t3/t4 turbo sizing on a 3400

[Syn]

i am debating on weather ot not to keep my garret t04b for my hybrid build or goto a t3/t4 hybrid, but not too sure because my 3.1 is not a normal 3.1 its cammed and has the hybrid top end all ported as well.....any ideas? i want full boost around 3 and beable to pull hard to 6k

[89jyturbo]

Re: t3/t4 turbo sizing on a 3400

Does anybody have knowledge of what size t3/t4 hybrid is the best fit for a 3400. T3's all seem to be too small to support these engines, and going to a t04 requires an external wastegate which adds a good amount of cost and piping complexity so the hybrid seems to be my best choice. I was thinking one with a 57 trim t04e compressor wheel and an A/R of .63 on the turbine side would be about optimal. For my application I'm looking to run about 7 psi non intercooled or 10 psi intercooled and I'm aiming for between 250-300 hp at the wheels. I'd like full boost to be able to be held until 6000 rpm and I'd like it to be generating boost by 2500 rpm. Would that turbocharger meet these requirements or would I have to change the compressor or exhaust size. Would an exhaust A/R of .82 be a better fit?

This is awesome. It is so rare I see someone ask for turbo matching and have all the needed info. People usually don't know what they want, and that makes it hard to help them.

The T3 .63 A/R turbine housing will work well for you. I would recommend a Stage 3 turbine wheel to keep the exhaust flow up. Keep in mind that the turbine section is the main influence on the turbo's response characteristcs. You size the compressor to give you the most effiecient boost (in the required PR and airflow range), but the turbine will determine when you get the boost. The .63 housing and stage 3 wheel will keep you smiling past 6k R's, and the boost should be in by 2500.

FWIW, my 3400 T in my Z24 runs a TO4B V-trim compressor and T3 Stage 2 turbine wheel in a .63 housing. The turbo is remote mounted (like the STS turbo kits), and it has full boost (10psi) at 3000 rpm.

[89jyturbo]

Fast spooling isn't necesarily as important as being able to hold full boost to redline in this case. Looking at compressor maps, I didn't see anything t3 that could hold the 3400 to 6000 rpm. 3400 would need more cfm's than the 3.1 due to the larger displacement and better flowing heads as well, right? From my understanding the tgp's had almost too small turbos and injectors stock. By any chance do you know where a compressor map for the stock tgp turbo could be found?

Here is where I charted a 3400 on a 57 trim t04e compressor at 7 and 10 psi at 4000 and 6000 rpm assuming 80% volumetric efficiency.

I think your points should be a littl emore to the right on that map, especially if you are going for 300whp. As a quick reference, if you take the lb/min x 10, that will roughly equal the HP that airflow will support. I would suggest going with the TO4E 60 so that the max efficiency island is better matched to your torque curve. It will give you a little more airflow before you are on the choke line. The better efficiency numbers will just be an extra benefit (the TO4E 60 trim map appears to have an 80% max efficiency island!).

[gboogie99]

word up

[TurboGt]

Here is the turbo I am planing in puting on my 3400. I havnt had time to map it for the 3400 but will be doing it soon. It is a TD06 20g off a gmc typhoon, I am also going to be running the water to air intercooler off it.

http://www.sytyarchives.com/gallery/main.php?g2_view=core.DownloadItem&g2_itemId=3255&g2_serialNumber=2&g2_GALLERYSID=e630dcee28a39e8639970b79858c0db6