3400 turbo.

[unchained01]

Randy post the link to you build let him check it out

[G.I.Ceo]

Randy post the link to you build let him check it out

Herer's the link. I will be posting more now that I have time to get back to work on it. I also have a lot more parts coming in for it.

http://www.grandamgt.com/forum/showthread.php?t=86932

[NateD4]

There's nothing wrong with VG turbos. Porsche uses two of them on a few of their cars. What matters is matching characteristics to your engine. There is a reason they are on both Porsche and diesel trucks. Unfortunately the Porsche ones are quite pricey on eBay.

[Guest]

There's nothing wrong with VG turbos. Porsche uses two of them on a few of their cars. What matters is matching characteristics to your engine. There is a reason they are on both Porsche and diesel trucks. Unfortunately the Porsche ones are quite pricey on eBay.

You didn't read my post, otherwise you would have seen that I said the diesel vg turbos aren't designed for the hotter exhaust gasses from a gasoline burning engine instead of the cooler exhaust from a diesel engine.

Diesel vg turbos were not made for that.

I also already stated that the Porsche does use a VG turbo for the 996 but at about $5k a pop, and you needing two of them, who is going to buy those just to claim they have vgt?

[NateD4]

That might be the case for Holset turbos... But take a look at what some of the Duramax guys are running for EGTs. I've found numbers as high as 1400 F from guys making 500-600 HP on stock turbos.

[TGP37]

You didn't read my post, otherwise you would have seen that I said the diesel vg turbos aren't designed for the hotter exhaust gasses from a gasoline burning engine instead of the cooler exhaust from a diesel engine.

Diesel vg turbos were not made for that.

I also already stated that the Porsche does use a VG turbo for the 996 but at about $5k a pop, and you needing two of them, who is going to buy those just to claim they have vgt?

NateD4 is really wise about this stuff. His knowledge of forced induction is extensive. If he says the diesel turbo will work, it will.


Lots of gas boosted engines run diesel turbos. It is all about the size of the inducer/exducer of the compressor/turbine. Match that to the engine and it will work, diesel or gas. Heat energy is heat energy regardless of the fuel used. The turbo utilizes heat energy to boost the engine.


But it is your car, just saying. You could get some great advise here.

[NateD4]

Is that a hint of sarcasm I detect?

[AleroB888]

Is that a hint of sarcasm I detect?

I did not see it as sarcasm. But I'm afraid to mention what I was considering for a turbo build. I have to find the right wording for the question, lol

[TurboGTU]

Most diesel vgt turbos are tolerant to high exhaust temps.

[Guest]

I've never known diesel exhaust temps to be any less than gas exhaust temps, especially when pushed.

It doesn't matter anyway, the original topic at hand will prove that the turbo is a bad idea, and not work like the OP expects it to, but you know, those of us that actually have turbocharged cars don't know better.

[NateD4]

Yeah I'm not sure how Holset turbos compare... But considering everyone seems to size turbos on A/R ratio and the VGTs have variable areas that approach full close (giving A/R probably down to .3 or less)... And about 400 CFM of air @3500 RPM for 6.6L displacement I'd say the turbine side should be just fine. For reference a 3.4L at 6500 RPM uses 389 CFM.





Compressor side...



This is from a 94mm 48 trim compressor wheel (stock is 88 mm for an LLY). The 77% island happens at @55lbsm/min and a 3:1 pressure ratio.

That gives similar single point performance as a Garret GT35R @55lbsm/min and a 3:1 pressure ratio except at the 72% island and near the top of the boost graph.

[NateD4]

As for earlier discussions... Diesel turbine housings are huge.... And packaging tough.

It sounds like the OP is on the right track with a properly sized turbo.....

[TGP37]

Is that a hint of sarcasm I detect?

No, I was serious. We had a discussion in this forum regarding turbo, flow, egt's over time. Unless I got you mixed up with someone else. Your one of the handful I trust on this site regarding engines/boosting.

I did not see it as sarcasm. But I'm afraid to mention what I was considering for a turbo build. I have to find the right wording for the question, lol

Pressure Wave Supercharger? They don't spin as fast as a turbo/SC and provides boost off the start. Interesting little device it is, I try to find more information about it but it is an uncommon way to boost up. It seems some exhaust recirculation would be a minor issue (tune around it) and higher temps IAT's. But the boost response is much better then a standard turbo as far as Ferrari tested in the 80's.

[Guest]

As for earlier discussions... Diesel turbine housings are huge.... And packaging tough.

A generality that is not always true. The Borg Warner I use from a 6.5L Diesel, has a turbine housing that is physically about the same size as a T3 turbine housing, though the turbine wheel would be closer to a stage 4 T3 wheel if I remember the sizing of the T3 wheels correctly. It actually has a T3 inlet flange on it, which made it easy to use in my application.

It sounds like the OP is on the right track with a properly sized turbo.....

I WHOLEHEARTEDLY disagree. With the end desires the OP laid out from the start, a turbo is not the right choice here.

[NateD4]

Oh I was referring to the Duramax turbo packaging wise it is a chore. Rather than a traditional flange the header 2:1 style inlet GM cast onto these adds almost 2" in turbine section diameter. It physically won't fit in my car. I'm going to end up either cutting that inlet and making a new one or casting/gabbing a new housing to make it my way.

The size of the Duramax turbo vs your 6.5L makes sense. If I'm not mistaken the 'max turbo is about the same physical and flow size as a T68 or T70 sized turbo. Might flow a bit les but the duty and power range they are designed for is larger than a 6.5L original design.

In my case my target is a minimum of 350 HP max possible 700. I'll probably be 'very' happy with 450-500.

How does that 6.5L turbo work on a gas engine?

As far as the OP I think with a bit of know how he can get what he wants from it. No idea why he's concerned with late spool and sub 350 HP numbers.... Generally high HP and lag go together.

If I were him I'd focus on the resulting torque curve... Or build the thing with the cheapest t3/t4 hybrid I can find with a square t3 flange and see how it runs. Learn and refine with a better turbo. Then sell the old turbo on eBay.

I'm slightly fascinated by this post. I tend to 'think' most t3/t4 sized turbos put you in the 200 to 400 HP range. a/r helps dial the spool rpm and trim the peak power. My vote is put something on and go with it.

BTW there used to be a lot of Solstice-Sky/Cobalt SS turbos cheap on eBay.

I've seen dyno pulls to the 300-350 range from them. I originally looked at two of those to hit my 600 HP goal. But decided a single Duramax turbo was easier to plumb. To bad I didn't realize how large the housings are.....

If you don't recommend a turbo what should the OP put in?