Gutted Header & Front Pipe - Dyno Inside

[Grady]

Originally Posted by Somerandom18

Wonder how the 2017 revised manifold will do if gutted.

Sent from my Pixel XL using Tapatalk

I will let you know. I just did this tonight on my Yellow. Was planing on gettin some dyno numbers after Delicious tuning is done setting up my E85 tune.

[gtengr]

Originally Posted by guybo

I just found this article. Interesting read on gutting the cats.

http://www.circuitmotorsports-blog.c...-fr-s-86s.html



Yes, in this series, they only allow you to gut the cats, not use an aftermarket header. You can have an aftermarket catback.

I wonder if that's loose wording and they actually replace the pipe with a test pipe. The rules allow for test pipes, and if they're racing it seems they'd be going after every last hp.

[guybo]

Read the article, they are pretty clear that they are not allowed to use an aftermarket header. Gutted OEM header, OP and FP with an aftermarket catback

Surprisingly, even with the factory header and overpipe/front-pipe in place, the absence of the main cat made a big difference in flow.

[gtengr]

Originally Posted by guybo

Read the article, they are pretty clear that they are not allowed to use an aftermarket header. Gutted OEM header, OP and FP with an aftermarket catback

I read it and the SCCA T4 rules. They are allowed to weld in a pipe where the cat is/was, so why wouldn't they?

[guybo]

Because they made 201 WHP by gutting alone. This is the first real evidence of what gutting and a tune can do that I have seen.

[Icecreamtruk]

Dont get hung up on the numbers guys. This is a dyno that is more generous than jesus himself. Quoting the article:

Most stock header cars we tune with an intake and exhaust are around 185-190whp

So really, the only thing gutting the header gave them was somewhere along 10-15whp. Which is what most "low end" headers give around here and what everyone else has been saying for a while. If anything, this just confirms what has been said for a while here. If you expect to get the same 200whp that a long tube headers will give you (Ace, Nameless, PML, Cosworth), you are in for a surprise.

[re-animator]

Originally Posted by bfrank1972

Yup looks kinda that way, although there are aftermarket catted headers out there that produce great results as well if you want to retain your primary cat.

I think the other reason to go aftermarket would be if you went with a supercharger or turbo system that doesn't replace your manifold - as you dramatically increase your hp via FI, you'd probably see a difference between a stock header with no cat and any aftermarket option.

But if you don't care about emissions, and want a cheap power upgrade (with a tune of course), this looks like a really viable option.

Originally Posted by Andyxin

is it possible to weld a high flow cat on stock header?

Originally Posted by churchx

Yes, but why? Unlike with just gutting it you'll get smaller performance gains, and added costs of buying cat and paying for welding work will nullify cheapness bit. And even if primary cat in header is HF one, you won't be 100% safe from seeing cat readiness CELs. If you are ok with doing something to stock cats, aftermarket header with HF cat or even catless aftermarket header will be better choice (one stock secondary cat should be sufficient to pass smog tests, if those don't include visual checks).

I'll weigh in as i am sort of in the same boat. I'm thinking about adding a header along with a tune to push whp and wtq a little bit. Thoughts:

- CEL is a given regardless of what direction you go, for most people this doesn't matter because your tune will cancel the CEL from suboptimal/nonexistent cats

- high flow cats vs. catless is a BIG difference in day to day livability and a small difference in horsepower. Between the greatly increased sound (which IMO gets very raspy and harsh as well) catless headers are also going to give you that nasty catless exhaust smell, especially so if you are gutting the front pipe as well and going fully catless. High flow cats greatly reduce the smell and take the edge off the noise without changing the basic exhaust character, which is nice if you already have a catback sound that you like. the difference in horses in an aftermarket high flow catted header vs a catless header of the same design is negligible. you're talking maybe 2-3 whp. makes sense for a dedicated track day car, but maybe not for a DD for most of us

- to my knowledge it isn't really feasible to add a high flow cat to the existing header, or replace the existing cat with a high flow. First, its going to cost money for the cat and the welding if you don't DIY (money comparable to a full aftermarket manifold). Second, going with a cat that was not designed for the specific header configuration is kind of dicey. It could end up more turbulent or effectively more restrictive than the stock design

- since no header is going to pass emissions, it is better in my opinion to hold on to the OEM header so that the car can be brought back to stock spec every 2 years for emissions testing. can't do this if you modify the original header

[chaoskaze]

Originally Posted by guybo

Because they made 201 WHP by gutting alone. This is the first real evidence of what gutting and a tune can do that I have seen.

Damn it...... what a lucky guy with his unicorn frs....

We all know some car simply makes more hp then others....

[gtengr]

Originally Posted by guybo

Because they made 201 WHP by gutting alone. This is the first real evidence of what gutting and a tune can do that I have seen.

It's nice that they made 201 whp, but they should be after every last hp that is available within the rules since they are racing. I'm not aware of any headers available for any car that incorporate a hollow expansion chamber near the header collector because it makes more power. That is why I question whether it's actually a gutted cat or a test pipe. I'm aware it's a small detail, but to me the numbers make more sense with a test pipe, and since they're in a racing series it makes more sense that they would have a test pipe since that is allowed and it's cheap to do.

[guybo]

none of you read the article. They don't tune for max power and the article covers that. It also talks about comparisons to other high end headers.

RTFA

[-Willis-86touge]

I'm running e85 and was thinking of doing this. The oft tune for el e85 should work with no problem, but I'm just curious if the second o2 needs to be disabled or if it's already in the tune

[gtengr]

Originally Posted by guybo

none of you read the article. They don't tune for max power and the article covers that. It also talks about comparisons to other high end headers.

RTFA

Again, I've read the article. They don't tune the ecu for max power for durability reasons. That has nothing to do with the header. Try to think critically for a minute.

[ApexEight]

Originally Posted by Joe-G

I used a Hero 3 to try and record the sound just now... It doesn't sound as good as it does in person...

Custom muffler delete, and both cats are gutted.

Video shows cold start, idle, minor blips, and banging off 4k launch control.

Thread bump.

I plan on running this same setup with my muffler delete. Got a Tactrix cable now. Sounds good! How loud is the exhaust in person? Does it drone like hell on the highway? I find that the drone is easily manageable on my car with just the muffler delete, but deleting both cats changes things.

[Lantanafrs2]

Notwithstanding competition rules and so forth, why would you go through the bullshit of ruining a stock header when you can buy a used aftermarket one and get better performance?