Engine/Transmission (1994 - 1998) Making power on 12V

[Vaughn MacKenzie]

I'm a 24-valver and am not up on 12V-speak, but I have some questions. I like my '01 HO but sometimes think an older 12V would be a lot of fun. I also like the quieter, smoother operation.



What I am wondering is how well they can make power without making a lot of smoke. I know, I'm not into smokeshows I would plan on a good porting and valve upsizing, but would mid-upper 300hp range numbers be possible with very little smoke, with the right exhaust, turbo and injectors? What does it take to make this HP? I see people run 215, 300 and 370hp injectors often, why not DD injectors? Does anyone run DD2s or DD3s?



Let's talk HX40s, does a ported 12V with the right injectors drive a '40 as well as the 24 valves?



I have seen a lot of 12V dyno, but the ones above 300-350hp seem to smoke, a lot, at least a lot more than my mid-300s 24V.



Let's assume 1997 or '98 5-speed.



Thanks guys, sorry for so many questions



Vaughn

 

[C. Harlan]

Well, I made very good power before I put in the 191's... you can adjust the smoke output to an extend by adjusting the star wheel. The 191's make a difference at all RPM's, and are the main cause of my smoke, along with a heavy right foot. Other than that, I only make smoke at WOT (yeah right):-laf ..... As long as you drive moderately, smoke is not an issue... if you ease into the throttle, and give the turbo time to spool with the fuel, it also will not smoke so bad, or at least from what I have noticed. Hope these are a few pointers that may help.





-Chris-

 

[thaile]

I have not yet put in the delivery valves, but recently changed injectors to the 370's. With the 300's and really a lot of fuel going into them I have made a lot of horsepower. Not for sure how a 24v does with the HX-40, but I put a Piers turbo HX-40 on my truck and found this to very responsive, quick spooling, and powerful addition. Not for sure how it would act with the 300 injectors since I put mine on with the 370's. With the 300's though and stock turbo putting in over 40pds of boost and a very good camplate I didn't really have an overecessive amount of smoke. It all depends on what you like. For even less smoke you could go with a number 10, or for a little less a number 11. The 11 woul probably leave you though on the lower side of the numbers you are looking for. With my 370's, HX-40, hot camplate,and other little goodies last weekend I dynoed 440 hp with almost 1000 ft/lbs of torque. But I put out a very good cloud of smoke which doesn't sound like what you are looking for. Hope this helps you out.

 

[C. Harlan]

I have still yet to dyno, but with my setup, I am guessing I am in the high 300's or low 400's in terms of horsies... Just a thought... did you dyno yours before the 370's? and if so what kind of #'s were you looking at?





-Chris-

 

[drawson]

Vaughn, I should have taken you for a ride while we where in the land up north this summer.



12 valves Spool turbos well!!!! Yes they do smoke alot but that's nothing nitrous won't take care of.



But your other truck won't like you or be driven much after you get the right amount of valves...

 

[thaile]

Never dynoed before the 370's but I would guess with teh 300's and stock turbo that i would have been arond 350-375, just guessing. That's at ther rear wheels though so add about 20 percent to those numbers for the actual engine horsepower.

 

[thaile]

Anyways you don't want to be going and running nitrous and other drugs through CTD After all that why we drive the CTD instead of the power jokes that have to run that stuff to even stay competitive with us. Drugs just raise the cost both to buy and maintain if anything would happen to go wrong with them:{

 

[Deezul1]

With my plate back from full forward about 1/8" my smoke is very little unless I apply full throttle at low rpm. Once boost starts to build hammer down will leave a little puff and haze and it cleans up pretty good. The AFE filter I just installed helped smoke quite a bit over the BHAF and that filter was a big improvement over stock.

 

[Boldt's Wagon]

Rottin Rhonda on the NWBombers site has dynoed at 342 hp and she has not installed a GSK yet. Don't know how bad it smokes. With a 12 valve, you can adjust the AFC housing position and star wheel to give you acceptable smoke versus spool-up and boost.

 

[Strick-9]

12 valves don't spool turbos as well as an equally powered 24 valve. Being a 12 valve guy, I hate to admit that, but it's true.



This is most apparent with automatic transmissions with tight torque converters. 24 valvers have less lag and quicker spoolup. It's not a matter of an AFC adjustment either. It has more to do with injection pressure, injection rate and timing. All things we have little control over.



You can tune a 12 valve into the mid 300's on horsepower with a clean tailpipe under full power.



-Chris

 

[Koa Man]

With the mods in my sig. , I have absolutely no hesistation from a dead stop even when towing. The HX40 spools pretty quick and if you roll on the power smoke is very minimal and almost none once you hit over 20 psi. I do have my plate set a hair back from the middle position. EGTs were getting too hot while towing when I had it forward.

 

[Hammer]

Strick-9. .

I'd admit to a point what you say about 12 valve spool up time and the inherent lag time,BUT,how many of these trucks like this have you seen that have had the tune-up off and are visibly way over-fueled???. Most of the heavy fueled 12 valvers I have seen spin a jet and are way over fueled tend to have a severe lag time in spool-up. Now I am not saying this is everyones problem but how many guys are just bolting on performance parts to gain numbers and end up loosing out on what you could really accomplish with the correct tune that allows the motor to use all(or most of it) the fuel its given.



Vaughn. .

My 98 12 valver(built in Dec 97) has little or no lag time to it and is capable of making usable power in its powerband. Lots of research,help from friends and a modest turbo modification to my stock hx35 helped it ease a very respectable 330hp and 831 ft lbs with the only added extra part a TST #11 plate. When watched by another member as it was spun I was told the smoke was evened out(a little dark to start then turned a lighter color as rpms increased). I have used a 10 plate and made the same hp and near the same amount of torque and the only difference that was seen was in the overfueling with it. One thing your 24 valver will do for you that we can not is control the overfueling which can be helpfull or a hinderence to some(ask Jetpilot how he'd like to rid his truck of it,defueling that is). There is a current TDR member here who has made somewhere between 350-400 hp with stock parts and the correct tune-up,maybe he will chime in here.



Power and smoke control can be done with the right tune up,just make your purchases wisely and watch what others are spending or wasting money on that does not work. It all comes out in the wash here at some point. Cylinder volumes,air & fuel flow will be critical to making power with little smoke. I relate this truck alot to my old 6bbl superstocker I had and its persnickity attitude. Over fuel it or under fuel it and your hurtin for power and won't run the number. Hit the right combo,fuel-timing-good air,watch her hit the tires hard,elevate and run the number. These 12 valve motors are no different than a good running B/RB motor,when the combo is right the torque will be made early and the power will be shortly behind and the closer they are together(max HP and torque)the more efficent the motor is... ... ..... Andy



P. S. -There is one thing your overvalved truck has I wish I could do though,turn off or turn down the power in bad weather.

 

[drawson]

Spool time down on 12 valve???????

Man I have drove and rid and alot of differant trucks and I have never been in a 24 valve that spooled fast with the exception of the HY-35/9CM2. I know a guy that put a Hy-35 on a 5 speed truck 24 valver and it spool quick. He was just running 275s and an early Edge 3 level box.



Since replacing my OE exhaust manifold with the ported ATS. I now get boost at 1300 RPMS with a HX-40/16 Piers special, and it jumps right to the waste gate boost by 1850 or so. AT least around here at our altitude (5000') the 24 valves don't even come close. Even guys with right at 400 HP in there 24 valve aren't happy with HX-40s.



The only way I'll have a 24 valver is if that the truck my wife want. Give me a 12 valve any day

 

[MDKram]

Vaughn, are we talking constant duty or intermittent HP? In Calgary, I made 290 RWHP with no smoke at all (ok, a very slight haze). The dyno operators commented that they were really impressed that my truck made no smoke at this HP level. At this time, I did not have the 370's or the PDR turbo. So, it is possible to make around 300 RWHP with little smoke. Note, I was only using enough fuel to keep the EGTs at 1300 max during these pull-down runs.



Now, I have found that the higher HP trucks with good smoke control have different cams, namely the PDR or DD cams. With lots of fuel, I feel it is very important to change the amount of valve overlap to reduce the smoke. A cam is a big investment and does not net much, if any HP, but you get better breathing which results in earlier spool-up and less smoke. So, to answer your question, I feel the cam is the secret to reducing smoke on heavy fueled 12 valves.

Marc