Turbo Lag

[J DeMaio]

Would a 4" Jardine exhaust take care of the turbo lag common with the 1 st generation intercooled trucks? If I do this improvement wiht the pump timing set at 1. 75 mm how much power would I be making? I would also have a straight pipe installed. Does advancing the timing hurt the engine whatsoever to make its longevity decrease? Just checking, i'm not sure what to do because I don't want to hurt the mighty Cummins!

 

[BillyKidd]

J Demaio:

If your running your stock turbo, bigger exhaust won't eliminate lag. Only a smaller turbo will decrease the lag(spin up). I have a '93 that had an 18Cm2 turbo and changed out to a 14Cm2 turbo that all but eliminated lag! A 12Cm2 would be faster still,to spin up. As to which is better,read this forum and you'll get ALL the opinions you want!! I also changed my pump timing to 1. 75 IMHO, this will get more fuel flowing sooner without increasing the fuel delivery of the already maxed output of our VE pumps. I believe this doesn't decrease the longivity of the "Mighty Cimmins"! Also IMHO you will need larger injectors to take advantage of the aforementioned mods. I put in PW injectors and really like the overall increased performance. Again, I believe these changes will not decrease the longivity of the Cummins! Stay Tuned for further Opinions I'm Sure!!!

 

[hdm48]

Hi there. you didn't say if you turned the pump up. the low boost adj. will really help the lag problem. does it puff a little smoke when you hit the peddle? it should. mine really sends out a cloud and it's great for when you 've got some jerk with a stereo so loud that it crosses your eyes. just a tuch and he's choking. sounds mean but i'm tired of these super loud boom boxes.

anyway, some lag is gonna be there because it is a turbo and untill you have exaust flow you will have no boost. turn up the smoke screw and see if that helps. you'll find the info on this here in the links. I think fritz has a very good section on this with pictures.

good luck and let us know if it helps[or if it does'nt]

 

[J DeMaio]

What exactly do you turn up, the fuel rate? I'm not real excited about giving her more fuel because i'm worried about higher E. G. T's. Isn't there a diaphram adjustment, power adjustment, and fuel rate adjustment? I have a book from T. S. T. and it shows how to turn up the pump. So with a new high-flow exhaust and this adjustment this will help out with turbo lag? Thanks!

 

[Dieselman359]

Torbo Lag??????

After my purchase of some 'Ol Blue Specials from Big Don, my truck lost its turbo lag I don't know where it went, but I do know that when you hit the go pedal, lag is almost nonexistant

 

[hdm48]

hello again. OK, first, don't worry about EGT's with the smoke screw adjustment. BUT, if you turn up the rest of the power then you should get a pyrometer.

OK, the smoke screw is located under the little cap that is in the center of the cap on top of the pump. the diaphram and star wheel is located under the cap. [lot's of caps here]

Listen, go to Fritz's Ram Tech [in links] and look at the photo's and all the adjustments are spelled out. It's very easy to do except for the idle adjustment. I have a photo tach which makes life simpler. if you don't have one, have your idle set at a shop.

I don't want to confuse you with my febble attemp at tech info. It's hard to discribe where all the adjustments are to be made without you seeing where to do it. But it is simple and you get better milage, more power, and makes the ole' girl more fun to drive. go get the info, it's free and it's fun. in the next class we with discuss intake and exhaust.

 

[KEENO]

I'm w/ BILLY KIDD on this one... Amen, Brother!

Hey J!



I'm assuming that you still running the HUGE 21cm2 turbo exhaust housing that came on the '92?



If so, this is the first item that must be changed to reduce "Turbo Lag"... No amouint of pump adjustment is going to overcome the OEM "NO Boost - Huge Lag" 21cm2 that came on your truck.



Decide which housing you favor, make a purchase, install and then do the exhaust & pop in a K&N air cleaner while you have the checkbook open. Any of the popular housings will work for you w/ the 16cm2 being the easiest & cheapest to install. The 14cm2 & 12cm2 require the use of 'shorter' downpipe to accommodate the increased wastgate length of the housing.



I wouldn't go to the pump for increased fueling needs until gages & higher flowing injectors can be installed. The 'smoke screw' & diaphram adjustments are acceptable but stay away from the "Max Fuel Screw" adjustment until after injectors.



KEENO's dime worth of advice today... .

 

[J DeMaio]

Yes, My turbo housing is 21 cm. When you buy a 16 cm turbo housing is it good to get a genuine Holset? What does a wastegate do? Is it basically a governor for the turbo so it won't overboost itself and make more boost at lower R. P. M's? I don't see how these help because with non-wastegated housings they make more boost right, which is better. I would liek to run maybe 30 lbs. If I install a 16 cm housing and a 4" straight pipe from turbo back I will have a lot better flow won't I? The K&N was on my truck when I bought it so I don't have to worry about that. can't I just adjust the power adjustment screw (more fuel). I don't want high E. G. T's but more smoke Thanks!

 

[F Simkowski (In Memory)]

Yes... Get a Holset hot end housing. I have installed a 16cm2 on my previous '92. It spooled up nicely with minimum restriction. KEENO and a few of the "old masters" of the 1st Gen. trucks have installed the 14cm and (cringe) even the 12 cm units.

Yes, get a larger free flowing exhaust system with a non restrictive muffler.

Yes, get gages.

A waste gate doesn't open at idle, but progressively opens to bleed off the exhaust to turbine flow path to prevent excess boost at higher RPMs.

As for wanting "smoke"... search for power instead, the smoke will come. Then you can properly tune for maximum power with minimal smoke.

Go on over to the Links section, check out and call the people selling the hardware... JRE, TST, Diesel Injection... etc. These folks have done this before, and are usually very helpful.

KEENO and BILLY KIDD have earned their bones by doing it and they offer some good advice.

Have fun and good hunting.

Frank

 

[KEENO]

Thanks Old School!

Hey Frank!



Great to see your back in you old "Backyard"! Great technical advice as always... . Thanks!



Yeap, still love the 12's & the 14cm2 housings... "Big Medicine" in still 16cm2 and will stay that way. I've actually taken off my much loved 12cm2 for the past few weeks and given the 14cm2 another run insearch of improved MPG. Don't see any difference... Miss the low end & sound and I'll be re-installing the 12 sometime soon.



Variety is a good thing!



Keeno

 

[J DeMaio]

So... What is the best way to get the fuel up to paar with the air. Should i time the pump to 1. 75 mm or turn up the screw on teh back of the pump. I don't really want to do thsi adjustment because I would have to re-adjust the idle and this will cause higher E. G. T's. My thoughts are that if Cummins wanted more fuel to the engine they would have "turned it up" from the factory. Timing advancement seems to be the bes because you get better m. p. g, less E. G. T's, and more power. Does this make the fuel inject later when the piston is closer to top dead center? This way it uses the same amount of fuel but changes when it's injected. I read somewhere when you advance the timing you should replace the injectors? I don't really want to spend the money because i don't feel it's necessary for the power gains i'm wanting.



So, with the boost and pyrometer gauges, timing set to 1. 75 mm, Jardine 4" turbo to tail exhaust, and Holset 16 cm turbo housing, how much horsepower and torque will I be making? Thanks!!!

 

[paccool]

Mines set at 1. 7 and it really made a difference. Make sure you check TDC of the timing pin though, mine was off about 2. 5 degrees.



I think the reason there is different set points is because the engine is used for so many different applications. Can you imagine the warranty issues Dodge would have if the higest HP version of this engine was put into the pickups?

 

[F Simkowski (In Memory)]

KEENO: Yep... this is my old backyard. thanks.

J Demaio: If you do what you said... free flow exhaust, 16cm2 hot end housing, timing properly advanced, and a set of JRE (or equavalent, not "seat of the pants, no name") injectors, You my friend will be a believer.

Your power will wet your 'lil pants, and your MPG might well improve.

Please don't run a straight pipe without a true free flow muffler..... there is enough Massey Ferguson tractors in the world already.

Hey J! Go for it as your budget allows! Get ahold of the folks on the links..... They live to do right by you.

Great to add to a 1st Gen. guy to do the right thing.

J... Good luck.

Frank