Best hp gains out of a 617
 

Ive heard that the best gains out our beloved 617 s is via the exhaust .The gains by adding a bigger exhaust pipe and have it straight out the back for performance purposes might interest me. I dont mind a little exhaust noise since Im use to my 300cd making a good amount of exhaust noise already.Anyone put this in play on their car yet? and Was it worth the effort?

I haven't done it, but straight through exhaust has been done plenty of times. General consensus, from what I've gleaned, is that 2.5" or 3" mandrel bent exhaust without mufflers is the way to go. Personally, on an otherwise stock motor, I doubt you'll see gains from going 3" over 2.5". This motor just isn't that big. It won't hurt to go bigger, though you'll have an easier time packaging the 2.5" stuff. The biggest contributor will be the mandrel bends versus stock crush bent tubing. Check out the builder kits over at Tube Bending & Fabrication - Columbia River Mandrel Bending.

Not to say that you won't feel a difference, but stock exhaust isn't that bad, anyway. Bang for buck, you'd be better off getting a manual boost controller (ebay it), bump it up to 14psi, ALDA adjust/delete, rack limiter adjust/delete. From anecdotal evidence between different owner's observations, it's good for +20-30 crank hp.

Stock intake and exhaust flows more than you will need without serious fuel and air upgrade.

A test pipe in place of the resonator will take 2 45* bends out of the piping...

Turbo or naturally aspirated?

A blk 83 300cd turbo with euro setup bumper and lights ,this car begs to be lowered a bit.I have a set of 99 clks waiting in the wings.Also have a set of 18" amgs but will need spacers to fit, not excited about using spacers.In doing everything right for performance I believe it will be a vintage eye catcher with alittle bit of rumble for adder.

How much louder does it get without the resonator but retaining the rear muffler?

not much, can still hear the radio

I just cut out my pair of resonators and straight piped a 2.5" 4 foot long section in place of them. It gave it a quite bassy sound and my butt dyno says it really moves from 55-85 mph.
Then again I have only had this 83 300sd for like 5 days, it could have to do with the low sulfur I put in as opposed to the tank of b100 I had run through it

My dyno butt says my straight exhaust, and cold air setup, gave it 15 hp.

Have you got that "dyno-butt" trade marked?

PS from the little I know best improvements from stock seem to be the IP not exhaust.

Have a look at the threads on www.superturbodiesel.com

X2
You can do what you like to the exhaust, fact is that the waste gate limits the amout of air going in & thats it ! With no extra air you can only get a very little extra via increased fuel ~ IP adjustment.
Bigger exhaust gives nothing but noise on a turbo with such a low waste gate setting. I have diesels here (not 617's) that run 25 to 30 # boost all day every day under load. Only restricted by EGT & MAF constraints.
To increase boost by a reasonable amount on a 617 you would probably need to install an inter-cooler like later MB's have.

the 617 is not a hot rod engine its a workhorse.You can drive a 100 mph all day,but not on redline.If your want power switch a 6 cylinder from newer models.

Modest gains are best had by ip tuning. Of course this is assuming fuel pressure, boost pressure, alda, and other basic maintenance have been done.

The added gains in hp would be nice to have ,its not the need for speed but just a desire to improve an avg 300cd at a minimium cost.I cant see why someone hasnt done a build up like this to show improved performance for a 617 ,doesnt sound like the cost would be a big factor . A tuner page with a DIY guide to enhance a 617 and what those cost might be individually.

;)

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