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turbo comparison


you can get a 2871 with a .64 AR exhaust housing , the 2871 will allow you to run up to 35lbs of boost where as the 28RS efficiency runs out around 26lbs. Call Ted Jannetty as he is the best guy to talk to regarding this and sells anything you might need .
 
The .6 you were refering to was probably the .60A/R of the compressor housing. All three compressor wheel trim sizes use the .60 A/R housing. Their difference between the 2871 compressor options are their wheel trim sizes which are 48,52, or 56. All are 71mm OD. We used the 56 and it is my favorite. The compressor wheel on the 2860RS is a 60mm OD with a 62 trim.
On the exhaust side there is the .64 A/R housing that ProstockBenji mentioned as well as a .86 A/R housing. When we were running the 2871, we used the .86, and really liked it. The .64 should theoretically spool faster but make more back pressure. The hot section and options are basically the same between the 2860RS and the 2871. Of the different turbos we have ran, the 2871 56 trim with a .86 A/R turbine housing is my favorite ;)! . Big gain over the 2860RS. If you are interested in the different options you can see them here. http://www.turbobygarrett.com/turbobyga ... _sheet.htm
When it comes time to choose one, definitely give someone like Ted a call.
 
I whole heartedly agree that the .64A/R should be faster to spool, and should be "quicker" in most cases. I disagree with the statement that "the .86 will need more boost to make the same power". If any thing I feel it should be the other way around. The .64A/R will make more backpressure at high boost, which would put it at a "slight" dissadvantage (again, at high boost). A couple of years ago we sold our old .86 28RS to a buddy that had a similar setup as us. The spool with our old turbo was about the same as his, but power was definitly up and it could build a couple of pounds more boost compared to his .64 A/R.
Having said that, I agree that for most applications the .64A/R is probably a better choice. For all out power with a 2860RS or a 2871 I would still use a .86A/R.
 
There is no way the .64 makes more power then the .86. The larger the turbine housing, the less back pressure, the more potential power. This is basic stuff. Yes, the smaller a/r might be better for 660' simply because of the bottom end you loose with the larger .86. If you spray, you should be able to compensate for that lag and reep the top end benefits of the larger a/r. And saying mph was up in comparison of the two shows that the .86 makes more power. No offense, but there are turbo designers that have tested, tested, and tested as you say, a lot more then you, and any one of them will tell you that the larger a/r will produce more power.
 
I don't need to test it, Garrett turbocharger engineers have already done that for me. What would be the purpose of offering a larger a/r on the turbine housing if the only thing you get is increased lag? It just doesn't make sense. But common turbo sense will tell anyone the larger the a/r the more power you can acheive. It's all about back pressure, make back pressure less with larger a/r, equal length headers, porting, more effecient turbine housings...all this reduces back pressure and allows for more power. I've tested several different turbo's on cars (from a Mitsubishi 14B, EvoIII 16G, Garrett 50 trim, Garrett 60-1, GT35R (produced 470 awhp on pump with a 2L 4 banger). On a Snowmobile I've had a Evo III 16g, Aerocharger, Gt25r, Gt2871. So I know a little about turbo's. I don't need to know much to say that the larger the a/r the more hp you will have. Regardless if it's a rx-1 or anything else.
 
The nice thing here is we can agree to disagree . We tested as well and the 28RS with the .86 was easily faster than the .64 "on the sled it was on". With the car, we have always used n20 to spool so spoolup has never been a concern for us. On the car we went from 20# to 25# and went from running 9.1's to a best of an 8.81 and mph went from 146mph to 154mph. That is a LOT more than a 15 hp gain. I do believe that the .64 probably does start loosing efficiency after 20#, but that the .86 does the same but not until about 24 #'s (read backpressure). That's probably why we picked up so much more than the 3hp/# that you found. Had we gone from 24# to 28# we would probably have seen something more in line with what you did. Without comparing details such as head mods, cam timing, ignition curves, header design, etc it's not a direct comparasin. I have to admit that I never tried the .64 on the 2871 because of how well the .86 had worked for us on the 28RS. We are playing with 30 series stuff now, but every time I do something to decrease backpressure in relation to boost, with any of the turbos we have ran, we have picked up MPH and dropped ET.
Were you working with Mark at Supreme on the MSD stuff or did you do your own? We've had the MSD since the summer of 2005 and I don't think we would have progressed as far as we have without it. With the turbo stuff, obviously what you are doing is working for you and that's great. ;)! Oh and those are some wicked looking sleds you guys are putting together, even with the cat plastic.
 
Well Jim, I own you thanks for your efforts in making the MSD work on these motors :flag: . Like I said "I don't think we would have progressed as far as we have without it." As for the turbo stuff, if we were all doing the same thing it would be boring. It's boost, and it's all good. ;)!
 
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