signature600

With Twins...somewhere around just under 500 would be my guess depending on whose injectors you're running!

Chris

HOHN

They CAN be faster, but you have to compare apples to apples. A 500HP twins set will spool faster than a 500hp single turbo.

But 700hp twins will not spool as fast as 500hp singles.

In other words, twins can improve spoolup for a given hp, or improve hp for a given spoolup, but they can't do both except in increment conditions (like you are replacing your 350hp stock turbo with a set of twins that will support 450hp-- you could possibly see both more spool and lower EGT, but this is not that likely.

I think of twins as "averaging" the performance of the two turbos in the set. Twins will spool slower than the smaller turbo alone, but faster than the big one alone. Some big chargers won't spool at all as a single unless you have a very high RPM setup.

jh

RonA

A k31 under an SPS62 runs great at the 400 to 525 level. Above 525 the egt's will start going over 1200 at wot(In my truck). I try to limit my boost to 65. If I goes above that, I up the charger size.

Mike Holmen

The nice thing about the 24v it only takes about 1-2hrs to slam in bigger injectors. I was talking to PDR they have twins now that are for the HX-35 and the S300 based on the K31. They are still doing some little fine tuning but its looking promissing. I'm throwing around the idea of a S300/S400 variant. PDR haven't put a big set together as of yet. A 700rwhp twins don't spool alot slower than the 500rwhp and they don't have the egt's issues while towing. For a while I was thinking about using a garret 3788 over a 4288, non ball bearing. I've heard to many guys with bearing issues with the those turbos if you actual use the turbos. Garrett does build a water cooled turbo BB turbo but at 2k to 2.5k per turbo, it starts to add up fast and you can't rebuild them, so every two to three years you have to drop 4-5k on turbos.

RonA

If I understand this correctly, you are saying that larger twin setups don't have egt problems when towing?

Mike Holmen

I should back-up. How heavy you towing? Any big hills? I like my big twins. I can use all of my big 130 size injectors. I don't know the egt's that other twins would have but mine is around 1200 deg's for that sized injector. I've towed using the 150 sized. Its a little more toasty but do able. 220 sized, your a bit hot. For 500rwhp boost under 60 pounds is lots. I'm only pulling around 50lbs with 130 and 150 sized injectors. Its nice passing guys on the hills pulling a bigger trailer than them. There a bit of tuning to get everything to run prefect. Boost leaks drive me crazy. Even the best twin set-up can be laggy and smoke and crank-up egt's. If my truck smokes lots and the egt's are high, I can tell that I have a leak some where. To run 50+lbs every day, it takes a bit more work than just running 35psi, IMO.

signature600

So far, I've beat the TAR out of my GT4088R...it barks A LOT, and still feels tight as new! Also, the BB cartridges are rebuildable now too

Chris

DieselMike

With my pickup and trailer loaded I weigh 25,500. No big hills, no long climbs or nothing like that, mostly flat ground with a few hills but nothing steep. I tow pretty good with my set up now, usually can leave it in 6th but I do shift down to 5th any time I start to go up hill. With twins would I beable to leave it in 6th more often or would I just shift to 5th and not really have to worry about egt's?

HOHN

It depends a lot on how the twins spool-- whether you get max power twins or "towing twins".

Downshifting to 5th is still a good idea, as the direct drive makes the trans a little stronger. But this would probably not be necessary with twins. It depends a lot on the weight, the hill, the weather, and the turbos.

Justin

Mike Holmen

hey 600 buddy, how hot have you got that new garrett turbo? Is it the liquid cooled version. Everyone I talk to, try to talks me out of the garrett turbo. Just doing the hand flick spin, you can see the difference. A big garrett turbo will spin as easy or easier than a Holset. Anybody measure the drive pressure difference comparison between a similar sized garrett to Holset? I bet that there is a big difference between them. I'm just worried about replacing the turbo that often. I'm already on my second HX-40. They start to carbon up and need to be overhauled to get them to spool right. It’s a cheap overhaul but its a pain in the back side. Camping this year I got the engine so hot I melted the tranny dipstick handle. It smelt like my truck was on fire. I blew out my turbo base/manifold gasket. They can't take the steady 50psi. Sometimes you just want go back to a stock truck, less maintenance.

Mountaineer

Maybe one of those heat exchanger hoods or put some vents on the hood would help let some of that heat out.

Idaho CTD

I use to do injector changes in 20-30 minutes with a scalding hot motor after racing. The CR motors take 45-60 minutes.

signature600

Well...the Pyro in the Xmonitor says about 1500 peak...but the case housing turned blue

New pyro is going in, so I think I'll get a better reading shortly...I'll make sure everyone hears what I find...but hopefully I break the 400hp mark, and get closer to 500-525

Chris

HOHN

The turbo should (edit: NOT) be carboning up. If you are that overfueled where carbon is building up on the turbo, I think you are losing a 40 simply due to a weak shaft.

I'm hoping you see 450 from that 4088. By my guesstimations, it should support almost 500 if the engine will breathe. That's means 450 on a 12V might be tough to do.

JMO

Luvnacumns

Good lord.. Will you teach me????