paulmoore

Ok, I have posted in a few other forums, and really haven't gotten any help. Now, I know that this isn't technically a 3rd gen, but the information that is on this site is quite immense, and I am proud to say that I am a part of it. I am going to be doing a 2.2L 16V DOHC turbo engine that I will be dropping into my ... ummm... camaro... yeah, and am having a hard time finding out which turbo to run. I have done all the math and some things just aren't adding up. I am planning on getting about 300 crank HP with 15 PSI of boost. First you have to convert your engine's CFM. Here are the numbers that I have...

2.2L T22SED CID=134.32
(CIDxRPM)/3456= CFM
in this case at....

2000 RPM-77.73
3000 RPM-116.60
4000 RPM-155.46
5000 RPM-194.33
6000 RPM-233.20

Now, that is assuming 100% VE, which we don't have. Most engines usually get between 80-90% so I will use 85% as my reference VE. SO to get the corrected CFM numbers, you simply multiply by .85 so that puts it at....

2000 RPM-66.10
3000 RPM-99.11
4000 RPM-132.14
5000 RPM-165.20
6000 RPM-198.22

Now, to convert the corrected CFM into lbs/min, you simply multiply by .069 and now the new figures are....

2000 RPM-4.60
3000 RPM-6.84
4000 RPM-9.12
5000 RPM-11.40
6000 RPM-13.68

So you would just use those numbers at the x axis..

Pressure ratio...

(P1+P2)/P2=Pressure ratio

P1 is desired boost in PSI, in my case 15 PSI, and P2 is atmospheric pressure ie. 14.7 PSI

AT 15 PSI of boost, my pressure ratio is 2.02. Use this number on the Y axis and now we can plot on the compressor map graph. Needless to say, I have looked at alot of turbos from T25 and T28's to Super 60 T3's, T4's, To4E and To4B's with no luck, they just don't seem to fit. The closest one that I have come across has been the T3-40 trim. I took a trip over to bimmerforums. They are a BMW website that had some info on turbos over there. They had a post about some things, one of them being how to see what the turbo will look like as it spools up on the compressor map. Let's see if I get this right. What you do is take your corrected Lbs/min at 2000 RPM(in my case 4.60) and then find the pressure ratio of 1.0 and make a dot. Then, you find the LBs/min for 3000 RPM, and the pressure ratio that the engine will see at max boost(in my case 15 PSI or a pressure ratio of 2.02) and make a mark there. Now, you connect those two dots and you can see how the turbo progression is while it is building boost. Let's see if my modified compressor map will load. Sorry if it looks a little crappy...



I also plotted the points for 4k, 5k, and 6k and I was quite amazed. Aside for the point at 3000 RPM where the mark is to the left of the surge limit, this engine stays pretty darn efficient. Once 4k comes around, it starts pulling. At 5k, the turbo is in it's peak efficiency range, and stays there until redline at 6k. Not too shabby. I am curious though, how bad is it going to be for the turbo to be slightly off the surge line while the engine is revving up? I am not looking to damage anything. So far my searches have not revealed anything that would tell me for certain if turbo damage would result due to that one fact. So what do you guys think, is this a good turbo to chosse for this application? I am hoping it is. Th only thing that bothers me is the 2k to 3k spool progression. You can see as the RPMs go up from 2k, the turbo is at least in some sort of efficiency island. As the engine approaches 2700 RPM(maybe??) is when it goes off the surge lne. It isn't unitl about 3200 RPM(maybe??) that it gets to the right of the surge line and all is well. So for that 500 RPM, can this thing grenade? Or is it possible that the 500 RPM will rev past so quickly that it won't matter? I am just trying to get all these things in some sort of order. Any help or info is greatly appreciated. Thanks again, Paul M

welby

Try this
http://www.squirrelpf.com/turbocalc/index.php

Is this a Turbo Mopar? If so what top end are you running? TIII top ends seem to be tempermental, Neon DOHC swaps are currently the big thing and people seem to be figuring them out pretty well. If it's a Maserati head then put it in a hermetically sealed case.

In any case check out http://www.turbo-mopar.com. These guys know their stuff.

paulmoore

Actually it is a Daewoo engine. I know, you can laugh if you want, I am used to it. I am putting it in my sunbird. After doing some more calculations and talking to some turbo companies, I have decided on going with a TO4E 50 trim turbo. Not sure if I am going to do the .48 or .62 A/R for the turbine side. The smaller .48 will help with lowering the spool time. A ball bearing center cartridge will also help lower the rpm at which boost is created.

askulte

There doesn't seem to be much info floating around regards to the surge limit line. Theoretically, the turbo just won't go there (too much of a restriction on the outlet, so not enough shaft power to make that pressure). Similar to closing the throttle on a fully spooled turbo (even the best blow off valve will spike pressure as the flow is blocked). Not sure if I'm getting it exact, so someone feel free to correct me. If you really want to stay out of there, you can use a programmable wastegate controller to limit full boost until 3500 rpms. My opinion - don't worry about it.