BT Economics Question

[shamie]

I’m at the stage many get to after doing all the bolt-ons and still wanting more power – I’m planning on going BT this summer. I’m not looking for insane power numbers, I just am sick of the k04 running out of steam too early especially up here at altitude.

As BT is usually toward the end of everyone’s mod progression after all the bolt-ons, it got me thinking of the overall economics of BT. After adding up all I’ve spent on intake, intercooler, and exhaust and the cost being comparable to a BT kit I wonder what power numbers I’d see with just a small BT (2867ish) and stock everything else (except AP and HPFP). I would think a 2867 alone would be at least as productive as where I am currently, but would the flow be restricted too much to even make my current power with my flow mods? Could it still pump air to redline or would it be no better than the k04?

I was just thinking maybe we (those that don’t want HUGE numbers) all have this backward. Maybe our first mod, after AP and HPFP, should be trash the k04 and go BT. You’d be able to look and sound mostly stock also. Swapping a turbo out for dealer visits can’t be any harder than reversing an SRI, TIP, FMIC, and DP.

Thoughts?

[sidekick]

To run a bigger turbo, you're going to want at least an intake, downpipe, upgraded IC, 3 bar MAP sensor, and most likely a 3 port EBCS. A BT is the next step after bolt ons, because you already have most of the supporting parts. You COULD bolt it on with some stock parts, but power production is going to suffer.

[Dimenus]

Also, your cost analysis is probably skewed because you bought one of the most expensive FMICs.

[shamie]

Originally Posted by Dimenus Also, your cost analysis is probably skewed because you bought one of the most expensive FMICs.

Yes my costs are skewed as you could go used/ebay on it and still get good results, but its basically the same type of questions we never asked years ago with DP vs TP. We now know you can almost get to the gains with just a TP and still be easily reversable.

So do you think a bigger stronger turbo could overcome the stock restrictions or would it just turn into a hot air pump like the k04?

Don't get me wrong - I'm not going to reverse all my mods and do just BT. I'm just wondering what I'd do if I had it to do all over again and knew what we know now.

[ihasmazda]

sure potential power will suffer but he's saying that the cost of just a turbo alone may net better results than intake + dp + ic, etc for less money.
It's a good question actually...

[sidekick]

The flow will still be restricted by everything around the turbo. The intake, the downpipe, the exhaust manifold, etc. You will probably still make some more power and flow more air than a K04, but without the supporting mods, it probably won't make much more than a maxed out K04. Restricting airflow into and out of the turbo is going to force it to work harder and is counter productive to upgrading the turbo in the first place. Again, a K04 with bolt ons will probably make similar power to something like a GT28 without the bolt ons.

In terms of "blowing hot air", the larger turbos will probably still see cooler BATs, due to less restriction from the larger hotside and more efficient compressor/turbine wheels. Still, you'll be choking a larger turbo without at LEAST a larger intake and freer flowing exhaust.

[ihasmazda]

Until someone tries this, I don't think it'll be possible to have an accurate answer. This is Honda territory - slapping on a turbo and nothing else. lol

[shamie]

Originally Posted by ihasmazda This is Honda territory - slapping on a turbo and nothing else. lol

Well a tune and HPFP is assumed.

[anavrinIV]

I'm pushing roughly 300whp with bolt ons. Standard corksport intake, catted dp, cbe, fmic. Everything else I've done to the car is completely unrelated to power production or is routine maintenance (mounts, bov, plugs, shift stuff, suspension and wheels) so we'll leave that out of the equation.

I went the opposite route as many and bought as much as I could used or on sale. All in all I have <$1500 in power parts (including the bov). $250 dp, $240 cbe, $<500 fmic, $150 bov, $130 IM self ported, $250 intake (I've swapped these around a few times so I'll go with the price of my current one when new), self tuned ($0).

On the other end of the spectrum you can easily spend $1000+ on a nice fmic, $1000 on a cbe, $750 on a dp, $300 on a ported mani, $600 on a big intake, battery box, and battery....you get the point.

All else being equal you can go full bolt ons for less than a big turbo and get probably the same gains given the other restrictions around it. BATs will be lower with a BT but restrictions on the intake, exhaust and IM will combat flow pretty badly.

This is something I would like to see tried honestly. On a budget as I was there's no real reason to do it IMO. But if you plan to buy all the nice parts new it would be something to look at.

[rfinkle2]

I would budget for a cheap methanol injection kit as well to make > 350 hp.

[amoosenamedhank]

I'd be pretty surprised if a GT28 or BNR S3 with an intake didn't make more hp than a fully bolted K04 setup.

There is definitely some merit to considering it that way. Sure the turbo will be choked up, but this wouldn't be about max efficiency.

[shamie]

I think most of us do it the way we do is because either we think THIS mod will be my last and I'll be satisfied (sounds like me) or we get to our power goals by "making payments" one small (financially) mod at a time.

[Easter Bunny]

I think that for those who live at altitude the answer will be go BT. The k04 is marginal in flow at sea level and it only gets worse.

[Soto]

I'll be going BT first then build from there. (AP,Tune, BPV, Intake, Internals, BT)

I'd rather have a BT that doesn't need to work as hard then a K04 that is struggling

[Mistersix]

Good thread imo. I've had the same pondering. If anything ever happened to my six and i was forced to start over i would go this route. Just because it's never been explored as far as i know.
It begs the question, what if the speeds came with a bigger turbo from the factory. One that could flow 20psi flat easily. With a map sensor, hpfp, and ap I feel like i could tune it up to do as good if not better than a fully bolted speed.
The hardware would be the limiting factor, ultimately. But what if fuel and software were not?