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Normal boost pressure for a 64/68?

3K views 43 replies 9 participants last post by  dbow20 
#1 ·
I have an engineered diesel 64/68 with a 13cm gated exhaust housing. From what I have read, most are seeing similar turbos start to spool around 1600 rpm and max boost around 40 psi. Mine starts to spool closer to 1800 rpm and the max boost I have seen is 29 psi.

Is my wastegate opening too early? I have the screw as tight as it will go so It seems like that shouldn't be the problem.

Thanks for any help.
 
#3 ·
I'm surprised there is no info on this turbo.

Does anyone have an opinion on switching from a gated 13cm housing to a .91 non gated? I don't know much about the size difference so I don't know if there will be a difference between the two exhaust housings.
 
#4 ·
When I had a 63/68/12 it'd max out the trucks ability to read the boost, which was 38 psi. Based on when in the powerband that happened, I think the truck/ turbo made around low 40s for boost. Maybe 40-42
 
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#9 ·
There are a few things that will affect the spool rpm, heat out of the head is a biggie which is effected by injection timing... Flow through the airbox/airfilter is another. I may be able to look at this with the data i am currently collecting for the airbox test over in the powertrain forum. Will have to wait until after the rest if the data is digested & presented though. Ping that thread if interested.
 
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#10 ·
Air will leak through the engine rather quickly during a leak check. I don't have an exact number but the high pitched noise my valves make while leaking goes away in about 5 seconds.

What tuning software dbow? Stock 03's make lower boost than 04.5's+. 29psi sounds about right.
 
#12 ·
That sounds about how my leak check went.

I am using smarty revo tunes right now. I have been playing with sw7 and sw9 with less timing because of the large injectors. I have found that by using less timing and tq2 with POD around 85 I have the best power and the least amount of smoke.
 
#23 · (Edited)
They are but I believe the map sensor will still limit fueling when it sees an overboost. Smarty is hit or miss on this. Some trucks fuel fine while others won't. :confused: Sounds like Dbow just needs more fueling though.
 
#15 ·
100% BMS isn't normal. Yes its possible they were opened up to that but just not very common. If you have access to previous owner I'd try to confirm that.


Since you have smarty, do you have a boost fooler? I wanna say 29psi is where it limits stock on an '03.
 
#17 ·
Yes people do open the Bosch Motorsport nozzles up to larger, but what I was getting at was; 100% overs + box smarty + stock cp3 = a smokey hot combo on that turbo. Normal 100hp bms nozzles would be great for a mild setup with proper rail pressure.

Smarty is supposed to boost fool, mine did all the way to 65 psi when I switched over to HPT.

Just saw your question about the POD. I always left mine on 99 since I hated the way the petal felt. Once I found the settings I liked, I controlled smoke with my foot. Just for reference I daily drove mine on sw5, had good power and wasn't as smokey as sw7.
 
#18 ·
Id throw a boost fooler at it. Smarty is hit or miss on that issue.

I leave my POD from 90-99 usually. Just takes the edge off. :rof
 
#19 ·
Little update. Today I changed the smarty down to sw5 to see how it would do. I was able to get up to 35psi on my insight multiple times and every time it was still pulling hard like there was more boost. Maybe the ecm is only reading to 35psi or it's the insight only going up that high. I plan to get a mechanical gauge to see if I'm right that it is still building boost past 35. I'll also try adding a boost fooler to see if it helps any.

The needs more air though because cruising at 75 EGTs are at ~900 with 3-5 psi of boost and wot they climb to 1750 if I stay on it hard.


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#25 ·
Played around with smarty settings a little this weekend. sw5 had good power but EGTs seemed really high and there was a haze from the exhaust at idle. Moved it down to sw3 and no more haze at idle but very smoky during acceleration. EGTs on sw3 were good, best Ive seen between 5, 7, and 9 but I suppose that is expected. Boost seemed to be the same on 3 and 5


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#29 ·
If you're shooting for big numbers a 74 turbine wheel would be better I believe it has a lot to do with drive pressures. If you were to compound yours with a 480 I would use an external gate


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#31 ·
The 68 turbine will choke power earlier than say the 74 wheel. You can external gate of you want or just watch drive pressure and maintain a safe power level without an external gate. I'm assuming your t3 64 is internally gated?

Now bigger singles on a 5.9 are better now with tuning advancements, but one thing to remember is spool up is a relative term. Most people have different opinions on spool.


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#32 · (Edited)
The 68/13 won't like much over 750 on compounds. It would probably do 775-800 but thats close to the edge. So whats the power goal? Starting fresh on a T4 setup would be better for compounds. I sure wish I woulda.

Yes its internally gated if its a 13 housing. Only HTT offers that one.
 
#33 ·
700 is not bad at all! I like to watch Jim Rendant's truck on youtube and he was running a large single, I think an 80mm, before he took it apart. Maybe after I get the cp3 taken care of I will try a large single with hp tuners. Haha too bad money doesn't grow on trees!

When you say on HTT offers that housing does that mean other turbo builders can buy them from HTT? My turbo is an engineered diesel, same as the one in this thread but with a 68 exhaust wheel. Engineered Diesel 64/71/13ss pics!!!! - Dodge Diesel - Diesel Truck Resource Forums

Now that I'm reading more into the thread there is a lot of heat over the exhaust housing. I need to give Chris a call and talk to him about it.
 
#34 · (Edited)
I believe HTT designed and cast the housing. But I also believe they have discontinued it. So yes, ED could have bought it from them. Also that thread is from '09. The 13 housing is old technology. Like we've said, if you are going compounds don't not stay with that housing unless you really are after quick spool and mild RPM's.
 
#35 ·
Deeper into the thread the talked about it being HTTs housing so that cleared all that up. It amazes me how much goes into picking the right size for turbos in a compound set up, and man there are so many choices.

I am building this truck slowly, basically only have weekends to really work on it because I go to school at the Naval Academy and they keep us busy. My questions about compounds are only for future reference because I am so slow on building the truck. But it sounds like a 63/74 with a 480 is a pretty nice compound set up but the price for two new turbos and piping makes me wonder if it's really better than a fine tuned large single.

If I understand correctly in the compound set I mentioned above, the 63mm turbo starts spinning and feeds the engine air. At higher rpms the 480 finally has enough hot air to spin it but at the top end it is limited by how much can flow through the 63? Is that close to correct?

If the 80mm turbo was there alone it would spool later but not be limited by the smaller charger on the top end. In this case the downfall is low end boost but can that be helped out with tuning?


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