K&N or other free flow

[bugmenot]

Would i see much improvement with a k&n on an otherwise stock 2005 double cab. I'm interested in improvment while towing. Truck has lots of b*lls with no trailer behind it. Trailer is only 4200 lbs dry but once i've loaded it and the family up you know it's there. I'm fine on the flats but wondering if some more airflow in would help me on the grades. Or would I have to do K&N in and exhaust out to see any improvement.

tia

[mustang67408]

Your not going to find much of an improvment anywhere in the 2005 model.
Toyota has pretty much taken care of that for you. Leave it alone and enjoy your vehicle.
The aftermarket air filter/exh may even hurt your towing capabilities.They give mostly high end help, not the low end grunt you need.

[RockyMtnRay]

Originally Posted by bugmenot

Would i see much improvement with a k&n on an otherwise stock 2005 double cab. I'm interested in improvment while towing. Truck has lots of b*lls with no trailer behind it. Trailer is only 4200 lbs dry but once i've loaded it and the family up you know it's there. I'm fine on the flats but wondering if some more airflow in would help me on the grades. Or would I have to do K&N in and exhaust out to see any improvement.

tia

A K&N intake is about the worst thing you could do for towing performance. I do a lot of "extreme" mountain towing where I can use all the power I can get and I wouldn't touch a K&N with a 10 foot pole.

K&N's own published torque curve...which has been verified by several very reputable TS.COM members....shows a loss, yes LOSS, of torque below about 3000 RPM. For a good towing experience, you want to boost...not lose...torque below 3000 RPM because it's the low end torque that gets you moving and allows the truck to avoid downshifts from 3rd (4th on the '05s) at highway speeds. Furthermore, because K&N intakes are designed to make lots of noise at high throttle openings (for the more-noise-has-to-mean-more-power crowd), the in-cab noise level would be very fatiguing over time. Finally, unless you are very sparing in re-oiling the filter, the oil is sucked off the filter and coats/gunks up the thin wires in the Mass Air Flow sensor, thereby making it less sensitive and causing the engine to run too lean for safety. And if you are too-sparing, the filter won't remove enough dust from the incoming air and that gets into your engine's internals.

If you only replace the stock air filter with the so-called "free flowing" K&N filter, you won't have the big torque loss of the K&N intake but you won't have any torque gain either. The problem is the K&N filter has less than half the surface area of the stock filter (because of the deep pleats in the stock filter) so the stock filter actually flows better than the K&N drop in filter. One TS member did back-to-back tests (dyno I think) with a K&N drop in and the stock filter and got better performance from the stock filter. The K&N filter also has the same nasty problem of gunking the MAF sensor wires as their intake.

If you feel you absolutely must do something to your intake...then try using a True Flow Oiled Foam Filter...at least a TrueFlow flows as well as (and filters as well as) the stock filter and doesn't screw up your MAF. Some people think the TrueFlow works better than the stock but I've not yet been convinced of this...nor has TS member KLS (our other towing guru)...last I knew he (like me) was still very happily using the OEM Toyota air filter.

If you want to actually see measurable improvements in towing performance, there are exactly 3 things you should do:
1. Install JBA headers. JBAs are great for towing because they actually do increase torque below 3000 RPM. Expect around a 7% jump in torque.
2. Install a Gibson muffler. Gibsons (unlike all the other performance mufflers) are specifically designed to improve low end towing torque, yet remain very quiet. For best results, buy only the muffler (their largest one) and have it welded into your stock tailpipe.
3. Have the axle(s) regeared with 4.30 gears. The stock 3.92 gearing is not "low" enough for towing, especially with the rather heavy double cab.

Regearing to 4.30 axles (in combination with JBA headers and Gibson muffler) has given my truck almost turbo-diesel like towing capability. Just be aware these are expensive mods (headers will be around $1200 installed, the muffler around $200 installed (but not worth doing if you don't have headers), and the axle regearing with 4.30 gears is around $1200 per axle).

[bugmenot]

Originally Posted by RockyMtnRay

A K&N intake is about the worst thing you could do for towing performance. I do a lot of "extreme" mountain towing where I can use all the power I can get and I wouldn't touch a K&N with a 10 foot pole.

K&N's own published torque curve...which has been verified by several very reputable TS.COM members....shows a loss, yes LOSS, of torque below about 3000 RPM. For a good towing experience, you want to boost...not lose...torque below 3000 RPM because it's the low end torque that gets you moving and allows the truck to avoid downshifts from 3rd (4th on the '05s) at highway speeds. Furthermore, because K&N intakes are designed to make lots of noise at high throttle openings (for the more-noise-has-to-mean-more-power crowd), the in-cab noise level would be very fatiguing over time. Finally, unless you are very sparing in re-oiling the filter, the oil is sucked off the filter and coats/gunks up the thin wires in the Mass Air Flow sensor, thereby making it less sensitive and causing the engine to run too lean for safety. And if you are too-sparing, the filter won't remove enough dust from the incoming air and that gets into your engine's internals.

If you only replace the stock air filter with the so-called "free flowing" K&N filter, you won't have the big torque loss of the K&N intake but you won't have any torque gain either. The problem is the K&N filter has less than half the surface area of the stock filter (because of the deep pleats in the stock filter) so the stock filter actually flows better than the K&N drop in filter. One TS member did back-to-back tests (dyno I think) with a K&N drop in and the stock filter and got better performance from the stock filter. The K&N filter also has the same nasty problem of gunking the MAF sensor wires as their intake.

If you feel you absolutely must do something to your intake...then try using a True Flow Oiled Foam Filter...at least a TrueFlow flows as well as (and filters as well as) the stock filter and doesn't screw up your MAF. Some people think the TrueFlow works better than the stock but I've not yet been convinced of this...nor has TS member KLS (our other towing guru)...last I knew he (like me) was still very happily using the OEM Toyota air filter.

If you want to actually see measurable improvements in towing performance, there are exactly 3 things you should do:
1. Install JBA headers. JBAs are great for towing because they actually do increase torque below 3000 RPM. Expect around a 7% jump in torque.
2. Install a Gibson muffler. Gibsons (unlike all the other performance mufflers) are specifically designed to improve low end towing torque, yet remain very quiet. For best results, buy only the muffler (their largest one) and have it welded into your stock tailpipe.
3. Have the axle(s) regeared with 4.30 gears. The stock 3.92 gearing is not "low" enough for towing, especially with the rather heavy double cab.

Regearing to 4.30 axles (in combination with JBA headers and Gibson muffler) has given my truck almost turbo-diesel like towing capability. Just be aware these are expensive mods (headers will be around $1200 installed, the muffler around $200 installed (but not worth doing if you don't have headers), and the axle regearing with 4.30 gears is around $1200 per axle).

That's for the posts - good info. I dont' think i'll bother doing anything. I'm sure I can find something more rewarding to spend my money on As a side note - I though the gear ration on the Tundra was 4.1. But now that i'm looking looking it does seem to be 3.9

http://vibratesoftware.com/html_help...ota_Tundra.htm

[RockyMtnRay]

Originally Posted by bugmenot

That's for the posts - good info. I dont' think i'll bother doing anything. I'm sure I can find something more rewarding to spend my money on

Excellent idea! As Victor (mustang67408....a Toyota master tech) notes above, Toyota already has grabbed all the "low hanging" performance fruit. So it's going to be mighty hard and very expensive to get measurable performance improvements. Furthermore, most of the so-called performance improvements on the market are aimed (as Victor also notes) at improving top end horsepower. Horsepower is great for bragging rights but doesn't do much if anything for towing capability...what improves towing is low to mid range torque and the majority of the mods that increase horsepower also hurt mid range torque. Sooooo, if you don't know exactly what you're doing and aren't willing to spend some serious bucks for proper mods, you're a whole lot better off just leaving the drivetrain alone.

As a side note - I though the gear ration on the Tundra was 4.1. But now that i'm looking looking it does seem to be 3.9

Gear ratio on the '04 Double Cab was 4.10 but Toyota reduced that to 3.92 for the '05 models due largely to (1) the lower (higher numerically) 1st gear ratio in the tranny, (2) more closely spaced transmission ratios (5 spd vs 4 spd) and (3) better top end torque in the engine because of the variable valve timing and dual runner intake.

[wktjr]

Ray,
Excellent write-up! I was thinking about a K&N but will pass after reading your post.