What turbo for a LQ4 Tow Rig??
10-03-2013, 04:19 PM
#41
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Its really looking like a better option to do the Cummins swap on this truck , esp when you factor in the fuel economy. My mind isn't made up but I will start to research this option. Thanks to everyone who has replied.
10-03-2013, 04:32 PM
#42
This is an excellently timed thread (for me at least). I have just picked up a new boat (6000lbs boat and trailer) and an 03 Tahoe Z71 to pull it. The 03 has the LM7 engine and handles the boat OK but not as well as I would like. I have considered doing a cam swap only but going to a LS2 cam (just as an example because I have one laying around) will help on hp (I have seen some showing up to 100hp) but moves the tq peak up in rpm (not something I want). My solution was to add a 76mm turbo and intercooler to bring the torque back up. Thoughts?
10-03-2013, 06:57 PM
#43
All I am saying is that on all the turbo cars I have experience with, my current LS based one included, the higher the gear the quicker the spool (in rpms, not time). If it is in first gear with a 15 psi spring, it may only hit 10 psi by 4500, 2nd may hit 15 psi by 4000, 3rd may hit 15 psi by 3750. This is one reason why they make gear based boost controllers. Subaru motors are a prime example. If you set the wastegate duty cycles for first gear max spool, you will for SURE overboost in 3rd or 4th gear.
On gear specific boost controllers, you may have to set wastegate duty cycles at 75% in 1st and 2nd and only 60% in 3rd and 4th. By 5th and 6th you may only need 45% to hit the same target boost.
This has been the case with every turbo car I have had the pleasure of working on. It is the load on the motor and the time it spends/rpm. 1st gear may be over so quickly that you never even hit full boost, but by the time you are in 3rd gear you are rocking and rolling. Give whatever thermodynamic explanation you want, but this has always been my experience and why they make gear specific boost controllers. If a car hits target boost by 3700 in 2nd gear, it will for sure make it sooner in 4th (all boost control devices being the same).
Edit: As a for instance, my current vehicle, 1st gear does not hit target boost (spring pressure) until 4200 in 1st, 3700ish in 2nd gear. Starts spooling at 3200 in 1st and 2500 in 2nd.
On gear specific boost controllers, you may have to set wastegate duty cycles at 75% in 1st and 2nd and only 60% in 3rd and 4th. By 5th and 6th you may only need 45% to hit the same target boost.
This has been the case with every turbo car I have had the pleasure of working on. It is the load on the motor and the time it spends/rpm. 1st gear may be over so quickly that you never even hit full boost, but by the time you are in 3rd gear you are rocking and rolling. Give whatever thermodynamic explanation you want, but this has always been my experience and why they make gear specific boost controllers. If a car hits target boost by 3700 in 2nd gear, it will for sure make it sooner in 4th (all boost control devices being the same).
Edit: As a for instance, my current vehicle, 1st gear does not hit target boost (spring pressure) until 4200 in 1st, 3700ish in 2nd gear. Starts spooling at 3200 in 1st and 2500 in 2nd.
Last edited by Sarg; 10-03-2013 at 07:03 PM.
10-03-2013, 07:12 PM
#44
You want a fairly laggy turbo with big exh side for towing. S475/96/1.32 would be about right. I've pulled 6-7000 lbs with my turbo truck and can tell you it will work but you only want to use boost for short periods. I try and keep it at 0-2 psi and only hit 6-8 to pass. You have to keep engine rpm up and throttle light or you will be in boost on the hills.
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Ford_Assassin (03-11-2020)
10-03-2013, 07:20 PM
#45
6BT diesel Cummins swap and never look back. You can get 20-22mpg highway empty and 13-4mpg towing 10,000lbs close flat front trailer.... and 16-17mpg towing an open trailer. Drag and speed/RPMs is more relevant to weight with diesel fuel economy. 600ft/lbs essentially stock.
You may as well just buy the entire Dodge truck running. I have had a few of them and best tow rig ever. They just don't ride as nice as Duramax trucks.
You may as well just buy the entire Dodge truck running. I have had a few of them and best tow rig ever. They just don't ride as nice as Duramax trucks.
10-03-2013, 07:31 PM
#46
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Thanks for weighing in Jarrett. I have been on 67-72 trucks all evening researching this swap(diesel) I think I'm staying with my plan turbo gas. I will hit you up for a cam when the time comes.
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1936 LS1 (04-25-2020)
10-04-2013, 02:36 AM
#49
This has been the case with every turbo car I have had the pleasure of working on. It is the load on the motor and the time it spends/rpm. 1st gear may be over so quickly that you never even hit full boost, but by the time you are in 3rd gear you are rocking and rolling. Give whatever thermodynamic explanation you want, but this has always been my experience and why they make gear specific boost controllers. If a car hits target boost by 3700 in 2nd gear, it will for sure make it sooner in 4th (all boost control devices being the same).
10-04-2013, 06:57 AM
#50
That being said if you spend a ton of time at low rpm, high load (like 4th gear hill pull) you are going to run into more chances of det if you are not careful. I have seen more detonation at peak torque than at peak hp. This is why I personally set timing and air fuels more conservative at those load areas (or map/rpm on a sd tune) than at peak hp higher up in the rpms. Just be careful about the timing if you get a super quick spooling turbo.
10-04-2013, 07:11 AM
#51
I agree with stock48, run a loarge laggy turbo. If you expect to pull all the time in boost you will have many engine failures. Gas burners with turbos and towing are very very tricky business. The OEMs have been at it for decades and Ford finally has one that will not melt down towing.
10-04-2013, 07:30 AM
#52
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I totally agree, I have to pull my transam on a trailer up the side of a mountain to get to my local race track with the truck in my sig, and there is one part that is a very long stretch of a big incline, and I can't keep into the throttle the whole way or else the temps raise to over 230*. My truck is stock though.... unfortunately. 
10-04-2013, 07:41 AM
#53
I agree with stock48, run a loarge laggy turbo. If you expect to pull all the time in boost you will have many engine failures. Gas burners with turbos and towing are very very tricky business. The OEMs have been at it for decades and Ford finally has one that will not melt down towing.
From what I have read its a dog when actually towing.
Heavy towing I will stick with a nice diesel, that just will chug along and not need much RPM or boost to do it with. Tow rigs are supposed to make the trip to the track relaxed and having to worry about not seeing boost, or overheating etc would seem to negate that.
Grab a early 6.0 lulz
10-04-2013, 08:17 AM
#54
The ecoboost?
From what I have read its a dog when actually towing.
Heavy towing I will stick with a nice diesel, that just will chug along and not need much RPM or boost to do it with. Tow rigs are supposed to make the trip to the track relaxed and having to worry about not seeing boost, or overheating etc would seem to negate that.
Grab a early 6.0 lulz
From what I have read its a dog when actually towing.
Heavy towing I will stick with a nice diesel, that just will chug along and not need much RPM or boost to do it with. Tow rigs are supposed to make the trip to the track relaxed and having to worry about not seeing boost, or overheating etc would seem to negate that.
Grab a early 6.0 lulz
10-04-2013, 10:05 AM
#56
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Ok between these 4 $650 dollar turbos which would you run?? s472/1.32/96....s472/1.10/83...0r these s475/1.32/96 and last the s475/1.10/83 all being t6 of course. Are these prices current at Forced Inductions?
10-04-2013, 12:20 PM
#58
10-04-2013, 12:49 PM
#59
That being said if you spend a ton of time at low rpm, high load (like 4th gear hill pull) you are going to run into more chances of det if you are not careful. I have seen more detonation at peak torque than at peak hp. This is why I personally set timing and air fuels more conservative at those load areas (or map/rpm on a sd tune) than at peak hp higher up in the rpms. Just be careful about the timing if you get a super quick spooling turbo.
What hellbents10 said is right, towing with a gas engine is difficult because its easy to break stuff. OP asked about building an LQ4 tow rig, and most of the responses are how to build a fast truck that occasionally has a trailer behind it. Actually making a gas engine turbo tow rig isn't easy...it takes more effort than just a general shadetree recommendation.
But hey, throw any old turbo on it lol. What do I know. It will make towing fun. Less effective than just towing NA though.