ManyMods

I want to know, before I decide to do anything, what the HP gain is with the TRD Headers. I don’t want hearsay or a regurgitation of TRD claims; I want actual facts.

So-o-o, has anyone Dyno’d there 5VZ-FEV6 engine with the OE headers and then with the TRD headers … _without_changing_any_other_characteristics?_

Dr. Zhivago

Hey Peter,

I'm guessing the answer is going to be "No".

However, with the head design of these engines, headers are going make big difference over the stock manifolds. You can tell by looking at the manifolds how much they choke off this engine.

I'm going to get headers at some point. Maybe later this year. I haven't decided which brand to go with yet. Thorley is working on some for the 4Runner, NWOR is too and JBA just came out with a design for the Tacos with the 3.4L. I spoke with JBA and asked if they would fit on a 4Runner and they said they had not tested them yet.

There is a local JBA dealer here. In fact, it is George, the guy who made my ISR pipe. I'm going to talk to him about the JBA headers sometime in the near future...

I'll post what I find out.

Peace!
Dr. Z

ManyMods

G -
You're covering my side bet.

I wonder if Stan in WA would consider making headers for us if the OE manifolds are that restrictive. I've had enough of ill-fitting headers. I hear that the TRD headers are a very good fit, although I don't understand the talk about a bracket that has to be altered and welded. :confused:

I want a really good fitting, good quality header ... isn't that unusual?

What I am going to do is hook them up with my OE exhaust and I think the results should be very satisfying, but I want to see some numbers. There's a Dyno in Worcester MA and I may try to get over there so that I can establish a baseline.

PLEASE ... LMK what you learn in your research. TIA

Dr. Zhivago

Hey,

I spoke with Stan also. I should have mentioned that. Anyway, he said "No" to making headers for our trucks. He said that other people are making them already, so he's not going to bother.

The JBA's look really sweet. Here's their website. The price for them is roughly the same as the TRD's. They even offer them with Ceramic Coating as an option.

Dr. Z

EDIT: I don't know what you are referring to when you say a bracket has to be welded. But the Downpipe and Cat are one piece on our trucks, so you have to cut off the DP and weld on a flange to the Cat. I thought maybe that's what you were talking about...

ManyMods

[QUOTE]Originally posted by Dr. Zhivago
The JBA's look really sweet. Here's their website. The price for them is roughly the same as the TRD's. They even offer them with Ceramic Coating as an option. [QUOTE]

I like to check out the headers before I have them coated and enhance the dimples for the manifold bolts so that I am sure not to have any clearance issues when I start wrenching them.

I didn't know what I was referring to either :confused: , but now that you are explaining it to me I think I understand. Who supplies the necessary flange? It sounds like this makes it more costly to reverse the process if you have to start cobbling up the cat.

What I want to see is a picture of the actual header made for the 4R. The JBA header looked okay but I will have to spend more time on the site; it's really hard to tell from the initial picture. Has anyone installed them with success?

I still want Dyno stats.

Dr. Zhivago

The flange is supplied by whomever supplies the header/x-over set up. You can just buy headers from Downey without buying their x-over pipe and have oone custom designed. They are the only company at this writing who has a setup like that. Their x-over is underneath the engine, while the TRD's is over the top and integral to the header itself.

From Gadget's site, here is a pic of the TRD Headers for the 4Runner:



and another one:



Here's a shot of the Edelbrock's which won't fit on your truck without modifications:



As you can see, the Edelbrock's x-over is underneath the engine.

You know, on your 2002 truck, you're going to have 2 Cats instead of one. You still have to modify the front Cat and weld a flange onto it. The Taco's have a separate Cat and Downpipe. I don't know why and neither does any Toyota tech that I've talked to...

Here's a pic of the underside of a Dual Cat equipped 4Runner:



Here's a page of some TRD Headers installed on a 99 single Cat 4Runner. Scroll down to see the pics.

I don't know of anyone who's installed the JBA's yet as it is a brand-new product for them. They make excellent systems for other vehicles, so I would expect their header for the Toyota trucks to be of similar quality and design. Unless someone beats me to the punch, and if they'll fit, I may be the first one to install them in a 4Runner later this year.

I'm outy!
Dr. Z

ManyMods

Thanks for the info.
I am wondering if one couldn't eliminate the second cat on the '01 - '02 and use a test pipe in areas where no visual inspections are done, or use a Random Tech cat. I hate like hell to butcher an expensive part like the OE cat. I know a legal reseller of cats so I may check with him when the time comes and see if he has a late model donor. Matter fact, I think I will contact him now and alert him to my need. I am guessing that a new cat is about $400 and I can probably get a used one for half.

JBA, doesn't list a header for any 4R from '99 to '02. I like the TRD stainless header but if it is going to be ceramic coated I guess mild steel would be all right. I just wish JBA's prices weren't so high.

Is JBA making their header with the crossover pipe on top or on the bottom? I would think the latter configuration would be better?

I think you and I have covered everything now despite teh faact that I didn't get any of the performance info I was hoping for. If TRD says they estimate the HP increase at 23hp, that sounds about right don't you think? I still want to establish a base line.

Please let me know when JBA has released info and product on their 4R headers.

Thank you again for all the pictures and info, it really helped me understand what's involved much better.

ravencr

Would this be correct in saying that the HP & Torque gain would be different between being supercharged and not being supercharged? I'd like to hope that on a S/C 4Runner the headers in combination with a high flow cat and muffler, it should bring more than 50 hp on a S/C 4Runner, right?

Chris

ManyMods

I cannot defend my answer in fact but I will say NO, unless you are talking about the cumulatiive HP number.

ManyMods

I just spoke with Dennis at JBA (800-830-3377) and he reiterated the information that Dr.Z received and said they did not have enough interest in headers for the 4Runner to do anything about it.

He said they do produce headers for the '95 - '02 PreRunner 3.4 V6 but did not know if the headers would fit the 4R? The only way they would find out is if they physically got a truck into the shop and tried to put them on. Also, he said that when they produce headers they follow the factory configuration and bolt right up to the factory exhaust flanges w/o any cutting or welding. I think someone should offer to got over to their shop and let them take a look.

I asked him about HP ratings and he said that with trucks they go more for torque. He would have to go look up that information if I wanted it. Since I didn't know if the headers would cross over to the 4Runner I didn't bother with that information.

So, the big mystery is … are the two header designs the same: PreRunner vs 4Runner?
:confused:

pfdaxe

I would think they would be different and not match only because every other maker has diff part numbers for the Runners and Tacos. They even have diff part numbers for 4 wheel and 2 wheel drives.

Dr. Zhivago

The guy I spoke with at JBA said their headers made about 20HP on a NA engine. Since the Cat on the 4Runners is attached to the downpipe, nobody makes headers that don't involve modifying the Cat. Even if JBA's headers fit on the 4Runner's, you'll still have to whack the DP off the CAT.

If I lived near them I'd gladly be a guinea pig.

Dr. Z