Engine/Transmission (1998.5 - 2002) Boost good enough?

[Nickaru]

I recently upgraded to a Hybrid turbo with a 14 cm housing and was wondering if my boost was normal. While pulling a big mountain road with my 40 foot 5th wheel, I was in 3rd gear (six speed manual) and pulling about 2500 to 2700 RPMs with about only 15 PSI boost @ 1200 degree EGT. That limited me to about 30 MPH. I tried this hill with my comp on 1X1 and completely off with the same results. I would think with that RPM and working the engine, that my boost would be higher for more cooling. I feel like there's more power under the pedal but the EGTs are making me back off. Input anyone?

 

[nps]

Assuming you had your foot planted on the floor, you're way too low - an ETH is set for about 25lbs from the factory. If you were cruising at 2500 RPMs and letting off the throttle, then no telling.



Check for boost leaks.

 

[PC12Driver]

Check the last line; he's not at full throttle, he's egt limited. Larger compressors and larger exhaust housings both result in less midrange performance.



I noticed the same thing when I put my hybrid/14 on. Try going back to the 12cm housing. That'll drive the compressor harder in the midrange, get'cha some more usable boost, and keep the egts in check a bit better. Top end egts will be hotter, but you don't use top end power for towing.



Before I head out on a trip with the 5ver, I'll put the stock turbo back on. Much better midrange, and the hill has to be really steep to get the egts past 1200* with the box on 1x1 and my Mach 2s (results from before I had the cam).

 

[Nate]

That seems low. I get 30psi with a stock setup. Keeps on popping the boot off the intercooler which is a PITA!

 

[JJ Jackson]

I recently upgraded to a Hybrid turbo with a 14 cm housing and was wondering if my boost was normal. While pulling a big mountain road with my 40 foot 5th wheel, I was in 3rd gear (six speed manual) and pulling about 2500 to 2700 RPMs with about only 15 PSI boost @ 1200 degree EGT. That limited me to about 30 MPH. I tried this hill with my comp on 1X1 and completely off with the same results. I would think with that RPM and working the engine, that my boost would be higher for more cooling. I feel like there's more power under the pedal but the EGTs are making me back off. Input anyone?

Nick, are you talking about the Grapevine on I-5?



Is that a toy hauler your pullin'? If so, sounds very heavy.



I am pulling 13500lbs over the Grapevine at 50mph feathering the throttle to keep it just below 1250*, and 27lbs of boost



Can you achieve 30lbs of boost? What I'm getting at, is do you have a boost leak somewhere?



Does running one gear higher and putting it to the floor make any difference?



I'm wondering if my ATS 3pc manifold really helps cool EGT's, cuz I'm running with the comp on 5x5 all the time.



Could there be a crack in the manifold or loose bolts?



BTW I've got mach 2's and stock HX35/12



Good luck... ... ... . Jim

 

[Beast2B]

what kind of boost numbers do you see empty? if you're racing around the streets, can you het to 30? 40?

i pulled the grapevine with 12k toy hauler 4th gear 50mph and kept 35-40 pounds of boost no problem. still had to feather the throttle to keep it under 1300 EGT, but the boost was up there. any kind of wasetgate on your turbo? adjusted wrong?

only time i have boost issues on the hills is when i get bogged down from a car or semi pinching me in, then it's real hard to get back up to speed without murdering the EGT gauge! if i get down to 2300rpm +/- it's time to downshift and ride out the hill. like i said, it's real tough to get much speed back after losing it with a big load. (3. 54 gears and 37" tires don't help)

 

[Nickaru]

Reply

I'll try and answer some of the questions posed.

I don't get it. I was always told the stock turbo is great for low end and midrange. For top end or climbing hills, the bigger turbine housing will move more air to help the EGT problem. I know that the bigger turbo will spool slower at bottom end and that doesn't help clean up smoke down there. The stock turbo just runs out of steam. I had the same situation with EGTs with this hill, with my stock turbo. The difference I noticed in the upgraded turbo is the EGTs just climb slower with the bigger turbo.



I don't have the pedal smashed to the floor at all. I'm EGT limited.



The hill I'm using is on the East 138 by Mountain High coming from the 15 (West bound).



I can get 30 PSI boost if I get on it at a low RPM situation without the trailer, but that only lasts a few seconds, then goes down to 15 or so.



I have checked for air leaks and everthing looks good. Took some hoses off to check for cracks, tightened clamps, shade tree pressure test, etc.



The trailer I tow is a toy hauler and it's a heavy beast. Probably around 14k to 15k loaded.



My RPM is around 2500 to 2700 and that sounds more in the upper RPM range for the motor than mid range and would expect more boost.



With the box off and just the EDMs working, it still gets hot fast. RV275s instead??? (probably just a weight issue)



Thanks

 

[WadePatton]

Your boost is low, period. Boost leak is my guess. What kind of boost can you make empty? (on edit)--oh 30#, seems low to me. Are you sure that the bottom boots are good? I've seen them blow up like a balloon on the dyno. I blew one the other day. I was used to making 45# plus. Then I noticed higher and higher EGT's. I could still make almost 30#, BUT EGT's were off the chart. When I pulled the OEM boot there was a 2" gash in it. I think it had been splitting for a while. Replaced with proper Piers product.



The same 12v had a flat spot when hill climbing empty. If I let the boost fall below 15#, it'd heat up. I'd have to kick it a bit and get the boost up to 20+ and then the EGT's would stablilize nicely. So I had to RUN up the hill or putt-putt up the hill. All empty.



Running a #4 plate with 370's and 4" turbo was the problem. Stepped the plate down and can't find a dead spot.



AND (on third reading) You're right. At 2500 RPM, you could have a REAL big turbo lit.



SO my suggestion is double check the lower boots and sell the hybrid and get a full 4" of your favorite flavor.

 

[Larry Willard]

The last 2 times I had problems with low boost pressure, it turned out to be a small hole in the line going to the boost gauge. It will all be replaced as soon as we get back to warm weather again.

Larry

 

[CumminsAholic]

If it hits 30 then drops... wastegate problem? Do you have an adjustable boost elbow? If so it may be out too far. If not you should get one. Try unhooking (or crimping off) your line running to your wastegate and see what the boost does, if it stays up, like it should especially at those rpm, you have a wastegate problem, if it's still low, probably a boost leak.

Corey

 

[Nickaru]

It's just one thing after another. Now, sell my Hybrid? I have a BD exhaust brake I use with that trailer. Now sell that also and spend another $1000 on an inline brake? Can you say MONEY PIT?

On the wastegate issue, I had the same lack of boost with my stock turbo and now it's the same with this new Hybrid. High Tech Turbo set up the Hybrid with the wastegate for me. On my stock turbo, I had the wastegate blocked off and still had low boost, around 10 to 15 steady and 30 to 35 very momentary at first.

 

[WadePatton]

NEWSFLASH!!!



One our local guys just had a problem with a High Tech Turbo (low boost). Seems that their calibration or something that they use to set the wastegates was out of whack.



Give them a call.



Or check with HeavyHauler (Hans).

 

[WadePatton]

With any of my trucks, empty on a hill, I can put the boost where I want it and it will HOLD there until I back out or the RPM's go past the defueling point.



That's with a B1 (no wastegate), two different hybrids (14cm), and a stock turbo (12cm).

 

[CumminsAholic]

If the wastegate is good then you have a boost leak somewhere.

Corey

 

[HeavyHauler]

Nickaru - I just replied to your PM but now see that you don't think you have any boost leaks.



But as I read on, if you were having a problem sustaining boost before the upgrade, then the problem is probably somewhere other than your turbo. I wouldn't go crazy and sell your turbo just yet. A set of PDR intercooler boots is always a good investment and they have surprised a lot of guys after installation. Most people never realize they had a problem until they put them on and seal all the tiny leaks.



I would try that before getting a new turbo. I really doubt there's anything wrong with your current spinner. As I said before, my experience with HTT has not been perfect, but they do put out a solid turbo.



Oh, and your wastegate setting should not be affecting your numbers pulling that hill in 3rd gear, unless it was set REALLY low from the factory, which we can rule out since you are albe to hit 30psi for a short time unloaded.



This really sounds like you're losing air somewhere. Don't rule out the boost leaks.



Good luck.

 

[HeavyHauler]

With the box off and just the EDMs working, it still gets hot fast. RV275s instead??? (probably just a weight issue)

I don't think smaller injectors are the answer, quite the contrary actually. A 14cm2 housing is pretty big, especially with small injectors like the 1. 5s. You would get even hotter with RV275s because you would have even less fuel to spin the wheel in that big housing. Let assume (probably incorrectly) that you don't have any boost leaks and your turbo is doing what it should. I would immediately say that you need more fuel, or go to a 12cm2 housing.



I ran Mach 1. 6s with a stock HX35 (12cm2 housing) and my temps never went above 1050-1100*. I had a max boost of 32psi with the drilled boost elbow.



I now run 200HP injectors and use a 12cm2 on my HTB2. Spool-up is excellent and temps are fine. Granted, a 12cm2 Holset housing and a 12cm2 housing from a Schwitzer-based turbo are not the same thing.