Twins issues?

[seeker1056]

Hi KTA

Please explain to me the correlation between egts and fueling?

If I have little fuel and lots of air, I was under the understanding that egts would be low, and if I have too much fuel and no air, egts would be high.

this would make sense for when the twins are hooked up and egts drop considerably cuz there is more air at 33 psi?

ergo, then on just the 35 with same fueling, I am not getting enough air?

and consequently only 18 psi boost.

of course thats the $64000 question - whats wrong on the 35 side of the boost/egt equation?

Is it possible the 35 is just no good? Is there a test to see if it is or isnt?

More testing this weekend then, with just the hx35.

[Philip]

The boost your showing on the HX35 by itself is not normal for a turned up pump. My pump only has the fuel pin turned. I make the same boost as your HX35 with a turned up pump.

I would find out what size that exhaust housing is. If you have one of the 9 cm's on it. It would be a massive bottle neck. I think that 40 psi drive pressure is high.

[gman07]

To have a 9cm housing would require the HY35, and I think even that would make more than 19psi with a turned up pump. I think either the HX35 is bad (it doesn't sound like it though) or you have a leak somewhere between the compressor outlet and the intake horn. You could also have a restriction somewhere in a pipe; I've heard of rags being forgotten in intake pipes before... it seems like a bit of a stretch, but something is definitely off to have 40psi drive pressure and only 18psi boost.

[seeker1056]

would having a 12 cm housing be causing my issues of high drive pressues, low boost, and the high egts when run by itself?

[Philip]

I don't think that 12 is causing all the problem. But it is small. With the fueling you have you should have a lot more boost. I would think you should have 30 PSI or more.

You have high EGT's so that means your injectors are throw at least enough fuel to build the heat. But if the pop pressures are low. It might be throwing the fuel in to early.

Are those injector stock or are they a modded set? If they are rebuilts do you know what shop rebuilt them?

Did you hve the HX35 on before the injector change? If you did how much boost was it makeing?

[Cschafer]

Your drive pressure is way to high for your boost number. Either you turbo is bad of you have a leak. It makes sence that your makeing more boost at the same drive pressure with the twins if your 55 is doing the work and your 35 isnt. How is your spoolup, with and without twins? How is the smoke? It doesn't matter what housing is on it as long as it isn't some crazy cobbled on 36cm or somthing . My 96 with a stock hx35 runs 39psi and 1300 deg. so the turbo is capable but somthing is not right with yours. Do you have an o-ring in the 35's outlet tube? I would double and then tripple check for leaks and then try a differnt turbo. Good luck.

[gman07]

The issue is either in the turbo itself or the intake piping. While injector issues could cause high EGT's, they wouldn't lead to a 2:1 drive ratio. They could cause low boost if the pop pressures were too low, but then the drive pressure wouldn't be as high as it is.

I would double and then tripple check for leaks and then try a differnt turbo.

That's what I'd do too.

[seeker1056]

hmm, ok. Thanx all for your suggestions.

I put it all back together last night and took it for a run with someone following me.

SMoke - black for about 15' takin off under hard throttle and a puff at each gear change - other than that - no smoke.

the motor shows steady rate climb of boost from about 1800 rpm to 2900 that maxes out at 32 psi.

There isnt any appreciable lag after about 15 kph

The primary doesnt show any boost till the main guage is showin 18-19 psi. Then full out the primary is showin max 8 psi between the turbos.

egts never go past 1100

drive pressure at 32 psi boost is 45-50 depending on how hard i bury the throttle

Game plan: This weekend I am gonna change out the injectors, pressure test the piping again, and run just the hx 35 till I get this figured out.

Is a hx40g a bolt on to our manifolds T3 vs T4 flange bolt pattern as there is one on Ebay right now at a decent price.

[KTA]

Hx40's are available in T3 and T4 patterns, you just have to check the individual one to see what it is. Also only go with the 16cm as the 18 is just too much and makes it a lag pig and runs more EGT too.

[seeker1056]

Well i finally found time on this long weekend to get some work done on the truck.

Now have the POD's and the 666 spring installed.

What a difference to drive, tops out at 3385 rpm in all gears, easier to drive, and motor noise is half of what it was.

Things they don't tell you, lol, anywhere. If you get a ball socket type allen key, one does not have to move the pump to get at the back screw on the pump housing. If you look closely there is a slot in the finger that holds the tophat assembly. If u push the spring end thru it the whole thing comes out without having to try n fish around with needlenose to get the spring off the tophat assembly first. Same for reassembly, put the top hat assembly on the spring then push the spring though the slot and push down, instant hook up, no muss no fuss. The other thing they dont tell you is that the fuel pin must be full forward for the top to fit down on the base again. Removing 1 and 5 valve covers allows one to move the injector lines enough to get the injectors out without havin to completely remove the lines.

So, I re-indexed the throttle, installed the injectors, have the fuel screw seated at its deepest. By the way the old injectors, even though only have 25000 on them had at least one hole plugged if not two or three on some.

On a full power run on just the hx35 I have 60+ drive pressure, and 28 psi boost, and 1600+ egts. - not good!! Still 2:1

Tried adjusting the wastegate, but very little differnce. Man does this thing (hx35) HOWL/SCREAM from 22+ psi by itself.

Next I put the hx55 back on. Full power run nets me 48-50 psi boost, 60+ drive pressure, and 1400+ egts with 18 psi boost showin between the two chargers. so about 1.5:1

Second run blew a hose connector off between the chargers - bad clamp.

So ok, 50 psi compound is fun, but what is wrong with the hx 35 - is it possible it is junk? I cant push it any harder by itself, or drive pressure is pegged on the drive guage at 60+ and egts are in the 1600 range and climbin til i let off.

Thoughts anyone?

Thanx

[dazedandconfused]

I think there is something wrong with that HX35. On my overvalved truck my Hy will push 25PSI stock. I have seen many HX35's run up to 50PSI, not that it is good on the charger. So the rest know what his setup looks like here are the photos.

http://www.cumminsforum.com/forum/member.php?u=1190[url][/url]

[gman07]

I'd try running a different charger in place of the HX35 to see if that's the problem.

By the way, where do you live? There may be some members nearby to swap turbos with you if you don't have a spare to replace the 35.

[wannadiesel]

Yeah, that HX-35 is not healthy. It ought to be able to do 28 psi with the wastegate wired OPEN with the fuel you are pushing.

[bgilbert]

Yeah you should see 28psi with stock injectors, hx35-12 and minimal pump tweaks. Many owners see 40psi with POD's, hx35-16 or 18, let alone the 12wg housing. At least you're on the right track now with something other than stock injectors.

[seeker1056]

is it possible not enough engine heat was contributing to my boost woes?

Today in 31 celcious heat, the motor finally got up to 190F from its normal 160F degrees water temp. No fan on it yet

Having said that the motor was much more responsive and I gained 5 psi boost.

Motor was climbin hard past 52 psi when i took my foot outa it cuz I dont have studs. YEt.

secondary was runnin 26 psi, primary was at 26 psi, and total boost was 52+ and egts 1250, drive pressue at 55 psi all at 2800 pm