Discussion in 'Exhaust' started by magimerlin, Mar 3, 2016.
Did the Holley rep ever get back with you ?
When I upgraded my stock engine years ago, I found that headers made no difference imo, maybe a tiny bit different sound, but no performance gain whatsoever. If they are cracked, I'd probably also go for headers too, but unless you get long tube headers with a full custom exhaust, there is no difference. If looking for performance gains, I can say personally that my favorite and best upgrade was the throttle body spacer, I noticed a difference in low end torque the day I installed it.
X2 on the tb spacer, i put one on my truck and it became a bat outta hell for low end, then again mines a 400 not a 350 or 305
I actually had a 4.3, and there was a hill I used to drive up on my way home from work. I could never get up it in 5th gear @ 55mph, I'd have to shift down to 4th. The day after I put the spacer in, I was able to hold 55 the whole way up in 5th. Quite honestly one of the very few times i've ever done a small upgrade and felt a difference.
A throttle body spacer will do nothing on a Vortec. I put one on my 97 5.7 L , and it slowed the truck down. It is sitting in my desk in my shop. On a TBI yes, but not on a Vortec. As for shortys, I have them on my truck, and I saw an good improvement in low end power. That may not matter on a TBI as the heads are different, and do not flow as much air as Vortec heads do.
Mine was a 94, so kind of the in between year, had vortec heads, but had TBI.
You know, there are a lot of header options out there. If you get a set that doesn't fit the heads properly they won't flow like they should. I have seen headers with round hole flanges. A Vortec head has square hole exhaust ports. If you were to put a round hole over this square port, it would restrict flow. After all, an engine is a big air compressor. The more air and fuel you can put into it, and the more that can flow out of it, the more power it will make. Most likely why you saw a good gain in power with the spacer. In the TBI there would be more room for air and fuel. In my CPI, the spacer only moved the throttle body. The fuel goes into the head on mine, not in the intake like a TBI, so it didn't add more fuel to the system. All it did was to put something else in the way of air flow.
I checked out you media, The 91 you had is almost exactly like the 93 I had. Mine was a 4.3
Nothing! I've called them again but couldn't give me an answer. Said they'd have a representative contact me.
So much for customer "service"
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