single vs twins please help im not trying to start a flame war

[paint94979]

i think what he was trying to say is you have boost at lower rpms which would keep the egts down which is what some people feel saves the motor.

from what i have learned with my truck that is not the case at ALL... torque down low has been a known problem of bending connecting rods. My truck dynoed 593hp/910ftlbs my rods as of now are holding just fine. These engines were built to run at 1350F the benefit of twins as i see it is less EGT's at WOT in the upper RPM range. High EGT's are said to melt/crack pistons i have not been a victim of this either running high EGT's(1600F).

 

[bullfrogjohnson]

i think what he was trying to say is you have boost at lower rpms which would keep the egts down which is what some people feel saves the motor.

Travis we should see how our trucks do racing. you still have a stock bottom end right?

I would love to run at the track but my by the OBX event my gearing will be to low to be able to run anything but the 1/8. I do still have a stock bottom end and its still running. Need to do a compression test for sure to see how well the stock bottom end is holding up.

 

[ChevyDieselLLY]

but how often does your motor see 1600?my guess is only at WOT. just because they are made to run at 1350 doesnt mean you want to right? wouldnt lower egts keep the motor alive longer regaurdless? i know twins make tq and that is what bends rods. no doubt about that.

 

[paint94979]

but how often does your motor see 1600?my guess is only at WOT. just because they are made to run at 1350 doesnt mean you want to right? wouldnt lower egts keep the motor alive longer regaurdless? i know twins make tq and that is what bends rods. no doubt about that.

1600*(at the end of the 1/4) is what most drag racers call the safe #.. OF COURSE cooler is better but there is also a point where too cool causes less heat for the turbos which causes slow spoolup and less hp... i will be twinning my 4094 with a 4718R whenever i get around to setting things in motion.

 

[ChevyDieselLLY]

I would love to run at the track but my by the OBX event my gearing will be to low to be able to run anything but the 1/8. I do still have a stock bottom end and its still running. Need to do a compression test for sure to see how well the stock bottom end is holding up.

1/8 is fine with me. just figured seeing how we both are close to the same set up minus the turbo(s) it would make for a semi fun race and give people an idea of what set up would be best for them. im sure i will lose but that fine with me.

 

[ChevyDieselLLY]

1600*(at the end of the 1/4) is what most drag racers call the safe #.. OF COURSE cooler is better but there is also a point where too cool causes less heat for the turbos which causes slow spoolup and less hp... i will be twinning my 4094 with a 4718R whenever i get around to setting things in motion.

but as long as you have the egts to spool your turbo(s) do you need more?

so if 1000* spools your turbo(s) what benifit are you going to see from 1300* on up?

 

[othrgrl]

Boy Dustin you would have to prove that to me, I seriously doubt that. Now I will say if run the same tune with both, especially a smaller tune I think the twins will not get as good fuel economy. Bigger tune get much better fuel economy, obviously you can't be WOT all the time.

Dustin I just read your post again and you are saying a stock turboed truck will get as good or better mileage and run faster? What the hell are you smoking??? That is total BS, love to have the chance to prove it to. It might come close on fuel economy but no way faster. I'm assuming that is a typo.

Have to prove what? Chris gets over 21mph, runs consistant 12.4s at 106 and 107 on 3 different set of all terrains. There are others that run 12.5s at 106-108, including Kat's. They are all stock turboed trucks getting as good or better mileage and running faster and quicker times.

Dustin my truck was set up about as mild as you could go with a small set of twin, it never had a race tune in it. I could have gotten it in the 11's if I had wanted to, but just ran a few bracket races with it so didn't bother. Never had anything but real street tires on it either. Small set of twin, lift pump, very minor tranny work, TC and standard stuff up front, sleeves and braces and clamps on the rear that is it. Hell I don't even ever take the tool box out of it when I raced. I left the hot street tune in it when I sold it and the guy who bought it wanted the tow tune in it because he was going to pull his big 5th wheel. Said the tow tune didn't get near the fuel economy as the hot street tune did just driving around.

Another thing how long you thing that single cab LMM's turbo is going to live running it like that? I know the twinned truck isn't working hard at all makeing the same performance. I'm not try to sell twins, hell I still have to pay Nathan for the last two sets I bought. But really you can't actually believe that statement?

But your statement that two truck set up the same and stock one would be as quick or quicker(I'm assuming you mean quick not fast) with twins is just absolutley ludicrous. Even with a stock tune in each I'd bet big money the twinned truck would be, how could it not, epecially if you had the time to spool the turbos on a stock tune???

The LMM is a 2WD Crew Cab short bed with all the listed added weight and the turbo will do just fine, just like all the other stock turbo trucks running mid 12s.

Now again (4th time now I think), :hug: I know that your truck was not turned up all the way and that it would run as fast as Rob's if if it was. My point was if you are going to try to sell twins you need to list Rob's all out times, which are much faster than a stock turbo truck has gone - not your bracket racing times that are slower than stock turbo trucks have gone.

Again I'll also so that for the OP twins are going to be the best all around choice and that twins will give you more all around performance (streetability, towing, EGTs, mpgs, and track times) compared to a big single like mine. However, my S475 tows 10,000 lbs with ease, with the EGTs staying under 1000 even if I purposely lug it up a slight incline at 1600 RPM, I still get 20 mpg on the highway with the 20s on it (not while towing), and it runs in line with what the guys have done with a 366/480 setup at similar (most likely less) weight and for alot less money. So it still does everything I want and need it to and it meets the rules I need it to for sled pulling.

 

[Mike]

As of today, I would venture a guess that if you wanted the most HP out of a Dmax:

Dual high-output CP3's
50-100% injectors
Racing fuel
High pressure lift pump system
A GT5533 sized single
1.5:1 P/R Roots blower
Nitrous intercooling between stages, no air-air or air/water.
Light propane fogging to assist ignition rate.
Maximum engine displacement
14:1 CR (see roots blower)
4500 peak HP rpm, shifting at 5000, flat powerband.

But that's just a wild-arse guess, nor would I assume that the engine would survive at that level, probably 1600+ rwhp.

And yes, I will have another beer.

If I offended anyone in this thread, my apologies. You wouldn't be the first folk I offended, and I can guarantee you won't be the last.

I'm offended, all this talk about a roots and 1600hp and you haven't started yet.

Sad fact is, if we don't know we talk till we do know. Then, when we try it we gotta get everyone else to agree before we make our mind up. We've learned tons by failing. I'll fail some more but will have some more experience. :happy2:

 

[Mike]

but as long as you have the egts to spool your turbo(s) do you need more?

so if 1000* spools your turbo(s) what benifit are you going to see from 1300* on up?

Depends on the temperature drop/difference between the inducer and exducer of the turbine of the turbocharger. If there is no temperature drop, there was no transition/conversion to mechanical power.

 

[Subman]

Pat if you really talking faster not quicker I have no idea if singles are or not, I'm not talking fast like salt flat style racing, I saying quick like drag racing and by by looking at the list, if you toss out the the rail, tube frame and 1/2 ton rigs the quckest truck is Bucks with a stock charger with a ton of NOS then Max'd Out, (twinned #2 only) Nasty Girl (twinned, not sure if he sprayed or not) and from there on I'm not totally sure of the trucks. I know many of them run NOS. I don't know if you were spraying or not with your and Kat's times in Casper. If a person really wanted to get chitty on the line you could stage with big twins and time the single charger out 90% of the time before they could build boost on #2 only. I'd never do it but it would be easy to do, especially if they had the auto start on, If you spray I don't consider that any different than running twins on a drag strip, infact I think NOS trucks have an edge most of the time.

All kind of a moot point. I'm trying to think of a downside to twins and other than not being treated fair in sled pulling rules I can't think of one. They cost more but like anything you get what you pay for.

By the way Pat will Casper be sporting a big single or twins in Phoenix in March?:secret:

 

[McRat]

Pat if you really talking faster not quicker I have no idea if singles are or not, I'm not talking fast like salt flat style racing, I saying quick like drag racing and by by looking at the list, if you toss out the the rail, tube frame and 1/2 ton rigs the quckest truck is Bucks with a stock charger with a ton of NOS then Max'd Out, (twinned #2 only) Nasty Girl (twinned, not sure if he sprayed or not) and from there on I'm not totally sure of the trucks. I know many of them run NOS. I don't know if you were spraying or not with your and Kat's times in Casper. If a person really wanted to get chitty on the line you could stage with big twins and time the single charger out 90% of the time before they could build boost on #2 only. I'd never do it but it would be easy to do, especially if they had the auto start on, If you spray I don't consider that any different than running twins on a drag strip, infact I think NOS trucks have an edge most of the time.

All kind of a moot point. I'm trying to think of a downside to twins and other than not being treated fair in sled pulling rules I can't think of one. They cost more but like anything you get what you pay for.

By the way Pat will Casper be sporting a big single or twins in Phoenix in March?:secret:

Our truck is certainly not the quickest single-charger 2500HD on fuel. It ran 10.83 with a 3.0 charger at a measured 6420lb at the HRP scale, with a few thousand folk in attendance. And that was over 2 years ago. 2 years is a long time with this stuff. I could make a similiar truck run faster today.

Exactly what is the fastest 3.0 twin truck with people watching?

What could be done today at that weight? Dunno. Back then it was much quicker than any twin truck sporting a 3.0 charger. By perhaps a full second.

What we will run in AZ is not decided.

 

[Mike]

With compounding turbochargers, the smaller charger builds cfm to spool the larger charger. Once the larger charger is spooled the smaller charger compounds that air from the larger charger. Sooo if there is a disadvantage off the line for a single charger it would be for spool up as noted. I say that puts the single at a disadvantage for off the mark. I say NOS would not get any more advantage over twins if used for spooling the single charger.

My vote goes to the BIG single with NOS as the manifold charger.

 

[McRat]

Big single with nitrous is certainly a proven way to make power.

 

[SteveFord]

Just for my info whats the fastest single on #2 only dmax?

 

[Mike]

Pat's single at Bonneville before the twins?

 

[SteveFord]

How about at the drag strip? Should have asked the question right the first time.

 

[McRat]

When we ran the single at Bonneville, we were under a 175mph restriction. We would have been sent home with no record if I exceeded that speed. They didn't like my window net, so even if did put on a parachute, we wouldn't have been allowed to go faster.

So I got it up to 174.586mph.

 

[zfuller123]

Ive noticed this as well, why is that? Can someone please explain.

I've found alot of it is in the tuning.... my 'race' tune will still do this, but i haven't really tried to work it out - but my 500 HP tow tune spools up nice and clean and doesn't really have any of the 'knock' or rattle from stomping on it from just about any starting RPM - might not instantly light up the tires, but if i'm under 35 MPH when i do, it will break the rears loose. Not saying that's very impressive overall - but what is nice is that it does is without all the cackling from too much fuel too quick, the big puffs of black smoke, etc.... Make the truck very 'sporty' to drive for 8000 + lbs

 

[zfuller123]

I think one thing that doesn't come into play, which has been proven i think over and over at the tracks in particular - is elevation.

Twins vs. Single - surely for 'all around' use, there really can't be a very good straight across comparison when you throw in elevation.

I think both sides of the argument have merit - however, i think when the "use for dd, towing heavy, racing, etc." argument gets used, and the poor guy doesn't live at sea level or within 1000' feet of it - the argument for twins gains alot of strength.

I'm not sure how many people can testify one way or the other to this - but i do know of a few people here, in Salt Lake running big singles. Most of you know them in fact on this board - but no need to toss names out. I know that one of them that put down about the fastest times i saw at our track on a single charger (Ken knows him too) had to spray more NOS than a guy should have access too - but it was still very impressive to say the least. His single charger does spool 'ok' for the elevation - but it still is nitrous assisted basically right off the line - point being there is no way this truck could tow more than about 5000 # without burning to the ground. EGTs at the track even with all the spray are off the chart.... he "quits looking when he sees 2000*"... I'm sure there's not alot of twinned trucks that have seen 2000* or much above - but i could be wrong.


Anyways - drifting off topic a little - point is that one thing not mentioned or factored in to anyones post so far, that i have seen - is elevation. If a guy is going to be towing up in the mountains, particularly with significant weight - or even just in higher elevations period - for 'all around' use, i just don't see how the argument for a bigger single could stand up. At the track, sure - with some help - but for all around use, i just don't see it.

For reference, for those that don't know - Salt Lake during the summer / racing months experiences usually 7200 - 7500' DA - a fact that has caught alot of out of town 'fast' trucks far enough off gaurd that they couldn't even get a single good pass in at some of the events (Edge Days, DHRA, NADM, etc.).

 

[Subman]

Some really good posts discussed, so anyone trying to decide which way to go can gleen some good info here. I'm very curious about the new single chargers that were said to be coming out this year, if they perform as stated it will certainly add another dimension to this discussion. I haven't heard much about the Cheetah tubos lately, they were really the rave in later 07 what is their status now?