessary component, this package will die - (and by the way, are you talking about an intercooler or an aftercooler?) either way though, that is not an acceptable way to go for this package - it pushes the price tag out of the window - i would prefer to do headwork and cams to get to the magic 305bhp number - that is the target - no more - no less
as to the rest, the intake air is definitely hotter in a turbo - the impeller is over 500 degrees, and transfers a LOT of heat to the intake charge - i would be happy to bring along my laser pyrometer and show you on any turbo you choose
the plumbing is also almost always a longer route to the intake point, due to the location of the turbocharger, and its need to be close to the exhaust - this makes the intake air heated by the engine bay along the way - that difference alone is usually about 30 degrees - heck, there is a 30 degree difference in intake temp from the OEM location to the front of the grill, and it doesn't get anywhere near the engine
yes, a turbo is a better unit, more efficient, yada yada - SO WHAT?
there is a big difference between "ultimate setup and efficiency", and doing "only what is needed" for a particular goal - i've been playing with turbochargers and superchargers on and off for 30 years - that's real world stuff, not something somebody read in a book somewhere - i've seen plenty of things that worked, and plenty that didn't, in all types of systems - the right choice is application specific - there is no "one type is better everywhere" solution
if you think you can come up with a turbo package that makes a 70hp bump for under $5k (using only new parts, because you have to be a special kind of idiot as a vendor to sell a used turbo)
PLEASE do it - i would be happy to cut a check tomorrow, and avoid this entire process
doesn't it seem at least a little silly to even be discussing this though, when i said earlier in the thread, very clearly, that there WAS NO POINT until it was done?[/quote]
How many have I done? 12. All custom turbo set ups on honda motors, running nearly as high of c/r, all using intercoolers, running anywhere from 5 psi to 12 psi. All of which I did all of the ecu tuning myself. Many of which were showing way more than 70 hp gains. All of which were done for a fraction of your 5k goal. Which is a moot point, because parts cost different amounts.
As for "utopian ideals" and such, I think you're missing the point. A properly sized turbo, given an identical boost/load/volume level will put out colder air than a properly sized supercharger. By how much depends on the particular unit, but it's a significant amount. I understand that the impeller on the turbo may be hotter than the compressor, but that's irrelevant. It's not the heat transfer from the metal thats the issue, its the efficiency of the compression. Don't compare the temps of the charger itself, compare the IAT's of the two set ups. You will find time and time again that the turbos win this battle at all power levels.
Honestly, I think a turbo would be more cost effective as well... in my experiences with hondas, they certainly always were... that may not be the case on these motors. I'll admit I haven't priced it out. There may be plenty of a market for a supercharger system. I'm just trying to express my concerns so that in the planning stage, you can take all of the available info into account.
The fact of the matter is that superchargers blow a lot of hot air. A properly sized intercooler is not that expensive, and will make a huge difference in how reliable the system is. Yes, it will involve more tubing. Yes, you will see a psi drop. Keep in mind, however, that 6 psi after an intercooler can very easily make more power than 7 psi before an intercooler due to a more efficient charge, ability to run more timing, etc. I am yet to see a usable situation where an intercooler wouldn't be helpful in adding a bit of power, but more importantly make a set up more reliable, regardless of the boost level.
Tuning, imo, should be done for each individual vehicle, especially when dealing with boost in a high compression motor. That said, I understand what you(and any mass produced charged set up) are trying to achieve with a bolt on kit without needing extra tuning. Given that request, an intercooler would be even more appropriate, as it allows for a bit more wiggle room when it comes to ignition timing and such.
Long story short, I understand what you're trying to achieve, but I think you're trying to cut too many corners in places they shouldn't be cut to reach your budget. There is a better way, just make sure you have all the info available digested. The whole point of these forums is for the sharing of information so we can learn from one anothers' experiences and knowledge. Use that to your advantage so that you can better the product you want to put out.
