Introduction, and turbo sizing for autocross question
10-17-2011, 06:45 PM
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Introduction, and turbo sizing for autocross question
Hello HMT. It's been a long time since I've visited this site. Back in the early 2000's, I ran turbo on my racecar for a few years, then decided to get serious and build it all-motor for SCCA E Prepared class. The car is an 86 Civic, with the 1.5 EW motor. I've had a lot of success with it in EP, even winning the National Championship in 2008 and 2009. I've grown a little bored with trying to keep the little 1.5 motors together at over double their original output in N/A form - I was getting 148whp from a motor rated 91 at the crank.
Anyway, I've decided to make a big change and build the car for X Prepared. The ultimate goal will be to convert to a AWD drivetrain, but I'm going to have to stage things out a little, so my plan for the winter is to build a new turbo motor and see how competitive the car is in FWD format (we do get a pretty big weight break).
The motor I'm building is a D16A1 DOHC motor, choosen because I was already running Integra transmissions, and because the mounts all line up with the 86 Civic body. I also love the way the twin cam motors look. The motor will get a proper race build, with forged internals, new valvetrain, ported head, etc. Compression will be about 9.5:1 with the pistons I am planning to use. No worries about the motor build. The fuel will be E85, delivered by 560cc EVO injectors (I think) and controlled by a crank trigger Megasquirt system already in the car. I've already been running E85 on the all-motor setup.
Right now, I'm trying to decide on a turbo, so I've been reading a bunch of compressor maps and seeing what is out there these days. Since the car is only 1536lbs (min weight - easily acheivable in this car), I don't need huge horsepower. My main goals are instant torque, excellent throttle response, and good drivability. I'd like to see 200ft lbs or more, from a low rpm on up, which puts the peak hp around 300 at high rpms. I'm less concerned about the hp falling a little at the top vs having to wait on the turbo to spool. I'd like to see significant boost by 3500rpm, and plan to spin the motor to 8500, but don't expect to need to very often, as it will be geared to go 70 in 2nd with an Accord 3.78 FD in the transmission.
Looking at compressor maps, I keep coming back to either a 50 or 60 trim T3 with a .48 exhaust. I can find 50 trim T3's very cheap on ebay (obviously team china, but I'm not sure if that is a problem these days). I can't seem to find a 60 trim T3 anywhere. Lots of listings for them, but the actual dimesions look more like a T3/T4 hybrid than a real T3 60 or Super 60. The GT2860 looks good, but pricy and water cooling adds complexity. I will be building my own manifold, so flanges aren't a big concern. Packaging is very tight on this car - much less space than even and EF Civic. Weight is also a concern, so if there is an option that is significantly lighter than a T3, I'd be interested in knowing about it. The T3 stuff is easy to package, and I have experience with them, but it seems like there might be better options.
Any ideas or suggestions would be appreciated.
For reference, here is a link that shows the car in action at a Pro Solo this year. Now, imagine what it will be like with double the power.
http://youtu.be/78RWAW_ut08
Thanks - Chris
Anyway, I've decided to make a big change and build the car for X Prepared. The ultimate goal will be to convert to a AWD drivetrain, but I'm going to have to stage things out a little, so my plan for the winter is to build a new turbo motor and see how competitive the car is in FWD format (we do get a pretty big weight break).
The motor I'm building is a D16A1 DOHC motor, choosen because I was already running Integra transmissions, and because the mounts all line up with the 86 Civic body. I also love the way the twin cam motors look. The motor will get a proper race build, with forged internals, new valvetrain, ported head, etc. Compression will be about 9.5:1 with the pistons I am planning to use. No worries about the motor build. The fuel will be E85, delivered by 560cc EVO injectors (I think) and controlled by a crank trigger Megasquirt system already in the car. I've already been running E85 on the all-motor setup.
Right now, I'm trying to decide on a turbo, so I've been reading a bunch of compressor maps and seeing what is out there these days. Since the car is only 1536lbs (min weight - easily acheivable in this car), I don't need huge horsepower. My main goals are instant torque, excellent throttle response, and good drivability. I'd like to see 200ft lbs or more, from a low rpm on up, which puts the peak hp around 300 at high rpms. I'm less concerned about the hp falling a little at the top vs having to wait on the turbo to spool. I'd like to see significant boost by 3500rpm, and plan to spin the motor to 8500, but don't expect to need to very often, as it will be geared to go 70 in 2nd with an Accord 3.78 FD in the transmission.
Looking at compressor maps, I keep coming back to either a 50 or 60 trim T3 with a .48 exhaust. I can find 50 trim T3's very cheap on ebay (obviously team china, but I'm not sure if that is a problem these days). I can't seem to find a 60 trim T3 anywhere. Lots of listings for them, but the actual dimesions look more like a T3/T4 hybrid than a real T3 60 or Super 60. The GT2860 looks good, but pricy and water cooling adds complexity. I will be building my own manifold, so flanges aren't a big concern. Packaging is very tight on this car - much less space than even and EF Civic. Weight is also a concern, so if there is an option that is significantly lighter than a T3, I'd be interested in knowing about it. The T3 stuff is easy to package, and I have experience with them, but it seems like there might be better options.
Any ideas or suggestions would be appreciated.
For reference, here is a link that shows the car in action at a Pro Solo this year. Now, imagine what it will be like with double the power.
http://youtu.be/78RWAW_ut08
Thanks - Chris
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