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Discussion Starter · #1 ·
I am putting my 4bta together now. It's got a he351cw turbo (very similar performance to a HY35W, many mods on the VE pump including a 3500 rpm spring. Marine high rpm valve springs. Stock injectors for now. Powerstroke IC, 4" low restriction air fliter and associated tubing. all 3" tubes for compressed air from the turbo through the IC. Bored out the intake manifold cover to 3" and installed 3" inlet. Full instrumentation ( pyro, boost, oil temp plus the normal assortment of standard gauges) I will not be constantly beating this thing, but do intend to take it to it's limits every now and then.
The question: Who runs their engines at this rpm, and do you have HD rod bolts? I can't find them from ARP or Cummins. If you use them, who makes them, or better yet, where did you get them? The guy that built my pump builds pulling motors, and only works on 6bt's and 4bt's. He said I will have NO PPOBLEMS if I keep it under 4000 rpms. Please comment if you have any experience in this regard.
Thanks,
Bob B.
 

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I think you will be suprized how over built these motors are! I know guys who are making over 800 horse with a stock bottom end 6cyl and are beating the crap out off them day in and out. I personaly havent had my 4bt that long, but I am planning some major mods and the bottom end isnt on my list right now. I am sure that if you have a big budget, you are building it before puting it in, and are planning on running some big numbers then what the heck, put the best stuff you can afford in there. Head studs would be on the list, and valve springs if you are going above 3200 rpm to keep the valves from playing tag with the pistons. Although I dont think its worth turing it over that as the power drops rapidly. Let some other guys chime in but IMO I dont think there is anything as overbuilt like the cummins B series. My 2 cents
 

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Discussion Starter · #3 · (Edited)
I don't think head studs are necessary with only an expected boost of 30 to possibly 35 psi. But If I have head gasket problems, then I will stud it! The valve springs that are going in are not really Cummins marine, but 60 lb. springs from Pure Diesel Power. They will sell a set for the 4bt for $92. They said that stock retainers, and keepers were fine for below 4000 rpms. Also the pump is modified to continue to build power up to 3500 rpms, and then taper off the fuel. Should change the torque curve considerably. It will still have massive torque off idle, but continue till a much higher rpm. One of the guys on this forum told me that the 4bt would not live long if I took it to 3500 rpms every now and then. In fact he said it probably wouldn't last 20,000 miles. If that's the case, I'll hold onto my Cat 3204t engine just in case. I rev that thing to 3500 ALL THE TIME, even with a load. It has lasted in two trucks a total of aprox 500,000 miles.:D It has blown 3 head gaskets--about every 150,000 miles. That's all I've done to it, with the exception of oil changes, and valve adjustments. I want more power though!

RE ROD BOLTS Here is what I found out today:
Even some of the suppliers that could have sold me better rod bolts said that they wouldn't be needed unless I was turning over 4000 rpms and loading a highly pumped engine. My engine will be "lively", but not all out. So, that money will be put in the injector fund.

Build thread coming as soon a I get through with two large handrail fab jobs that will take two months.

Buy the way guys--thanks for all the info and opinions on this site.
 

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Discussion Starter · #5 ·
Thanks for the input Racinwayne. I forgot to mention, another cheap upgrade I'm doing is replacing the 4bt oil pump with a 6bt pump. It has 33% more volume. Keeps the bottom end much cooler. It is a very simple bolt in job if you have your front cover off.
Bob B.
 

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Thanks for the input Racinwayne. I forgot to mention, another cheap upgrade I'm doing is replacing the 4bt oil pump with a 6bt pump. It has 33% more volume. Keeps the bottom end much cooler. It is a very simple bolt in job if you have your front cover off.
Bob B.

Hmmmm, Has anybody else done this swap and has any info to add. This is a new one to me. :idea:
 

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Discussion Starter · #7 ·
Hi toolmanoffroad,
The pumps will interchange. You can even use one of the aftermarket super high volume 6bt pumps, but you don't really need it on a 4bt. But, If you are using a compound turbo setup, it would help. Those turbos take a large volume of oil!
 

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Hi toolmanoffroad,
The pumps will interchange. You can even use one of the aftermarket super high volume 6bt pumps, but you don't really need it on a 4bt. But, If you are using a compound turbo setup, it would help. Those turbos take a large volume of oil!
Wrong 6bt has a wider gerotor. Pumps are NOT interchangeable
 

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Discussion Starter · #9 · (Edited)
4 cyl and 6 cyl pumps

reedheadbronco

The larger gearotor is one of the reasons the 6cyl oil pump will pump more volume. The second reason is that the driven gear on the gearotor is smaller on the 6 cly pump, so the pump has a taller gear ratio, and spins faster. The gearotor is internal, and the external dimension of the pumps are identical. Also, the 4 cyl and 6 cyl blocks are machined identically in the oil pump area. The 6cyl pump is a cheap and worthwile upgrade. I agree, you shouldn't install a 4 cyl pump in a 6 cyl. I know the Cummins manual says they are not interchangable, and that is probably so you won't install a 4 cyl pump in the 6. My 4bt has a 6 cyl pump and it works just fine!
:D
Bob B.
 

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I removed the info in this post and started a new thread on oil pumps and coolers in the following thread:
http://4btswaps.com/forum/showthread.php?t=1501

Please continue your discussion on the oil pump topic there where it is not hidden within another thread.

Thanks!
 

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I cant imagine you chunking a rod. Those engines are well built with a large cap screw rod design. I do some tractor pulling and have seen many 6bt trucks and talked to alot of owners. They stand more abuse than you can ever deliver on the highway or off road and I have never heard of one loosing a rod....
 

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