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More "realistic" power increases / engine reliability, etc...

Lee Alessi (McInfantry) & I were Bsing around back channel partially from some different threads about 4BT tweaking.. Both he & I were a little worried that hte threads with 350hp / 400 hp (not that there is anything wrong with them) but people start reading 400 hp or 350 hp and believe you can do that easily with a 4BT when I think both he & I don't necessarily agree...

Here is a thread where a guy blew up his Bosch VE pump at 320 hp because his (performance) injections (still) could not no release enough fuel..
http://www.dieseltruckresource.com/dev/showthread.php?t=84054

With an inline pump this may be different..

Lee was talking to another guy in another thread about 4BTs and tweaking, on IFSJA (International Full Size Jeep Association),
http://www.ifsja.org/forums/vb/showthread.php?t=61289 and this thread largely came out of it...

His big thing is that you can tweak that high but will it be reliable in the same fashion that our 4BTs are currently reliable (200K miles + usually)... He was saying if a 4BT gets less than 100K miles is it reliable? I personally don't think so..

I posted this up in response on that thread:

I'm on my second 4BT.. I think 250 hp is probably reliable with a 4BT but I'm not 100% sure.. I'd say I easily got well over 160 hp completely stock just by turning up the pump, but it is true, mileage went down drastically. Noisewise, in stock form with not too much fuel I think they sound exactly like a gen 1 (89-93) Dodge, maybe a hair louder but not much. When I turned up a lot and had a lot of fuel at idle, and gobs, I mean gobs of power bone stock, it sounded about that of an early 24 valve, loud as hell, almost bone jarringly loud.. anyway, I think about 250 hp max is about right out of a 4BT/rotary IMO, also without losing some relability. I previously would say about 200 hp except that I saw the dyno results that were up on the new 4BTswaps.com site at 183 hp completely bone stock other than fueling increase and that is not all the way up. With the right turbo and some cooling I think you could get it.

But that said, I must say honestly I agree with lee. It is not the HP that matters, its the torque. At 160 hp (which is less than my old *** saab), my FJ55 land cruiser wago, sprung over, 35" tires, 5500 lbs, HAULED ***. I got pulled over going 83 mph with lots of power to spare up the steelest freeway incline around here (we have some big long inclines here in Utah).. Cop was impressed enough that he actually let me go LOL. But that was when I had it turned up. I eventually went pretty close to stock, about 120 hp in the end (I had a 4BTA), I had a HX35 turbo on with the 12cm2 housing, and it powered my truck absolutely great, no loss of mileage at all except going up hills of course..

The guys wanting/expecting big HP can do it but it does take $$ and lowers your mileage significantly.. Stock 105 hp is 265ft/lbs. stock 120 hp is 305 ft/lbs, more than most stock V8s. Somewhere around 140-150 I think you reach 400 ft/lbs. That is more reasonable and won't compromise mileage too much at all.. My $.02 on it..
So my finaly $.02 is probably upto 250 hp but I think fuel mileage will suffer and I really don't know the results. I think 160-200hp is optimum and will not cuase much/any damage at all to a 4BT and probably won't affect mileage too much...

So guys looking to tow and large rigs etc, the motor will have to be really tweaked and the question is, will it still be reliable and cost wise still worth it?

Comments/thoughts?
Open discussion here, curious what you guys think... :smile:
 

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well while i think just about every thing in your post is correct i think it is important to remember that these where posted in the performance section. If you are doing your conversion for economy or durability reasons none of what i have suggested would be practical. I want it to be understood that what i am building will maybe see the roads a half dozen times a year and i am doing it just for the reason of bieng different(and if i break it im ok with that). I see no reason that these engines cant be comparable to the 6bs in terms of mods and percent of power increase that can be had. However ask anyone with a 600hp dodge and they will tell you that the 500,000 miles seen in a stock engine is out of the question. Please dont see this as an argument just the other side of the coin.
 

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hendricks, the reason i had the discussin was the fact that, unfortunatly, people read your post, then start posting it as "truth" hence the ifsja arguement. the quick post form a guy that says "250hp is a really easy achievable goal"

thats the b.s. the real issue i see are all the people building this, or that and havent built or run a 4bt AT ALL. like i said, i ran stock 4bt mounts and cant figure out where all the internet experts keep saying vibes are intolerable. a better one is the old "a 4bt can produce 2/3 the power of a 6bt, since its the same motor, minus two cylinders. i really love that one. a 4 cyl crank, is NOT as "balanced" as a 6. thats why 6's run smoother. start spinning one around 3200 and 350hp, and i just dont see it lasting.

when you go to a 1972 chevy truck site no clown posts how he is going to build a top fuel motor pushing 5000hp and put it in his truck, only to have 20 other wannabes run around on the net saying "you can easily get 2500hp from a v6, since it really just 2 less cylinders"

again, its no attack on you, or anyone else. just trying to keep facts out there for those who really are building a streetable vehicle, not an internet keyboardcrawler.
 

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I run my 4bt up to 3200 and it's probably more balanced at that RPM than it is at 800! I need to have my idle turned up to keep the shaking down.

Personally I think the 4bt is a great engine and have seen people running 12s in the 1/4 with the engine in a ranger with a rotary pump.

I'm about to do some more pump tweaking and maybe some injectors then we'll see how it does.
 

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I've got some questions on this. Note: I'm just the keyboard pounder that Lee refers to as I only recently have my conversion up and running, and only know what I read on the net.

This thread begins by saying that 4BT's are good for only about 200,000 miles? I commonly hear 6BT's referred to as 'Million Mile Motors' and have seen numerous posts from guys that have run them into the 750+K miles, no problems. How come you say a 4BT is only good for 1/5 the reliable miles that a 6BT is? If this is true I just spent a whole bunch of money and several months of very hard work almost for nothing!

For towing and hard running it seems that EGT's are the #1 issue. From what I can gather there are several mods that increase performance AND REDUCE EGT's, like a better compressor side, more free-flowing exhaust, water/meth injection. With minor pump tweaks and 366 governor spring it seems that 140-150HP with lower EGT's is easily possible with this sort of mods. Do you feel this would lower reliability?

The installation of an aftercooler increases power with lower EGT's from what I hear. Seems like this would cause the engine to run longer miles, not shorter, right? Added to the tweaks in above paragraph I suppose a guy would be approaching 160-175HP?

Head porting lowers EGT's and increases power. This would not shorten engine life from what I know.

Seems to me, and I have no experience here, that an engine with improved compressor like HTT Stage II, 16 cm2 exhaust housing, a 366 spring, aftercooler, water/meth injection, minor pump tweaks, and maybe larger exhaust would be a strong performing and reliable engine for towing and performance? I'm talking about engine reliability and NOT VE pump longevity.

Do y'all see this as a good RELIABLE build for towing? I'm talking about a daily driver and frequent towing. That's not including the possibility of head porting added for those who can afford it. For my own use I'm not really after higher HP as much as improved torque but of course they're closely related.
 

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hendricks, the reason i had the discussin was the fact that, unfortunatly, people read your post, then start posting it as "truth" hence the ifsja arguement. the quick post form a guy that says "250hp is a really easy achievable goal"

thats the b.s. the real issue i see are all the people building this, or that and havent built or run a 4bt AT ALL. like i said, i ran stock 4bt mounts and cant figure out where all the internet experts keep saying vibes are intolerable. a better one is the old "a 4bt can produce 2/3 the power of a 6bt, since its the same motor, minus two cylinders. i really love that one. a 4 cyl crank, is NOT as "balanced" as a 6. thats why 6's run smoother. start spinning one around 3200 and 350hp, and i just dont see it lasting.

when you go to a 1972 chevy truck site no clown posts how he is going to build a top fuel motor pushing 5000hp and put it in his truck, only to have 20 other wannabes run around on the net saying "you can easily get 2500hp from a v6, since it really just 2 less cylinders"

again, its no attack on you, or anyone else. just trying to keep facts out there for those who really are building a streetable vehicle, not an internet keyboardcrawler.
mcin,

Wow, I am getting famous for discussing my unproven theories on 4BT performance. You are correct I have not done it yet. But, as far as the two-thirds argument being invalid, how about taking two 1996 GM motors. The first being a 5.7 liter small block V8 that makes 250 horsepower from the factory and comes in half-ton pick-ups and suburbans. The second is a 4.3 liter V6 that makes 190 horsepower from the factory and comes in S10 pick-ups and Blazers. If you divide 190 by 250 you get .76. If you divide 4.3 by 5.7 you get .754386. So, the V6 makes three-fourths the power of the V8 that has the same bore and stroke, just two less cylinders.

I am sure you find some problem with the logic in all of this though. The inherent differences in the balancing of the V6 and V8 in no way compare to the I4 and I6 or something else I have said will be wrong.

Let me say that I do not disagree with your hardline on getting facts to back up what is being said. I totally agree. There is plenty of subjective reasoning going on and some people may get misled if they do not have the facts. So, keep searching for the facts, but try not to keep people from theorizing too much. Discussing different ways to increase power may lead to some new ideas and expand someone's knowledge base.
 

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and besides as performance enthusiast i myself would like to the max torque one of these little beauties make.
 

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and besides as performance enthusiast i myself would like to the max torque one of these little beauties make.
I am too, that's why I'm not going to use a 4BT. I'm going with a DT466 fom IH to put in an F350 pickup. Sure, you can make a 6BT make that kind of power, but everybody seems to be doing 6BT swaps these days.:rasta: Lots of work? Absolutely, but it's a good challenge.:smokin:
 

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i would use 4bt in my ranger so i think my diesel choices are limited. lol
and i agree that there are too many 6bt swaps.
 

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One BIG difference in the Marine 4BT: seawater aftercooler! No way you can provide that much cold water to a land based vehicle. A reliable power limit for a Marine engine may be far less reliable in a vehicle without unlimited cold coolant.
 

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well..... more torque at the engine means more torque at the wheels. I'd say it's a valid question.

And I mean in a real-world, same axle ratio type scenario, not gearing the lawnmower up or down to get the same Ft.lbs.

:thefinger:
 

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Discussion Starter #15 (Edited)
Another semi real world application issue, torque even stock for these motors is killer as we know.. @ 150 hp: 265 ft/lbs. @ 120 hp, 305 ft/lbs. More than a V8. Plus it comes on from idle. At stock or close to it, I always described the motor as borderline "unstallable", it almost has a wall of torque. With the cruiser though its a daily driver, I do wheel it.. My buddies say I am like 100 or 120:1 when I am at about 60:1, because of the "wall of torque" as I call it :grinpimp: .. Idle over anything, down to even 400 rpms, "the wall" is sort of how it won't stall. One of the coolest things ever.. Also,only thing I have broken ever is a Birfield (front axle CV joint) which is pretty common regardless with Toyotas regardless off road... Again at these lower numbers, 160-200 hp, torque will get upto over 400 ft/lbs but that is over kill. 160 hp from a 4BT, even in a heavy ass truck, is screaming power IMO.. At 200 hp, it sounds like a early 24 valve, loud and clattery as hell, borderline bone jarring.. Or at least if you have it tuned to get that power off idle.. Which I recommend, but again your mileage goes way down. We really need to post up a fuel adjustment thread somewhere :dustin:. This was all stock too, 4BTA with air-air intercooler, with reasonable EGTs...
 

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once again i will state exactly what it is that my intention is with my motor. I am not building for reliabilitly or logjevity, I am building what most consider a street rod and if i break it-guess what i bought it. with that being said I have a couple of thoughts. If i was trying to do as most on here are I would not consider pushing one of these motors over around 200 becouse at some point any engine will reach its limits before it becomes "tempermental". While i do think that mcinfantry's views are concervative, especially in a performance thread, I have to agree to some point. I dont think that anyone reading my post should use my build as an example of how to make a daily driver. I will also say that i do take personal the refrence to a keyboard crawler (im assuming that was aimed at me). I may not have built a 4bt before but im a long way from being new to this type of work. And if we get the attitude that the people not having finished there project yet are some how less worthy to show there ideas, I think you will see many good ideas overlooked or not brought to the table. build your motor for what you think is needed. If building a rock crawler think gearing not power. If your building a commuter think mpg not power. If you cant afford to break it I suggest you leave it where the 200 engineers at cummins designed it to run. ok rant over:pissed:
 

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My 4BT in a fullsized Dodge Town Wagon just got really driveable a couple of weeks ago. I still haven't driven it that much but every time I do I'm simply amazed at the power/torque in this LITTLE 4 banger! As mentioned, the off-idle "...wall of torque..." is astounding! I live in the mountains and it's like somebody is going ahead of me flattening them out before I get there.

I will be turning it up a little for more towing power but even bone stock this is one amazing little engine. Can't really imagine what one would be like with 140-150HP and 400+ ft lbs of torque, YIPES!
 

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Discussion Starter #20 (Edited)
Henricks don't know if it helps, and I agree with all this and your point of views here... I personally don't have "negative" views about people building or that haven't run the engine yet, we were all there...!

My only point was that what I got was a little different than I expected, and my original point that I was siding with Lee on is there is all this talk of high HP motors and that "it was really easy to get to" and "it doesn't affect mileage" and that these aren't necessarily correct... But this is also my opinion too, having never gone performance to those levels either, only dinking with the fuel screws and some minor turbo stuff...

And also given my earlier comments about what 120 and ~150 hp feels like real world application even in a big heavy truck, pretty powerful. Again its about the torque! I couldn't imagine how powerful a 250 hp 4BT would be, probably over 600 ft/lbs, knock your socks off... So that's all...!

beer





once again i will state exactly what it is that my intention is with my motor. I am not building for reliabilitly or logjevity, I am building what most consider a street rod and if i break it-guess what i bought it. with that being said I have a couple of thoughts. If i was trying to do as most on here are I would not consider pushing one of these motors over around 200 becouse at some point any engine will reach its limits before it becomes "tempermental". While i do think that mcinfantry's views are concervative, especially in a performance thread, I have to agree to some point. I dont think that anyone reading my post should use my build as an example of how to make a daily driver. I will also say that i do take personal the refrence to a keyboard crawler (im assuming that was aimed at me). I may not have built a 4bt before but im a long way from being new to this type of work. And if we get the attitude that the people not having finished there project yet are some how less worthy to show there ideas, I think you will see many good ideas overlooked or not brought to the table. build your motor for what you think is needed. If building a rock crawler think gearing not power. If your building a commuter think mpg not power. If you cant afford to break it I suggest you leave it where the 200 engineers at cummins designed it to run. ok rant over:pissed:
 
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