Is there any benefit of running a full HX40 over a hybrid 35/40? It seems to me that as long as I can keep the boost under control with the hybrid, might take an external wastegate, that both of these turbos should support the same amount of power due to the fact that they are both using the same compressor, or am I missing something?

 

I think it's the bigger hot side (4'' output flange) on the full 40 that would make it able to support more power...Bill, where you at?

 

Full 40 has a bigger exhaust wheel= greater flow of air. Full 4" downpipe/exhaust on the true 40. I would only run a 40-16wg if you found one cheap. If you are gonna spend the money go the HTB2 route. It's a Schwitzer based turbo which is tougher and more reliable. Plus with no intercooler, if/when that 40 goes pop, its gonna deposit its internals directly into the engine, no intercooler to eat it.

A 40 if good for fun trucks but I know thats not what you want. You will want more.

 

I comparing the two turbos as to which one I should use for my top turbo in my twin setup. Im aware that the full 40 has a larger exhaust wheel which is why it is capable of flowing more air, but why cant a 35/40 with an external wastegate flow the same amount of air? Unless I am missing something here either way should be able to support the same amount of airflow and HP? correct me if im wrong.

 

35/40 has a hx35 exhaust wheel. How is that gonna flow and support the same hp/airflow as a hx40 exhaust wheel? I am not the expert, so better ask the man.

 

With an external gat...they should be equal, and the 35 should be a bit tougher, too! Just watch the barking

Chris

 

Even though the same amount of exhaust could theoretically flow past a 35 wheel+external gate as would flow past just a 40 wheel, you're not getting any work out of the gated exhaust, whereas the 40 wheel is 'seeing' ALL of the exhaust flow, so it is able to put 100% of that flow (theoretically) to work spinning the compressor wheel. The ability to put rapidly expanding exhaust gasses to work is the essence and beauty of turbocharging. Any of that energy going to 'waste' (pun intended) is just that...a waste. In a low hp vehicle like mine, running a wastegated housing (basically the same idea) is indeed a waste, but I put up with it in exchange for good street manners. For all out power, driveability be darned, all that exhaust flow needs to be leveraged against the compressor wheel to move the air. Of course, I'm shooting from the hip here and my truck probably only puts 200 hp to the ground

 

So what im gathering is that both options would be able to "flow" the same amount of air, its just that the full 40 would do it slightly more efficently due to the fact that more of the exhaust gasses would be used to spin the exhaust wheel, with less force needing to be applied on the wheel due to its larger diameter? So now the question is, how much of a difference in efficency is there? Im thinking not enough to want to trade the 35/40 spoolup for.

 

Rock I was just about to get to that. Spool up would be the same IMO. Not enough of a benefit to warrant the purchase of a 40 and do the swap for twin application. But why do you want to go small on your twins? 35/40 over whatever. How about BIG over BIGGER .... You'd probly do fine with the hybrid over whatever for quick spool and quick/fast times at the track. Me, I'm not looking for quick times, so spool up isn't an issue. I'm looking at using my sledpuller 66 on top of a hx60.

 

The main reason im going to run the 35/40 in the twins is because I have it, I was just trying to find out if a full 40 would be superior, which I dont think is the case. I would like to run an s300 based turbo on top but the funds will have control over that.

 

There are lots of successful 35/40 twins out there, I think for your use that is the way to go. If you can afford to add an external wastegate that would be even better.

 

I was planning on running an external wastegate, but after seeing the work that member got...Diesel? did to the internal wastegate on his hx-35 housing, I might be looking into that option. It would make for a nice clean install without the high price of an external gate, and would still flow just as well.

https://www.dieseltruckresource.com/...ad.php?t=89525

 

Yeah, if you build a new backplate so you're not shrouding the wastegate I think that would work well.

 

Yes, I would build a new backplate that is something similar to the magamouth downpipe, this would be incorporated into the hot pipe.

 

the wastgates (internal or external I don't understand the difference) on the hx 35 is for only three of the cylinders as well. a bigger b1 type turbo I heard has all six cylinders gated