Clifton Posted March 29, 2006 Share Posted March 29, 2006 Yes you will be hitting a wall even with those mods. They may help but the turbo is the big problem. Airflow is HP. The turbo has to support the airflow/power needed. If you have MS and 420's I would be thinking about a turbo upgrade. The silver one is the 7M car, 533 rwhp. Quote Link to comment Share on other sites More sharing options...
evildky Posted March 29, 2006 Share Posted March 29, 2006 if you've got a decent I/C you can run 20 psi with either turbo, hell I ran 20 psi through a crappy I/C and it still had intake temps in the 120 range max!, I haven't logged with my new set up but I can tell you it's cooler of course I've only run 14.7 on the new setup as I've not added the boost controller yet Quote Link to comment Share on other sites More sharing options...
Pyro Posted March 29, 2006 Share Posted March 29, 2006 A T3 at 15 psi is not a good match for a 2.8 with stock cam. I managed 368 rwhp at 15 psi with a stock n/a cam with a full T4. Same boost with a T3 or T3/4 would be 100 hp less. I'm not talking about max power, I'm saying a T3 is a good match for the stock cam. The T3 comes on full boost as early as 2500 rpm and will pull hard to 5000. A 2500 rpm power band which is nice on the street. A straight T4 on a L28 will only start to build boost at 3500 and maybe get max boost by 4000 rpms then the cam is done by 5000. Not a good street engine with a very narrow power band. Sure, a T4 could make more peak power even with the stock cam but that isn't the only way to determine a good matched setup. Try comparing the torque and hp of a straight T3 versus a straight T4 on a L28 at from 2500 to 3500 rpm. Quote Link to comment Share on other sites More sharing options...
Guest 280ZForce Posted March 29, 2006 Share Posted March 29, 2006 I'm not talking about max power' date=' I'm saying a T3 is a good match for the stock cam. The T3 comes on full boost as early as 2500 rpm and will pull hard to 5000. A 2500 rpm power band which is nice on the street. A straight T4 on a L28 will only start to build boost at 3500 and maybe get max boost by 4000 rpms then the cam is done by 5000. Not a good street engine with a very narrow power band. Sure, a T4 could make more peak power even with the stock cam but that isn't the only way to determine a good matched setup. Try comparing the torque and hp of a straight T3 versus a straight T4 on a L28 at from 2500 to 3500 rpm.[/quote'] on my stock turbo motor I was running a full t4 and was pulling boost by 3k rpms. Quote Link to comment Share on other sites More sharing options...
Pyro Posted March 29, 2006 Share Posted March 29, 2006 What is pulling boost? Full boost are starting to make boost at 3000? A T4 exhaust tubine on a 2.8L takes a certain amount of rpms to make full boost. I have seen full t4's run on completely stock turbo engines and they only make 1 psi at 3500 and full boost by 4000. If you are getting boost at 3000 with a T4 turbine then I would say your setup isn't typical and you have done a fantastic job tuning your engine. Even my little T3 housing with a higher flow turbine takes 3500 rpm before full boost and only starts to make boost at 3000. And even this was too high a rpm for the stock cam. 1500 rpms on full boost was to short for me. So I had to upgrade to a bigger cam (MSA stage 1 turbo cam) that could make power to 6000. In hindsight, I would have stayed with the stock cam and the T3 turbo since I drive the car mainly on the street. My car was much more pleasant to drive on the street with 14 psi of boost, stock cam, and stock turbo. As you can tell, I'm not a big fan of turbo lag. Quote Link to comment Share on other sites More sharing options...
Guest 280ZForce Posted March 29, 2006 Share Posted March 29, 2006 What is pulling boost? Full boost are starting to make boost at 3000? A T4 exhaust tubine on a 2.8L takes a certain amount of rpms to make full boost. I have seen full t4's run on completely stock turbo engines and they only make 1 psi at 3500 and full boost by 4000. If you are getting boost at 3000 with a T4 turbine then I would say your setup isn't typical and you have done a fantastic job tuning your engine. Even my little T3 housing with a higher flow turbine takes 3500 rpm before full boost and only starts to make boost at 3000. And even this was too high a rpm for the stock cam. 1500 rpms on full boost was to short for me. So I had to upgrade to a bigger cam (MSA stage 1 turbo cam) that could make power to 6000. In hindsight' date=' I would have stayed with the stock cam and the T3 turbo since I drive the car mainly on the street. My car was much more pleasant to drive on the street with 14 psi of boost, stock cam, and stock turbo. As you can tell, I'm not a big fan of turbo lag.[/quote'] i'm starting boost around 3k rpm...it's been about 3 months since I've driven my car cuz I severly broke my arm, so I forget about when I'm hitting full boost by. but I've got the mods in my sig. Quote Link to comment Share on other sites More sharing options...
Clifton Posted March 29, 2006 Share Posted March 29, 2006 A 2500 rpm power band which is nice on the street. A straight T4 on a L28 will only start to build boost at 3500 and maybe get max boost by 4000 rpms then the cam is done by 5000. Not a good street engine with a very narrow power band. Sure' date=' a T4 could make more peak power even with the stock cam but that isn't the only way to determine a good matched setup. Try comparing the torque and hp of a straight T3 versus a straight T4 on a L28 at from 2500 to 3500 rpm.[/quote'] True it spools later but the stock cam will work. Torque between 2500 and 3500 doesn't matter unless I'm towing. This is with a stock cam and exhaust manifold, stock bore and stroke, actually it is an unkown junk yard motor with stiffer valve springs. Full T4 (O trim turbine).Yes it comes on later but it makes up for it and I have more than a 2500 rpm power band. Almost an extra 1000 rpms over your 2500 rpm power band. Quote Link to comment Share on other sites More sharing options...
Pyro Posted March 30, 2006 Share Posted March 30, 2006 Nice looking dyno. Looks likes your engine starts making decent power at 3500 and power starts falling off at 5500 to 5700. I guess those heavy springs are giving a few more rpms. However, torque is very low at 3000. A stock T3 would be about twice as high. I guess it all depends on your defination of a good match. To me, it seems like your engine would really make some serious power with a cam swap. Quote Link to comment Share on other sites More sharing options...
Clifton Posted March 30, 2006 Share Posted March 30, 2006 It falls off a little but still makes as much at 7k as it does at 5.5k, probably 5k if it didn't have that funny dip.. Ya, I have a cam sitting there just waiting to go in. Smaller turbos do make more torque way down low but how many times have you needed all that torque at 3k? It's like prefering a Harley and it's low power output over an R1 just because of the bottom end torque. Quote Link to comment Share on other sites More sharing options...
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