Want to improve low-end torque

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Thread: Want to improve low-end torque

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    Default Want to improve low-end torque

    My pops has an I-Force V8 tundra. I think it's an 02. He's already done I/H/E and is looking for a way to improve low-end torque (aside from a s/c or something). Would a port and polish job help this out? How much would it cost? Any other ways to improve the low-end?
    Thanks.

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    Default Unichip and go back to the stock intake and exhaust.

    Quote Originally Posted by what the...
    My pops has an I-Force V8 tundra. I think it's an 02. He's already done I/H/E and is looking for a way to improve low-end torque (aside from a s/c or something). Would a port and polish job help this out? How much would it cost? Any other ways to improve the low-end?
    Thanks.
    What kind of intake and what kind of exhaust?

    If it's any of the FIPK intakes like K&N, then going back to the stock intake will substantially improve low end torque (below about 3100). The FIPK intakes do improve horsepower above 3200 RPM but really hurt maximum torque below that engine speed.

    Similarly, if the replacement exhaust was any, repeat any, of the commercial catback systems, replacing those with the stock exhaust will restore low end torque. This is especially true if the replacement exhaust was any of the 1 into 2 dual "systems"...they provide waaaaay too much pipe for low end power. For low end torque, it's absolutely critical that the stock single 2 3/8 inch exhaust pipe be retained. The only exhaust modification that helps low end torque is replacing just the muffler with a known low restriction muffler like Spintech, MagnaFlow, or Dynomax. I can testify that a Gibson muffler really helped my low end torque but can't recommend it unless the truck is primarily used for serious towing (trailer weight over 4000 lbs). In any case, do not use any of the Flowmasters...they make great sound but are quite restrictive compared to Spintech, Magnaflow, Dynomax or even the stock muffler.

    The supercharger is no longer sold for this engine so that's not an option. Porting and Polishing might help high end power where flow is high but will do little to nothing for low end power. Furthermore, because this is a dual overhead cam engine with 32 valves, the labor for port polishing (including R&R on the heads) would be astronomical...probably around $1500 to $2000. Just replacing the timing belt usually costs around $800 in labor alone.

    My truck was bought primarily to tow my travel trailer and every single performance mod that I've done was aimed at improving low end (below 3000 RPM) torque. I can therefore confidently state that the only other modification besides headers and the right muffler (not exhaust but muffler) that will definitely help low end torque is the Unichip piggyback ECU. The Unichip provides torque boosts similar to headers but is a bit costly...around $900.

    You can also get a real boost in torque throughout the power band by regearing the axle(s). With stock or slightly larger than stock tires, changing to a 4.30 ratio immediately increases torque at the wheels by 10%. Very costly though...with new parts it will run about $1500 per axle for OEM 4.30 gears, about half that for aftermarket 4.56 gears.
    Ray


    Natural White '03 Access Cab V8 SR5 4X4 with TRD Off Road Suspension, Limited Slip Differential, and Towing Package

    Towing & Performance Mods: JBA Headers, Gibson Muffler, 4.30 gears, Michelin LTX M/S Tires, Hellwig Anti-Roll bar, Prodigy Trailer Brake Controller, Autometer Z-Series Transmission Temperature Gauge, Magnefine Transmission Filter
    Utility & Misc Mods: Genuine Toyota OEM Step (Nerf) bars, Peragon Tonneau Cover, TracRac Rack and Rail System, Muth Signal Mirrors, Pop&Lock tailgate lock, TruSpeed speedometer calibrator, "$20" RS-3200 Upgrade, Auto-Dimming mirror w/ Temp and Compass, Clear/Red/Clear Taillights with Silverstar Signal bulbs, 3M Clear Bra


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    Default

    thanks for the reply. The intake he's got is an AEM brute force, the exhaust is the optional factory dual, and I think the headers are JBL. So you're saying that the only things I can do to improve low-end torque are to:
    regear (1500/axle)
    high flow muffler
    piggyback ecu. (900)

    I have an Apex'i VAFC piggyback on my prelude, and I only paid about 200 bucks for that. Why is the Unichip so much more expensive?

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    Default Yep

    Quote Originally Posted by what the...
    thanks for the reply. The intake he's got is an AEM brute force, the exhaust is the optional factory dual, and I think the headers are JBL. So you're saying that the only things I can do to improve low-end torque are to:
    regear (1500/axle)
    high flow muffler
    piggyback ecu. (900)
    Just as I thought. Because it has a longer runner, the AEM is a little better for low end than the K&N but still not as good as stock. The factory dual (probably TRD or perhaps Borla in the SE states) is definitely hurting low end torque. Switching to the stock single (with a low restriction muffler) would help a lot. NOTE: replacing just the muffler in the dual system won't help a bit and may make matters worse. The problem with the factory dual system isn't the muffler but the fact that it's a 1 into 2 dual system with too much exhaust pipe volume. Even having a muffler shop craft a single system won't help a lot because they'll use 2 1/2 inch pipe and that's just too large a diameter. The single 2 3/8 inch stock pipe is the critical element for low end torque.
    I have an Apex'i VAFC piggyback on my prelude, and I only paid about 200 bucks for that. Why is the Unichip so much more expensive?
    The Unichip is probably the most advanced piggyback in the world plus it is shipped with custom fuel and ignition timing maps for the specific combinations of intake/exhaust/supercharging on each vehicle. A lot of dyno time went into making those custom maps and the cost somewhat reflects that.

    I regularly tow a 4000 lb trailer over high and steep mountain passes here in Colorado. Maximizing low end torque (below 3000 RPM) has been my focus for over a year and every mod I've done was targeted to that goal. The only mod I listed that helps and that I haven't yet done is the Unichip. As an Engine and a towing moderator here I've also paid very close attention to what hurts low end torque and I'm convinced that the two best ways to hurt low end torque are FIPK intakes (K&N or AEM) and 1 into 2 dual exahusts.
    Ray


    Natural White '03 Access Cab V8 SR5 4X4 with TRD Off Road Suspension, Limited Slip Differential, and Towing Package

    Towing & Performance Mods: JBA Headers, Gibson Muffler, 4.30 gears, Michelin LTX M/S Tires, Hellwig Anti-Roll bar, Prodigy Trailer Brake Controller, Autometer Z-Series Transmission Temperature Gauge, Magnefine Transmission Filter
    Utility & Misc Mods: Genuine Toyota OEM Step (Nerf) bars, Peragon Tonneau Cover, TracRac Rack and Rail System, Muth Signal Mirrors, Pop&Lock tailgate lock, TruSpeed speedometer calibrator, "$20" RS-3200 Upgrade, Auto-Dimming mirror w/ Temp and Compass, Clear/Red/Clear Taillights with Silverstar Signal bulbs, 3M Clear Bra


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    Default

    Ray, just for clairification, by exhaust pipe you mean tailpipe, right?

    Larry
    2004 Tundra V8 Limited Access Cab 4X4, Michelin 265/65/R17 LTX-AT2's, Auto Dim Comp/Temp Mirror, Aero Turbine #2525 muffler, Access Roll Up Cover, Optima D31A battery, Multi-Vex adaptive outside mirrors, Eclipse AVN5510 Nav unit and Sirius SIR-ECL1 tuner, as of 10/07 pictures in my photo gallery

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    Thumbs down Flowrestricters

    Quote Originally Posted by RockyMtnRay
    ... In any case, do not use any of the Flowmasters...they make great sound but are quite restrictive compared to Spintech, Magnaflow, Dynomax or even the stock muffler.
    So, Flowmasters are in fact Flowrestricters.

    Good to know

    2002 REGULAR CAB - LONG BED - 4WD - V8 - SR5

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    Default

    alright. I think he might still have the stock airbox assembly laying around somewhere. He's not towing anything right now, but he's been mumbling things about wanting to buy a boat - hence the questions about low-end torque. I doubt he'll want to give up his dual exhaust, so he might decide to spring for the Unichip. I'll relay your advice on to him.

    Thanks for your help. I'm a Tech Advisor on a prelude forum, and it's nice to go someplace completely out of my element and talk to someone who's knowledgeable and willing to break it down for a tundra n00b.

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    Wink Yes, IMO FlowRestrictors is a good description

    Quote Originally Posted by 7.62mm
    So, Flowmasters are in fact Flowrestricters.

    Good to know
    Consider this bench flow comparison chart. It clearly shows a Flowmaster 40 series has a measly 35% of the flow of a Dynomax UltraFlo. That's pretty darn pathetic IMO.

    Consider also that no-one, AFAIK, has ever presented documentary evidence here that any Flowmaster model has improved low end torque. There are a lot of reports about the great sound but few, if any, credible reports about improved low end power (there have been a number of complaints about power loss though).

    My impression is that Flowmaster has done a wonderful job of designing an audio device for the exhaust...a pipe organ. But not a known performance enhancing device, at least for RPMs below 3000.
    Ray


    Natural White '03 Access Cab V8 SR5 4X4 with TRD Off Road Suspension, Limited Slip Differential, and Towing Package

    Towing & Performance Mods: JBA Headers, Gibson Muffler, 4.30 gears, Michelin LTX M/S Tires, Hellwig Anti-Roll bar, Prodigy Trailer Brake Controller, Autometer Z-Series Transmission Temperature Gauge, Magnefine Transmission Filter
    Utility & Misc Mods: Genuine Toyota OEM Step (Nerf) bars, Peragon Tonneau Cover, TracRac Rack and Rail System, Muth Signal Mirrors, Pop&Lock tailgate lock, TruSpeed speedometer calibrator, "$20" RS-3200 Upgrade, Auto-Dimming mirror w/ Temp and Compass, Clear/Red/Clear Taillights with Silverstar Signal bulbs, 3M Clear Bra


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    Default

    Quote Originally Posted by LGL002
    Ray, just for clairification, by exhaust pipe you mean tailpipe, right?
    "Tailpipe" has two definitions...traditionally it's solely the section of the exhaust tubing after the muffler. Others consider it the entire exhaust from the cats to the back of the vehicle.

    When I say exhaust pipe, I mean the pipe from the Y-pipe to the back of the vehicle including the sections ahead of the resonator (or 3rd California cat), between the resonator and muffler, and from muffler to the exhaust tip. That does include the traditional "tail pipe" but it also includes the pipe that's not traditionally part of the "tail pipe". For best low end torque, all of this exhaust tubing should be 2 3/8 inches outside diameter on a single exhaust system.
    Ray


    Natural White '03 Access Cab V8 SR5 4X4 with TRD Off Road Suspension, Limited Slip Differential, and Towing Package

    Towing & Performance Mods: JBA Headers, Gibson Muffler, 4.30 gears, Michelin LTX M/S Tires, Hellwig Anti-Roll bar, Prodigy Trailer Brake Controller, Autometer Z-Series Transmission Temperature Gauge, Magnefine Transmission Filter
    Utility & Misc Mods: Genuine Toyota OEM Step (Nerf) bars, Peragon Tonneau Cover, TracRac Rack and Rail System, Muth Signal Mirrors, Pop&Lock tailgate lock, TruSpeed speedometer calibrator, "$20" RS-3200 Upgrade, Auto-Dimming mirror w/ Temp and Compass, Clear/Red/Clear Taillights with Silverstar Signal bulbs, 3M Clear Bra


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    Default

    Quote Originally Posted by what the...
    alright. I think he might still have the stock airbox assembly laying around somewhere. He's not towing anything right now, but he's been mumbling things about wanting to buy a boat - hence the questions about low-end torque. I doubt he'll want to give up his dual exhaust, so he might decide to spring for the Unichip. I'll relay your advice on to him.
    Changing back to the stock intake from an AEM probably won't make a really noticeable improvement in low end torque until the engine has to really do some work...like with towing. It will make a huge reduction in sound and a lot of people correlate less sound with less power.

    Understandable but too bad about staying with the dual exhaust cause that's his real killer of low end torque. This is a fairly small (only 285 cu inch) V8 and Toyota really did a great job of tuning it for maximum torque (an impressive 315 ft-lbs) at a very usable RPM (only 3400). Part of that tuning was choosing the 2 3/8 inch single exhaust (the stock system in most of the USA and Canada)...it's just the right size for optimize scavaging at mid RPM. Dual pipes or overly large single pipes result in too much cooling, density increase, and loss of energy/velocity in the gasses until RPM gets pretty high.
    Thanks for your help. I'm a Tech Advisor on a prelude forum, and it's nice to go someplace completely out of my element and talk to someone who's knowledgeable and willing to break it down for a tundra n00b.
    Welcome. Glad to help.
    Ray


    Natural White '03 Access Cab V8 SR5 4X4 with TRD Off Road Suspension, Limited Slip Differential, and Towing Package

    Towing & Performance Mods: JBA Headers, Gibson Muffler, 4.30 gears, Michelin LTX M/S Tires, Hellwig Anti-Roll bar, Prodigy Trailer Brake Controller, Autometer Z-Series Transmission Temperature Gauge, Magnefine Transmission Filter
    Utility & Misc Mods: Genuine Toyota OEM Step (Nerf) bars, Peragon Tonneau Cover, TracRac Rack and Rail System, Muth Signal Mirrors, Pop&Lock tailgate lock, TruSpeed speedometer calibrator, "$20" RS-3200 Upgrade, Auto-Dimming mirror w/ Temp and Compass, Clear/Red/Clear Taillights with Silverstar Signal bulbs, 3M Clear Bra


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    Default Single in Duel out muffler with 2 1/4 outlets

    Spintech offers a single in duel out muffler with 2 1/4 inch outlets. Do you think I would loose a lot of low end with this setup? I need a new muffler anyway and I was thinking of this mod. Thanks.
    Go Sabres

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    Default Some, perhaps not much

    Quote Originally Posted by BackInBlack
    Spintech offers a single in duel out muffler with 2 1/4 inch outlets. Do you think I would loose a lot of low end with this setup? I need a new muffler anyway and I was thinking of this mod. Thanks.
    Lose a lot, no; some, very likely yes. How much, I can't pin down for you because no-one has done a dyno test or before/after timed acceleration tests of that configuration. The loss will definitely be less than with the various catback "systems" that use 2 1/2 inch (or larger) pipe.

    Check with moderator TundraStruckDave...a while back he was talking about doing that exact exhaust mod but I don't know if he ever did it.
    Ray


    Natural White '03 Access Cab V8 SR5 4X4 with TRD Off Road Suspension, Limited Slip Differential, and Towing Package

    Towing & Performance Mods: JBA Headers, Gibson Muffler, 4.30 gears, Michelin LTX M/S Tires, Hellwig Anti-Roll bar, Prodigy Trailer Brake Controller, Autometer Z-Series Transmission Temperature Gauge, Magnefine Transmission Filter
    Utility & Misc Mods: Genuine Toyota OEM Step (Nerf) bars, Peragon Tonneau Cover, TracRac Rack and Rail System, Muth Signal Mirrors, Pop&Lock tailgate lock, TruSpeed speedometer calibrator, "$20" RS-3200 Upgrade, Auto-Dimming mirror w/ Temp and Compass, Clear/Red/Clear Taillights with Silverstar Signal bulbs, 3M Clear Bra


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