Thread: 400whp, Whats needed?

I would say do more research if u can't decide on a simple boost build, there shouldn't be much to think about if you have something in mind already imho

Let's try to be helpful here. I am noticing a lot of down talk which = no bueno.

Hobbs it's best to look @ the compressor maps. Also seems like your looking for a lot of area under the curve. But as a lot of helpful members have said here you have options as to how to get there it's just a matter of choosing.

Do you want more headroom for improvement later etc.

then run a boost controller. I ran wastegate most of the time which was around 8 psi and 18 psi under high boost. That was with a GT2871R, 540cc injectors, apexi power fc standalone, and custom FMIC. Anything is obtainable in the SR20 up to around 500whp and then you need to build the bottom. Oh yeah you better do a metal headgasket and arp head studs while your at it so it will hold together at those levels. With the proper time, money and effort you can have a very reliable 350-400 whp sr powered car and with a LSD in FWD or RWD configuration. That is fast as hell probably around 11 sec quarters and that is in mid 300 power range. Good luck with it.

i see u guys say running 20lbs daily is a bad idea, but shouldn't that only matter if your flooring it like all the time?

20psi is a lot to manage, mostly because of the heat it generates. The Gt2871r is a little bit of a mismatch turbo, like the GT3076r is. The turbine is small for the compressor flow rate imo and the best performing options are the ones which utilize the T31 turbine with a t2 housing. This is basically a GT3071r, but with a T2 housing, and these versions perform better for the 400whp range. Some even take them to nearly 450whp.

20psi creates a lot of backpressure, and with that large of compressor it increases backpressure even more (as opposed to a smaller compressor which turns with less energy). That is why you see GT2860rs turbos making so much power on such low boost. It is a very well matched turbo. Well, imagine taking the compressor from the GT3071r which is 11mm larger, and sticking it on the disco potato turbine. It works great! Just not as great as the disco in regards to overall response and output.

I'm not doggin on the 2871r, I'm just saying to get the right one. The 52 and 56 trim are the ones to get. The latter with the .86 housing will perform the best. Choking up a turbine to increase spool from a larger compressor is the wrong way to go. The larger housing is the best option in the real world, and the difference in spool is completely negligible. You can see tons of dynos on the net where ppl switch from the .64 to the .86 and don't lose any powerband past 3000rpm. The .86 will make around 20whp more on the same boost.

When you really start to push the setup is when you will find weakness. pushing more boost to get the power you want is great if you have a really good cooling system. Radiator and Intercooler upgrades are a must if you go this route. Larger turbos will make more power on less boost, lose some transient response as well. But the lower torque numbers will likely help prolong transmission life. So this situation is full of tradeoffs.

Coheed to the rescue!

And here it is again the best 400 WHP option you will ever find.


A GT28RS will make 360 WHP & 330 LB Ft Torque @ 17 PSI with mods listed above. I have done this combo about 10 times on customers cars.

A GT2871R will make 380 WHP & 330 LB Ft Torque @ 17 PSI with mods listed above. I have done this combos about 7 times on customers cars.

I would always get these turbos with a .86 ar turbine housing. Spools alittle slower but keeps exhaust temps down a bit while keeping the power band up top to hold longer in the RPM band.

I have a guide line to keep things 100% safe. There is alot of give but this is just a guide line. keeps things idiot proof.

1-16 PSI 93 octane
16-22 PSI 97 octane


5 gallons of 93 + 1 gallon C16 = 97 octane

Now if you have your boost controller set at 15 PSI low boost and make 365 WHP with your GT2871R. The car will run 12.1-11.8 at 116-118 MPH. If thats not a safe and fun daily driver then, I dont know what to tell you guys.

On days you want to go race and have some serious fun, go up to 20-22 PSI and run some 11.7-11.4 @ 123 125 MPH 1/4 mile times. Buy a 5 gallon drum of C 116 and it will last you for a month of fun once a week. 6 gallons of 97 octane is good for more than 40 1/4 mile runs street or race.

Happy huntings.

QFT, listen to this guy.

i have made sick power with a roller rocker every one just follow what others say and refuse to try for them self

I like the RR motor actually. Not a fan of the bottom end for boost because it has no girdle and is not as stable.

I just did my friends 2002 G20S which has a RR head and JWT S3R cams. I put on a W10 SR20DET short block under the RR head with GT2871R and 3 inch exhaust and it actually made more WHP than any other head setup to 12 PSI other than the SR20VE head.