gearing,and exhaust

[HITUNDRA]

i have a 2001 tundra sr5 trd and was wondering how i can determine the stock gear ratios or if anyone knew them.After adding 38 inch tires my truck has the pick up of a geo metro i need to get my truck regeared,I also need to find a place to do it in the southern part of new jersey or nearby. Also any comments on aftermarket dual exhaust would be appreciated: what make,adds most horsepower,best quality,apearence etc.
thanks alot

[v8Toilet]

Stock axle ratio is 3.91. Those bigger tires also added more reciprocating weight, which seriously hurts acceleration too. Power adders would be TRD, DOWNEY, or JBA headers. There are also numerous exhaust systems you can get and a TRD supercharger coming out soon.

TRD makes the best headers but Downey is a close second in my opinion. Besides the supercharger headers seem to make the biggest difference.

[KLS]

I haven't heard anyone say that an aftermarket exhaust adds any hp. It sure sounds stronger....

With the big tires, you need the power at low rpms. Even if dual exhaust helped, it'd probably be at high rpms. You really need lower gears in your differentials.

I'm looking into headers:
JBA's dyno chart looks too good to be true. I'm not sure I trust it. The header's runners don't look to be anywhere near equal length, the collector cone is really short, and the four tubes seem to have a flat filler plate filling the gap between the tubes where they enter the collector. None of these contribute to good performance.

Downey says that they haven't dyno tested their headers. If that's right, how did they develop the best pattern? If they did dyno test and didn't like the results, would they tell us? Downey's headers are 1-5/8" tubing; wouldn't 1-1/2" be better for low rpm performance?

I need to talk to TRD. They don't even put a picture of their headers on their web page. Does anyone out there have a description of the TRD headers?

Do any of the available headers really improve low rpm performance?
Ken

[HITUNDRA]

so the front and the rear gear ratios are 3:91s

[TSJ]

I have been into racing 5 liter ford v8's for quite some time now and I can say that several tests have been done on the primary tube size for this displacement (302") and it has been proven time and time again that 1 1/2" primaries are better for both torque and hp production until you either pass the 300hp at the tire mark (330-350 crank) or add a supercharger or turbo for forced induction in which case 1 5/8" are better. The best possible situation would be to add a set of long tube headers for torque production but I don't believe that any are made for this application. Then equal length short tube headers and then unequal lenght. 1 5/8" shorty headers are just too much for the displacement and power output of the motors. JMO
The difference in equal and unequal length shorty headers on a 5 liter motor making approx 300 hp at the crank would 2-3 hp peak. More importantly would be the inlet of the header matching exactly to the head and for there to be no turbulance created. When installing the headers also check that the collector doesn't have excess length and cone down into the mid pipe too far as this is another area for turbulance. I have seen many hrs. spent on "porting headers" for the best possible fit.
Sorry for the long winded reply.

[KLS]

Originally posted by TSJ
I have been into racing 5 liter ford v8's for quite some time now and I can say that several tests have been done on the primary tube size for this displacement (302") and it has been proven time and time again that 1 1/2" primaries are better for both torque and hp production until you either pass the 300hp at the tire mark (330-350 crank) or add a supercharger or turbo for forced induction in which case 1 5/8" are better. The best possible situation would be to add a set of long tube headers for torque production but I don't believe that any are made for this application.
........

I'm hunting for header makers who would make equal length long tube headers for Tundra V8s, and hunting for TS folks to contact those header makers and show possible interest in buying properly designed headers.

I've been thinking of 1-1/2" tubes about 34-36" long into a 2 or 2-1/4" collector.

I've already made preliminary contact with S&S Headers. Do you have any suggestions on who else makes good equal length long tube headers at a reasonable price? Check my previous link: A potential new header maker

Ken

[y2ktruc]

HITUNDRA.........Please post a picture of your Truck with the 38"s on it .
Thx

[TSJ]

KLS,
There are a few custom header manufacturers however I don't know of any of them that would like to add this to there line. Kooks headers are who I use on my car and they are stepped long tubes and really helped out the low to midrange on my car. Let me know if you get a company to take a look at this and what the initial "buy in" would be. I might be interested in a set if the specs look right.
Todd

[KLS]

Todd,

S&S is showing interest. They say that they need an initial order of 20 headers. They're looking at a Tundra in order to estimate the price and performance gains. They want a TS member in their Arizona area to leave his truck with them for a week so they can prototype a header. That member will get a discount if they buy. I think S&S supplies headers to LC Engineering, among others, as well as selling under their own name.

Contact them. Let them know that you're interested.
http://www.ssheaders.com/header.htm
email: techtalk@ssheaders.com

Ken

[TSJ]

I will email them and once the get something jig'd up I will take a close look. Thanks KLS for the effort to find something nice.
Todd