300/200's stock bottom end.
- Thread starter earlybroncoboy
- Start date
4.0l sahara
New member
Just because it has 400/400's doesn't mean it's going to make big power. That truck would prob make the same or more power with a 200% nozzle and that 68mm turbo. As for the bottom end it will likely come apart at some point. How long it last has many variables.
smokinstroker92
Member
It still should do better than that. Shoot i made that with a 38r and 300/200s with my s468 it is well in the 6s. Not to mention the hp falls off way early in the rpms and gives it a narrow power band
Morgan@Midwest Diesel & Auto
New member
Idk, mine lasted 5k miles with Gearhead tuning, sled pulling, drag racing and daily driving. Only had 145k on the clock too. Then, block gets cut in half by connecting rods.... Lol, some people just don't have any luck!
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Powerstroke1098
Member
Im looking into running a set of 300/200's on a stock bottom end as well.
earlybroncoboy
Member
It's been 2-1/2 years since I dropped in the 250/200's. Stock PMR motor, stock springs, stock pushrods, no head studs. Makes the power in my sig, and the clock is just about to turn 200K. Tows a trailer almost every day of the week too. As of last weekend I just took the lift off. Safe to say it's had an abused life, but it's still kicking.
Secret to keeping any motor alive with large injectors is to limit the damn fuel at lower RPM's. Sorry if the torque number suffers as a side effect, but at least your engine doesn't include a window.
Secret to keeping any motor alive with large injectors is to limit the damn fuel at lower RPM's. Sorry if the torque number suffers as a side effect, but at least your engine doesn't include a window.
Morgan@Midwest Diesel & Auto
New member
Back in the day. 300/100, 38r and everything else but a built bottom end, in a zf truck. It spent a lot of time with methanol and 4k rpms. It wasn't expected to live. And forged rods do break around 600hp I've found..... Pistons still looked good though. Too bad I was 6 hrs from home when it let go.
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earlybroncoboy
Member
works for some, some it don't just wanted to see how successful it has been. tuning has came along way.
Groomzybanshee
New member
To the op put it together run the piss out of it, have fun. But don't be surprised if I blows. I never broke a rod at 650hp. I got a set of Inj with a ****ty spray pattern aNd cracked a piston. But a buddy had 238s and a 38r and his went boom with only 5k On that setup. Luck of the draw it seems.
earlybroncoboy
Member
do you have pmrs? or forged?
I have 300/200s in my SD truck for about 3yrs now. 30+ dyno runs, 12 or so sled pulls, some towing, and about 35k miles. 200k stock bottom end. It's dynod 650+ many times.
I killed a SB DD clutch without blowing the block apart.
I'm actually looking for some 300/200s for my obs truck. It's only around 500hp and I think it can do more:thumbsup:
Doesn't mean it's going to be like that for everybody. It's just like one guy tunes and deletes his 6.4 and runs it 100k problem free. The next one cracks a piston and needs a motor build in 5k miles.
I killed a SB DD clutch without blowing the block apart.
I'm actually looking for some 300/200s for my obs truck. It's only around 500hp and I think it can do more:thumbsup:
Doesn't mean it's going to be like that for everybody. It's just like one guy tunes and deletes his 6.4 and runs it 100k problem free. The next one cracks a piston and needs a motor build in 5k miles.
earlybroncoboy
Member
exactly but im totally willing to take the chance lol. who's tunes you running?
Morgan@Midwest Diesel & Auto
New member
Yep, we can have a dozen customers trucks come through for a build with zero problems. Then we bring mine in and it will be that "one". I believe it's the "just my luck" syndrome.
This is what needs to change.
It's not the horsepower, it's the torque.
PMR's are supposed to break around 400hp or less. So why am I still running a PMR motor near 500 hp for well over 2 years?
Let me give you guys a scenario that actually happened the day I dyno'ed my truck.
I threw my truck on the rollers, saw the HP number, and my jaw dropped. Everything I had ever been told about PMR's ran through my mind. I was amazed my motor was still alive.
Then a few trucks later, another guy runs 1hp higher than my truck, but WELL over 100 ft/lbs of torque. At that point it became crystal clear (unlike the smoke out of his tailpipe).
He was running injectors "capable" of that power, but he had 1) smaller nozzles, and 2) far more low RPM fueling. Those two combined gave him really no increase in HP, but a huge jump in torque...... simply because of the amount of fuel he was getting in the lower RPM range.
In case anyone was wondering, he was running 238/100's. I was running 250/200's.
Now if I ran the same HP and gobs more torque, would my wimpy PMR motor survive? Who really knows. However, the higher that torque number goes, the less chance there is of it living.
If I was really shooting for torque, I could have easily given it a ton more fuel at lower RPM's. That would have brought my peak torque at a much lower RPM. I would have blown that guy away on the dyno.
But here's the key.... I would have achieved that at a sacrifice of much more fueling at lower RPM's, resulting in much higher cylinder pressures. That's what kills engines, folks.
Those of you worried about stock PMR's, or stock bottom ends.... know this: keep the bottom-end fueling in check. Those torque numbers are for show, and nothing else. If you really want a motor to perform, and live at the same time.... keep that low RPM fueling dialed waaaaaaaaaaaaay back.
Of course there is absolutely ZERO guarantee of any motor living beyond the factory calibrations. I'm simply pointing out the obvious here regarding performance modifications with fueling and cylinder pressures. Keep CP's in check, and the easiest way to diagnose that is to see what kind of torque numbers you're putting up. More torque = higher cylinder pressures. Period.
earlybroncoboy
Member
Well said Curtis
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PSDEng
New member
So I've heard...unfortunately the people I know of have all used daddy's money. I can't wait to move back and start pulling again, I'm inches away from a finished motor.
And thank you for the compliment!
Powerstroke1098
Member
