Adam S. Posted August 19, 2004 Report Share Posted August 19, 2004 `Gents' I'm rebuilding my engine. I don't have the exact specs but I can print them if it's required. Simply I'm increasing the compression and capacity of my pistons (probably 3.2) It will have the forged pistons, and dynamically balalnced bottom end with roller rockers and a mild cam. So the engine will rev quite a bit. Now for the question: I've read that the T28 is the best, some others talked about the T3, are there any new developments in turbo sizing? Anyone know the website that shows the efficiency charts and turbo selection based on engine capacity, rpm etc. It was printed in car and driver back in 2001. Thanks Adam S. Quote Link to comment Share on other sites More sharing options...
Guest TurboSedan Posted August 19, 2004 Report Share Posted August 19, 2004 why would you increase the compression? it's too high as it is IMO. using a T28 would allow you to keep a stock crossover pipe. a T3 would be much better suited to a 3.1L V6 engine but you'll need a custom crossover with a T3 flange, as well as a custom downpipe and oil/coolant lines for the turbo. btw, if you really want to make that sucker rev throw a 2.8 crank in it the 2.8 crank is probably stronger than the 3.1 crank, has a better rod/stroke ratio, slower piston speed, and the piston will be at TDC for a shorter period of time which may help decrease the chances of knock. Quote Link to comment Share on other sites More sharing options...
Beretta Posted August 20, 2004 Report Share Posted August 20, 2004 So the T 28 will just bolt up to the crossover with no problem ? Todd Quote Link to comment Share on other sites More sharing options...
FastSE2DR Posted August 20, 2004 Report Share Posted August 20, 2004 compression doesnt matter as long as you have a good tune and good cooling...its all about setup not about how high the compression ratio is...less boost for the same amount of power, less spool up time, better powerband...you should run as much compression as you can oh yeah for turbo go for a little T4 Quote Link to comment Share on other sites More sharing options...
gp90se Posted August 20, 2004 Report Share Posted August 20, 2004 compression doesnt matter as long as you have a good tune and good cooling...its all about setup not about how high the compression ratio is...less boost for the same amount of power, less spool up time, better powerband...you should run as much compression as you can oh yeah for turbo go for a little T4 i disagree entirely. If you run the compression around 8.2:1, you can run a shitload more boost and pul a lot more timing out, which means more power. higher compression with boost is bad because you will ping faster with less boost and having a lot more total compression to make power with, which in turn means less power. I would go with either a disco potato (ballbearing t28 with little lag and killer top end), or with a new crossover and oil/cooling line, a t3/t4 which will be cheaper then a disco potato and have a better top end but lag some off the line -Jeff Quote Link to comment Share on other sites More sharing options...
Guest TurboSedan Posted August 20, 2004 Report Share Posted August 20, 2004 So the T 28 will just bolt up to the crossover with no problem ? Todd yup, the T25/T28 has the same exhaust inlet flange (crossover flange). the T3 flange however is noticeably larger and the bolt holes wouldn't line up at all with a T25 turbo or vice versa. this is my TGP Garrett T-25 turbo compared to my Garrett T3 turbo that my Lebaron GTS uses: http://www.turbosedan.com/cutlass/tgp_parts/T03vsT25.jpg exhaust inlet flange: http://www.turbosedan.com/cutlass/tgp_parts/T03vsT25-1.jpg note: my T3 turbo has a Chrysler specific bolt pattern - you can see that one of the lower bolt holes is offset....but otherwise it is a standard T3 flange. it's kind of ironic that my 2.2 4 cylinder engine uses a MUCH larger turbo than my 3.1 V6. the 'comparison pics' i posted don't really show how much different they really are....if you were to hold both turbo's with your hands and directly compare them in person you'd agree that the T3 turbo is wayyyyy bigger than the T25 i guess ASC/Mclaren chose the dinky little T25 for the TGP to help eliminate lag, but they did it to a fault IMO. i've actually thought about using my Garrett T3 turbo with my Turbo 3.1 but i've never looked at a compressor map or anything like that... fwiw, 8.2:1 compression ratio with a hybrid T3/T4 sounds like a killer combo i'd like to try using a 2.8 crank with that...i betcha that thing would scream on the top end. Quote Link to comment Share on other sites More sharing options...
TurboZ24 Posted August 20, 2004 Report Share Posted August 20, 2004 I've actually settled on a T3 .48 A/R stage 2 turbine / T04E 46 trim compressor for a 3.1 turbo project car (The turbo Cavalier Wagon). The compressor map is an excellent fit for the 3.1 and the turbine should allow enough exhaust flow for upto 300 crank HP no problems, but only time will tell of course. I sent one to someone else with a 3.1 turbo setup and he says it works extremely well. http://www.turboz24.com/Wagon/P8030067.JPG There is a pic (there is a lot more done to it now, just too lazy to take a pic....) Quote Link to comment Share on other sites More sharing options...
Jcrow Posted August 20, 2004 Report Share Posted August 20, 2004 I have a 3.8 grand national turbo about to go on a 3.1 It has .60 cold and .63 hot side. I am not sure but I think it is T3/T4 Quote Link to comment Share on other sites More sharing options...
Adam S. Posted August 21, 2004 Author Report Share Posted August 21, 2004 Thanks guys. I'm thinking of 9:1 with forged pistons, and than get a bigger turbo, and up the pressure. Probably a T3. They do sell these new don't they? I'm not a fan of rebuiliding these. Adam S. Quote Link to comment Share on other sites More sharing options...
FastSE2DR Posted August 21, 2004 Report Share Posted August 21, 2004 how good are the stock rods on these cars? Quote Link to comment Share on other sites More sharing options...
Canada Posted August 22, 2004 Report Share Posted August 22, 2004 I have a 3.8 grand national turbo about to go on a 3.1 It has .60 cold and .63 hot side. I am not sure but I think it is T3/T4 Thats a T3 Super 60. A friend of mine used that turbo on his Probe GT (2.5L V6 on 5-6 psi)......worked quite nicely (matched an S4 from a 20 mph till just past 100 mph) until he took out a light pole. I'd have to agree with FastSE2Dr on the entire compression ratio thing......I don't see the advantage in lower N/A power output to increase boost. You'll end up with the same total output only with a motor that sucks to peg leg around town. Remember, these aren't Supras. I'd rather see the turbo setup correctly.....trying to keep as much heat in the exhaust until the turbine and then dumping it promptly at the turbine......trying to keep the exhaust pulses as seperate as long as possible (have the banks meet at the turbine)....having a good fuel and ignition system....there are so many ways to effect power on a turbo motor. The rods flat out suck.......they are a forged I-beam rod.....but dinky little shits about the size of my index finger. I don't know if I would go through all the trouble of destroking a 2.8L for more revs....the stroke isn't the problem.....the valve train is. GM says a max of 6200 rpm....and just look at the 3.4 X motor (same basic bottom end and same stroke as a 3.1).....7k isn't an issue. How are you guys calculating mass air flow for the compressor maps? I made this spreadsheet...... http://www.berettaspeed.com/canada/mass_air_flow.xls Mike Koijima's math is just to weird and picky.....I usally stick with the table on the left. Quote Link to comment Share on other sites More sharing options...
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