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First off let me preface by saying this is not a street driven car, It’s a race car used exclusively for SCCA RallyCross, essentially an AutoCross on dirt where every run counts for cumulative time. We (myself and co-driver) run in the Modified 2wd class where almost anything goes for drivetrain. The car is fast, National Champion last year and second this year so it’s no slouch in current form but it needs more oomph, we are one of the lightest cars but also one of the lowest HP. We just don’t have the pull out of slow corners others such as Sentra SE-R’s have.
Current setup: D15B2 bottom end, rebuilt but essentially stock with a D16Y8 top end complete with intake, head milled .040”. According to the Zeal calculator it’s around 11.8:1 but understanding it’s off some because of the altered head volume. AEM cam gear to account for the deck height change, DC header, AEM dryflow intake. Running on S300 P28 and 101 octane race gas. Made 107 hp at the wheels at 6300 rpm and 94 ft lbs at 5500 rpm with a fairly flat torque curve with 80 ft lbs from 2300 rpm. Definitely a very modest budget build.
Goal is to get approximately 160 hp and around 140-150 ft lbs of torque as low as possible. Much more than that we probably couldn’t put down in the dirt and may make it harder to drive smoothly. We could certainly hit the HP goals with a further built NA motor but I don’t think we could see similar torque gains. After further researching options such as 90civichillclimber’s build it looks like a high compression, small turbo setup is the way to go. Looks like we could put together a setup that spools super quick and essentially drives like a NA car with power building fairly linearly. Of course we’re trying to keep things reasonable cost and can’t go too crazy. Reliability is also a huge priority since runs are cumulative. Car has only had one mechanical DNF in 7 years and it was broke axles.
Is the torque and low end goal realistic? Would a turbo motor fall on it's face at higher RPM's? I don't mind a plateau, just not a cliff.
So far I’m thinking stick with the Y8 head, intake mani and cam, should be fine for the goals. DSM 450 injectors. Generic charge piping should work, small is good. Maybe step up a bit from eBay for the intercooler.
So, since I’ve never built a turbo setup, my questions are:
Stick with the current long block and maybe a thicker headgasket and ARP head studs as theoretically the stock rods might be ok for the HP goal? Second option but more $$ is to find a D16Z6/Y8/Y7 builder. Buy new high compression pistons and H-beam rods, might make me feel a little better for reliability but is it really needed for the stated HP goals?
Cast Manifold for faster spool, is the Go-Autoworks mani really worth double a eBay manifold? I like the central wastegate port, with a small turbo I’d like to keep it as close to the block as possible to retain a full size rad. There’s also a Greddy mani on CL nearby.
Big item is what turbo to use, I keep coming back to a small Tubonetics T3 with ball bearings for faster spool but it’s pricy, for the modest power goals would any number of the various DSM, EVO, or other OEM turbos serve us as well and save bucks for another area? I’ve only seen a few non-T3 manifolds and I think they were T-25 what the best option for a non-standard flange turbo?
Is there significant benefits between name brand BOV’s and Wastegates over the cheaper no-names? Are you just paying for bling factor on the name brands?
Meth/water injection have any benefits at these power levels? It would be really easy to recharge a small reservoir after each run. For that matter why not run water/air intercooling vs. air to air?
Thanks in advance, I haven’t found a build with goals like this yet and maybe for good reason. I’m most concerned if the torque goal is attainable. If there is a better alternative I'm all ears.
Current setup: D15B2 bottom end, rebuilt but essentially stock with a D16Y8 top end complete with intake, head milled .040”. According to the Zeal calculator it’s around 11.8:1 but understanding it’s off some because of the altered head volume. AEM cam gear to account for the deck height change, DC header, AEM dryflow intake. Running on S300 P28 and 101 octane race gas. Made 107 hp at the wheels at 6300 rpm and 94 ft lbs at 5500 rpm with a fairly flat torque curve with 80 ft lbs from 2300 rpm. Definitely a very modest budget build.
Goal is to get approximately 160 hp and around 140-150 ft lbs of torque as low as possible. Much more than that we probably couldn’t put down in the dirt and may make it harder to drive smoothly. We could certainly hit the HP goals with a further built NA motor but I don’t think we could see similar torque gains. After further researching options such as 90civichillclimber’s build it looks like a high compression, small turbo setup is the way to go. Looks like we could put together a setup that spools super quick and essentially drives like a NA car with power building fairly linearly. Of course we’re trying to keep things reasonable cost and can’t go too crazy. Reliability is also a huge priority since runs are cumulative. Car has only had one mechanical DNF in 7 years and it was broke axles.
Is the torque and low end goal realistic? Would a turbo motor fall on it's face at higher RPM's? I don't mind a plateau, just not a cliff.
So far I’m thinking stick with the Y8 head, intake mani and cam, should be fine for the goals. DSM 450 injectors. Generic charge piping should work, small is good. Maybe step up a bit from eBay for the intercooler.
So, since I’ve never built a turbo setup, my questions are:
Stick with the current long block and maybe a thicker headgasket and ARP head studs as theoretically the stock rods might be ok for the HP goal? Second option but more $$ is to find a D16Z6/Y8/Y7 builder. Buy new high compression pistons and H-beam rods, might make me feel a little better for reliability but is it really needed for the stated HP goals?
Cast Manifold for faster spool, is the Go-Autoworks mani really worth double a eBay manifold? I like the central wastegate port, with a small turbo I’d like to keep it as close to the block as possible to retain a full size rad. There’s also a Greddy mani on CL nearby.
Big item is what turbo to use, I keep coming back to a small Tubonetics T3 with ball bearings for faster spool but it’s pricy, for the modest power goals would any number of the various DSM, EVO, or other OEM turbos serve us as well and save bucks for another area? I’ve only seen a few non-T3 manifolds and I think they were T-25 what the best option for a non-standard flange turbo?
Is there significant benefits between name brand BOV’s and Wastegates over the cheaper no-names? Are you just paying for bling factor on the name brands?
Meth/water injection have any benefits at these power levels? It would be really easy to recharge a small reservoir after each run. For that matter why not run water/air intercooling vs. air to air?
Thanks in advance, I haven’t found a build with goals like this yet and maybe for good reason. I’m most concerned if the torque goal is attainable. If there is a better alternative I'm all ears.
...90hillclimber bought my old gt17 setup to use and he can confirm the fact it insta spools, its like a supercharger, it was awsome ran it for a couple years...15psi out of that little bugger will give you more than you could want...my setup was also good for mid 13's in the quartermile so it had some umph to it
