Engine/Transmission (1994 - 1998) EGTs too hot? More timing or boost needed?

[WadePatton]

More flow--not boost. But yall know that.



3. 73's or 4. 10's would be great. Timing is less trouble. Slide the plate---ding ding ding! quick and easy solution!



Your truck setup is very very similar to my Wife's truck. I had the HTB2 on it, but it was too loud for her. Now it has the B1-2 and runs very cool. The plate is hand-ground #10 copy. The injectors are local pump-shop specials--still smoking with full boost and R's. But, like I said it runs nice and cool unloaded and pulling hills--with either turbo.



I did a little port work on the head. Otherwise it's all the same stuff and timing as yours (twinram, firerings, 16, studs, manifold) and on 35's. Makes 46 psi.



edit: I can still bury the pyro WFO. And the pyro crapped out on her in FL. New Hewitt Industries pyro will be going in when she gets back.

 

[JGheen]

Thanks for the info guys,



Matthug, thanks for the AFC info, I might try that spring out since it is an in expensive addition that could yield a lot less smoke in my application. I'm gonna play with the housing a bit this weekend and see how she reacts.

Bob, gears have been a hard choice to make lately since that is not a cheap upgrade and I am still very unsure if I want to run a 4. 10 for off-roading purposes. It probably will be better for the off-roading I do but I really like the ratio now in 4 low. It suits my trails speeds very adequately.

DBraunig, I have a #10 as well as a homemade #0 from my stock plate. The #10 was nice but to me it is doing the same as the #100. I had the gov. lever set on the #10 to stop at the mid point of the curve and not de-fuel at the peak, and only adjusted it a bit more foward to hit the #100. I like the #100 and no de-fueling(or deceleration :-laf ) at the top end just don't like hitting 1500* on the pyro every hard run in 4th and 5th. And your question of more timing is something I am still wondering that might help but I don't think they would lower to a temperature I am more comfortable with.

Wade, your wife's set-up sounds like mine alright aside from the B1-2 turbo. I too hit about 45-46 psi but after about 2300rpm those EGTs just go through the roof. Gears are again a bit expensive and drastic at this point in time for me so maybe a few more degrees of timing up to say 18* as well as the rearward plate adjustment sounds like my piece of pie.



Joe

 

[Matthug]

350 is still in a different field... ... ... ..... hx35 :-laf



Relax buddy

Bob

Turbo doesn't matter, you can have 500 RWHP with the HX35... . it's been done. I could peg the pyro faster than the tachometer before the timing got bumped, and I can still get it to 1500 degrees empty. The turbo is way too small, I know that. BTW I'm running the 16cm housing so that would make it way worse as far as smoke, but I don't have smoke problems 90% because of the AFC kit. Before the AFC kit went in I was planning on getting stacks because I couldn't control the smoke unless I drove like a 90 year old woman. Now I can accelerate with traffic or better with no smoke at all with the light spring in and the starwheel full forward. The reason they make the medium spring is for 215 trucks with 400+HP, to compensate for the extra fuel. It even says that in the instructions.

For your reading pleasure-

http://www.tstproducts.com/index.asp?PageAction=VIEWPROD&ProdID=10

 

[Matthug]

JGHEEN, there's a very general rule of thumb that for every 2 degrees advance on the timing it will lower EGT's 100 degrees.

 

[JGheen]

Thanks Matthug, I was looking for that "rule of thumb" you mentioned but couldn't find it. I knew it was somewhere in that ballpark range of 1 or 2 degrees gives you a given lowered EGT amount. I don't think that 100* is going to cut it for my top end temps cuz hitting 1500* is so easy, it's not even funny and I don't even want to know how fast it could hit a higher, more dangerous piston melting temp.

Here's a question for ya..... is there a rule of thumb for an amount of time the engine sees those high temps(1400+*) before the piston crown temp reaches a melting point?? I try to get out of the throttle and shift in a hurry when I see anything over 1400* and I know it takes the crowns a little time @ some really hot temps to meltdown but what would be a time limit to stay in the high temps with stock pistons??



Joe

 

[Matthug]

You can exceed 1250 degrees for 20 seconds according to cummins. I've seen as high as 2000 degrees sled pulling, but of course thats for like 10 seconds. I don't think you are in piston melting territory, it's almost like you have to try to do it if you are empty and not towing because by the time even 15 seconds is up you are topped out.

 

[JGheen]

That is true, I tend to run out of RPM by the time it hits 1500 and I need to shift. But I could easily stay in that temp range in 5th gear for a long time with the RPMs I turn in that gear. With my large tires I rarely ever see any speeds above 80mph and any RPMs above 2100. Things get pretty toasty in 5th gear climbing the Grapevine @ 1900rpm.



Joe

 

[Signal73]

my TST afc kit smokes like a train. I thought the idea behind it was to use a softer spring to get the govenor arm to the fuel plate with less boost for more takeoff. explain to me where I have this mixed up...

 

[pwerwagn]

Joe, sounds like you need a cam!!

I think the AFC kit has a common mis-conception that the spring kit is lighter than stock.

It is lighter. The stock 215 spring is the stiffest.

The stock 215 spring does the best for smoke control, if set up right. Some of the big power numbers outta 12V's have been made with the stock 215 spring rate as opposed to the lighter TST kits, due to the fact that you can control the lower end fueling more precisely and not just "flood" it. (Call and talk to Joe D about afc springs... he'll talk your ear off about them).

my TST afc kit smokes like a train. I thought the idea behind it was to use a softer spring to get the govenor arm to the fuel plate with less boost for more takeoff. explain to me where I have this mixed up...

you are correct...



I have all 3 springs, I personally like the stocker the best when properly adjusted.



--Jeff

 

[Matthug]

my TST afc kit smokes like a train. I thought the idea behind it was to use a softer spring to get the govenor arm to the fuel plate with less boost for more takeoff. explain to me where I have this mixed up...

You and I both have 175 pumps so the comparison is a good one. Except, I had the exact opposite results and according to TST's sight and if you read the instructions it's suppose to be the way that I have it.

PWERWAGN, I have felt in my hand the TST spring and the stocker on my truck for a 175 pump. The TST light spring is about the same but if anything it's very very slightly stiffer NOT lighter, and since it's 1/2'' longer it puts more preload on the diaphram of the AFC anyway. The medium spring is very stiff, no way I would want to run that but I definitely wouldn't have any smoke problems with that. If I had some kind of testing equipment I would test the spring rate in inch pounds with a certain amount of compression to get you guys real numbers but I don't have access to that stuff.

I already tested it with shop air too, with the stock spring the AFC arm got full travel at about 18-20 PSI. TST light spring was about 30 PSI.

 

[Signal73]

dam mine goes full travel at like 10-15 psi

 

[Matthug]

Thats pretty weird! I even have the starwheel full forward, if I moved the starwheel back I probably wouldn't even get full travel since I'm only running 35 PSI boost. I was actually planning on putting the stock back in for more response, but I figured I would get better fuel mileage this way.

 

[pwerwagn]

If I had some kind of testing equipment I would test the spring rate in inch pounds with a certain amount of compression to get you guys real numbers but I don't have access to that stuff.

Email Joe. he has the numbers in lb/in. I have it to, but I dont wanna post it because I think a few of the numbers are a little skewed. I dont want to confuse anyone later on reading this post. .

 

[JGheen]

Joe, sounds like you need a cam!!



I personally like the stocker the best when properly adjusted.



--Jeff

Jeff, it would be nice to run a different cam but I am no where near that yet. I am still trying to convince the wife I need a new truck and need to put the 'ol big red beast away. Once I get my '07 Megacab 3500 4x4 SRW then I will have the time to get a cam in there and see how it reacts, but for now the truck is still my daily driver.



I would like to hear some insight on this "proper adjustment" of my stock AFC spring if you have any quick and dirty advice.



Thanks, Joe

 

[pwerwagn]

I would like to hear some insight on this "proper adjustment" of my stock AFC spring if you have any quick and dirty advice.

Joe,

I think "proper" afc adjustment is a subjective area. Some like it loose, some like it tight. :-laf

Anyways, the point of the afc (as Im sure you are well aware of), is to control the amount of fuel you have at low boost situations.

Mark Chappel says to loosen the spring until you start to get some smoke, then tighten it up a click or two. I like mine to be looser than that.

However, i have noticed that if it is to loose, and you roll into it, lets say in 3rd, from like 1200 rpm it actually runs worse. For instance, if I put my foot in it at around 1700-1800 rpm, it spools, still smokes something fierce, and will break the tires loose when it hits about 2100rpm.

Yet, if I put it to the floor in 3rd at 1200 rpm, it fuels waaaay to much and sorta floods it, and it runs worse, and the egts are way more uncontrollable.

I personally like to set mine up for the gov lever to make full plate contact around 12psi. I use shop air and a regulator and get it where I want it.



Dunno if that helps at all, but it was worth a shot. If you would like more info, lemme know. I'll write all day long... .



BTW, whatcha doin with the 98 when you get your mega?



--Jeff

 

[JGheen]

Joe,



Dunno if that helps at all, but it was worth a shot. If you would like more info, lemme know. I'll write all day long... .



BTW, whatcha doin with the 98 when you get your mega?



--Jeff

Thanks for that advice there Jeff. I got a good regulated air source so I'll give it a try this weekend during my lash adjust and other routine maintenance.



Definately keeping the '98 for my official toy rig and not a daily driver/toy anymore, besides it been paid for since '00 and I have way to much money, time and effort into it over the years to rid myself of it. Probably get a gooseneck trailer for the Megacab and trailer it to events, maybe turn it into a sled puller and not just and hill climb/off-road rig.



Joe

 

[pwerwagn]

maybe turn it into a sled puller and not just and hill climb/off-road rig.

Nice!! I would love to see a puller on 38. 5 on boggers!!

 

[JGheen]

Well, I messed around with the AFC housing and the plate a bit this weekend. I moved the AFC housing back from full foward to about half way. This helped lower my cruising EGTs about 100*F, so I was happy to see that. My plate adjustment I didn't like though cuz it didn't have as much pull to it as with the plate full forward, so I moved it back to full forward. EGTs on the top end sure did decrease with the plate moved back a little, but I think I can control the EGTs with it full forward with the right foot.

Now for a fuel mileage test since I moved the AFC housing back.



Joe