Moneypit6

I have a 99 24v that runs perfectly. It has an edge comp, Mach 4 injectors, SPS 62 single turbo and Diesel Dynamics cam. The motor has 85,000 on it and starts if you just look at the key. Power is excellent for the mods I've done. My problem is that it can be sooty if not spooled. That's to be expected of course but I have to do more thinking about where my boost is than I want. Also, I've seen very small hints of smoke at idle while at a stop light, etc. I was trying to stay with a single but it doesn't seem to work out for me the way I want. My idea is to drop from Mach 4's to a Mach 3 and put on a small twin setup that utilizes an updated HX-35 turbo. The smaller sticks would clean it up down low a little and the extra air throughout the range would make it burn fuel better and possibly without losing power on top. Can I get some thoughts on this thinking from the guru's please? Spent a lot of money on it in the past and only want to do this one more time.

Thanks for any input

nascar mark

Your not saying you want to keep the power you have, so if I were you, I’d start with just dropping down on your inj size, like you mentioned.
A 2nd gen 24v’s won't spool the same size turbo/turbo's as well as a 12v, so with only giving up approx 40hp, dropping down a size on your inj’s, will give you better spool-up due to a bit less fuel not bogging the engine down before spool up. You will also have no haze while stopped too. Your happy with your power, so you will be giving up very little. Your drivability will improve greatly. You could sell your low mile Mach 4’s to recoup some $.

Moneypit6

Years ago I went from an original Mach 2 (100hp) to a Mach 4 (150hp) Also changed from a DD jammer turbo to the SPS 62. The increase in power was nice. I'd love to keep it, but rarely use it. My edge comp stays off 99% of time. I had to change back to stock injectors and turbo at one time for inspection. Afterwards I changed injectors back and left the HX35 on for a week. OMG, that was nice. Spool, spool, spool. Just drive it like a regular car. Of course I didn't put my foot way in it. Since changing back to the SPS 62 I've wondered about my decision to stay away from twins. Stepping down to a Mach 3 is only 20 hp drop (130hp). But with 3.55 gears I have to be careful driving 55 and going up a hill as the turbo won't spool at that RPM. I'm thinking I need to change something there but won't go back to the Jammer as EGT is not controlled. Hence thinking about twins using a nearly stock secondary. While the 62 runs over 50 psi, I'm wanting to use a small twin setup and limit it to less than that as the air is more dense. That's the biggest part of the question. Will a warmed up HX35 completely choke off the primary or will the primary still be able to do most of it's function?

gorms

I'm not on the 24v page with my 98, but was torn between a 62-63mm turbo and twins. Did some research and decided to go with twins. I got lucky and found a few HT60 turbos locally for reasonable. I have also been told that a he351 over the ht60 will spool faster, and overall flow better with a ported wastegate vs the HX35. Have just about everything I need, just waiting on some warm weather and time to put it all together, getting anxious to try it out.

I'm running a 5speed and load it regularly, and the poor little hx35 runs out of steam as fast as it builds it.

AlpineRAM

I built a twinset for a 24V with an HY35 as a secondary and an HX 55 as a primary.
I did modify the exhaust housing on the HY to get a lot more flow with the wastegate open.
Basically it is not the classic compound but works rather like a sequential system. (Most of the exhaust is bypassing the secondaries turbine when you are on boost.)
The housing mods consist of drilling the divider to the same diameter as the stock wastegate opening, drilling the stock opening apprrox. 40% bigger diameter, building a flange that goes between the end plate of the WG housing and the exhaust housing to allow the flapper to open up wider.
I think that this could also be done with the charger you have as a primary and an HY as a secondary, maybe even use a big external wastegate going to the primarie's turbine to get around the secondarie's turbine even better.

Moneypit6

"I built a twinset for a 24V with an HY35 as a secondary and an HX 55 as a primary. "

How did that work for you??

I was looking at the BD towing twins but as with everything, there is conflicting info about how they spool.

AlpineRAM

It works OK for what it is supposed to do- reduce soot and black smoke while operating at high altitudes. It is a little higher in EGT than a big single, but it spools like the HY- so it's really quick.
This is in an excavator that works placing ski lift equipments on glaciers, and every little bit of soot promotes melting of the ice.

You will have to consider some things about the turbo diesel and about boost.

Spooling will only happen with energy in the exhaust gas, and there is a distinct point where spooling can start to happen. This is the boost threshhold.

Spooling speed is the time between spooling threshhold and full boost when you get on it.

A lot of folks are dissatisfied with what they install not because it spools to slow but because boost threshhold is happening at a power output that is hard to reach in everyday driving. That is why Dodge selected the HY with the small housing for the later 24V autos, it reaches boost threshhold under very low engine load conditions, and therefore makes the engine more responsive- meaning you step on the pedal and get torque really quickly.
Naturally with the 9cm2 housing it chokes the exhaust severely when the engine makes even a little more than stock power.
That is why I built that set on the excavator, during normal operation under "no load", equalling just putting around with the truck, the HY is really close to threshhold, and any increase in load spools the little bugger right now , and since there is enough exhaust gas to spool the big one as soon as the little one is spooled there is virtually no soot. Naturally you really need a very efficient wastegate to get around the small turbo when you are pushing power, as to not create too much backpressure.
Tuning that set has been tricky, but it was worth it.

I don't know about the BD trwins, never got my hands on them but I think that a lot of the differing opinions about "spool" are actually discussions about "do I get them over the threshhold without fogging out the intersection" and not on how quickly they spool once the threshhold is reached.