Just wondering what you guys found works best for a custom exhaust.
Ideal exhaust diameter on a stock 80
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You're probably thinking about a gas engine, but for what it's worth I've had phenomenal results going to a 3" exhaust on my 1HD-T HDJ81.
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Yea I'm thinking about the gas engine. Is 2.5 too small or just right?
I like the 2 1/2 inch on mine, but I have the good old 3f-e!
I have heard that anything more than 2.5 on stock is wasted and that 2.0 is ideal. JFWIW. 
Go as big as you can, anything smaller than 2.5" is restricting you. Anything over 3" is usually more expensive than it is worth.
Not accurate actually; you need some backpressure. Anything over 2.5 on a stock 1FZFE is not necessarily helpful.
\Not accurate actually; you need some backpressure. Anything over 2.5 on a stock 1FZFE is not necessarily helpful.
I agree with this. Pipe isn't restriction on an 80. On the inline cats (OBDII) it's the cats, on the dual parallel (OBD I) trucks it's the center muffler. On a stock truck, I'd run a high flow center and rear can and leave the exhaust size alone. On manual shift cars, increasing the pipe size can increase HP, usually at the expense of torque. On autobox cars, increasing pipe size just makes great sounds and rarely adds enough ponies to measure.
2.5 is more than enough.
Scott Justusson
I'm still going with the headers/manifolds being the point of backpressure on a LC atleast, and that anything past that is just directing the exhaust where you want it.
So yer sayin the cat/s make no matter?
In my opinion, no...but others disagree. I'm running gutted cats and a glass pack, 2.5 cats back, feels like it has more torque (starts off better espically when towing) and raw horses (freeway speeds hold easier). Could be just my 3FE, but I dont see why it wouldnt be better on any other engine with propper headers/manifolds that maintain the backpressure.
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I usually use 2.5 on v8's, unless there is a SC or turbo installed...
On an engine this size, [straight six like in my LX450] I would go 2.25....
2.5 would be the largest I would go with...2.25 is a more common dia. used and would work fine , IMHO.......
You could use a 1in/2out muff , using a 3" in and two 2.25's out, this is a common practice....or even a 2.5 in and two 2.25's out..this wouldn't be too bad on the pocket book either...for most shops 2.25 pipe is alot cheaper then 2.5" pipe...and of course if you go 3", it will be alot more money.....IMHO
On an engine this size, [straight six like in my LX450] I would go 2.25....
2.5 would be the largest I would go with...2.25 is a more common dia. used and would work fine , IMHO.......
You could use a 1in/2out muff , using a 3" in and two 2.25's out, this is a common practice....or even a 2.5 in and two 2.25's out..this wouldn't be too bad on the pocket book either...for most shops 2.25 pipe is alot cheaper then 2.5" pipe...and of course if you go 3", it will be alot more money.....IMHO
going off on a tangent here, but i was watching one of those TV shows on Spike TV the other morning and they were using Bank's equipment to get more horsepower from a ford F150. What got me thinking is that with all the R&D that goes into a new vehicle, one would think that they would not put restrictive intake and exhaust equipment on a vehicle. Especially with gas prices where they are and folks wanted to squeeze as much mileage out of a gallon of gas as they can. It just baffles me that you can take the OEM stuff on a new vehicle, toss it in the trash, bolt on someone else's product and get 25-30 horsepower and better gas mileage.
I just think it's really strange that OEM would not be THE BEST.
I just think it's really strange that OEM would not be THE BEST.
With our trucks I think it's more about available technology at the time of design. Sorry for the plug, but the MAF I designed uses much newer technology which is how it achieves it's better performance. The newer sensor not only has a better overall sensing range but uses a smaller sample to measure the air flow. You can readily see that when looking through the housing. The housing with the newer sensor is less restrictive and allows more air to move more freely through it.
I don't know this but I'd suspect catalytic converter designs over the years has also become more efficient and freer flowing.
If there are freer flowing converters out there I'd guess an increase of 35+hp when paired with my MAF.
When talking about engines, it's always compared to a pump. Restrictions on either ends of that pump has a detrimental effect on it's output. The MAF and the converter are the two restrictions at those ends.
I'm not an expert on catalytic converters, but it is my understanding that we have two in-line on the fZJ because each is a two-way type and combined they cover the three emmissions reductions that are required. You could replace both in-line cats with a single newer three-way type and still meet the emissions requirements.
Toyota OEM catalytics are typically fairly restrictive. Replacing them with a single free flow that is also a three-way would likely change the sound and free up the flow a little. Going with larger piping on a normally aspirated motor is not likely to do much more than drain the pocket book. You might gain a little in the mid and upper rpm, but that was not Toyota's target with this motor.
35 ponies is a lot Rick. IME, I rarely see that much volumetric efficiency gains in pre and post engine add ons in normally aspirated motors. In fact, if you look at a lot of the cold air high flow stuff, it's usually a lot less hp, even bolting on a good exhaust. Before and after measures of vacuum between the MAF might show that the improvement is a lot less, but certainly calculatable. In the pre OBDII trucks the twin parallel cats have less restriction than most single 3in cats. But a single 3 in hi flow cat should have less restriction on the 'in series cats' of the OBDII trucks.
I won't hold you to 35hp, but sure would like to compare that with some sort of actual measure or calculation. If I plug .5psi boost into the spreadsheet for the 1FEFZ (VE factors correlated to TRD SC dyno #), I get a gain of ~11hp crank. So without 'pressure' in the intake won't increase the HP much.
Scott Justusson
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I cut off the restrictor (after it was crumpled) and my stock muffler was trashed. So I am running a magnaflow with 3" pipe into a glass pack with 3" pipe out.
The Glass pack is to quite it down a bit. Been thinking about replacing those cats, but they haven't failed yet.
The Glass pack is to quite it down a bit. Been thinking about replacing those cats, but they haven't failed yet.
