Hey everyone,

I've been lurking for a couple of years but this is my first post.

I'm looking for advice on which turbo I should order for a new build. Motor I'm building is a 2007 4.6 2v, stock PI hci, 9.1 - 9.6 compression, haven't chosen Pistons yet, coyote rods, cast crank.

I'm hoping for 4-450whp, through a t45. Never sees the track so I'm more worried about transient response than ultimate hp limits. I live at 3200ft elevation so I think it could be at least 2.0 pressure ratio to get into the mid 400s.

For simplicity in plumbing I'd like to use an internally gated turbine housing, if I can find one suitable. I'm ok cutting it for an oversized puck to keep the boost in check.

So far I've been looking at hx35/hx40 or S364.5/S366 options. I like the BW wastegate because it bleeds both scrolls of the housing, but I could drill a holset to combine the divided inlet too.

Which one would give me the best spool? Is there any other options I should look at? I've also seen, what looks like a 68mm S300 gated turbine housing to fit an hx40. Would that give me a quick spool and enough capacity? Or is a straight hx35 enough?

Thanks for your help, I've really enjoyed reading and learning about this stuff.

 

Did you consider doing a twin setup. You might get a better selection with 2 IWG turbos in a smaller size than a larger one

 

Yeah I thought about 2 gt2860s. I wasn't sure if twins were worth the trouble at my HP goals. What twins would you recommend if I did go that way?

 

IMO, twins aren't worth the hassle. A small single that spools fast will be a LOT of fun on the street and offer tire frying response and minimize the hassle of mounting and oil returns.

ks

 

Thanks for the input. That was my train of thought as well, I'm just trying to figure out which IWG option will best suit my build.

Has anyone had luck with a T3 single for a 450whp 4.6 2v? There's a fair number of options in both twin scroll and undivided T3 and T4... I'm just trying to get some idea what will be the most fun/responsive without choking on itself at 400hp

 

You should be looking at something in t4 for a single. S362 would do it for you and be responsive. Genuine article is a little expensive, look for a 60-66mm compressor on a t4 exhaust side with a 68-72mm (minor) turbine in your budget. The rods in these motors suck, bringing in boost a little later wont hurt.

 

Thanks, I'm really liking the s362 or s364.5 the more I look at it. I'm building my spare motor outside the car right now, so the rods shouldn't be an issue . How much difference is there between the 68 and 72mm turbines? I think I know how to read compressor maps but I can't get a feel for the hot side sizes

 

It depends on the manufacturer, if you go with an s300 series you will get a choice between a 68/76mm or a 73/80mm. For your base horsepower and goals the 68mm will be a good choice. If you had more cubic inches, and/or more HP you could move up to the 73. You can take a look at their flow maps, or play around with your combo in Matchbot and take a look at the turbine matching.

 

Everybody knows how much I Love S364

however you said IWG and transient response so, I'm not sure you've heard of this company called Garret and they make this really cool IWG style turbo called 'ball bearing' and it is king of transient response ;D


For spool character try to minimize shaft weight (total shaft including turbine) Look for the smallest flowing (total flow not target flow) that will meet your needs.

 

I went down a hell of a rabbit hole on matchbot... I think I learned that the twin 2860s won't really start to spool until 2500 or 3000 depending on the exhaust housing, but then they are small and ball bearing, so the response should be awesome. I wonder how hard it would be to drive with that massive hit though.

On the flip side, the HX40 would spool right off idle. It shows it making awesome power up to almost 6000RPM, but it'll definitely be maxed out trying to make 500bhp.

I'm tempted to run the holset to get the setup together, and see how it runs. I feel like I could sell it to a Cummins guy later if I wanted to upgrade to an s362. At that point I'd probably need to do some fuel side work anyway. Might be time to go ask in the junkyard forum about holsets