.60 A/R Compressor, 1.15A/R Turbine. LOL

[Forever-Fiero]

I got some questions about the size of this turbo. 1.15A/R is a huge turbine. is it to big for the 3.4 DOHC? Will it spool? And will the .60A/R compressor be a good mach for it?

And yes this is a ebay turbo. Im just cereus to see if its a good size turbo or not.

Hers the link.
http://cgi.ebay.com/ebaymotors/ws/eBayI ... 0370132802

[whipped]

Looks like a T3? You'll probably need 2!

[EMX5636]

Thats a really weird setup. The turbine housing looks like a divided T4 footprint. Why they would put a big T4 exhaust housing with a small To4B cover is beyond me. I guess they are trying to get a bit more efficiency out of it. Either way, the exhaust housing is pretty big, but a TDC shouldn't have a problem spooling it. See what Wil and Aaron says when they chime in, they are a bit more familiar with the DOHC 3.4 than I am.

[Aaron]

Why don't you just run though the compressor maps?

*rant*
One thing I like about this site, I rarely ever see the question that fills boards like Old Europe. "Which turbo should I get?" "Is this turbo the right size?" "How about this one?"

None of those threads ever go anywhere, they are doomed to begin with. Because the sole item deciding the turbo is the engine, and they're all different. And looking at that eBay page, I don't see a compressor map. Any place selling a turbo without a map should be out of business by now. Fortunately for them, people are stupid, and will buy items on the unreliable advice they get from places like here. So unless someone here is willing to run though the calculations, you won't get any useful advice, because no one knows for sure. I can say that a GT35R T4 on a highly modified 3.4 DOHC is slightly overkill at this altitude. As fa as for a stock motor, no one knows, not even Will (Without running through the calculations). At sea level, the 35R should theoretically be perfect. But no one knows for sure, because no one will cut the check for one.

So do yourself a favor. Sit down with a pen, paper, and a calculator, and see where it'll be on the map. Can't find a map? Find a different supplier.
*/rant*

Unfortunately, I no longer really have any of the info I compiled. I still have the Excel spreadsheet that TimG made for the 3.4 DOHC and a few random turbochargers. Give me your email and I'll send that to you. The only real number you need is displacement (3.35L), and Volumetric Efficiency (I think the 'going' number for the average 7,000rpm DOHC motor is like 90%, I used 93 on mine because of the heads and stuff). That's another thing. VE. Why isn't there set numbers for VE? Since specific output is generally closely related to VE, it should be rather easy to figure out. Yah sure other things affect specific output, but those are pretty generic across the board. Most every car today has a perfect tune, decent intake/exhausts, and a relatively similar accessory system. So why hasn't someone come up with a VE to HP/L relationship? Sure it wouldn't be perfect, but it'd be better than guessing 85% for a OHV engine, 90 for a DOHC.
*/rant*

[The Dark Side of Will]

The highest specific torque I've seen in naturally aspirated production cars is 85 ftlbs/litre out of the BMW 3.2 litre 333 HP engine (don't know the designation). I call that 100% VE by default and scale everything else accordingly.

Compression ratio affects the VE/specific torque relationship, so you'll need fudge factors when comparing engines with very different compression ratios (IIRC, the BMW above is over 11.5:1).

[Aaron]

Ok, going off that, and the 3.4l (3.35l) DOHC making 210tq, it'd be making about 63tq/l. That equates to about 74% VE. Seems kinda low, but that's also off 9.25-9.5 compression, compared to the E46's 11.5.

[Shaun41178(2)]

that ebay turbo is junk. stay away. The only thing it has going for it is price.

And yes it is a t4 footprint on the exhaust and its a t4 intake side too but with a B housing. B housings aren't really used anymore because a slightly larger E housing flows more air and allows for the use of larger compressor wheels. The S housing is the largest. So basically B housings are junk for a 3,4 dohc.

Look for a precision SC61 turbo. Its got the GT35r wheel but in a non ball bearing package so the cost is less. YOu can find good deals for around $600 as thats what I paid for my last one. Hell I know where you can get a new precision 67mm turbo for 600 bucks and it will whip the pants off that ebay junk

[Aaron]

If you do what Shaun is saying, definitely go for a divided T3 hotside. The T4 is just too big, even if you were at sea level. Mine comes on pretty late in the RPMs, and while that's great for my car and power numbers, on a stock motor, I'd want it to come on earlier and smoother.

[Forever-Fiero]

Ok to be truthful Im not looking to buy this turbo. I just like that turbine. Its huge and I wanted to know if it were a good mach for the twin cam. If so I would buy it just for that housing. Aaren you say a t3 is better for a dohc. Well you would know. They just look to small.

And as for GOOD BUYS on great turbos......

http://cgi.ebay.com/ebaymotors/ws/eBayI ... &viewitem=

DAMN I Missed it!!

[Aaron]

Ok to be truthful Im not looking to buy this turbo. I just like that turbine. Its huge and I wanted to know if it were a good mach for the twin cam. If so I would buy it just for that housing. Aaren you say a t3 is better for a dohc. Well you would know. They just look to small.

And as for GOOD BUYS on great turbos......

http://cgi.ebay.com/ebaymotors/ws/eBayI ... &viewitem=

DAMN I Missed it!!

Problem is, I don't know. My experience is with a highly modified DOHC motor operating at 6500ft altitude (That means a 21% torque loss, which means a lot of spool time). My educated guess would be that a divided T3 hotside would make for a very responsive 3.4 DOHC, that's still efficient to 6500rpm. But I've never experienced this first hand, or on a stock motor, so I don't know, I can only guess.

You can get some killer deals on eBay. But I don't trust used turbos. There's just so much that can be fucked up from the previous owner, as the turbo needs so much. Did it have an air filter? An oil restrictor? Good oil lines to and from the turbo? If it was water cooled, did it have enough water flow? I just don't trust people, because we all know the story. Kid just had to feel 10psi on his Honda, before making sure everything was setup right.

[Shaun41178(2)]

divided t3 housing on a 3.4 dohc is pointless and not necessary. you can get a nice t3 hotside with a .82 a/r instead of the .63 hotside if you want more top end potential. It all depends on ones hp goals. The .63 can support 500 whp but will fall off on tq faster up top then the .82 housing. Not that a 3.4 dohc makes any power up top anyways as the cams blow at 7k rpm. so a .63 is fine.

Not only that but I think the divided t3 housings are only available with GT series turboes and from certain venders like I think ATP that have their own housings cast. They aren't cheap.

Arod is running a t4 housing on his 35R. Not sure of hte a/r though he would have to fill you in. My t3 hotside on my 3.4 makes 15 lbs by 3500 rpm. Its got just the right amount of lag.

That 1.15 hotside in the ebay link is large for a 3.4 dohc imo. I wouldn't get anything that big unless you plan to spin your motor to 7500+

[Forever-Fiero]

OK. Thanks alot. I got all the info I need. You guys are a great help.

[Shaun41178(2)]

you want something like this

http://cgi.ebay.com/ebaymotors/Precisio ... dZViewItem