Going 20b, simple question. I'm debating between a large streetport or a semi-pp. 1.0 or 1.15? Don't want to push it much over 8k or at all. Going to be road racing with it if it makes a difference. Thanks.

thewird

 

Streetport. And a ride please.

 

Oh my post wasn't very clear. I'll be making the porting choice myself when the time comes to use the grinder. I was mostly wondering about the turbo A/R as I have no past experience in selecting turbo a/r's for the 20b.

thewird

 

1.32

 

+1

 

Why so big? What is the powerband going to be like?

thewird

 

If you are going a semi-port your powerband is going to be more midrange and top end, therefore they suggest bigger a/rs that match that powerband.

Personally I would stick with a medium streetport, the smaller GTX4294R, and a 1.15( or even better the 1.16 Tial Vband) with 4" exhaust. Then if you wanted to make your fabrication life easy you could even get our smaller GT40 compressor housing for the above turbo..

 

Why the 94 over the 102? I always wanted to try semi-pport but maybe I shouldn't do it off the bat on the 20b lol.

thewird

 

Faster spool and still enough airflow to make more power than you could EVER put down at the road course..

 

That is true but what I wanted to be able to hit 800 rwhp on pump with this setup just because . I even considered the 4508R but I think thats going overboard. I won't be running max at the track, I'd be happy with 600 rwhp just for the track but I'd like to be able to kick it up to 800 by raising the boost just for fun on the street LOL. I was going to use the Haltech P2000 to tune boost by gear so I'm not just spinning tires.

thewird

 

why not add a Racelogic to the mix?

 

Traction control would be boring. I've driven a GT-R on the track, I can fall asleep.

thewird

 

If I were you, I'd run exact turbo as this guys:

https://www.rx7club.com/20b-forum-95/740whp-645wtq-%40-18psi-962042/

the response and hp is documented on the track videos on youtube too.

 

Same turbo except I want the billet wheel ^_^. I'll probably use the 1.15 tial.

thewird

 

I'm pretty sure that he's running GTX4202 with 1.15 T6 turbine housing. You should come pretty close to his numbers even with the smaller tial housing.

 

Yes you should be good, there's a local running the same turbo , buddy of mine , 1.15 ar , your gonna love it especially when she spools

 

For road racing I would stick to a large street port and the 1.16. If you go semi-peripheral the 1.30 will become necessary.

 

Hmm, I'm starting think think about going a different route to get a broader powerband and keep the RPM down. What you guys think about a smaller GTX4294R and just crank up the boost? And I'll just forget about the semi-pp.

thewird

 

x2. . My friend competes in the Edmonton Indy against Wouters and his 20B. . .very balanced and potent setup. . .phone Marco at Force Fed Performance and talk to him about what you would like. . .extremely knowledgeable and a stand up guy. . .

 

That would be a better choice overall. You could even go with a slightly smaller turbo, like the 67 or 68mm GTX options.

The BW S467 billet turbo is also a very good choice, something to consider.

 

I'm not going with anything that small, since when does Garrett 67 and 68mm GTX wheels? Only interested in Garrett turbos's for this build.

thewird

 

A 67/68mm compressor would be enough for 700whp, plenty for road racing. You get more mid-range punch and quicker response from the smaller compressor.

They have been available for awhile now but they are special units and not advertised.

 

We've done a few 20B's here, mild street ports with 4202R's on TiAL 1.0 housings. They easily make 500whp around 9-10psi on pump gas. They keep pulling all the way up to 7500rpm which is where we choose to put redline on the street cars. They are responsive with decent low end making 300ft/lbs at or before 4krpm and 400ft/lbs or more at or before 4500rpm. 600whp is easily possible. T6's we've done were also all 1.0's and unfortunately were divided but they are still pretty responsive and make good power they are just big and heavy(46lbs).I'm not sure you need much bigger than a 1.0 for what you are trying to do. You could try a 1.15 but you need nothing bigger for sure. The TiAL is a nice unit combine it with a lightweight back plate and you have a winner for ease of packaging and weight(28lbs). You should be able to get away with a GTX4294 over the older GT4202R just by going off of maps but honestly the 4202's on 20B's running a TiAL 1.0 feel pretty much like 35R's on 13B's. As for the smaller compressor Garrett makes racing units that run machined down GTX4202 comp wheels in various sizes.

~S~

 

What would be the reason I would need to use a 1.15 on a 4202R? I do plan to be able to run higher boost at some point but I don't want to rev over 8k. I think I've given up on the semi-pp idea so it would just be a street port.

thewird

 

Honestly I see no need for the 1.15 other than trying to get better flow up top. I've made 896whp on a T6 1.10 13B Though I did run a much larger 96mm turbine, but if you know anything about what I post up I almost always favor larger turbine discharges over larger turbine A/r's.

If it were me and I wanted a responsive 650whp car at moderate boost levels. I would run a GTX42R/1.0 TiAL housing on a well sorted port designed for torque. The car will feel like a 35R car with better torque if done right. If you plan on truly racing that engine your biggest hurdles will be thermal management (oil/coolant etc) as well as proper build. I would certainly balance and clearance everything on it as well as consider pinning it. Some will say it's not needed most of those never tried running one around a track for extended periods of time at 650whp.

~S~