[strokin_early_99]

Right now the 4" bend through my bed gets damn hot and I don't want to sacrifice power by a system being restricted. Modded H2E or GT42R will be going on in about 6 weeks and I want things to flow properly for the new lung.

For 550-600hp, is 4" down pipe enough?

When you turn up through the bed for stacks do you keep it 4" or up-size to 5" and then turn it up for less restriction?


Thanks,

 

[gregrob]

House said he got more power by going to a single stack and one smooth elbow as opposed to duals and a restrictive splitter IIRC.

Point being, there is something to be gained in a high HP application by ensuring an open, properly sized, and the least restrictive exhaust possible.

Don't know how much testing there will be out there on 4"+ down pipes. Looks impossible to fit bigger to me without a body lift or firewall bashing, and not even sure anyone makes a bigger dp that will bolt in.

I think a 4" dp is fine, just make sure the rest of your exhaust is as open and unrestrictive as possible.

It's gonna get hot, that's hot stuff comin out of it!

 

[Aljay]

Damn GR that was well said and even informative.

 

[69W900A]

If the Y and elbows are mandrel bent and are properly sized they will work just fine. In real trucks going from single to dual stacks is a must if you increase HP or do an engine swap to something bigger.

4" DP is plenty big for the CFM these engines will flow. If you are worried you can go to 5" just after the DP and then all the way out to 5" stacks, but they'll still get hot.

 

[TerminatorEngineering]

For 550-600hp, is 4" down pipe enough?

Thanks,

Howard, I hope you have billet rods.oke:
:gun:

 

[strokin_early_99]

Howard, I hope you have billet rods.oke:
:gun:

I am working on a lower unit fully built. I will be shooting for 600+ on fuel only. No spray of any kind. Right now I am looking at the future with every step I make.

To add a girdle, do I need to do any machining to the block?

 

[TerminatorEngineering]

Yup, line bore through the mains, with the girdle on.

 

[02Bluestroker]

Thats odd... because all of the girdles for all the gasser engines do not require a line hone... is this girdle made different... from the pictures that I have seen it just bolts on top of the main caps like all the others... :shrug:

 

[02Bluestroker]

on another note... you can get a 6" oval pipe down through the firewall area without much modification at all... it would be a custom downpipe though... its almost 4" thick but its about 7-7.5" long on the cross section... easily flows more than 4" round

 

[Short Bus]

For 550-600hp, is 4" down pipe enough?


Thanks,

made 596/ 1200+ #2 only with a 3" downpipe, so yes a 4" will be plenty

 

[Aljay]

made 596/ 1200+ #2 only with a 3" downpipe, so yes a 4" will be plenty

Nice. :rockwoot:

 

[imelmo]

4" downpipe is what I have. Makes it a mf'r to put the trans back in though.

 

[imelmo]

Yup, line bore through the mains, with the girdle on.

We didn't do any machining to put my *** girdle on.

 

[Charles]

I regularly watch my buddie's supra make 1000-1200rwhp pulls fuel only.

It has a 4" downpipe. I think we "might" be okay.

 

[69W900A]

You don't HAVE to machine an engine to put main girdle on. I wouldn't put one on without line boring if you want to do it right. I have built quite a few race engines and I have measured distortion from just switching bolts to studs. When you make changes like that you change the clamp load on the caps, which changes there shape.

A lot has to do with how well the machine work from the factory was as well. Some blocks are better than others to start with. The cost of a line bore is cheap insurance and piece of mind.

Proper machine work will make or break the engine. You could use cheaper parts and spend more money on the machine work and come out with a better engine than if you just bolt all the big dollar stuff in without much attention to the details.

As far as exhaust. I drove home a truck today that is a hair under 1000 cubic inches of displacement and makes just over 2700ft/lbs of torqe and only has a 5" DP and doesn't get overly hot. I think a 4" DP will be plenty for a 444 Cu In engine.

 

[Aljay]

You don't HAVE to machine an engine to put main girdle on. I wouldn't put one on without line boring if you want to do it right. I have built quite a few race engines and I have measured distortion from just switching bolts to studs. When you make changes like that you change the clamp load on the caps, which changes there shape.

A lot has to do with how well the machine work from the factory was as well. Some blocks are better than others to start with. The cost of a line bore is cheap insurance and piece of mind.

Proper machine work will make or break the engine. You could use cheaper parts and spend more money on the machine work and come out with a better engine than if you just bolt all the big dollar stuff in without much attention to the details.

As far as exhaust. I drove home a truck today that is a hair under 1000 cubic inches of displacement and makes just over 2700ft/lbs of torqe and only has a 5" DP and doesn't get overly hot. I think a 4" DP will be plenty for a 444 Cu In engine.

Ok I'll bite what in gods name did you drive home .

 

[69W900A]

I drove the old W900 home. I learned to drive on a truck almost identical to it and I drive this one every once in a while cause it's fun. Besides, it's loud and REALLY pisses off the neighbors when I hang it on the high idle at 4:00 AM to build some air.

 

[Stroked95]

I'll bet they really love it if it happens to be straight piped and you throw the jakes on, LOL!

 

[Aljay]

I drove the old W900 home. I learned to drive on a truck almost identical to it and I drive this one every once in a while cause it's fun. Besides, it's loud and REALLY pisses off the neighbors when I hang it on the high idle at 4:00 AM to build some air.

Sweet, I used to do the same thing guess my ol 3406 with a 6" straight does not compare to that beast you have. Man I just got leased on to landstar ranger today I can't wait to get back out on the road and see some country side. P.S. my high idle and cruise(suicide) are of the same Pull knob under dash and turn to lock LOL I need to replace this truck but I will see if it eats me out of house and home if it don't I will keep it another 1.5 million miles, she needs some pump work and a coat of paint. I just cannot bring myself to get rid of her even after driving my step bros. 600 ISX cummins powered peterbilt. I am wanting a long hood real bad but hate to get too new of a truck do to all the smog crap.

 

[69W900A]

Truck has muffs, but there are the "glass-pack" type, similar to the grand rock pieces. Yes the truck has jakes and I use them everywhere. If I have to be up at all hours of the night and mornings so does everyone else

Truck has been making about 2700 ft/lbs for the last 293K miles and it still runs good. I'm not nice to it either, I don't care what the pryo says, I built it with some HP cause I don't like slowing down there is no back down. It's run 1600*F for 10+ miles at full throttle for years. I do keep it in the same gear I pulled up the hill in and cool it down easy after topping the hill. Those old BC would crack pistons stock if you just bring it down to an idle and jake on going down.

It's also kinda fun to pull up next to Honda in a truck that weights 21,863lbs empty and smoke the tires leaving a stop light :rockwoot: Well, that is until I have to buy yet another drive line :lame:

I enjoy driving, but I'm glad I don't do it for a living.