HP Gains From Getting Rid of Cats on N/A Motor?

[Baltimorejohn1]

Interesting

[VR Baron]

Yeah love hp speculations and if cars and dynos reacted all the same to a given part it sure would be easier to know for sure what all these parts made hp wise.
I just did JBA shortys, the hiflow cats and a tune and got 32hp on a 85 degree day that is back to back repeatable even after a brief cooldown.A freind got about the same with the same setup and another freind did 5 better with a auto car. On mine 12 was from the tune and 20 from the shortys and hiflows.How much from each combined I dont know but from what most see, and JDP said the same, is probably 10-12 with the hiflows and 8-10 with the shortys? The shorty's being helped with the better cats. Now by themselves I would think the hiflows could be 15-20 as people have seen, the shortys 0-5

[Birm]

Our stock manifolds flow about as efficiently as the "Shorty" headers, the only real gain from them is appearance for the most part.

Nice #s

[litle88]

^^yes

[Learjetguru]

i think Jannetty did some dyno run with and without. If memory serves me it like 1 or 2 hp.

[grocerygetter]

nope...get a shop to get on the level with you and they will tell you that you can get half the hp as a set of longtubes with a set of cat deletes (not high flows, I said deletes)...N/A. Now, make this motor a forced induction (blower) application and you can get almost the same hp...you leave maybe 10whp on the table with a set of longtubes on just a supercharged car. Forced induction likes to have something to push against to put it in simple terms. You are trying to build positive pressure.
NOW...2 disclaimers to my above comments.
1. you add a cam or cam/heads, you totally could see gains on a 2" primary header.
2. Pfadt's new tri-Y is yet to be tested on a forced induction application. I'm curious on these. Even if they made the same horsepower as a set of cat deletes, they may gain substantial torque down low...don't know yet. I've pm'd them. Trust me.

[litle88]

Originally Posted by grocerygetter

nope...get a shop to get on the level with you and they will tell you that you can get half the hp as a set of longtubes with a set of cat deletes (not high flows, I said deletes)...N/A. Now, make this motor a forced induction (blower) application and you can get almost the same hp...you leave maybe 10whp on the table with a set of longtubes on just a supercharged car. Forced induction likes to have something to push against to put it in simple terms. You are trying to build positive pressure.
NOW...2 disclaimers to my above comments.
1. you add a cam or cam/heads, you totally could see gains on a 2" primary header.
2. Pfadt's new tri-Y is yet to be tested on a forced induction application. I'm curious on these. Even if they made the same horsepower as a set of cat deletes, they may gain substantial torque down low...don't know yet. I've pm'd them. Trust me.

I'm going to somewhat disagree. FI responds very well to long tubes and allows you to add a Lil more boost. But that's not the topic here. The op is NA and deleting the cats will give you 10-15 hp.

[Birm]

^^this

[Bell040]

Originally Posted by Learjetguru

i think Jannetty did some dyno run with and without. If memory serves me it like 1 or 2 hp.

Jannetty Racing did a test using HF cats vs. no cats during the header primary size tests. They did not try stock cats vs no cats. The only way to even do that test would be with stock manifolds or shorty headers.

A big reason that you pick up 30 - 35 HP with LT headers is the deletion of the stock cats.

[VR Baron]

Originally Posted by Learjetguru

i think Jannetty did some dyno run with and without. If memory serves me it like 1 or 2 hp.

Added Edelbrock shorties on my 98 and got maybe 5.Those and the cat back made it run lean. Richened it up, took out some timing and got 10 total, so yeah probably most from the tune

[VR Baron]

Originally Posted by Birm

Our stock manifolds flow about as efficiently as the "Shorty" headers, the only real gain from them is appearance for the most part.

Nice #s

Yeah and thanks! I think shorties, like mufflers from the few dynos I've even seen dont get much peak hp but you do get and notice more tq down low and in the mid range. Probably want folks say they "feel"

[grocerygetter]

yup...little88 hit it...10-15=half of long tubes gain (not counting tunes here). on the money IMO. $250 JBA cat deletes vs $1k on some headers. OP....you just need to look at your goals with the car on down the road. If you plan to put a cam in it, do headers now.