FromSilvia2seven

Ever since i saw the hot version Battle at 10,000 rpm NA 20B has been i my mind if i end up keeping my car that long. Sounds really nice and the power delivery is smooth and at close to 400whp for a street. what more could you ask for?

Jumbogumbp

Hmmm I didn't even think of useing some s5 na rotors in there.... I think I'll be budgeting them in also.. along with some custom beveling of the rotors... on a side note... I put one of my na s4 motors in my other fc and damn I love the feel of an n/a granted my t2 would blow it out the water... the n/a just felt better... more responsive I guess.. then again it's street ported with a rb header and track pipe to a single can. I'll update this later once I've figured out what I'm going to do, then I'll drop a price list and I'd apretiate it if some of you can critique it so I can see if this is gonna be what I really want to do... oh yea and thanks for all the responses.. they've been helpful!

GUITARJUNKIE28

i'm not bashing on the streetability...especially when i used a turbo bridgeport as a daily driver.

but do you know what it costs to make a 3 rotor capable of 10k rpm?

recon fd

^ agreed. This is my vote even though I love the 20B

-josh

spintriangles

iTrader: (3)

I know this an old thread but we are now in 2019. Does anyone think anything has changed? We now have faster boosting turbos but we also have some guys making good power with 20b na motors

gmonsen

I am somewhat reluctant to chime in here, but will anyway. I love the NA 20b and have spent a lot of time working on different things with them. I would say that, if you would be happy with about 350 whp, the 20b is a great alternative. Its a great motor. Pulls great and is extremely reliable. Plus it weighs less as installed than the usual single turbo 13b setup. I made 397 whp with mine but heard a little pinging and backed off the power to about 375-380. But 350 is a good number that is attainable without spending a fortune. Defined Auto made 425 with an extreme 20b before going to 4 rotors.

Montego

iTrader: (1)

RIP guitarjunkie28

Montego

iTrader: (1)

Hey G!

Are you going to sevenstock this year? I'd love to see that beautiful car of yours again.

spintriangles

iTrader: (3)

I know that the 3 rotor na rx8 in Imsa made over 400. I wonder if it could be reliable at that hp. I would love to have a 3 rotor na making 430wrhp but I dont think it would be reliable or to steerable with a peripheral port. I imagine it would require that type of port to make that type of power.

newtgomez

There are simply too many factors that go in to this decision. Doing a big single 13B or building an NA 20B will most likely cost around the same by the time you turn the key. Now, you can definitely get a better street driving experience with a big single 13b as you don't need the porting a 20B will need to make equivalent power. One thing you should absolutely consider is parts availability with the 20B. I've heard a lot of issues with people finding that rare center iron for the 20b as it's a very special item and comes at a premium cost when needed. I know you said you didn't care too much about cost, but it's still a consideration. The only problem with the turbo 13b I could see is if you cheap out with your cooling and system design i.e. buying a front mount intercooler from ebay. Cheaping out does no good as does a lack of education in the matter. Howard Coleman has a website that you can get lost in that teaches such about the importance of system design. Whatever you do, just be sure about it and don't look back. The biggest importance is research and to do it right and do it once. Don't forget that the 20b does have better power potential if you ever decide to throw a big single at it. Don't forget about that future planning step either!

Gilgamesh

PPorts in race cars (no compromises) make about 150hp per rotor at a min. That Grand Am Rx8 3 rotor made "450ish with Grand Am restrictions on RPM."

Johnny Kommavongsa

iTrader: (13)

Based on your experience how much do you think it would cost to build a similar setup to what you have today?

And what engine mount would you use?

gmonsen

Hi, Johnny. I'm not really sure about the cost today. A lot depends on what you start with. It's hard to get a nice 20b short block. They are pretty expensive these days, I think. The short block, ITB's, headers, exhaust, and EMS are the big costs. I would think you build a solid 350 whp motor for maybe $25-30,000. Going from there to close to 400 whp will add at least $10,000 for the "little things". For instance, to get a motor that revs to over 9,000 rpm you need to dry sump the engine. That adds maybe $3-4,000 right there. I'll tell you that an NA 20b is a connoisseur's motor. There is no way its cost-effective for the power it can make. It is simply a much different kind of power, as I have gone on and on about. Far better for twisty roads and tracks.

gmonsen

Hi, Johnny. 20b shortblocks have become very expensive. Not sure what that cost is, but it could be $7500+++. Then, you need ITB's and they are maybe $3500. You need a good EMS system. I am using Motec and that's at the high end of cost, but there are others that would work, although MicroTech won't work well. Maybe a better Haltech. Figure maybe $3000 for the EMS. Then, you need good headers and exhaust fo0r a few grand. Plus, porting and assembly, including improved oiling. I would think you could get to 325-350 whp for maybe $25-30,000 on the low end. Getting over that means you have to push everything. In particular, you need to dry sump the motor to run over 9,000 rpm and that will pick up a lot of power. Dry sump costs about $3500 or so. Hope that helps a bit.

Johnny Kommavongsa

iTrader: (13)

Yes. Very helpful thanks for all the info Gordon.

neit_jnf

iTrader: (17)

holy threadsurrection! I started reading from the top without looking at the dates then suddenly "$2.5k for 20B core" and I was like wut? where? when? It's like $7.5k last i checked! And then i looked at the dates!