tried4x2signN

Lol, he's only running 60-70 now... And you want him to regear so he can use OD at what 50mph?


And gas motors need back pressure?


At least I know a Wankel does...

c0ugar69

I think the back pressure does help a bit on the gas engines, if the exhaust is too big you loose low end power and torque. even though its only 60-70 hp it probably has lots of torque which is what a diesel is good for. I would try the turbo and maybe regear a little just because of the bigger tires. the exhaust mod sounds good too to increase power a bit, exspecially if you go turbo, let it breath..

peow130

Lol. I didnt say gas engines needed them. 4 stroke engines don't need back-pressure.HOWEVER. Gas engines cant have a ridiculously huge exhaust, because you need a thing called gas velocity. Bigger pipes = less vacuum behind that pulse of gas. YOu need scavenging to pull the gas vapors out of the exhaust. Diesels DON'T NEED THIS. So they can run 10" stacks and have plenty of power.
2 stroke engines DO need back pressure. See: Dirtbikes. Alot of 2 stroke diesels need back pressure, too.

Back on topic:
Hes running 4.56's now, 4.88s WILL give him the power back bud.
He might run 5MPH lower? With the larger tires though... the wheels are going to SPIN FASTER ON THE GROUND AND REGAIN ANY SPEED HE LOST.
Read the first post.
He has 31's now, and wants to increase his tire circumference. By the laws of physics, with 4.88's and 33's hell most likely be right around the same speed.

tried4x2signN

Physics? You wanna talk about physics? He's got an 85hp motor?

85hp and a 3,800 to 4,800lb truck?

All gears are gonna do is slow him down more, and make it redline faster!


And the tires are semantic... B/c so far, he doesn't have them... And 2" hardly makes ANY difference to a Diesel...

I want a 400 horse 22RTE too, but so far...

Ok, so you don't have any power now with 4:56's and 31's... Now you wanna run 4:88's and 33's?

Congratulations, you've just accomplished nothing! Well, except spending $2,000 USD.


I've said it before, and I'll say it again. Building a gas and Diesel truck have NOTHING in common. You can not build a Diesel truck with the rules of a gas. They are two different things.

yoder519

great posting.
thrasher, regear. Then see how it does. I'll say it again even thought someone is gonna say the opposite, PEOPLE REGEAR TO PULL LARGER TIRES. PERIOD. He asked if he should engine swap or regear, regear iis the best bet. Keep the sweet diesel that we all want no matter what the dyno says. This is the first time I have heard someoe sa to not regear to pull bigger tires. Wow

yoder519

yes, iif your runnin tiny tires with 4.88s or 5.29s, your gonna be revving high, but larger tires plus lower gears equals closer to factory power. Why do think people do this?

tried4x2signN

Not really, and I'll tell you why...

Lb. for Lb., Diesels will have about x2 the torque, and half as much hp. So a gas usually has half the torque and twice the hp...

Also, the Diesel will almost be x2 the mpg. So the gas is almost half the MPG a Diesel would get...

Not to mention, RPMs... Most gas engines will turn 5,500 rpm before redline.
Diesels, 2,500 to 3,000. And I don't care what the internet says the redline is. You get a 2L and rev it to 3k and I promise you you won't want it to go any higher...

Almost EXACTLY like comparing a 2 stroke dirtbike and a 4 stroke..


Now, since you have x2 the torque, you can use less the gear... B/c 1, you don't like high RPMs anyway, remember? And 2, you develop the peek lower in the RPM band anyway...


So now you can accomplish more, efficient work... B/c you produce more torque...

Think of a gas/ Diesel engine like the volume on a stereo. As you turn up the volume, the sound gets louder... Like a gas engine... The more you turn it up, the more power it produces.

Now a Diesel... The more you turn the volume up, the LESS power it wants to make...

tried4x2signN

Why do I think ppl with Diesel Ferds and Doges put 35's and up and don't regear?

Or why most ppl do what you're talking about, b/c MOST engines are GAS?

How many Toyota's are Diesel in North America?

2DoorRunner

tried4x2sign-your logic is proven false by the fact that most of the members on this forum has done exactly what Peow and Yoder are talking about. Im with them on this one.

2DoorRunner

Because those are huge ass motors putting out extream amounts of torque, unlike the small diesel of the OPs rig. Yes its more torque than a gas motor, but its still nothing mind blowing. Not to mention that those are mall crawlers

tried4x2signN

Do you know why engineers put the gear ratio they do in trucks?

It's called a power band.

What they do is figure a nice, average speed. And fix the speed to where it's in the engines max effective torque curve.

That's why bigger tires suck as much as they do. Number 1, Toyota's didn't have "Merican" power back then. And number 2, they were engineered to run with a specific tire, at a specific speed, at a specific RPM.


Take a truck out of it's powerband and see what happens... Oh wait, we all know that...

2DoorRunner

So then you are always going to keep stock tires and gearing on your rig then? LAME! hahaha

tried4x2signN

Very smart... And all the ppl with 85hp Diesel motors have done?


I wish I had your logic and reasoning...

yotaman85

you should be careful when your throwing around assumptions. I know plenty about diesels..

tried4x2signN

No smart guy. READ! Especially the part where he has a completely different motor then we do...


Who's talking about not re gearing a ***gas*** motor here? Nobody BUT you.

tried4x2signN

oh, one guy pops up...

So I'm wrong... A whole board knows about Diesels here...


only on the internet...

http://www.youtube.com/watch?v=_QyYaPWasos

yotaman85

keep the motor. with the tech around for diesels you can more then enough power out of it for a pretty small amount of money. if you really want to get yourself going dont wast time on a swap. just get a turbo and some pump work. you will spend less $ and have a great power band and great fuel mileage. as for gears, just look around this site and you will find all the pros and cons of re-gearing.

yotaman85

fair enough..

2DoorRunner

I cant wait till tried4x2sign gets his ass gets banned, i have seen nothing but negative comments from him everywhere.

Its a disscusion, not an argument man. Stop making everything such a big deal.

yotaman85

OK, after sounding like a dick in my first post. tried4x2sign is correct.. period. I was just saying im not ignorant about diesels. if you rev any motor outside of its powerband you will be slower. your 2L makes all of its power at about 2500rpm if its running tits at sea level. if you regear, you will go threw this powerband in way too little time and wast most of your power on sinning tires. put bigger tires on it and leave it alone.

also, a huge exhaust and no back pressure only works on a turbo diesel, it helps allow exhaust flow to pass the turbo faster and allows for the extra air bieng forced into the motor. with N/A diesels you will still need some back pressure. unless you replace the exhaust valve springs with stiffer ones.. the reason a super huge exhaust robs you of low end power and efficiency is because the back pressure helps close the exhaust valve letting the pressure build in the cylinders as soon as possible.so with a turbo you can use heavy exhaust valve springs and high flowing exhaust to let the turbo spool sooner and faster while still making sure your exhaust valve is closing as fast as possible to give you good low end response and high RPM power.