wana12v

[QUOTE=signature600]The 24v head is just better than the 12v...

the only benefits are flow and injection centered instead of offset. the valve guides wear out much faster the heads are much more prone to cracking and the isn't hardley any material to remove when porting. not to mention the valve springs and rockers/bridges unable to handle rpm.

signature600

[QUOTE=wana12v]Sorry, I meant "better" in terms of airflow right out of the box. Once ported, the 12v head is better, as far as I've been told. My head isn't done yet...but it's getting worked on right now

For high RPM, 12v is the way to go...it takes a LOT more money to make a 24v handle 4000+RPM

Chris

Jim Fulmer

If you know me then you know I have run Twins for several years. I'm now running my SPS 66 as a single. The main deal with Twins is they work great but there are down sides to them as with anything. Plumbing, leaks, issues but you pay to play. All the bolting surfaces like flanges ect need to be machined flat once again after there all welded. I know on the PDR kits they have this done to eliminate leaking issue, remember a flat surface needs no gasket, only a little Hondabond or gasket sealant. Singles have there limits too and will make big power but not sustain big power towing like Twins will do but there close. Also remember if your towing with 450hp and Twins you will more than likely heat the water up.

I don't have any of the issues of surging like people talk about, maybe it's just me.

Jim

Bart Timothy

There are two things which I don't understand. One is, why, on earth, you would want a turbo which doesn't spool fast? And the other is, how are you able to tow with a SPS66 and not have surging problems? You foot must be jammed into the floorboard and rpm redlined 100% of the time, or the truck is just idleing and doing no work at all.

Forrest Nearing

ported head, cam, etc.

signature600

That would be my guess too!

Chris

JD Dearden

Well I don't like being thrown back in my seat unless I want to be, this is just me I am going to do twins soon and I probably wont run the 66 as my first. Also when I purchased my turbo from Wide Open they knew that I pull heavy weight, so I say will I surge and Zane says no. Wide open knows what they are doin, and I don't redline it when pulling this weekend with 18000 pounds I shift at 23 to 25 hundred rpm's, and have no problems pulling up 8% grades for 10 miles.
So the answer to your question is I don't know why I don't surge except for the fact Wide Open knows there stuff. And the best part is Bart you have them right in your back yard.

kawi600

Hm, so how bad is the spool up on the pro street compared to the stocker? This would be on a heavily fueled 12v. Maybe this is something I can live with if I go the cheaper route.

RowJ

I've heard this (and believed it) for several yrs. I no longer do!

Several people that have driven mine say it feels just as fast as their stock HX-35, at least on the street. In all honesty, I've been away from the stock turbo so long, I can't say, personally.
But they are so much faster (with NO lag) than both of my 'big' singles that I'm all .

I have no idea how BD does it, but suspect it's the S-300 (with big turbine housing) on the bottom. This is the only major difference from other twins that I can see. There may be something there worth looking into for members building their own twins, and not shooting for 700+ hp?

RJ

Dshiftff

Ill have a report for you in a few weeks, I have the head off now Doing the o-rings, after I have everything seated nice-nice and torqued There going on.

kawi600

Hmm, well everyone Ive talked to with the BD twins likes em. I havent heard a bad thing yet. Maybe Ill be happy with the truck at the 500hp level? Dunno.
What is the cutoff point where orings are recommended? Whats safe on studs and stock HG on a 12v?

ratsun

RJ
What top charger do you have in the set?
My top charger is the stock 35 and I wonder what HP your top one would suport by itself? Chances are the same as the 35? Where I'm going with this is to support the hp they were designed for, most chargers will be close in spool-up when compared evenly? I would guess we are comparing apples to apples here. I have a pretty good base line feel as I had the truck with the stock 35 and Drag comp/ DDIIIs then put the PDR towing twin set on using my stock 35 and noticed zero difference. Then the trans toasted and with the new super tight converter truck seemed laggy?(more HP needed I guess) Then when I took the stuff off the truck to sell it I pulled the injectors and the comp off but had to drive the truck for a week with the twins on before I had time to remove them. I have to tell you I could not tell the difference with them there or not I'm sure the converter was not the right unit for the combo but I will see this next month with the new DTT design and the same twin set?

ratsun

I am sure you will be happy with them over 500hp
I'm not sure how they limmit boost on their set but on the Piers set they have two adjustable blow off valves in the cold tube to the IC you can set where ever you want. I would say your timing will be more important than the boost level and I would guess 500hp of fuel with that twin set will be around 55-60psi . Run a set of studs in and have fun.

Dshiftff

I dont think there is a defenite answer to this, But I will say with stock HG+bolts I was running 54lbs, without any sign of failure. Timing at 16.5

RowJ

It's BD's Super B with twin exhaust ports and adjustable wastegate..... Basically same as primary (an S-300) but with a 12 cm2 equivalent turbine and smaller wheel. On right in Pic.


Since the original question was - What to do for 500-700 hp.... that's a big swing in HP. I would do 500 hp differently than 700 hp!
For 700 hp I would wait for BD's Super twins (coming Sept, 2006) with an S-400 as primary turbo.... or talk to Piers about an HX-40 on top. Suspect both will have additional lag. I would do studs for 500 hp... and a full head job for 700 hp. JMO.

RJ