Engine/Transmission (1998.5 - 2002) HTB2 backpressure testing

[mcoleman]

Thanks to John at Floor It Diesel Performance I now have some backpressure numbers on my HTB2. At 40 pounds of boost it has 53 pounds of backpressure. For those hesitating on this turbo don't. It's awesome. It spools extremely hard and fast and EGTs are only an issue with the Drag Comp on 5X5 and speeds over 80 mph. I drive the truck daily with the box on 3X3 and Don Ms Mach 3 injectors with no EGT issues and no smoke issues and it is extremely responsive. A trip to the dragstrip is on the agenda for the next dry weekend. Oo.

 

[SRadke]

Is that the standard B2 or the Killer B2? Do they have the same exhaust housing?



-Scott

 

[cerberusiam]

At 40 pounds of boost it has 53 pounds of backpressure

Curious you think this a good thing. ??????

 

[mcoleman]

It's the standard 62mm/ with the 12cm exhaust housing. I think the killerB has a 14cm housing. I would need a lot more fuel to need the KillerB and still keep backpressure in this neighborhood. I will be trying a 14cm housing with bigger injectors later. I'm pretty sure mach 4s will run great with the 14. And yes 53 psi is a very good backpressure reading.

 

[SRadke]

I would need a lot more fuel to need the KillerB and still keep backpressure in this neighborhood.

Can you clarify this for me a little? 53psi was your peak drive pressure @40psi boost right? Why do you want to keep it that high? Would it not be better to have less peak drive pressure with the same boost? My killer B2 spools plenty fast to be driveable with stock injectors and the box turned off,,,,,, although that rarely happens



-Scott

 

[cerberusiam]

And yes 53 psi is a very good backpressure reading

I would agree if boost was at 60 psi not at 40 psi. As a rule peak efficiency is obtained with drive pressure less than boost pressure. The other way around is doing nothing but creating heat and expending unusable energy unless HT has come up with a way to break the laws of physics. Please do clarify that drive pressures at 130% of boost is a "good" thing.

 

[Snow man]

i always thought your drive pressures and boost should be at 1 to 1 at full power. 40psi of boost should have had 40psi of drive pressure. It sounds like the exhaust housing is too small for starters.

 

[mcoleman]

With no EGT issues except on a full throttle 1/4 pass using the DRAG Comp and the Mach 3s and then it just barely hits 1600 at over 100mph I don't see a problem at all with my exhaust housing. 998 pounds of torque at 2300 is also testimony to the ability of this turbo to run clean and strong. I've not driven in nor drove a cleaner more responsive truck than this combination. 22 mpg and able to tow my steel 3 horse slant load with the comp on 3X3 is also a plus. The truck is as responsive as any gasser and will not smoke out everyone I pass. When it kicks down to pass all you get is a very small puff of gray haze before clear-up and instant boost with the comp on 3X3. If it was a standard comp it would be lucky to even hit 1500 at wide open throttle. The wastegate also actually works. What you set it on is what it stays at under full boost. Maintaining boost on the dyno is also not a problem. No loading up and no laboring what so ever. I drive my truck 75 miles round trip a day which is way more driving than it will ever see in dyno time and dragstrip time. The driveability is more important to me for daily use I can live with slightly warm EGTS with the Drag comp on 5X5 as you will see that with any turbo setup short of twins on a drag programmed box. But that is not where the truck spends the majority of it's running time. I can always upgrade housings later when I change to Mach 4s or Mach 5s. HTT is also looking into twin set-ups which will be my choice later down the road to maintain the excellent driveability.

 

[propuller]

You have to be careful with high drive pressures they can pop a head gasket just as easily as to much boost. You will have a very hard time contolling egts with mach 4's & 5's should only be run with twins. With that much fuel you will push past the small gate in that turbo & your boost will get out of contol not to mention your drive pressures will be out of sight. Im not saying anything bad about your turbo but just like anything else it has its limits. When you go beyond a 1 to 1 ratio your intake temp starts to skyrocket & hot boosted air is not what you want. I think i would look at a larger housing to try & lower those drive pressure numbers. You might want to get that head O-ringed. Good luck.



Kurt

 

[Jim Fulmer]

Normally Twins run at 1 to 1 till the higher boost levels, my old Twins were 1 to 1 till after 60 (just like the current set) then they went south fast after 65, these stay on 1 to 1 till past 70 then creap to 85 drive, 80 boost..... still in the game.



Piers did testing a long time ago on an hx-35 and at 30 psi, drive was 45..... that's 1. 5 to 1 so what I'd like to see is what the HTB2 does at 50 psi as well as all the B-1 series turbo's... ... . R&D is fun.



Jim

 

[cerberusiam]

Mcoleman, thanks for the info and the insite. Sounds like you spend most of your time running unloaded. The fact that it is responsive and clean is plus. Do you have any numbers on boost vs drive pressure from 20 psi up? I would like to see what it does at a more lazy level of boost.



You guys that have done a lot of tests, is it possible to keep the drive pressures +- 5% of boost and still get good driveability without lag and smoke with a single charger? with twins?

 

[mcoleman]

Actually I spend most of time pulling my horse trailer and hauling hay when I'm not commuting 70 miles day to work. That's why I like this combo so much. I can deal with EGTs going over 1500 for 1. 5 to 2 seconds on the dragstrip much more than I could while towing. The 14 cm housing would actually cause the truck to run a higher EGT with these injectors towing in the hills than the 12cm will due to not staying spooled as well. I can tow in our short hills with lots of curves where you are under 55 mph the majority of the time and not have to deal with surging, barking, or falling off the turbo that is common with some of the larger exhaust housings and turbos. It's always right there and ready to go which also keeps EGTs in check. I didn't get numbers for what it's doing with the Drag comp turned on a more normal setting like 3X3 but I would assume that it has a closer to 1 to 1 backpressure reading. The Drag Comp is rather radical on 5X5 much more so than a standard comp. The smoke difference alone is unreal between a regular comp on my truck and the Drag comp. I can just barely hit 1400 at well over 100 mph and thats well past what I would run in the 1/4 with a regular comp on 5X5. Once we get the wife a 3rd gen for a daily driver and tow rig I will probably step up to a more competition only setup that is less street friendly for this truck. For now this combo really rocks for towing and weekend playing. Hopefully HTT will have their twin setup ready to go by then using my HTB2 as a part of that.

 

[drawson]

Can you say EGR

When the drive pressure is greater than the boost it leaves alot of exhaust inside the combution chamber which is just like the dredded EGR system w/ the exception of it isn't taking up intake air charge space!! Anything over 5-7 PSI above boost is too high IMO